diff --git a/compiler/rustc_errors/src/emitter.rs b/compiler/rustc_errors/src/emitter.rs
index 6552cf224eaa8..a386129e8145e 100644
--- a/compiler/rustc_errors/src/emitter.rs
+++ b/compiler/rustc_errors/src/emitter.rs
@@ -22,7 +22,7 @@ use rustc_error_messages::{FluentArgs, SpanLabel};
 use rustc_lint_defs::pluralize;
 use rustc_span::hygiene::{ExpnKind, MacroKind};
 use rustc_span::source_map::SourceMap;
-use rustc_span::{FileLines, FileName, SourceFile, Span, char_width};
+use rustc_span::{FileLines, FileName, SourceFile, Span, char_width, str_width};
 use termcolor::{Buffer, BufferWriter, Color, ColorChoice, ColorSpec, StandardStream, WriteColor};
 use tracing::{debug, instrument, trace, warn};
 
@@ -44,6 +44,7 @@ const DEFAULT_COLUMN_WIDTH: usize = 140;
 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
 pub enum HumanReadableErrorType {
     Default,
+    Unicode,
     AnnotateSnippet,
     Short,
 }
@@ -112,8 +113,12 @@ impl Margin {
     fn was_cut_right(&self, line_len: usize) -> bool {
         let right =
             if self.computed_right == self.span_right || self.computed_right == self.label_right {
+                // FIXME: This comment refers to the only callsite of this method.
+                //        Rephrase it or refactor it, so it can stand on its own.
                 // Account for the "..." padding given above. Otherwise we end up with code lines
                 // that do fit but end in "..." as if they were trimmed.
+                // FIXME: Don't hard-code this offset. Is this meant to represent
+                //        `2 * str_width(self.margin())`?
                 self.computed_right - 6
             } else {
                 self.computed_right
@@ -595,6 +600,12 @@ impl ColorConfig {
     }
 }
 
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum OutputTheme {
+    Ascii,
+    Unicode,
+}
+
 /// Handles the writing of `HumanReadableErrorType::Default` and `HumanReadableErrorType::Short`
 #[derive(Setters)]
 pub struct HumanEmitter {
@@ -613,6 +624,7 @@ pub struct HumanEmitter {
     macro_backtrace: bool,
     track_diagnostics: bool,
     terminal_url: TerminalUrl,
+    theme: OutputTheme,
 }
 
 #[derive(Debug)]
@@ -637,6 +649,7 @@ impl HumanEmitter {
             macro_backtrace: false,
             track_diagnostics: false,
             terminal_url: TerminalUrl::No,
+            theme: OutputTheme::Ascii,
         }
     }
 
@@ -664,6 +677,7 @@ impl HumanEmitter {
         // Create the source line we will highlight.
         let left = margin.left(line_len);
         let right = margin.right(line_len);
+        // FIXME: The following code looks fishy. See #132860.
         // On long lines, we strip the source line, accounting for unicode.
         let mut taken = 0;
         let code: String = source_string
@@ -680,17 +694,19 @@ impl HumanEmitter {
             })
             .collect();
         buffer.puts(line_offset, code_offset, &code, Style::Quotation);
+        let placeholder = self.margin();
         if margin.was_cut_left() {
             // We have stripped some code/whitespace from the beginning, make it clear.
-            buffer.puts(line_offset, code_offset, "...", Style::LineNumber);
+            buffer.puts(line_offset, code_offset, placeholder, Style::LineNumber);
         }
         if margin.was_cut_right(line_len) {
+            let padding = str_width(placeholder);
             // We have stripped some code after the rightmost span end, make it clear we did so.
-            buffer.puts(line_offset, code_offset + taken - 3, "...", Style::LineNumber);
+            buffer.puts(line_offset, code_offset + taken - padding, placeholder, Style::LineNumber);
         }
         buffer.puts(line_offset, 0, &self.maybe_anonymized(line_index), Style::LineNumber);
 
-        draw_col_separator_no_space(buffer, line_offset, width_offset - 2);
+        self.draw_col_separator_no_space(buffer, line_offset, width_offset - 2);
     }
 
     #[instrument(level = "trace", skip(self), ret)]
@@ -702,6 +718,7 @@ impl HumanEmitter {
         width_offset: usize,
         code_offset: usize,
         margin: Margin,
+        close_window: bool,
     ) -> Vec<(usize, Style)> {
         // Draw:
         //
@@ -732,6 +749,7 @@ impl HumanEmitter {
         // Left trim
         let left = margin.left(source_string.len());
 
+        // FIXME: This looks fishy. See #132860.
         // Account for unicode characters of width !=0 that were removed.
         let left = source_string.chars().take(left).map(|ch| char_width(ch)).sum();
 
@@ -767,13 +785,10 @@ impl HumanEmitter {
         for ann in &line.annotations {
             if let AnnotationType::MultilineStart(depth) = ann.annotation_type {
                 if source_string.chars().take(ann.start_col.display).all(|c| c.is_whitespace()) {
-                    let style = if ann.is_primary {
-                        Style::UnderlinePrimary
-                    } else {
-                        Style::UnderlineSecondary
-                    };
-                    annotations.push((depth, style));
-                    buffer_ops.push((line_offset, width_offset + depth - 1, '/', style));
+                    let uline = self.underline(ann.is_primary);
+                    let chr = uline.multiline_whole_line;
+                    annotations.push((depth, uline.style));
+                    buffer_ops.push((line_offset, width_offset + depth - 1, chr, uline.style));
                 } else {
                     short_start = false;
                     break;
@@ -970,7 +985,7 @@ impl HumanEmitter {
             // 3 │       X0 Y0 Z0
             //   │ ┏━━━━━┛  │  │     < We are writing these lines
             //   │ ┃┌───────┘  │     < by reverting the "depth" of
-            //   │ ┃│┌─────────┘     < their multilne spans.
+            //   │ ┃│┌─────────┘     < their multiline spans.
             // 4 │ ┃││   X1 Y1 Z1
             // 5 │ ┃││   X2 Y2 Z2
             //   │ ┃│└────╿──│──┘ `Z` label
@@ -997,7 +1012,10 @@ impl HumanEmitter {
         // 4 |   }
         //   |
         for pos in 0..=line_len {
-            draw_col_separator_no_space(buffer, line_offset + pos + 1, width_offset - 2);
+            self.draw_col_separator_no_space(buffer, line_offset + pos + 1, width_offset - 2);
+        }
+        if close_window {
+            self.draw_col_separator_end(buffer, line_offset + line_len + 1, width_offset - 2);
         }
 
         // Write the horizontal lines for multiline annotations
@@ -1013,21 +1031,17 @@ impl HumanEmitter {
         // 4 |   }
         //   |  _
         for &(pos, annotation) in &annotations_position {
-            let style = if annotation.is_primary {
-                Style::UnderlinePrimary
-            } else {
-                Style::UnderlineSecondary
-            };
+            let underline = self.underline(annotation.is_primary);
             let pos = pos + 1;
             match annotation.annotation_type {
                 AnnotationType::MultilineStart(depth) | AnnotationType::MultilineEnd(depth) => {
-                    draw_range(
+                    self.draw_range(
                         buffer,
-                        '_',
+                        underline.multiline_horizontal,
                         line_offset + pos,
                         width_offset + depth,
                         (code_offset + annotation.start_col.display).saturating_sub(left),
-                        style,
+                        underline.style,
                     );
                 }
                 _ if self.teach => {
@@ -1035,7 +1049,7 @@ impl HumanEmitter {
                         line_offset,
                         (code_offset + annotation.start_col.display).saturating_sub(left),
                         (code_offset + annotation.end_col.display).saturating_sub(left),
-                        style,
+                        underline.style,
                         annotation.is_primary,
                     );
                 }
@@ -1055,11 +1069,7 @@ impl HumanEmitter {
         // 4 | | }
         //   | |_
         for &(pos, annotation) in &annotations_position {
-            let style = if annotation.is_primary {
-                Style::UnderlinePrimary
-            } else {
-                Style::UnderlineSecondary
-            };
+            let underline = self.underline(annotation.is_primary);
             let pos = pos + 1;
 
             if pos > 1 && (annotation.has_label() || annotation.takes_space()) {
@@ -1067,21 +1077,64 @@ impl HumanEmitter {
                     buffer.putc(
                         p,
                         (code_offset + annotation.start_col.display).saturating_sub(left),
-                        '|',
-                        style,
+                        match annotation.annotation_type {
+                            AnnotationType::MultilineLine(_) => underline.multiline_vertical,
+                            _ => underline.vertical_text_line,
+                        },
+                        underline.style,
+                    );
+                }
+                if let AnnotationType::MultilineStart(_) = annotation.annotation_type {
+                    buffer.putc(
+                        line_offset + pos,
+                        (code_offset + annotation.start_col.display).saturating_sub(left),
+                        underline.bottom_right,
+                        underline.style,
+                    );
+                }
+                if let AnnotationType::MultilineEnd(_) = annotation.annotation_type
+                    && annotation.has_label()
+                {
+                    buffer.putc(
+                        line_offset + pos,
+                        (code_offset + annotation.start_col.display).saturating_sub(left),
+                        underline.multiline_bottom_right_with_text,
+                        underline.style,
                     );
                 }
             }
             match annotation.annotation_type {
                 AnnotationType::MultilineStart(depth) => {
+                    buffer.putc(
+                        line_offset + pos,
+                        width_offset + depth - 1,
+                        underline.top_left,
+                        underline.style,
+                    );
                     for p in line_offset + pos + 1..line_offset + line_len + 2 {
-                        buffer.putc(p, width_offset + depth - 1, '|', style);
+                        buffer.putc(
+                            p,
+                            width_offset + depth - 1,
+                            underline.multiline_vertical,
+                            underline.style,
+                        );
                     }
                 }
                 AnnotationType::MultilineEnd(depth) => {
-                    for p in line_offset..=line_offset + pos {
-                        buffer.putc(p, width_offset + depth - 1, '|', style);
+                    for p in line_offset..line_offset + pos {
+                        buffer.putc(
+                            p,
+                            width_offset + depth - 1,
+                            underline.multiline_vertical,
+                            underline.style,
+                        );
                     }
+                    buffer.putc(
+                        line_offset + pos,
+                        width_offset + depth - 1,
+                        underline.bottom_left,
+                        underline.style,
+                    );
                 }
                 _ => (),
             }
@@ -1102,7 +1155,11 @@ impl HumanEmitter {
             let style =
                 if annotation.is_primary { Style::LabelPrimary } else { Style::LabelSecondary };
             let (pos, col) = if pos == 0 {
-                (pos + 1, (annotation.end_col.display + 1).saturating_sub(left))
+                if annotation.end_col.display == 0 {
+                    (pos + 1, (annotation.end_col.display + 2).saturating_sub(left))
+                } else {
+                    (pos + 1, (annotation.end_col.display + 1).saturating_sub(left))
+                }
             } else {
                 (pos + 2, annotation.start_col.display.saturating_sub(left))
             };
@@ -1135,18 +1192,60 @@ impl HumanEmitter {
         // 3 |
         // 4 |   }
         //   |  _^  test
-        for &(_, annotation) in &annotations_position {
-            let (underline, style) = if annotation.is_primary {
-                ('^', Style::UnderlinePrimary)
-            } else {
-                ('-', Style::UnderlineSecondary)
-            };
+        for &(pos, annotation) in &annotations_position {
+            let uline = self.underline(annotation.is_primary);
             for p in annotation.start_col.display..annotation.end_col.display {
+                // The default span label underline.
                 buffer.putc(
                     line_offset + 1,
                     (code_offset + p).saturating_sub(left),
-                    underline,
-                    style,
+                    uline.underline,
+                    uline.style,
+                );
+            }
+
+            if pos == 0
+                && matches!(
+                    annotation.annotation_type,
+                    AnnotationType::MultilineStart(_) | AnnotationType::MultilineEnd(_)
+                )
+            {
+                // The beginning of a multiline span with its leftward moving line on the same line.
+                buffer.putc(
+                    line_offset + 1,
+                    (code_offset + annotation.start_col.display).saturating_sub(left),
+                    match annotation.annotation_type {
+                        AnnotationType::MultilineStart(_) => uline.top_right_flat,
+                        AnnotationType::MultilineEnd(_) => uline.multiline_end_same_line,
+                        _ => panic!("unexpected annotation type: {annotation:?}"),
+                    },
+                    uline.style,
+                );
+            } else if pos != 0
+                && matches!(
+                    annotation.annotation_type,
+                    AnnotationType::MultilineStart(_) | AnnotationType::MultilineEnd(_)
+                )
+            {
+                // The beginning of a multiline span with its leftward moving line on another line,
+                // so we start going down first.
+                buffer.putc(
+                    line_offset + 1,
+                    (code_offset + annotation.start_col.display).saturating_sub(left),
+                    match annotation.annotation_type {
+                        AnnotationType::MultilineStart(_) => uline.multiline_start_down,
+                        AnnotationType::MultilineEnd(_) => uline.multiline_end_up,
+                        _ => panic!("unexpected annotation type: {annotation:?}"),
+                    },
+                    uline.style,
+                );
+            } else if pos != 0 && annotation.has_label() {
+                // The beginning of a span label with an actual label, we'll point down.
+                buffer.putc(
+                    line_offset + 1,
+                    (code_offset + annotation.start_col.display).saturating_sub(left),
+                    uline.label_start,
+                    uline.style,
                 );
             }
         }
@@ -1217,7 +1316,7 @@ impl HumanEmitter {
         padding: usize,
         label: &str,
         override_style: Option<Style>,
-    ) {
+    ) -> usize {
         // The extra 5 ` ` is padding that's always needed to align to the `note: `:
         //
         //   error: message
@@ -1281,6 +1380,7 @@ impl HumanEmitter {
                 buffer.append(line_number, text, style_or_override(*style, override_style));
             }
         }
+        line_number
     }
 
     #[instrument(level = "trace", skip(self, args), ret)]
@@ -1294,6 +1394,7 @@ impl HumanEmitter {
         max_line_num_len: usize,
         is_secondary: bool,
         emitted_at: Option<&DiagLocation>,
+        is_cont: bool,
     ) -> io::Result<()> {
         let mut buffer = StyledBuffer::new();
 
@@ -1303,12 +1404,29 @@ impl HumanEmitter {
             for _ in 0..max_line_num_len {
                 buffer.prepend(0, " ", Style::NoStyle);
             }
-            draw_note_separator(&mut buffer, 0, max_line_num_len + 1);
+            self.draw_note_separator(&mut buffer, 0, max_line_num_len + 1, is_cont);
             if *level != Level::FailureNote {
                 buffer.append(0, level.to_str(), Style::MainHeaderMsg);
                 buffer.append(0, ": ", Style::NoStyle);
             }
-            self.msgs_to_buffer(&mut buffer, msgs, args, max_line_num_len, "note", None);
+            let printed_lines =
+                self.msgs_to_buffer(&mut buffer, msgs, args, max_line_num_len, "note", None);
+            if is_cont && matches!(self.theme, OutputTheme::Unicode) {
+                // There's another note after this one, associated to the subwindow above.
+                // We write additional vertical lines to join them:
+                //   ╭▸ test.rs:3:3
+                //   │
+                // 3 │   code
+                //   │   ━━━━
+                //   │
+                //   ├ note: foo
+                //   │       bar
+                //   ╰ note: foo
+                //           bar
+                for i in 1..=printed_lines {
+                    self.draw_col_separator_no_space(&mut buffer, i, max_line_num_len + 1);
+                }
+            }
         } else {
             let mut label_width = 0;
             // The failure note level itself does not provide any useful diagnostic information
@@ -1439,9 +1557,13 @@ impl HumanEmitter {
                                 Style::LineAndColumn,
                             );
                             if annotation_id == 0 {
-                                buffer.prepend(line_idx, "--> ", Style::LineNumber);
+                                buffer.prepend(line_idx, self.file_start(), Style::LineNumber);
                             } else {
-                                buffer.prepend(line_idx, "::: ", Style::LineNumber);
+                                buffer.prepend(
+                                    line_idx,
+                                    self.secondary_file_start(),
+                                    Style::LineNumber,
+                                );
                             }
                             for _ in 0..max_line_num_len {
                                 buffer.prepend(line_idx, " ", Style::NoStyle);
@@ -1454,12 +1576,14 @@ impl HumanEmitter {
                             } else {
                                 Style::LabelSecondary
                             };
-                            buffer.prepend(line_idx, " |", Style::LineNumber);
+                            let pipe = self.col_separator();
+                            buffer.prepend(line_idx, &format!(" {pipe}"), Style::LineNumber);
                             for _ in 0..max_line_num_len {
                                 buffer.prepend(line_idx, " ", Style::NoStyle);
                             }
                             line_idx += 1;
-                            buffer.append(line_idx, " = note: ", style);
+                            let chr = self.note_separator();
+                            buffer.append(line_idx, &format!(" {chr} note: "), style);
                             for _ in 0..max_line_num_len {
                                 buffer.prepend(line_idx, " ", Style::NoStyle);
                             }
@@ -1480,7 +1604,7 @@ impl HumanEmitter {
                     // remember where we are in the output buffer for easy reference
                     let buffer_msg_line_offset = buffer.num_lines();
 
-                    buffer.prepend(buffer_msg_line_offset, "--> ", Style::LineNumber);
+                    buffer.prepend(buffer_msg_line_offset, self.file_start(), Style::LineNumber);
                     buffer.append(
                         buffer_msg_line_offset,
                         &format!(
@@ -1510,15 +1634,28 @@ impl HumanEmitter {
                 // remember where we are in the output buffer for easy reference
                 let buffer_msg_line_offset = buffer.num_lines();
 
-                // Add spacing line
-                draw_col_separator_no_space(
+                // Add spacing line, as shown:
+                //   --> $DIR/file:54:15
+                //    |
+                // LL |         code
+                //    |         ^^^^
+                //    | (<- It prints *this* line)
+                //   ::: $DIR/other_file.rs:15:5
+                //    |
+                // LL |     code
+                //    |     ----
+                self.draw_col_separator_no_space(
                     &mut buffer,
                     buffer_msg_line_offset,
                     max_line_num_len + 1,
                 );
 
                 // Then, the secondary file indicator
-                buffer.prepend(buffer_msg_line_offset + 1, "::: ", Style::LineNumber);
+                buffer.prepend(
+                    buffer_msg_line_offset + 1,
+                    self.secondary_file_start(),
+                    Style::LineNumber,
+                );
                 let loc = if let Some(first_line) = annotated_file.lines.first() {
                     let col = if let Some(first_annotation) = first_line.annotations.first() {
                         format!(":{}", first_annotation.start_col.file + 1)
@@ -1543,7 +1680,7 @@ impl HumanEmitter {
             if !self.short_message {
                 // Put in the spacer between the location and annotated source
                 let buffer_msg_line_offset = buffer.num_lines();
-                draw_col_separator_no_space(
+                self.draw_col_separator_no_space(
                     &mut buffer,
                     buffer_msg_line_offset,
                     max_line_num_len + 1,
@@ -1651,6 +1788,7 @@ impl HumanEmitter {
                         width_offset,
                         code_offset,
                         margin,
+                        !is_cont && line_idx + 1 == annotated_file.lines.len(),
                     );
 
                     let mut to_add = FxHashMap::default();
@@ -1666,7 +1804,13 @@ impl HumanEmitter {
                     // the code in this line.
                     for (depth, style) in &multilines {
                         for line in previous_buffer_line..buffer.num_lines() {
-                            draw_multiline_line(&mut buffer, line, width_offset, *depth, *style);
+                            self.draw_multiline_line(
+                                &mut buffer,
+                                line,
+                                width_offset,
+                                *depth,
+                                *style,
+                            );
                         }
                     }
                     // check to see if we need to print out or elide lines that come between
@@ -1676,11 +1820,15 @@ impl HumanEmitter {
                             - annotated_file.lines[line_idx].line_index;
                         if line_idx_delta > 2 {
                             let last_buffer_line_num = buffer.num_lines();
-                            buffer.puts(last_buffer_line_num, 0, "...", Style::LineNumber);
+                            self.draw_line_separator(
+                                &mut buffer,
+                                last_buffer_line_num,
+                                width_offset,
+                            );
 
                             // Set the multiline annotation vertical lines on `...` bridging line.
                             for (depth, style) in &multilines {
-                                draw_multiline_line(
+                                self.draw_multiline_line(
                                     &mut buffer,
                                     last_buffer_line_num,
                                     width_offset,
@@ -1695,7 +1843,7 @@ impl HumanEmitter {
                                         // In the case where we have elided the entire start of the
                                         // multispan because those lines were empty, we still need
                                         // to draw the `|`s across the `...`.
-                                        draw_multiline_line(
+                                        self.draw_multiline_line(
                                             &mut buffer,
                                             last_buffer_line_num,
                                             width_offset,
@@ -1728,7 +1876,7 @@ impl HumanEmitter {
                             );
 
                             for (depth, style) in &multilines {
-                                draw_multiline_line(
+                                self.draw_multiline_line(
                                     &mut buffer,
                                     last_buffer_line_num,
                                     width_offset,
@@ -1740,7 +1888,7 @@ impl HumanEmitter {
                                 for ann in &line.annotations {
                                     if let AnnotationType::MultilineStart(pos) = ann.annotation_type
                                     {
-                                        draw_multiline_line(
+                                        self.draw_multiline_line(
                                             &mut buffer,
                                             last_buffer_line_num,
                                             width_offset,
@@ -1824,13 +1972,24 @@ impl HumanEmitter {
         );
 
         let mut row_num = 2;
-        draw_col_separator_no_space(&mut buffer, 1, max_line_num_len + 1);
-        for (complete, parts, highlights, _) in suggestions.iter().take(MAX_SUGGESTIONS) {
+        for (i, (complete, parts, highlights, _)) in
+            suggestions.iter().enumerate().take(MAX_SUGGESTIONS)
+        {
             debug!(?complete, ?parts, ?highlights);
 
             let has_deletion = parts.iter().any(|p| p.is_deletion(sm));
             let is_multiline = complete.lines().count() > 1;
 
+            if i == 0 {
+                self.draw_col_separator_start(&mut buffer, row_num - 1, max_line_num_len + 1);
+            } else {
+                buffer.puts(
+                    row_num - 1,
+                    max_line_num_len + 1,
+                    self.multi_suggestion_separator(),
+                    Style::LineNumber,
+                );
+            }
             if let Some(span) = span.primary_span() {
                 // Compare the primary span of the diagnostic with the span of the suggestion
                 // being emitted. If they belong to the same file, we don't *need* to show the
@@ -1838,7 +1997,9 @@ impl HumanEmitter {
                 // telling users to make a change but not clarifying *where*.
                 let loc = sm.lookup_char_pos(parts[0].span.lo());
                 if loc.file.name != sm.span_to_filename(span) && loc.file.name.is_real() {
-                    let arrow = "--> ";
+                    // --> file.rs:line:col
+                    //  |
+                    let arrow = self.file_start();
                     buffer.puts(row_num - 1, 0, arrow, Style::LineNumber);
                     let filename = sm.filename_for_diagnostics(&loc.file.name);
                     let offset = sm.doctest_offset_line(&loc.file.name, loc.line);
@@ -1852,6 +2013,7 @@ impl HumanEmitter {
                     for _ in 0..max_line_num_len {
                         buffer.prepend(row_num - 1, " ", Style::NoStyle);
                     }
+                    self.draw_col_separator_no_space(&mut buffer, row_num, max_line_num_len + 1);
                     row_num += 1;
                 }
             }
@@ -1882,7 +2044,6 @@ impl HumanEmitter {
             assert!(!file_lines.lines.is_empty() || parts[0].span.is_dummy());
 
             let line_start = sm.lookup_char_pos(parts[0].span.lo()).line;
-            draw_col_separator_no_space(&mut buffer, row_num - 1, max_line_num_len + 1);
             let mut lines = complete.lines();
             if lines.clone().next().is_none() {
                 // Account for a suggestion to completely remove a line(s) with whitespace (#94192).
@@ -1972,7 +2133,14 @@ impl HumanEmitter {
                             )
                         }
 
-                        buffer.puts(row_num, 0, "...", Style::LineNumber);
+                        let placeholder = self.margin();
+                        let padding = str_width(placeholder);
+                        buffer.puts(
+                            row_num,
+                            max_line_num_len.saturating_sub(padding),
+                            placeholder,
+                            Style::LineNumber,
+                        );
                         row_num += 1;
 
                         if let Some((p, l)) = last_line {
@@ -2040,7 +2208,6 @@ impl HumanEmitter {
             if let DisplaySuggestion::Diff | DisplaySuggestion::Underline | DisplaySuggestion::Add =
                 show_code_change
             {
-                draw_col_separator_no_space(&mut buffer, row_num, max_line_num_len + 1);
                 for part in parts {
                     let span_start_pos = sm.lookup_char_pos(part.span.lo()).col_display;
                     let span_end_pos = sm.lookup_char_pos(part.span.hi()).col_display;
@@ -2057,11 +2224,11 @@ impl HumanEmitter {
                     };
                     // ...or trailing spaces. Account for substitutions containing unicode
                     // characters.
-                    let sub_len: usize =
-                        if is_whitespace_addition { &part.snippet } else { part.snippet.trim() }
-                            .chars()
-                            .map(|ch| char_width(ch))
-                            .sum();
+                    let sub_len: usize = str_width(if is_whitespace_addition {
+                        &part.snippet
+                    } else {
+                        part.snippet.trim()
+                    });
 
                     let offset: isize = offsets
                         .iter()
@@ -2082,7 +2249,7 @@ impl HumanEmitter {
                             buffer.putc(
                                 row_num,
                                 (padding as isize + p) as usize,
-                                if part.is_addition(sm) { '+' } else { '~' },
+                                if part.is_addition(sm) { '+' } else { self.diff() },
                                 Style::Addition,
                             );
                         }
@@ -2099,8 +2266,7 @@ impl HumanEmitter {
                     }
 
                     // length of the code after substitution
-                    let full_sub_len =
-                        part.snippet.chars().map(|ch| char_width(ch)).sum::<usize>() as isize;
+                    let full_sub_len = str_width(&part.snippet) as isize;
 
                     // length of the code to be substituted
                     let snippet_len = span_end_pos as isize - span_start_pos as isize;
@@ -2114,10 +2280,23 @@ impl HumanEmitter {
 
             // if we elided some lines, add an ellipsis
             if lines.next().is_some() {
-                buffer.puts(row_num, max_line_num_len - 1, "...", Style::LineNumber);
-            } else if let DisplaySuggestion::None = show_code_change {
-                draw_col_separator_no_space(&mut buffer, row_num, max_line_num_len + 1);
-                row_num += 1;
+                let placeholder = self.margin();
+                let padding = str_width(placeholder);
+                buffer.puts(
+                    row_num,
+                    max_line_num_len.saturating_sub(padding),
+                    placeholder,
+                    Style::LineNumber,
+                );
+            } else {
+                let row = match show_code_change {
+                    DisplaySuggestion::Diff
+                    | DisplaySuggestion::Add
+                    | DisplaySuggestion::Underline => row_num - 1,
+                    DisplaySuggestion::None => row_num,
+                };
+                self.draw_col_separator_end(&mut buffer, row, max_line_num_len + 1);
+                row_num = row + 1;
             }
         }
         if suggestions.len() > MAX_SUGGESTIONS {
@@ -2125,6 +2304,7 @@ impl HumanEmitter {
             let msg = format!("and {} other candidate{}", others, pluralize!(others));
             buffer.puts(row_num, max_line_num_len + 3, &msg, Style::NoStyle);
         }
+
         emit_to_destination(&buffer.render(), level, &mut self.dst, self.short_message)?;
         Ok(())
     }
@@ -2157,6 +2337,8 @@ impl HumanEmitter {
             max_line_num_len,
             false,
             emitted_at,
+            !children.is_empty()
+                || suggestions.iter().any(|s| s.style != SuggestionStyle::CompletelyHidden),
         ) {
             Ok(()) => {
                 if !children.is_empty()
@@ -2164,7 +2346,15 @@ impl HumanEmitter {
                 {
                     let mut buffer = StyledBuffer::new();
                     if !self.short_message {
-                        draw_col_separator_no_space(&mut buffer, 0, max_line_num_len + 1);
+                        if let Some(child) = children.iter().next()
+                            && child.span.primary_spans().is_empty()
+                        {
+                            // We'll continue the vertical bar to point into the next note.
+                            self.draw_col_separator_no_space(&mut buffer, 0, max_line_num_len + 1);
+                        } else {
+                            // We'll close the vertical bar to visually end the code window.
+                            self.draw_col_separator_end(&mut buffer, 0, max_line_num_len + 1);
+                        }
                     }
                     if let Err(e) = emit_to_destination(
                         &buffer.render(),
@@ -2176,9 +2366,14 @@ impl HumanEmitter {
                     }
                 }
                 if !self.short_message {
-                    for child in children {
+                    for (i, child) in children.iter().enumerate() {
                         assert!(child.level.can_be_subdiag());
                         let span = &child.span;
+                        // FIXME: audit that this behaves correctly with suggestions.
+                        let should_close = match children.get(i + 1) {
+                            Some(c) => !c.span.primary_spans().is_empty(),
+                            None => i + 1 == children.len(),
+                        };
                         if let Err(err) = self.emit_messages_default_inner(
                             span,
                             &child.messages,
@@ -2188,11 +2383,12 @@ impl HumanEmitter {
                             max_line_num_len,
                             true,
                             None,
+                            !should_close,
                         ) {
                             panic!("failed to emit error: {err}");
                         }
                     }
-                    for sugg in suggestions {
+                    for (i, sugg) in suggestions.iter().enumerate() {
                         match sugg.style {
                             SuggestionStyle::CompletelyHidden => {
                                 // do not display this suggestion, it is meant only for tools
@@ -2207,6 +2403,9 @@ impl HumanEmitter {
                                     max_line_num_len,
                                     true,
                                     None,
+                                    // FIXME: this needs to account for the suggestion type,
+                                    //        some don't take any space.
+                                    i + 1 != suggestions.len(),
                                 ) {
                                     panic!("failed to emit error: {e}");
                                 }
@@ -2323,10 +2522,17 @@ impl HumanEmitter {
                     buffer.puts(*row_num, max_line_num_len + 1, "+ ", Style::Addition);
                 }
                 [] => {
-                    draw_col_separator_no_space(buffer, *row_num, max_line_num_len + 1);
+                    // FIXME: needed? Doesn't get excercised in any test.
+                    self.draw_col_separator_no_space(buffer, *row_num, max_line_num_len + 1);
                 }
                 _ => {
-                    buffer.puts(*row_num, max_line_num_len + 1, "~ ", Style::Addition);
+                    let diff = self.diff();
+                    buffer.puts(
+                        *row_num,
+                        max_line_num_len + 1,
+                        &format!("{diff} "),
+                        Style::Addition,
+                    );
                 }
             }
             //   LL | line_to_add
@@ -2346,7 +2552,7 @@ impl HumanEmitter {
             buffer.append(*row_num, &normalize_whitespace(line_to_add), Style::NoStyle);
         } else {
             buffer.puts(*row_num, 0, &self.maybe_anonymized(line_num), Style::LineNumber);
-            draw_col_separator(buffer, *row_num, max_line_num_len + 1);
+            self.draw_col_separator(buffer, *row_num, max_line_num_len + 1);
             buffer.append(*row_num, &normalize_whitespace(line_to_add), Style::NoStyle);
         }
 
@@ -2374,6 +2580,306 @@ impl HumanEmitter {
         }
         *row_num += 1;
     }
+
+    fn underline(&self, is_primary: bool) -> UnderlineParts {
+        //               X0 Y0
+        // label_start > ┯━━━━ < underline
+        //               │ < vertical_text_line
+        //               text
+
+        //    multiline_start_down ⤷ X0 Y0
+        //            top_left > ┌───╿──┘ < top_right_flat
+        //           top_left > ┏│━━━┙ < top_right
+        // multiline_vertical > ┃│
+        //                      ┃│   X1 Y1
+        //                      ┃│   X2 Y2
+        //                      ┃└────╿──┘ < multiline_end_same_line
+        //        bottom_left > ┗━━━━━┥ < bottom_right_with_text
+        //   multiline_horizontal ^   `X` is a good letter
+
+        // multiline_whole_line > ┏ X0 Y0
+        //                        ┃   X1 Y1
+        //                        ┗━━━━┛ < multiline_end_same_line
+
+        // multiline_whole_line > ┏ X0 Y0
+        //                        ┃ X1 Y1
+        //                        ┃  ╿ < multiline_end_up
+        //                        ┗━━┛ < bottom_right
+
+        match (self.theme, is_primary) {
+            (OutputTheme::Ascii, true) => UnderlineParts {
+                style: Style::UnderlinePrimary,
+                underline: '^',
+                label_start: '^',
+                vertical_text_line: '|',
+                multiline_vertical: '|',
+                multiline_horizontal: '_',
+                multiline_whole_line: '/',
+                multiline_start_down: '^',
+                bottom_right: '|',
+                top_left: ' ',
+                top_right_flat: '^',
+                bottom_left: '|',
+                multiline_end_up: '^',
+                multiline_end_same_line: '^',
+                multiline_bottom_right_with_text: '|',
+            },
+            (OutputTheme::Ascii, false) => UnderlineParts {
+                style: Style::UnderlineSecondary,
+                underline: '-',
+                label_start: '-',
+                vertical_text_line: '|',
+                multiline_vertical: '|',
+                multiline_horizontal: '_',
+                multiline_whole_line: '/',
+                multiline_start_down: '-',
+                bottom_right: '|',
+                top_left: ' ',
+                top_right_flat: '-',
+                bottom_left: '|',
+                multiline_end_up: '-',
+                multiline_end_same_line: '-',
+                multiline_bottom_right_with_text: '|',
+            },
+            (OutputTheme::Unicode, true) => UnderlineParts {
+                style: Style::UnderlinePrimary,
+                underline: '━',
+                label_start: '┯',
+                vertical_text_line: '│',
+                multiline_vertical: '┃',
+                multiline_horizontal: '━',
+                multiline_whole_line: '┏',
+                multiline_start_down: '╿',
+                bottom_right: '┙',
+                top_left: '┏',
+                top_right_flat: '┛',
+                bottom_left: '┗',
+                multiline_end_up: '╿',
+                multiline_end_same_line: '┛',
+                multiline_bottom_right_with_text: '┥',
+            },
+            (OutputTheme::Unicode, false) => UnderlineParts {
+                style: Style::UnderlineSecondary,
+                underline: '─',
+                label_start: '┬',
+                vertical_text_line: '│',
+                multiline_vertical: '│',
+                multiline_horizontal: '─',
+                multiline_whole_line: '┌',
+                multiline_start_down: '│',
+                bottom_right: '┘',
+                top_left: '┌',
+                top_right_flat: '┘',
+                bottom_left: '└',
+                multiline_end_up: '│',
+                multiline_end_same_line: '┘',
+                multiline_bottom_right_with_text: '┤',
+            },
+        }
+    }
+
+    fn col_separator(&self) -> char {
+        match self.theme {
+            OutputTheme::Ascii => '|',
+            OutputTheme::Unicode => '│',
+        }
+    }
+
+    fn note_separator(&self) -> char {
+        match self.theme {
+            OutputTheme::Ascii => '=',
+            OutputTheme::Unicode => '╰',
+        }
+    }
+
+    fn multi_suggestion_separator(&self) -> &'static str {
+        match self.theme {
+            OutputTheme::Ascii => "|",
+            OutputTheme::Unicode => "├╴",
+        }
+    }
+
+    fn draw_col_separator(&self, buffer: &mut StyledBuffer, line: usize, col: usize) {
+        let chr = self.col_separator();
+        buffer.puts(line, col, &format!("{chr} "), Style::LineNumber);
+    }
+
+    fn draw_col_separator_no_space(&self, buffer: &mut StyledBuffer, line: usize, col: usize) {
+        let chr = self.col_separator();
+        self.draw_col_separator_no_space_with_style(buffer, chr, line, col, Style::LineNumber);
+    }
+
+    fn draw_col_separator_start(&self, buffer: &mut StyledBuffer, line: usize, col: usize) {
+        match self.theme {
+            OutputTheme::Ascii => {
+                self.draw_col_separator_no_space_with_style(
+                    buffer,
+                    '|',
+                    line,
+                    col,
+                    Style::LineNumber,
+                );
+            }
+            OutputTheme::Unicode => {
+                self.draw_col_separator_no_space_with_style(
+                    buffer,
+                    '╭',
+                    line,
+                    col,
+                    Style::LineNumber,
+                );
+                self.draw_col_separator_no_space_with_style(
+                    buffer,
+                    '╴',
+                    line,
+                    col + 1,
+                    Style::LineNumber,
+                );
+            }
+        }
+    }
+
+    fn draw_col_separator_end(&self, buffer: &mut StyledBuffer, line: usize, col: usize) {
+        match self.theme {
+            OutputTheme::Ascii => {
+                self.draw_col_separator_no_space_with_style(
+                    buffer,
+                    '|',
+                    line,
+                    col,
+                    Style::LineNumber,
+                );
+            }
+            OutputTheme::Unicode => {
+                self.draw_col_separator_no_space_with_style(
+                    buffer,
+                    '╰',
+                    line,
+                    col,
+                    Style::LineNumber,
+                );
+                self.draw_col_separator_no_space_with_style(
+                    buffer,
+                    '╴',
+                    line,
+                    col + 1,
+                    Style::LineNumber,
+                );
+            }
+        }
+    }
+
+    fn draw_col_separator_no_space_with_style(
+        &self,
+        buffer: &mut StyledBuffer,
+        chr: char,
+        line: usize,
+        col: usize,
+        style: Style,
+    ) {
+        buffer.putc(line, col, chr, style);
+    }
+
+    fn draw_range(
+        &self,
+        buffer: &mut StyledBuffer,
+        symbol: char,
+        line: usize,
+        col_from: usize,
+        col_to: usize,
+        style: Style,
+    ) {
+        for col in col_from..col_to {
+            buffer.putc(line, col, symbol, style);
+        }
+    }
+
+    fn draw_note_separator(
+        &self,
+        buffer: &mut StyledBuffer,
+        line: usize,
+        col: usize,
+        is_cont: bool,
+    ) {
+        let chr = match self.theme {
+            OutputTheme::Ascii => "= ",
+            OutputTheme::Unicode if is_cont => "├ ",
+            OutputTheme::Unicode => "╰ ",
+        };
+        buffer.puts(line, col, chr, Style::LineNumber);
+    }
+
+    fn draw_multiline_line(
+        &self,
+        buffer: &mut StyledBuffer,
+        line: usize,
+        offset: usize,
+        depth: usize,
+        style: Style,
+    ) {
+        let chr = match (style, self.theme) {
+            (Style::UnderlinePrimary | Style::LabelPrimary, OutputTheme::Ascii) => '|',
+            (_, OutputTheme::Ascii) => '|',
+            (Style::UnderlinePrimary | Style::LabelPrimary, OutputTheme::Unicode) => '┃',
+            (_, OutputTheme::Unicode) => '│',
+        };
+        buffer.putc(line, offset + depth - 1, chr, style);
+    }
+
+    fn file_start(&self) -> &'static str {
+        match self.theme {
+            OutputTheme::Ascii => "--> ",
+            OutputTheme::Unicode => " ╭▸ ",
+        }
+    }
+
+    fn secondary_file_start(&self) -> &'static str {
+        match self.theme {
+            OutputTheme::Ascii => "::: ",
+            OutputTheme::Unicode => " ⸬ ",
+        }
+    }
+
+    fn diff(&self) -> char {
+        match self.theme {
+            OutputTheme::Ascii => '~',
+            OutputTheme::Unicode => '±',
+        }
+    }
+
+    fn draw_line_separator(&self, buffer: &mut StyledBuffer, line: usize, col: usize) {
+        let (column, dots) = match self.theme {
+            OutputTheme::Ascii => (0, "..."),
+            OutputTheme::Unicode => (col - 2, "‡"),
+        };
+        buffer.puts(line, column, dots, Style::LineNumber);
+    }
+
+    fn margin(&self) -> &'static str {
+        match self.theme {
+            OutputTheme::Ascii => "...",
+            OutputTheme::Unicode => "…",
+        }
+    }
+}
+
+#[derive(Debug, Clone, Copy)]
+struct UnderlineParts {
+    style: Style,
+    underline: char,
+    label_start: char,
+    vertical_text_line: char,
+    multiline_vertical: char,
+    multiline_horizontal: char,
+    multiline_whole_line: char,
+    multiline_start_down: char,
+    bottom_right: char,
+    top_left: char,
+    top_right_flat: char,
+    bottom_left: char,
+    multiline_end_up: char,
+    multiline_end_same_line: char,
+    multiline_bottom_right_with_text: char,
 }
 
 #[derive(Clone, Copy, Debug)]
@@ -2666,50 +3172,6 @@ fn normalize_whitespace(s: &str) -> String {
     })
 }
 
-fn draw_col_separator(buffer: &mut StyledBuffer, line: usize, col: usize) {
-    buffer.puts(line, col, "| ", Style::LineNumber);
-}
-
-fn draw_col_separator_no_space(buffer: &mut StyledBuffer, line: usize, col: usize) {
-    draw_col_separator_no_space_with_style(buffer, line, col, Style::LineNumber);
-}
-
-fn draw_col_separator_no_space_with_style(
-    buffer: &mut StyledBuffer,
-    line: usize,
-    col: usize,
-    style: Style,
-) {
-    buffer.putc(line, col, '|', style);
-}
-
-fn draw_range(
-    buffer: &mut StyledBuffer,
-    symbol: char,
-    line: usize,
-    col_from: usize,
-    col_to: usize,
-    style: Style,
-) {
-    for col in col_from..col_to {
-        buffer.putc(line, col, symbol, style);
-    }
-}
-
-fn draw_note_separator(buffer: &mut StyledBuffer, line: usize, col: usize) {
-    buffer.puts(line, col, "= ", Style::LineNumber);
-}
-
-fn draw_multiline_line(
-    buffer: &mut StyledBuffer,
-    line: usize,
-    offset: usize,
-    depth: usize,
-    style: Style,
-) {
-    buffer.putc(line, offset + depth - 1, '|', style);
-}
-
 fn num_overlap(
     a_start: usize,
     a_end: usize,
diff --git a/compiler/rustc_errors/src/json.rs b/compiler/rustc_errors/src/json.rs
index 91e2b9996cd50..e3b6dcea89202 100644
--- a/compiler/rustc_errors/src/json.rs
+++ b/compiler/rustc_errors/src/json.rs
@@ -27,7 +27,7 @@ use termcolor::{ColorSpec, WriteColor};
 
 use crate::diagnostic::IsLint;
 use crate::emitter::{
-    ColorConfig, Destination, Emitter, HumanEmitter, HumanReadableErrorType,
+    ColorConfig, Destination, Emitter, HumanEmitter, HumanReadableErrorType, OutputTheme,
     should_show_source_code,
 };
 use crate::registry::Registry;
@@ -377,6 +377,11 @@ impl Diagnostic {
             .terminal_url(je.terminal_url)
             .ui_testing(je.ui_testing)
             .ignored_directories_in_source_blocks(je.ignored_directories_in_source_blocks.clone())
+            .theme(if let HumanReadableErrorType::Unicode = je.json_rendered {
+                OutputTheme::Unicode
+            } else {
+                OutputTheme::Ascii
+            })
             .emit_diagnostic(diag);
         let buf = Arc::try_unwrap(buf.0).unwrap().into_inner().unwrap();
         let buf = String::from_utf8(buf).unwrap();
diff --git a/compiler/rustc_parse/src/parser/tests.rs b/compiler/rustc_parse/src/parser/tests.rs
index 92684505ab0ba..decaecd2682ce 100644
--- a/compiler/rustc_parse/src/parser/tests.rs
+++ b/compiler/rustc_parse/src/parser/tests.rs
@@ -12,7 +12,7 @@ use rustc_ast::tokenstream::{DelimSpacing, DelimSpan, Spacing, TokenStream, Toke
 use rustc_ast::{self as ast, PatKind, visit};
 use rustc_ast_pretty::pprust::item_to_string;
 use rustc_data_structures::sync::Lrc;
-use rustc_errors::emitter::HumanEmitter;
+use rustc_errors::emitter::{HumanEmitter, OutputTheme};
 use rustc_errors::{DiagCtxt, MultiSpan, PResult};
 use rustc_session::parse::ParseSess;
 use rustc_span::source_map::{FilePathMapping, SourceMap};
@@ -36,16 +36,17 @@ fn string_to_parser(psess: &ParseSess, source_str: String) -> Parser<'_> {
     ))
 }
 
-fn create_test_handler() -> (DiagCtxt, Lrc<SourceMap>, Arc<Mutex<Vec<u8>>>) {
+fn create_test_handler(theme: OutputTheme) -> (DiagCtxt, Lrc<SourceMap>, Arc<Mutex<Vec<u8>>>) {
     let output = Arc::new(Mutex::new(Vec::new()));
     let source_map = Lrc::new(SourceMap::new(FilePathMapping::empty()));
     let fallback_bundle = rustc_errors::fallback_fluent_bundle(
         vec![crate::DEFAULT_LOCALE_RESOURCE, crate::DEFAULT_LOCALE_RESOURCE],
         false,
     );
-    let emitter = HumanEmitter::new(Box::new(Shared { data: output.clone() }), fallback_bundle)
+    let mut emitter = HumanEmitter::new(Box::new(Shared { data: output.clone() }), fallback_bundle)
         .sm(Some(source_map.clone()))
         .diagnostic_width(Some(140));
+    emitter = emitter.theme(theme);
     let dcx = DiagCtxt::new(Box::new(emitter));
     (dcx, source_map, output)
 }
@@ -69,7 +70,7 @@ fn with_expected_parse_error<T, F>(source_str: &str, expected_output: &str, f: F
 where
     F: for<'a> FnOnce(&mut Parser<'a>) -> PResult<'a, T>,
 {
-    let (handler, source_map, output) = create_test_handler();
+    let (handler, source_map, output) = create_test_handler(OutputTheme::Ascii);
     let psess = ParseSess::with_dcx(handler, source_map);
     let mut p = string_to_parser(&psess, source_str.to_string());
     let result = f(&mut p);
@@ -189,34 +190,55 @@ impl<T: Write> Write for Shared<T> {
 }
 
 #[allow(rustc::untranslatable_diagnostic)] // no translation needed for tests
-fn test_harness(file_text: &str, span_labels: Vec<SpanLabel>, expected_output: &str) {
+fn test_harness(
+    file_text: &str,
+    span_labels: Vec<SpanLabel>,
+    notes: Vec<(Option<(Position, Position)>, &'static str)>,
+    expected_output_ascii: &str,
+    expected_output_unicode: &str,
+) {
     create_default_session_globals_then(|| {
-        let (dcx, source_map, output) = create_test_handler();
-        source_map.new_source_file(Path::new("test.rs").to_owned().into(), file_text.to_owned());
-
-        let primary_span = make_span(&file_text, &span_labels[0].start, &span_labels[0].end);
-        let mut msp = MultiSpan::from_span(primary_span);
-        for span_label in span_labels {
-            let span = make_span(&file_text, &span_label.start, &span_label.end);
-            msp.push_span_label(span, span_label.label);
-            println!("span: {:?} label: {:?}", span, span_label.label);
-            println!("text: {:?}", source_map.span_to_snippet(span));
-        }
+        for (theme, expected_output) in [
+            (OutputTheme::Ascii, expected_output_ascii),
+            (OutputTheme::Unicode, expected_output_unicode),
+        ] {
+            let (dcx, source_map, output) = create_test_handler(theme);
+            source_map
+                .new_source_file(Path::new("test.rs").to_owned().into(), file_text.to_owned());
+
+            let primary_span = make_span(&file_text, &span_labels[0].start, &span_labels[0].end);
+            let mut msp = MultiSpan::from_span(primary_span);
+            for span_label in &span_labels {
+                let span = make_span(&file_text, &span_label.start, &span_label.end);
+                msp.push_span_label(span, span_label.label);
+                println!("span: {:?} label: {:?}", span, span_label.label);
+                println!("text: {:?}", source_map.span_to_snippet(span));
+            }
 
-        dcx.handle().span_err(msp, "foo");
+            let mut err = dcx.handle().struct_span_err(msp, "foo");
+            for (position, note) in &notes {
+                if let Some((start, end)) = position {
+                    let span = make_span(&file_text, &start, &end);
+                    err.span_note(span, *note);
+                } else {
+                    err.note(*note);
+                }
+            }
+            err.emit();
 
-        assert!(
-            expected_output.chars().next() == Some('\n'),
-            "expected output should begin with newline"
-        );
-        let expected_output = &expected_output[1..];
+            assert!(
+                expected_output.chars().next() == Some('\n'),
+                "expected output should begin with newline"
+            );
+            let expected_output = &expected_output[1..];
 
-        let bytes = output.lock().unwrap();
-        let actual_output = str::from_utf8(&bytes).unwrap();
-        println!("expected output:\n------\n{}------", expected_output);
-        println!("actual output:\n------\n{}------", actual_output);
+            let bytes = output.lock().unwrap();
+            let actual_output = str::from_utf8(&bytes).unwrap();
+            println!("expected output:\n------\n{}------", expected_output);
+            println!("actual output:\n------\n{}------", actual_output);
 
-        assert!(expected_output == actual_output)
+            assert!(expected_output == actual_output)
+        }
     })
 }
 
@@ -242,135 +264,1005 @@ fn make_pos(file_text: &str, pos: &Position) -> usize {
 }
 
 #[test]
-fn ends_on_col0() {
+fn ends_on_col0() {
+    test_harness(
+        r#"
+fn foo() {
+}
+"#,
+        vec![SpanLabel {
+            start: Position { string: "{", count: 1 },
+            end: Position { string: "}", count: 1 },
+            label: "test",
+        }],
+        vec![],
+        r#"
+error: foo
+ --> test.rs:2:10
+  |
+2 |   fn foo() {
+  |  __________^
+3 | | }
+  | |_^ test
+
+"#,
+        r#"
+error: foo
+  ╭▸ test.rs:2:10
+  │
+2 │   fn foo() {
+  │ ┏━━━━━━━━━━┛
+3 │ ┃ }
+  ╰╴┗━┛ test
+
+"#,
+    );
+}
+
+#[test]
+fn ends_on_col2() {
+    test_harness(
+        r#"
+fn foo() {
+
+
+  }
+"#,
+        vec![SpanLabel {
+            start: Position { string: "{", count: 1 },
+            end: Position { string: "}", count: 1 },
+            label: "test",
+        }],
+        vec![],
+        r#"
+error: foo
+ --> test.rs:2:10
+  |
+2 |   fn foo() {
+  |  __________^
+... |
+5 | |   }
+  | |___^ test
+
+"#,
+        r#"
+error: foo
+  ╭▸ test.rs:2:10
+  │
+2 │   fn foo() {
+  │ ┏━━━━━━━━━━┛
+  ‡ ┃
+5 │ ┃   }
+  ╰╴┗━━━┛ test
+
+"#,
+    );
+}
+#[test]
+fn non_nested() {
+    test_harness(
+        r#"
+fn foo() {
+  X0 Y0
+  X1 Y1
+  X2 Y2
+}
+"#,
+        vec![
+            SpanLabel {
+                start: Position { string: "X0", count: 1 },
+                end: Position { string: "X2", count: 1 },
+                label: "`X` is a good letter",
+            },
+            SpanLabel {
+                start: Position { string: "Y0", count: 1 },
+                end: Position { string: "Y2", count: 1 },
+                label: "`Y` is a good letter too",
+            },
+        ],
+        vec![],
+        r#"
+error: foo
+ --> test.rs:3:3
+  |
+3 |      X0 Y0
+  |  ____^  -
+  | | ______|
+4 | ||   X1 Y1
+5 | ||   X2 Y2
+  | ||____^__- `Y` is a good letter too
+  | |_____|
+  |       `X` is a good letter
+
+"#,
+        r#"
+error: foo
+  ╭▸ test.rs:3:3
+  │
+3 │      X0 Y0
+  │ ┏━━━━┛  │
+  │ ┃┌──────┘
+4 │ ┃│   X1 Y1
+5 │ ┃│   X2 Y2
+  │ ┃└────╿──┘ `Y` is a good letter too
+  │ ┗━━━━━┥
+  ╰╴      `X` is a good letter
+
+"#,
+    );
+}
+
+#[test]
+fn nested() {
+    test_harness(
+        r#"
+fn foo() {
+  X0 Y0
+  Y1 X1
+}
+"#,
+        vec![
+            SpanLabel {
+                start: Position { string: "X0", count: 1 },
+                end: Position { string: "X1", count: 1 },
+                label: "`X` is a good letter",
+            },
+            SpanLabel {
+                start: Position { string: "Y0", count: 1 },
+                end: Position { string: "Y1", count: 1 },
+                label: "`Y` is a good letter too",
+            },
+        ],
+        vec![],
+        r#"
+error: foo
+ --> test.rs:3:3
+  |
+3 |      X0 Y0
+  |  ____^  -
+  | | ______|
+4 | ||   Y1 X1
+  | ||____-__^ `X` is a good letter
+  |  |____|
+  |       `Y` is a good letter too
+
+"#,
+        r#"
+error: foo
+  ╭▸ test.rs:3:3
+  │
+3 │      X0 Y0
+  │ ┏━━━━┛  │
+  │ ┃┌──────┘
+4 │ ┃│   Y1 X1
+  │ ┗│━━━━│━━┛ `X` is a good letter
+  │  └────┤
+  ╰╴      `Y` is a good letter too
+
+"#,
+    );
+}
+
+#[test]
+fn multiline_and_normal_overlap() {
+    test_harness(
+        r#"
+fn foo() {
+  X0 Y0 Z0
+  X1 Y1 Z1
+  X2 Y2 Z2
+  X3 Y3 Z3
+}
+"#,
+        vec![
+            SpanLabel {
+                start: Position { string: "Y0", count: 1 },
+                end: Position { string: "X2", count: 1 },
+                label: "`X` is a good letter",
+            },
+            SpanLabel {
+                start: Position { string: "X0", count: 1 },
+                end: Position { string: "Y0", count: 1 },
+                label: "`Y` is a good letter too",
+            },
+        ],
+        vec![],
+        r#"
+error: foo
+ --> test.rs:3:6
+  |
+3 |     X0 Y0 Z0
+  |  ___---^-
+  | |   |
+  | |   `Y` is a good letter too
+4 | |   X1 Y1 Z1
+5 | |   X2 Y2 Z2
+  | |____^ `X` is a good letter
+
+"#,
+        r#"
+error: foo
+  ╭▸ test.rs:3:6
+  │
+3 │     X0 Y0 Z0
+  │ ┏━━━┬──┛─
+  │ ┃   │
+  │ ┃   `Y` is a good letter too
+4 │ ┃   X1 Y1 Z1
+5 │ ┃   X2 Y2 Z2
+  ╰╴┗━━━━┛ `X` is a good letter
+
+"#,
+    );
+}
+
+#[test]
+fn different_overlap() {
+    test_harness(
+        r#"
+fn foo() {
+  X0 Y0 Z0
+  X1 Y1 Z1
+  X2 Y2 Z2
+  X3 Y3 Z3
+}
+"#,
+        vec![
+            SpanLabel {
+                start: Position { string: "Y0", count: 1 },
+                end: Position { string: "X2", count: 1 },
+                label: "`X` is a good letter",
+            },
+            SpanLabel {
+                start: Position { string: "Z1", count: 1 },
+                end: Position { string: "X3", count: 1 },
+                label: "`Y` is a good letter too",
+            },
+        ],
+        vec![],
+        r#"
+error: foo
+ --> test.rs:3:6
+  |
+3 |      X0 Y0 Z0
+  |  _______^
+4 | |    X1 Y1 Z1
+  | | _________-
+5 | ||   X2 Y2 Z2
+  | ||____^ `X` is a good letter
+6 |  |   X3 Y3 Z3
+  |  |____- `Y` is a good letter too
+
+"#,
+        r#"
+error: foo
+  ╭▸ test.rs:3:6
+  │
+3 │      X0 Y0 Z0
+  │ ┏━━━━━━━┛
+4 │ ┃    X1 Y1 Z1
+  │ ┃┌─────────┘
+5 │ ┃│   X2 Y2 Z2
+  │ ┗│━━━━┛ `X` is a good letter
+6 │  │   X3 Y3 Z3
+  ╰╴ └────┘ `Y` is a good letter too
+
+"#,
+    );
+}
+
+#[test]
+fn different_note_1() {
+    test_harness(
+        r#"
+fn foo() {
+  X0 Y0 Z0
+  X1 Y1 Z1
+  X2 Y2 Z2
+  X3 Y3 Z3
+}
+"#,
+        vec![SpanLabel {
+            start: Position { string: "Y0", count: 1 },
+            end: Position { string: "Z0", count: 1 },
+            label: "`X` is a good letter",
+        }],
+        vec![(None, "bar")],
+        r#"
+error: foo
+ --> test.rs:3:6
+  |
+3 |   X0 Y0 Z0
+  |      ^^^^^ `X` is a good letter
+  |
+  = note: bar
+
+"#,
+        r#"
+error: foo
+  ╭▸ test.rs:3:6
+  │
+3 │   X0 Y0 Z0
+  │      ━━━━━ `X` is a good letter
+  │
+  ╰ note: bar
+
+"#,
+    );
+}
+
+#[test]
+fn different_note_2() {
+    test_harness(
+        r#"
+fn foo() {
+  X0 Y0 Z0
+  X1 Y1 Z1
+  X2 Y2 Z2
+  X3 Y3 Z3
+}
+"#,
+        vec![SpanLabel {
+            start: Position { string: "Y0", count: 1 },
+            end: Position { string: "Z0", count: 1 },
+            label: "`X` is a good letter",
+        }],
+        vec![(None, "bar"), (None, "qux")],
+        r#"
+error: foo
+ --> test.rs:3:6
+  |
+3 |   X0 Y0 Z0
+  |      ^^^^^ `X` is a good letter
+  |
+  = note: bar
+  = note: qux
+
+"#,
+        r#"
+error: foo
+  ╭▸ test.rs:3:6
+  │
+3 │   X0 Y0 Z0
+  │      ━━━━━ `X` is a good letter
+  │
+  ├ note: bar
+  ╰ note: qux
+
+"#,
+    );
+}
+
+#[test]
+fn different_note_3() {
+    test_harness(
+        r#"
+fn foo() {
+  X0 Y0 Z0
+  X1 Y1 Z1
+  X2 Y2 Z2
+  X3 Y3 Z3
+}
+"#,
+        vec![SpanLabel {
+            start: Position { string: "Y0", count: 1 },
+            end: Position { string: "Z0", count: 1 },
+            label: "`X` is a good letter",
+        }],
+        vec![(None, "bar"), (None, "baz"), (None, "qux")],
+        r#"
+error: foo
+ --> test.rs:3:6
+  |
+3 |   X0 Y0 Z0
+  |      ^^^^^ `X` is a good letter
+  |
+  = note: bar
+  = note: baz
+  = note: qux
+
+"#,
+        r#"
+error: foo
+  ╭▸ test.rs:3:6
+  │
+3 │   X0 Y0 Z0
+  │      ━━━━━ `X` is a good letter
+  │
+  ├ note: bar
+  ├ note: baz
+  ╰ note: qux
+
+"#,
+    );
+}
+
+#[test]
+fn different_note_spanned_1() {
+    test_harness(
+        r#"
+fn foo() {
+  X0 Y0 Z0
+  X1 Y1 Z1
+  X2 Y2 Z2
+  X3 Y3 Z3
+}
+"#,
+        vec![SpanLabel {
+            start: Position { string: "Y0", count: 1 },
+            end: Position { string: "Z0", count: 1 },
+            label: "`X` is a good letter",
+        }],
+        vec![(
+            Some((Position { string: "X1", count: 1 }, Position { string: "Z1", count: 1 })),
+            "bar",
+        )],
+        r#"
+error: foo
+ --> test.rs:3:6
+  |
+3 |   X0 Y0 Z0
+  |      ^^^^^ `X` is a good letter
+  |
+note: bar
+ --> test.rs:4:3
+  |
+4 |   X1 Y1 Z1
+  |   ^^^^^^^^
+
+"#,
+        r#"
+error: foo
+  ╭▸ test.rs:3:6
+  │
+3 │   X0 Y0 Z0
+  │      ━━━━━ `X` is a good letter
+  ╰╴
+note: bar
+  ╭▸ test.rs:4:3
+  │
+4 │   X1 Y1 Z1
+  ╰╴  ━━━━━━━━
+
+"#,
+    );
+}
+
+#[test]
+fn different_note_spanned_2() {
+    test_harness(
+        r#"
+fn foo() {
+  X0 Y0 Z0
+  X1 Y1 Z1
+  X2 Y2 Z2
+  X3 Y3 Z3
+}
+"#,
+        vec![SpanLabel {
+            start: Position { string: "Y0", count: 1 },
+            end: Position { string: "Z0", count: 1 },
+            label: "`X` is a good letter",
+        }],
+        vec![
+            (
+                Some((Position { string: "X1", count: 1 }, Position { string: "Z1", count: 1 })),
+                "bar",
+            ),
+            (
+                Some((Position { string: "X2", count: 1 }, Position { string: "Y2", count: 1 })),
+                "qux",
+            ),
+        ],
+        r#"
+error: foo
+ --> test.rs:3:6
+  |
+3 |   X0 Y0 Z0
+  |      ^^^^^ `X` is a good letter
+  |
+note: bar
+ --> test.rs:4:3
+  |
+4 |   X1 Y1 Z1
+  |   ^^^^^^^^
+note: qux
+ --> test.rs:5:3
+  |
+5 |   X2 Y2 Z2
+  |   ^^^^^
+
+"#,
+        r#"
+error: foo
+  ╭▸ test.rs:3:6
+  │
+3 │   X0 Y0 Z0
+  │      ━━━━━ `X` is a good letter
+  ╰╴
+note: bar
+  ╭▸ test.rs:4:3
+  │
+4 │   X1 Y1 Z1
+  ╰╴  ━━━━━━━━
+note: qux
+  ╭▸ test.rs:5:3
+  │
+5 │   X2 Y2 Z2
+  ╰╴  ━━━━━
+
+"#,
+    );
+}
+
+#[test]
+fn different_note_spanned_3() {
+    test_harness(
+        r#"
+fn foo() {
+  X0 Y0 Z0
+  X1 Y1 Z1
+  X2 Y2 Z2
+  X3 Y3 Z3
+}
+"#,
+        vec![SpanLabel {
+            start: Position { string: "Y0", count: 1 },
+            end: Position { string: "Z0", count: 1 },
+            label: "`X` is a good letter",
+        }],
+        vec![
+            (
+                Some((Position { string: "X1", count: 1 }, Position { string: "Z1", count: 1 })),
+                "bar",
+            ),
+            (
+                Some((Position { string: "X1", count: 1 }, Position { string: "Z1", count: 1 })),
+                "baz",
+            ),
+            (
+                Some((Position { string: "X1", count: 1 }, Position { string: "Z1", count: 1 })),
+                "qux",
+            ),
+        ],
+        r#"
+error: foo
+ --> test.rs:3:6
+  |
+3 |   X0 Y0 Z0
+  |      ^^^^^ `X` is a good letter
+  |
+note: bar
+ --> test.rs:4:3
+  |
+4 |   X1 Y1 Z1
+  |   ^^^^^^^^
+note: baz
+ --> test.rs:4:3
+  |
+4 |   X1 Y1 Z1
+  |   ^^^^^^^^
+note: qux
+ --> test.rs:4:3
+  |
+4 |   X1 Y1 Z1
+  |   ^^^^^^^^
+
+"#,
+        r#"
+error: foo
+  ╭▸ test.rs:3:6
+  │
+3 │   X0 Y0 Z0
+  │      ━━━━━ `X` is a good letter
+  ╰╴
+note: bar
+  ╭▸ test.rs:4:3
+  │
+4 │   X1 Y1 Z1
+  ╰╴  ━━━━━━━━
+note: baz
+  ╭▸ test.rs:4:3
+  │
+4 │   X1 Y1 Z1
+  ╰╴  ━━━━━━━━
+note: qux
+  ╭▸ test.rs:4:3
+  │
+4 │   X1 Y1 Z1
+  ╰╴  ━━━━━━━━
+
+"#,
+    );
+}
+
+#[test]
+fn different_note_spanned_4() {
+    test_harness(
+        r#"
+fn foo() {
+  X0 Y0 Z0
+  X1 Y1 Z1
+  X2 Y2 Z2
+  X3 Y3 Z3
+}
+"#,
+        vec![SpanLabel {
+            start: Position { string: "Y0", count: 1 },
+            end: Position { string: "Z0", count: 1 },
+            label: "`X` is a good letter",
+        }],
+        vec![
+            (
+                Some((Position { string: "X1", count: 1 }, Position { string: "Z1", count: 1 })),
+                "bar",
+            ),
+            (None, "qux"),
+        ],
+        r#"
+error: foo
+ --> test.rs:3:6
+  |
+3 |   X0 Y0 Z0
+  |      ^^^^^ `X` is a good letter
+  |
+note: bar
+ --> test.rs:4:3
+  |
+4 |   X1 Y1 Z1
+  |   ^^^^^^^^
+  = note: qux
+
+"#,
+        r#"
+error: foo
+  ╭▸ test.rs:3:6
+  │
+3 │   X0 Y0 Z0
+  │      ━━━━━ `X` is a good letter
+  ╰╴
+note: bar
+  ╭▸ test.rs:4:3
+  │
+4 │   X1 Y1 Z1
+  │   ━━━━━━━━
+  ╰ note: qux
+
+"#,
+    );
+}
+
+#[test]
+fn different_note_spanned_5() {
+    test_harness(
+        r#"
+fn foo() {
+  X0 Y0 Z0
+  X1 Y1 Z1
+  X2 Y2 Z2
+  X3 Y3 Z3
+}
+"#,
+        vec![SpanLabel {
+            start: Position { string: "Y0", count: 1 },
+            end: Position { string: "Z0", count: 1 },
+            label: "`X` is a good letter",
+        }],
+        vec![
+            (None, "bar"),
+            (
+                Some((Position { string: "X1", count: 1 }, Position { string: "Z1", count: 1 })),
+                "qux",
+            ),
+        ],
+        r#"
+error: foo
+ --> test.rs:3:6
+  |
+3 |   X0 Y0 Z0
+  |      ^^^^^ `X` is a good letter
+  |
+  = note: bar
+note: qux
+ --> test.rs:4:3
+  |
+4 |   X1 Y1 Z1
+  |   ^^^^^^^^
+
+"#,
+        r#"
+error: foo
+  ╭▸ test.rs:3:6
+  │
+3 │   X0 Y0 Z0
+  │      ━━━━━ `X` is a good letter
+  │
+  ╰ note: bar
+note: qux
+  ╭▸ test.rs:4:3
+  │
+4 │   X1 Y1 Z1
+  ╰╴  ━━━━━━━━
+
+"#,
+    );
+}
+
+#[test]
+fn different_note_spanned_6() {
     test_harness(
         r#"
 fn foo() {
+  X0 Y0 Z0
+  X1 Y1 Z1
+  X2 Y2 Z2
+  X3 Y3 Z3
 }
 "#,
         vec![SpanLabel {
-            start: Position { string: "{", count: 1 },
-            end: Position { string: "}", count: 1 },
-            label: "test",
+            start: Position { string: "Y0", count: 1 },
+            end: Position { string: "Z0", count: 1 },
+            label: "`X` is a good letter",
         }],
+        vec![
+            (None, "bar"),
+            (
+                Some((Position { string: "X1", count: 1 }, Position { string: "Z1", count: 1 })),
+                "baz",
+            ),
+            (
+                Some((Position { string: "X1", count: 1 }, Position { string: "Z1", count: 1 })),
+                "qux",
+            ),
+        ],
         r#"
 error: foo
- --> test.rs:2:10
+ --> test.rs:3:6
   |
-2 |   fn foo() {
-  |  __________^
-3 | | }
-  | |_^ test
+3 |   X0 Y0 Z0
+  |      ^^^^^ `X` is a good letter
+  |
+  = note: bar
+note: baz
+ --> test.rs:4:3
+  |
+4 |   X1 Y1 Z1
+  |   ^^^^^^^^
+note: qux
+ --> test.rs:4:3
+  |
+4 |   X1 Y1 Z1
+  |   ^^^^^^^^
+
+"#,
+        r#"
+error: foo
+  ╭▸ test.rs:3:6
+  │
+3 │   X0 Y0 Z0
+  │      ━━━━━ `X` is a good letter
+  │
+  ╰ note: bar
+note: baz
+  ╭▸ test.rs:4:3
+  │
+4 │   X1 Y1 Z1
+  ╰╴  ━━━━━━━━
+note: qux
+  ╭▸ test.rs:4:3
+  │
+4 │   X1 Y1 Z1
+  ╰╴  ━━━━━━━━
 
 "#,
     );
 }
 
 #[test]
-fn ends_on_col2() {
+fn different_note_spanned_7() {
     test_harness(
         r#"
 fn foo() {
-
-
-  }
+  X0 Y0 Z0
+  X1 Y1 Z1
+  X2 Y2 Z2
+  X3 Y3 Z3
+}
 "#,
         vec![SpanLabel {
-            start: Position { string: "{", count: 1 },
-            end: Position { string: "}", count: 1 },
-            label: "test",
+            start: Position { string: "Y0", count: 1 },
+            end: Position { string: "Z0", count: 1 },
+            label: "`X` is a good letter",
         }],
+        vec![
+            (
+                Some((Position { string: "X1", count: 1 }, Position { string: "Z3", count: 1 })),
+                "bar",
+            ),
+            (None, "baz"),
+            (
+                Some((Position { string: "X1", count: 1 }, Position { string: "Z1", count: 1 })),
+                "qux",
+            ),
+        ],
         r#"
 error: foo
- --> test.rs:2:10
+ --> test.rs:3:6
   |
-2 |   fn foo() {
-  |  __________^
-... |
-5 | |   }
-  | |___^ test
+3 |   X0 Y0 Z0
+  |      ^^^^^ `X` is a good letter
+  |
+note: bar
+ --> test.rs:4:3
+  |
+4 | /   X1 Y1 Z1
+5 | |   X2 Y2 Z2
+6 | |   X3 Y3 Z3
+  | |__________^
+  = note: baz
+note: qux
+ --> test.rs:4:3
+  |
+4 |   X1 Y1 Z1
+  |   ^^^^^^^^
+
+"#,
+        r#"
+error: foo
+  ╭▸ test.rs:3:6
+  │
+3 │   X0 Y0 Z0
+  │      ━━━━━ `X` is a good letter
+  ╰╴
+note: bar
+  ╭▸ test.rs:4:3
+  │
+4 │ ┏   X1 Y1 Z1
+5 │ ┃   X2 Y2 Z2
+6 │ ┃   X3 Y3 Z3
+  │ ┗━━━━━━━━━━┛
+  ╰ note: baz
+note: qux
+  ╭▸ test.rs:4:3
+  │
+4 │   X1 Y1 Z1
+  ╰╴  ━━━━━━━━
 
 "#,
     );
 }
+
 #[test]
-fn non_nested() {
+fn different_note_spanned_8() {
     test_harness(
         r#"
 fn foo() {
-  X0 Y0
-  X1 Y1
-  X2 Y2
+  X0 Y0 Z0
+  X1 Y1 Z1
+  X2 Y2 Z2
+  X3 Y3 Z3
 }
 "#,
+        vec![SpanLabel {
+            start: Position { string: "Y0", count: 1 },
+            end: Position { string: "Z0", count: 1 },
+            label: "`X` is a good letter",
+        }],
         vec![
-            SpanLabel {
-                start: Position { string: "X0", count: 1 },
-                end: Position { string: "X2", count: 1 },
-                label: "`X` is a good letter",
-            },
-            SpanLabel {
-                start: Position { string: "Y0", count: 1 },
-                end: Position { string: "Y2", count: 1 },
-                label: "`Y` is a good letter too",
-            },
+            (
+                Some((Position { string: "X1", count: 1 }, Position { string: "Z1", count: 1 })),
+                "bar",
+            ),
+            (
+                Some((Position { string: "X1", count: 1 }, Position { string: "Z1", count: 1 })),
+                "baz",
+            ),
+            (None, "qux"),
         ],
         r#"
 error: foo
- --> test.rs:3:3
+ --> test.rs:3:6
   |
-3 |      X0 Y0
-  |  ____^  -
-  | | ______|
-4 | ||   X1 Y1
-5 | ||   X2 Y2
-  | ||____^__- `Y` is a good letter too
-  | |_____|
-  |       `X` is a good letter
+3 |   X0 Y0 Z0
+  |      ^^^^^ `X` is a good letter
+  |
+note: bar
+ --> test.rs:4:3
+  |
+4 |   X1 Y1 Z1
+  |   ^^^^^^^^
+note: baz
+ --> test.rs:4:3
+  |
+4 |   X1 Y1 Z1
+  |   ^^^^^^^^
+  = note: qux
+
+"#,
+        r#"
+error: foo
+  ╭▸ test.rs:3:6
+  │
+3 │   X0 Y0 Z0
+  │      ━━━━━ `X` is a good letter
+  ╰╴
+note: bar
+  ╭▸ test.rs:4:3
+  │
+4 │   X1 Y1 Z1
+  ╰╴  ━━━━━━━━
+note: baz
+  ╭▸ test.rs:4:3
+  │
+4 │   X1 Y1 Z1
+  │   ━━━━━━━━
+  ╰ note: qux
 
 "#,
     );
 }
 
 #[test]
-fn nested() {
+fn different_note_spanned_9() {
     test_harness(
         r#"
 fn foo() {
-  X0 Y0
-  Y1 X1
+  X0 Y0 Z0
+  X1 Y1 Z1
+  X2 Y2 Z2
+  X3 Y3 Z3
 }
 "#,
+        vec![SpanLabel {
+            start: Position { string: "Y0", count: 1 },
+            end: Position { string: "Z0", count: 1 },
+            label: "`X` is a good letter",
+        }],
         vec![
-            SpanLabel {
-                start: Position { string: "X0", count: 1 },
-                end: Position { string: "X1", count: 1 },
-                label: "`X` is a good letter",
-            },
-            SpanLabel {
-                start: Position { string: "Y0", count: 1 },
-                end: Position { string: "Y1", count: 1 },
-                label: "`Y` is a good letter too",
-            },
+            (None, "bar"),
+            (None, "baz"),
+            (
+                Some((Position { string: "X1", count: 1 }, Position { string: "Z1", count: 1 })),
+                "qux",
+            ),
         ],
         r#"
 error: foo
- --> test.rs:3:3
+ --> test.rs:3:6
   |
-3 |      X0 Y0
-  |  ____^  -
-  | | ______|
-4 | ||   Y1 X1
-  | ||____-__^ `X` is a good letter
-  |  |____|
-  |       `Y` is a good letter too
+3 |   X0 Y0 Z0
+  |      ^^^^^ `X` is a good letter
+  |
+  = note: bar
+  = note: baz
+note: qux
+ --> test.rs:4:3
+  |
+4 |   X1 Y1 Z1
+  |   ^^^^^^^^
+
+"#,
+        r#"
+error: foo
+  ╭▸ test.rs:3:6
+  │
+3 │   X0 Y0 Z0
+  │      ━━━━━ `X` is a good letter
+  │
+  ├ note: bar
+  ╰ note: baz
+note: qux
+  ╭▸ test.rs:4:3
+  │
+4 │   X1 Y1 Z1
+  ╰╴  ━━━━━━━━
 
 "#,
     );
 }
 
 #[test]
-fn different_overlap() {
+fn different_note_spanned_10() {
     test_harness(
         r#"
 fn foo() {
@@ -380,30 +1272,49 @@ fn foo() {
   X3 Y3 Z3
 }
 "#,
+        vec![SpanLabel {
+            start: Position { string: "Y0", count: 1 },
+            end: Position { string: "Z0", count: 1 },
+            label: "`X` is a good letter",
+        }],
         vec![
-            SpanLabel {
-                start: Position { string: "Y0", count: 1 },
-                end: Position { string: "X2", count: 1 },
-                label: "`X` is a good letter",
-            },
-            SpanLabel {
-                start: Position { string: "Z1", count: 1 },
-                end: Position { string: "X3", count: 1 },
-                label: "`Y` is a good letter too",
-            },
+            (
+                Some((Position { string: "X1", count: 1 }, Position { string: "Z1", count: 1 })),
+                "bar",
+            ),
+            (None, "baz"),
+            (None, "qux"),
         ],
         r#"
 error: foo
  --> test.rs:3:6
   |
-3 |      X0 Y0 Z0
-  |  _______^
-4 | |    X1 Y1 Z1
-  | | _________-
-5 | ||   X2 Y2 Z2
-  | ||____^ `X` is a good letter
-6 |  |   X3 Y3 Z3
-  |  |____- `Y` is a good letter too
+3 |   X0 Y0 Z0
+  |      ^^^^^ `X` is a good letter
+  |
+note: bar
+ --> test.rs:4:3
+  |
+4 |   X1 Y1 Z1
+  |   ^^^^^^^^
+  = note: baz
+  = note: qux
+
+"#,
+        r#"
+error: foo
+  ╭▸ test.rs:3:6
+  │
+3 │   X0 Y0 Z0
+  │      ━━━━━ `X` is a good letter
+  ╰╴
+note: bar
+  ╭▸ test.rs:4:3
+  │
+4 │   X1 Y1 Z1
+  │   ━━━━━━━━
+  ├ note: baz
+  ╰ note: qux
 
 "#,
     );
@@ -436,6 +1347,7 @@ fn foo() {
                 label: "`Z` label",
             },
         ],
+        vec![],
         r#"
 error: foo
  --> test.rs:3:3
@@ -451,6 +1363,22 @@ error: foo
   | |______|  `Y` is a good letter too
   |        `X` is a good letter
 
+"#,
+        r#"
+error: foo
+  ╭▸ test.rs:3:3
+  │
+3 │       X0 Y0 Z0
+  │ ┏━━━━━┛  │  │
+  │ ┃┌───────┘  │
+  │ ┃│┌─────────┘
+4 │ ┃││   X1 Y1 Z1
+5 │ ┃││   X2 Y2 Z2
+  │ ┃│└────╿──│──┘ `Z` label
+  │ ┃└─────│──┤
+  │ ┗━━━━━━┥  `Y` is a good letter too
+  ╰╴       `X` is a good letter
+
 "#,
     );
 }
@@ -482,6 +1410,7 @@ fn foo() {
                 label: "`Z` label",
             },
         ],
+        vec![],
         r#"
 error: foo
  --> test.rs:3:3
@@ -495,6 +1424,20 @@ error: foo
   | |____`Y` is a good letter too
   |      `Z` label
 
+"#,
+        r#"
+error: foo
+  ╭▸ test.rs:3:3
+  │
+3 │ ┏   X0 Y0 Z0
+4 │ ┃   X1 Y1 Z1
+5 │ ┃   X2 Y2 Z2
+  │ ┃    ╿
+  │ ┃    │
+  │ ┃    `X` is a good letter
+  │ ┗━━━━`Y` is a good letter too
+  ╰╴     `Z` label
+
 "#,
     );
 }
@@ -527,6 +1470,7 @@ fn foo() {
                 label: "`Z`",
             },
         ],
+        vec![],
         r#"
 error: foo
  --> test.rs:3:6
@@ -544,6 +1488,24 @@ error: foo
 6 |  |   X3 Y3 Z3
   |  |_______- `Z`
 
+"#,
+        r#"
+error: foo
+  ╭▸ test.rs:3:6
+  │
+3 │      X0 Y0 Z0
+  │ ┏━━━━━━━┛
+4 │ ┃    X1 Y1 Z1
+  │ ┃┌────╿─┘
+  │ ┗│━━━━┥
+  │  │    `X` is a good letter
+5 │  │   X2 Y2 Z2
+  │  └───│──────┘ `Y` is a good letter too
+  │  ┌───┘
+  │  │
+6 │  │   X3 Y3 Z3
+  ╰╴ └───────┘ `Z`
+
 "#,
     );
 }
@@ -571,6 +1533,7 @@ fn foo() {
                 label: "`Y` is a good letter too",
             },
         ],
+        vec![],
         r#"
 error: foo
  --> test.rs:3:3
@@ -583,6 +1546,19 @@ error: foo
 6 | |   X3 Y3 Z3
   | |__________- `Y` is a good letter too
 
+"#,
+        r#"
+error: foo
+  ╭▸ test.rs:3:3
+  │
+3 │ ┏   X0 Y0 Z0
+4 │ ┃   X1 Y1 Z1
+  │ ┗━━━━┛ `X` is a good letter
+5 │     X2 Y2 Z2
+  │ ┌──────┘
+6 │ │   X3 Y3 Z3
+  ╰╴└──────────┘ `Y` is a good letter too
+
 "#,
     );
 }
@@ -610,6 +1586,7 @@ fn foo() {
                 label: "`Y` is a good letter too",
             },
         ],
+        vec![],
         r#"
 error: foo
  --> test.rs:3:6
@@ -624,6 +1601,21 @@ error: foo
 6 |  |   X3 Y3 Z3
   |  |__________- `Y` is a good letter too
 
+"#,
+        r#"
+error: foo
+  ╭▸ test.rs:3:6
+  │
+3 │      X0 Y0 Z0
+  │ ┏━━━━━━━┛
+4 │ ┃    X1 Y1 Z1
+  │ ┃┌────╿────┘
+  │ ┗│━━━━┥
+  │  │    `X` is a good letter
+5 │  │   X2 Y2 Z2
+6 │  │   X3 Y3 Z3
+  ╰╴ └──────────┘ `Y` is a good letter too
+
 "#,
     );
 }
@@ -653,6 +1645,7 @@ fn foo() {
                 label: "",
             },
         ],
+        vec![],
         r#"
 error: foo
  --> test.rs:3:7
@@ -660,6 +1653,57 @@ error: foo
 3 |   a { b { c } d }
   |   ----^^^^-^^-- `a` is a good letter
 
+"#,
+        r#"
+error: foo
+  ╭▸ test.rs:3:7
+  │
+3 │   a { b { c } d }
+  ╰╴  ────━━━━─━━── `a` is a good letter
+
+"#,
+    );
+}
+
+#[test]
+fn multiline_notes() {
+    test_harness(
+        r#"
+fn foo() {
+  a { b { c } d }
+}
+"#,
+        vec![SpanLabel {
+            start: Position { string: "a", count: 1 },
+            end: Position { string: "d", count: 1 },
+            label: "`a` is a good letter",
+        }],
+        vec![(None, "foo\nbar"), (None, "foo\nbar")],
+        r#"
+error: foo
+ --> test.rs:3:3
+  |
+3 |   a { b { c } d }
+  |   ^^^^^^^^^^^^^ `a` is a good letter
+  |
+  = note: foo
+          bar
+  = note: foo
+          bar
+
+"#,
+        r#"
+error: foo
+  ╭▸ test.rs:3:3
+  │
+3 │   a { b { c } d }
+  │   ━━━━━━━━━━━━━ `a` is a good letter
+  │
+  ├ note: foo
+  │       bar
+  ╰ note: foo
+          bar
+
 "#,
     );
 }
@@ -684,6 +1728,7 @@ fn foo() {
                 label: "",
             },
         ],
+        vec![],
         r#"
 error: foo
  --> test.rs:3:3
@@ -691,6 +1736,14 @@ error: foo
 3 |   a { b { c } d }
   |   ^^^^-------^^ `a` is a good letter
 
+"#,
+        r#"
+error: foo
+  ╭▸ test.rs:3:3
+  │
+3 │   a { b { c } d }
+  ╰╴  ━━━━───────━━ `a` is a good letter
+
 "#,
     );
 }
@@ -720,6 +1773,7 @@ fn foo() {
                 label: "",
             },
         ],
+        vec![],
         r#"
 error: foo
  --> test.rs:3:7
@@ -729,6 +1783,16 @@ error: foo
   |       |
   |       `b` is a good letter
 
+"#,
+        r#"
+error: foo
+  ╭▸ test.rs:3:7
+  │
+3 │   a { b { c } d }
+  │   ────┯━━━─━━──
+  │       │
+  ╰╴      `b` is a good letter
+
 "#,
     );
 }
@@ -753,6 +1817,7 @@ fn foo() {
                 label: "`b` is a good letter",
             },
         ],
+        vec![],
         r#"
 error: foo
  --> test.rs:3:3
@@ -762,6 +1827,16 @@ error: foo
   |       |
   |       `b` is a good letter
 
+"#,
+        r#"
+error: foo
+  ╭▸ test.rs:3:3
+  │
+3 │   a { b { c } d }
+  │   ━━━━┬──────━━
+  │       │
+  ╰╴      `b` is a good letter
+
 "#,
     );
 }
@@ -786,6 +1861,7 @@ fn foo() {
                 label: "",
             },
         ],
+        vec![],
         r#"
 error: foo
  --> test.rs:3:3
@@ -795,6 +1871,16 @@ error: foo
   |   |
   |   `a` is a good letter
 
+"#,
+        r#"
+error: foo
+  ╭▸ test.rs:3:3
+  │
+3 │   a  bc  d
+  │   ┯━━━────
+  │   │
+  ╰╴  `a` is a good letter
+
 "#,
     );
 }
@@ -819,6 +1905,7 @@ fn foo() {
                 label: "",
             },
         ],
+        vec![],
         r#"
 error: foo
  --> test.rs:3:3
@@ -826,6 +1913,14 @@ error: foo
 3 |   a { b { c } d }
   |   ^^^^-------^^
 
+"#,
+        r#"
+error: foo
+  ╭▸ test.rs:3:3
+  │
+3 │   a { b { c } d }
+  ╰╴  ━━━━───────━━
+
 "#,
     );
 }
@@ -855,6 +1950,7 @@ fn foo() {
                 label: "",
             },
         ],
+        vec![],
         r#"
 error: foo
  --> test.rs:3:7
@@ -862,6 +1958,14 @@ error: foo
 3 |   a { b { c } d }
   |   ----^^^^-^^--
 
+"#,
+        r#"
+error: foo
+  ╭▸ test.rs:3:7
+  │
+3 │   a { b { c } d }
+  ╰╴  ────━━━━─━━──
+
 "#,
     );
 }
@@ -886,6 +1990,7 @@ fn foo() {
                 label: "`b` is a good letter",
             },
         ],
+        vec![],
         r#"
 error: foo
  --> test.rs:3:3
@@ -896,6 +2001,17 @@ error: foo
   |   |   `b` is a good letter
   |   `a` is a good letter
 
+"#,
+        r#"
+error: foo
+  ╭▸ test.rs:3:3
+  │
+3 │   a { b { c } d }
+  │   ┯━━━┬──────━━
+  │   │   │
+  │   │   `b` is a good letter
+  ╰╴  `a` is a good letter
+
 "#,
     );
 }
@@ -913,6 +2029,7 @@ fn foo() {
             end: Position { string: "d", count: 1 },
             label: "`a` is a good letter",
         }],
+        vec![],
         r#"
 error: foo
  --> test.rs:3:3
@@ -920,6 +2037,14 @@ error: foo
 3 |   a { b { c } d }
   |   ^^^^^^^^^^^^^ `a` is a good letter
 
+"#,
+        r#"
+error: foo
+  ╭▸ test.rs:3:3
+  │
+3 │   a { b { c } d }
+  ╰╴  ━━━━━━━━━━━━━ `a` is a good letter
+
 "#,
     );
 }
@@ -937,6 +2062,7 @@ fn foo() {
             end: Position { string: "d", count: 1 },
             label: "",
         }],
+        vec![],
         r#"
 error: foo
  --> test.rs:3:3
@@ -944,6 +2070,14 @@ error: foo
 3 |   a { b { c } d }
   |   ^^^^^^^^^^^^^
 
+"#,
+        r#"
+error: foo
+  ╭▸ test.rs:3:3
+  │
+3 │   a { b { c } d }
+  ╰╴  ━━━━━━━━━━━━━
+
 "#,
     );
 }
@@ -981,6 +2115,7 @@ fn foo() {
                 label: "`Y` is a good letter too",
             },
         ],
+        vec![],
         r#"
 error: foo
   --> test.rs:3:6
@@ -999,6 +2134,25 @@ error: foo
 16 |  |   X3 Y3 Z3
    |  |__________- `Y` is a good letter too
 
+"#,
+        r#"
+error: foo
+   ╭▸ test.rs:3:6
+   │
+3  │      X0 Y0 Z0
+   │ ┏━━━━━━━┛
+4  │ ┃    X1 Y1 Z1
+   │ ┃┌────╿────┘
+   │ ┗│━━━━┥
+   │  │    `X` is a good letter
+5  │  │ 1
+6  │  │ 2
+7  │  │ 3
+   ‡  │
+15 │  │   X2 Y2 Z2
+16 │  │   X3 Y3 Z3
+   ╰╴ └──────────┘ `Y` is a good letter too
+
 "#,
     );
 }
@@ -1036,6 +2190,7 @@ fn foo() {
                 label: "`Z` is a good letter too",
             },
         ],
+        vec![],
         r#"
 error: foo
   --> test.rs:3:6
@@ -1057,6 +2212,28 @@ error: foo
 16 | |    X3 Y3 Z3
    | |________^ `Y` is a good letter
 
+"#,
+        r#"
+error: foo
+   ╭▸ test.rs:3:6
+   │
+3  │      X0 Y0 Z0
+   │ ┏━━━━━━━┛
+4  │ ┃  1
+5  │ ┃  2
+6  │ ┃  3
+7  │ ┃    X1 Y1 Z1
+   │ ┃┌─────────┘
+8  │ ┃│ 4
+9  │ ┃│ 5
+10 │ ┃│ 6
+11 │ ┃│   X2 Y2 Z2
+   │ ┃└──────────┘ `Z` is a good letter too
+   ‡ ┃
+15 │ ┃  10
+16 │ ┃    X3 Y3 Z3
+   ╰╴┗━━━━━━━━┛ `Y` is a good letter
+
 "#,
     );
 }
diff --git a/compiler/rustc_session/src/config.rs b/compiler/rustc_session/src/config.rs
index fa2403db92551..41cbca89af5ad 100644
--- a/compiler/rustc_session/src/config.rs
+++ b/compiler/rustc_session/src/config.rs
@@ -1721,6 +1721,9 @@ pub fn parse_json(early_dcx: &EarlyDiagCtxt, matches: &getopts::Matches) -> Json
         for sub_option in option.split(',') {
             match sub_option {
                 "diagnostic-short" => json_rendered = HumanReadableErrorType::Short,
+                "diagnostic-unicode" => {
+                    json_rendered = HumanReadableErrorType::Unicode;
+                }
                 "diagnostic-rendered-ansi" => json_color = ColorConfig::Always,
                 "artifacts" => json_artifact_notifications = true,
                 "unused-externs" => json_unused_externs = JsonUnusedExterns::Loud,
@@ -1767,14 +1770,17 @@ pub fn parse_error_format(
                 ErrorOutputType::Json { pretty: true, json_rendered, color_config: json_color }
             }
             Some("short") => ErrorOutputType::HumanReadable(HumanReadableErrorType::Short, color),
+            Some("human-unicode") => {
+                ErrorOutputType::HumanReadable(HumanReadableErrorType::Unicode, color)
+            }
             Some(arg) => {
                 early_dcx.abort_if_error_and_set_error_format(ErrorOutputType::HumanReadable(
                     HumanReadableErrorType::Default,
                     color,
                 ));
                 early_dcx.early_fatal(format!(
-                    "argument for `--error-format` must be `human`, `json` or \
-                     `short` (instead was `{arg}`)"
+                    "argument for `--error-format` must be `human`, `human-annotate-rs`, \
+                    `human-unicode`, `json`, `pretty-json` or `short` (instead was `{arg}`)"
                 ))
             }
         }
@@ -1827,18 +1833,21 @@ pub fn parse_crate_edition(early_dcx: &EarlyDiagCtxt, matches: &getopts::Matches
 fn check_error_format_stability(
     early_dcx: &EarlyDiagCtxt,
     unstable_opts: &UnstableOptions,
-    error_format: ErrorOutputType,
+    format: ErrorOutputType,
 ) {
-    if !unstable_opts.unstable_options {
-        if let ErrorOutputType::Json { pretty: true, .. } = error_format {
-            early_dcx.early_fatal("`--error-format=pretty-json` is unstable");
-        }
-        if let ErrorOutputType::HumanReadable(HumanReadableErrorType::AnnotateSnippet, _) =
-            error_format
-        {
-            early_dcx.early_fatal("`--error-format=human-annotate-rs` is unstable");
-        }
-    }
+    if unstable_opts.unstable_options {
+        return;
+    }
+    let format = match format {
+        ErrorOutputType::Json { pretty: true, .. } => "pretty-json",
+        ErrorOutputType::HumanReadable(format, _) => match format {
+            HumanReadableErrorType::AnnotateSnippet => "human-annotate-rs",
+            HumanReadableErrorType::Unicode => "human-unicode",
+            _ => return,
+        },
+        _ => return,
+    };
+    early_dcx.early_fatal(format!("`--error-format={format}` is unstable"))
 }
 
 fn parse_output_types(
diff --git a/compiler/rustc_session/src/session.rs b/compiler/rustc_session/src/session.rs
index 9d9434a77760d..d8d6b79974fe1 100644
--- a/compiler/rustc_session/src/session.rs
+++ b/compiler/rustc_session/src/session.rs
@@ -16,7 +16,9 @@ use rustc_data_structures::sync::{
 };
 use rustc_errors::annotate_snippet_emitter_writer::AnnotateSnippetEmitter;
 use rustc_errors::codes::*;
-use rustc_errors::emitter::{DynEmitter, HumanEmitter, HumanReadableErrorType, stderr_destination};
+use rustc_errors::emitter::{
+    DynEmitter, HumanEmitter, HumanReadableErrorType, OutputTheme, stderr_destination,
+};
 use rustc_errors::json::JsonEmitter;
 use rustc_errors::registry::Registry;
 use rustc_errors::{
@@ -966,6 +968,11 @@ fn default_emitter(
                     .macro_backtrace(macro_backtrace)
                     .track_diagnostics(track_diagnostics)
                     .terminal_url(terminal_url)
+                    .theme(if let HumanReadableErrorType::Unicode = kind {
+                        OutputTheme::Unicode
+                    } else {
+                        OutputTheme::Ascii
+                    })
                     .ignored_directories_in_source_blocks(
                         sopts.unstable_opts.ignore_directory_in_diagnostics_source_blocks.clone(),
                     );
@@ -1470,6 +1477,11 @@ fn mk_emitter(output: ErrorOutputType) -> Box<DynEmitter> {
             let short = kind.short();
             Box::new(
                 HumanEmitter::new(stderr_destination(color_config), fallback_bundle)
+                    .theme(if let HumanReadableErrorType::Unicode = kind {
+                        OutputTheme::Unicode
+                    } else {
+                        OutputTheme::Ascii
+                    })
                     .short_message(short),
             )
         }
diff --git a/compiler/rustc_span/src/lib.rs b/compiler/rustc_span/src/lib.rs
index 5b1be5bca0593..ef775068515ef 100644
--- a/compiler/rustc_span/src/lib.rs
+++ b/compiler/rustc_span/src/lib.rs
@@ -2223,6 +2223,10 @@ pub fn char_width(ch: char) -> usize {
     }
 }
 
+pub fn str_width(s: &str) -> usize {
+    s.chars().map(char_width).sum()
+}
+
 /// Normalizes the source code and records the normalizations.
 fn normalize_src(src: &mut String) -> Vec<NormalizedPos> {
     let mut normalized_pos = vec![];
diff --git a/src/librustdoc/core.rs b/src/librustdoc/core.rs
index 7ba3cfb66bd23..d5f6bfe415de8 100644
--- a/src/librustdoc/core.rs
+++ b/src/librustdoc/core.rs
@@ -6,7 +6,9 @@ use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexMap};
 use rustc_data_structures::sync::Lrc;
 use rustc_data_structures::unord::UnordSet;
 use rustc_errors::codes::*;
-use rustc_errors::emitter::{DynEmitter, HumanEmitter, stderr_destination};
+use rustc_errors::emitter::{
+    DynEmitter, HumanEmitter, HumanReadableErrorType, OutputTheme, stderr_destination,
+};
 use rustc_errors::json::JsonEmitter;
 use rustc_errors::{ErrorGuaranteed, TerminalUrl};
 use rustc_feature::UnstableFeatures;
@@ -154,6 +156,11 @@ pub(crate) fn new_dcx(
                     .teach(unstable_opts.teach)
                     .diagnostic_width(diagnostic_width)
                     .track_diagnostics(unstable_opts.track_diagnostics)
+                    .theme(if let HumanReadableErrorType::Unicode = kind {
+                        OutputTheme::Unicode
+                    } else {
+                        OutputTheme::Ascii
+                    })
                     .ui_testing(unstable_opts.ui_testing),
             )
         }
diff --git a/src/librustdoc/doctest.rs b/src/librustdoc/doctest.rs
index 11d8f1947d6ef..25e576e9e63aa 100644
--- a/src/librustdoc/doctest.rs
+++ b/src/librustdoc/doctest.rs
@@ -15,6 +15,7 @@ pub(crate) use make::DocTestBuilder;
 pub(crate) use markdown::test as test_markdown;
 use rustc_ast as ast;
 use rustc_data_structures::fx::{FxHashMap, FxIndexMap, FxIndexSet};
+use rustc_errors::emitter::HumanReadableErrorType;
 use rustc_errors::{ColorConfig, DiagCtxtHandle, ErrorGuaranteed, FatalError};
 use rustc_hir::CRATE_HIR_ID;
 use rustc_hir::def_id::LOCAL_CRATE;
@@ -520,10 +521,14 @@ fn run_test(
     });
     if let ErrorOutputType::HumanReadable(kind, color_config) = rustdoc_options.error_format {
         let short = kind.short();
+        let unicode = kind == HumanReadableErrorType::Unicode;
 
         if short {
             compiler.arg("--error-format").arg("short");
         }
+        if unicode {
+            compiler.arg("--error-format").arg("human-unicode");
+        }
 
         match color_config {
             ColorConfig::Never => {
diff --git a/src/tools/clippy/tests/ui/empty_line_after/doc_comments.stderr b/src/tools/clippy/tests/ui/empty_line_after/doc_comments.stderr
index c238b4c9a17f2..2852e26680f65 100644
--- a/src/tools/clippy/tests/ui/empty_line_after/doc_comments.stderr
+++ b/src/tools/clippy/tests/ui/empty_line_after/doc_comments.stderr
@@ -3,7 +3,7 @@ error: empty line after doc comment
    |
 LL | / /// for the crate
 LL | |
-   | |_
+   | |_^
 LL |   fn first_in_crate() {}
    |   ------------------- the comment documents this function
    |
@@ -22,7 +22,7 @@ error: empty line after doc comment
    |
 LL | /     /// for the module
 LL | |
-   | |_
+   | |_^
 LL |       fn first_in_module() {}
    |       -------------------- the comment documents this function
    |
@@ -39,7 +39,7 @@ error: empty line after doc comment
    |
 LL | /     /// # Indented
 LL | |
-   | |_
+   | |_^
 LL |       /// Blank line
 LL |       fn indented() {}
    |       ------------- the comment documents this function
@@ -55,7 +55,7 @@ error: empty line after doc comment
    |
 LL | / /// This should produce a warning
 LL | |
-   | |_
+   | |_^
 LL |   fn with_doc_and_newline() {}
    |   ------------------------- the comment documents this function
    |
@@ -69,7 +69,7 @@ LL | |
 LL | | /** This is also a doc comment and is part of the warning
 LL | |  */
 LL | |
-   | |_
+   | |_^
 ...
 LL |   fn three_attributes() {}
    |   --------------------- the comment documents this function
@@ -82,7 +82,7 @@ error: empty line after doc comment
 LL | /     /// docs for `old_code`
 LL | |     // fn old_code() {}
 LL | |
-   | |_
+   | |_^
 LL |       fn new_code() {}
    |       ------------- the comment documents this function
    |
@@ -102,7 +102,7 @@ LL | |     /// Docs
 LL | |     /// for OldB
 LL | |     // struct OldB;
 LL | |
-   | |_
+   | |_^
 ...
 LL |       struct Multiple;
    |       --------------- the comment documents this struct
@@ -125,7 +125,7 @@ LL | /     /**
 LL | |      * Meant to be inner doc comment
 LL | |      */
 LL | |
-   | |_
+   | |_^
 LL |       fn first_in_module() {}
    |       -------------------- the comment documents this function
    |
@@ -143,7 +143,7 @@ LL | |      * Docs for `old_code`
 LL | |      */
 LL | |     /* fn old_code() {} */
 LL | |
-   | |_
+   | |_^
 ...
 LL |       fn new_code() {}
    |       ------------- the comment documents this function
@@ -161,7 +161,7 @@ error: empty line after doc comment
 LL | /     /// Docs for `old_code2`
 LL | |     /* fn old_code2() {} */
 LL | |
-   | |_
+   | |_^
 LL |       /// Docs for `new_code2`
 LL |       fn new_code2() {}
    |       -------------- the comment documents this function
diff --git a/src/tools/clippy/tests/ui/empty_line_after/outer_attribute.stderr b/src/tools/clippy/tests/ui/empty_line_after/outer_attribute.stderr
index 958b40424a928..75fc23e9e7ebd 100644
--- a/src/tools/clippy/tests/ui/empty_line_after/outer_attribute.stderr
+++ b/src/tools/clippy/tests/ui/empty_line_after/outer_attribute.stderr
@@ -3,7 +3,7 @@ error: empty line after outer attribute
    |
 LL | / #[crate_type = "lib"]
 LL | |
-   | |_
+   | |_^
 LL |   fn first_in_crate() {}
    |   ------------------- the attribute applies to this function
    |
@@ -20,7 +20,7 @@ error: empty line after outer attribute
    |
 LL | / #[inline]
 LL | |
-   | |_
+   | |_^
 LL |   /// some comment
 LL |   fn with_one_newline_and_comment() {}
    |   --------------------------------- the attribute applies to this function
@@ -32,7 +32,7 @@ error: empty line after outer attribute
    |
 LL | / #[inline]
 LL | |
-   | |_
+   | |_^
 LL |   fn with_one_newline() {}
    |   --------------------- the attribute applies to this function
    |
@@ -44,7 +44,7 @@ error: empty lines after outer attribute
 LL | /     #[crate_type = "lib"]
 LL | |
 LL | |
-   | |_
+   | |_^
 LL |       fn with_two_newlines() {}
    |       ---------------------- the attribute applies to this function
    |
@@ -59,7 +59,7 @@ error: empty line after outer attribute
    |
 LL | / #[doc = "doc attributes should be considered attributes"]
 LL | |
-   | |_
+   | |_^
 LL |   enum Baz {
    |   -------- the attribute applies to this enum
    |
@@ -70,7 +70,7 @@ error: empty line after outer attribute
    |
 LL | / #[repr(C)]
 LL | |
-   | |_
+   | |_^
 LL |   struct Foo {
    |   ---------- the attribute applies to this struct
    |
@@ -81,7 +81,7 @@ error: empty line after outer attribute
    |
 LL | / #[allow(dead_code)]
 LL | |
-   | |_
+   | |_^
 LL |   mod foo {}
    |   ------- the attribute applies to this module
    |
@@ -93,7 +93,7 @@ error: empty line after outer attribute
 LL | / #[inline]
 LL | | // Still lint cases where the empty line does not immediately follow the attribute
 LL | |
-   | |_
+   | |_^
 LL |   fn comment_before_empty_line() {}
    |   ------------------------------ the attribute applies to this function
    |
@@ -106,7 +106,7 @@ LL | / #[allow(unused)]
 LL | |
 LL | | // This comment is isolated
 LL | |
-   | |_
+   | |_^
 LL |   pub fn isolated_comment() {}
    |   ------------------------- the attribute applies to this function
    |
diff --git a/src/tools/clippy/tests/ui/four_forward_slashes.stderr b/src/tools/clippy/tests/ui/four_forward_slashes.stderr
index a2218ea4d10b0..3606a2227a001 100644
--- a/src/tools/clippy/tests/ui/four_forward_slashes.stderr
+++ b/src/tools/clippy/tests/ui/four_forward_slashes.stderr
@@ -3,7 +3,7 @@ error: this item has comments with 4 forward slashes (`////`). These look like d
    |
 LL | / //// whoops
 LL | | fn a() {}
-   | |_
+   | |_^
    |
    = note: `-D clippy::four-forward-slashes` implied by `-D warnings`
    = help: to override `-D warnings` add `#[allow(clippy::four_forward_slashes)]`
@@ -18,7 +18,7 @@ error: this item has comments with 4 forward slashes (`////`). These look like d
 LL | / //// whoops
 LL | | #[allow(dead_code)]
 LL | | fn b() {}
-   | |_
+   | |_^
    |
 help: make this a doc comment by removing one `/`
    |
@@ -32,7 +32,7 @@ LL | / //// whoops
 LL | | //// two borked comments!
 LL | | #[track_caller]
 LL | | fn c() {}
-   | |_
+   | |_^
    |
 help: turn these into doc comments by removing one `/`
    |
@@ -46,7 +46,7 @@ error: this item has comments with 4 forward slashes (`////`). These look like d
 LL | / //// between attributes
 LL | | #[allow(dead_code)]
 LL | | fn g() {}
-   | |_
+   | |_^
    |
 help: make this a doc comment by removing one `/`
    |
@@ -58,7 +58,7 @@ error: this item has comments with 4 forward slashes (`////`). These look like d
    |
 LL | /     //// not very start of contents
 LL | | fn h() {}
-   | |_
+   | |_^
    |
 help: make this a doc comment by removing one `/`
    |
diff --git a/src/tools/clippy/tests/ui/four_forward_slashes_first_line.stderr b/src/tools/clippy/tests/ui/four_forward_slashes_first_line.stderr
index 23937034b7e28..81732346412a3 100644
--- a/src/tools/clippy/tests/ui/four_forward_slashes_first_line.stderr
+++ b/src/tools/clippy/tests/ui/four_forward_slashes_first_line.stderr
@@ -3,7 +3,7 @@ error: this item has comments with 4 forward slashes (`////`). These look like d
    |
 LL | / //// borked doc comment on the first line. doesn't combust!
 LL | | fn a() {}
-   | |_
+   | |_^
    |
    = note: `-D clippy::four-forward-slashes` implied by `-D warnings`
    = help: to override `-D warnings` add `#[allow(clippy::four_forward_slashes)]`
diff --git a/src/tools/clippy/tests/ui/too_long_first_doc_paragraph-fix.stderr b/src/tools/clippy/tests/ui/too_long_first_doc_paragraph-fix.stderr
index 6403265a39c54..6ef333f0cfd29 100644
--- a/src/tools/clippy/tests/ui/too_long_first_doc_paragraph-fix.stderr
+++ b/src/tools/clippy/tests/ui/too_long_first_doc_paragraph-fix.stderr
@@ -6,7 +6,7 @@ LL | | /// A much longer explanation that goes into a lot more detail about
 LL | | /// how the thing works, possibly with doclinks and so one,
 LL | | /// and probably spanning a many rows. Blablabla, it needs to be over
 LL | | /// 200 characters so I needed to write something longeeeeeeer.
-   | |_
+   | |_^
    |
    = note: `-D clippy::too-long-first-doc-paragraph` implied by `-D warnings`
    = help: to override `-D warnings` add `#[allow(clippy::too_long_first_doc_paragraph)]`
diff --git a/src/tools/clippy/tests/ui/too_long_first_doc_paragraph.stderr b/src/tools/clippy/tests/ui/too_long_first_doc_paragraph.stderr
index 39926647f5437..95f42349b9b35 100644
--- a/src/tools/clippy/tests/ui/too_long_first_doc_paragraph.stderr
+++ b/src/tools/clippy/tests/ui/too_long_first_doc_paragraph.stderr
@@ -23,7 +23,7 @@ error: first doc comment paragraph is too long
 LL | / /// Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nunc turpis nunc, lacinia
 LL | | /// a dolor in, pellentesque aliquet enim. Cras nec maximus sem. Mauris arcu libero,
 LL | | /// gravida non lacinia at, rhoncus eu lacus.
-   | |_
+   | |_^
 
 error: first doc comment paragraph is too long
   --> tests/ui/too_long_first_doc_paragraph.rs:36:1
@@ -32,7 +32,7 @@ LL | / /// Lorem
 LL | | /// ipsum dolor sit amet, consectetur adipiscing elit. Nunc turpis nunc, lacinia
 LL | | /// a dolor in, pellentesque aliquet enim. Cras nec maximus sem. Mauris arcu libero,
 LL | | /// gravida non lacinia at, rhoncus eu lacus.
-   | |_
+   | |_^
 
 error: aborting due to 3 previous errors
 
diff --git a/tests/rustdoc-ui/invalid-syntax.stderr b/tests/rustdoc-ui/invalid-syntax.stderr
index 46d7cdb4f7e64..c6e1f6fd41384 100644
--- a/tests/rustdoc-ui/invalid-syntax.stderr
+++ b/tests/rustdoc-ui/invalid-syntax.stderr
@@ -130,7 +130,7 @@ warning: could not parse code block as Rust code
 LL |   ///     \____/
    |  _________^
 LL | | ///
-   | |_
+   | |_^
    |
    = note: error from rustc: unknown start of token: \
 
diff --git a/tests/ui/codemap_tests/huge_multispan_highlight.svg b/tests/ui/codemap_tests/huge_multispan_highlight.ascii.svg
similarity index 94%
rename from tests/ui/codemap_tests/huge_multispan_highlight.svg
rename to tests/ui/codemap_tests/huge_multispan_highlight.ascii.svg
index 12058176dc0f1..6f46df0101e73 100644
--- a/tests/ui/codemap_tests/huge_multispan_highlight.svg
+++ b/tests/ui/codemap_tests/huge_multispan_highlight.ascii.svg
@@ -1,4 +1,4 @@
-<svg width="818px" height="848px" xmlns="http://www.w3.org/2000/svg">
+<svg width="743px" height="848px" xmlns="http://www.w3.org/2000/svg">
   <style>
     .fg { fill: #AAAAAA }
     .bg { background: #000000 }
@@ -21,7 +21,7 @@
   <text xml:space="preserve" class="container fg">
     <tspan x="10px" y="28px"><tspan class="fg-ansi256-009 bold">error[E0308]</tspan><tspan class="bold">: `match` arms have incompatible types</tspan>
 </tspan>
-    <tspan x="10px" y="46px"><tspan>  </tspan><tspan class="fg-ansi256-012 bold">--&gt; </tspan><tspan>$DIR/huge_multispan_highlight.rs:96:18</tspan>
+    <tspan x="10px" y="46px"><tspan>  </tspan><tspan class="fg-ansi256-012 bold">--&gt; </tspan><tspan>$DIR/huge_multispan_highlight.rs:99:18</tspan>
 </tspan>
     <tspan x="10px" y="64px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan>
 </tspan>
@@ -31,7 +31,7 @@
 </tspan>
     <tspan x="10px" y="118px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan>           true =&gt; (</tspan>
 </tspan>
-    <tspan x="10px" y="136px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan>  </tspan><tspan class="fg-ansi256-012 bold">_________________-</tspan>
+    <tspan x="10px" y="136px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold"> _________________-</tspan>
 </tspan>
     <tspan x="10px" y="154px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan>             // last line shown in multispan header</tspan>
 </tspan>
@@ -45,7 +45,7 @@
 </tspan>
     <tspan x="10px" y="244px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan>           false =&gt; "</tspan>
 </tspan>
-    <tspan x="10px" y="262px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan>  </tspan><tspan class="fg-ansi256-009 bold">__________________^</tspan>
+    <tspan x="10px" y="262px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold"> __________________^</tspan>
 </tspan>
     <tspan x="10px" y="280px"><tspan class="fg-ansi256-012 bold">...</tspan><tspan>  </tspan><tspan class="fg-ansi256-009 bold">|</tspan>
 </tspan>
@@ -59,7 +59,7 @@
 </tspan>
     <tspan x="10px" y="370px"><tspan class="fg-ansi256-009 bold">error[E0308]</tspan><tspan class="bold">: `match` arms have incompatible types</tspan>
 </tspan>
-    <tspan x="10px" y="388px"><tspan>  </tspan><tspan class="fg-ansi256-012 bold">--&gt; </tspan><tspan>$DIR/huge_multispan_highlight.rs:213:18</tspan>
+    <tspan x="10px" y="388px"><tspan>  </tspan><tspan class="fg-ansi256-012 bold">--&gt; </tspan><tspan>$DIR/huge_multispan_highlight.rs:216:18</tspan>
 </tspan>
     <tspan x="10px" y="406px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan>
 </tspan>
@@ -69,7 +69,7 @@
 </tspan>
     <tspan x="10px" y="460px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan>           true =&gt; (</tspan>
 </tspan>
-    <tspan x="10px" y="478px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan>  </tspan><tspan class="fg-ansi256-012 bold">_________________-</tspan>
+    <tspan x="10px" y="478px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold"> _________________-</tspan>
 </tspan>
     <tspan x="10px" y="496px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan>
 </tspan>
@@ -85,7 +85,7 @@
 </tspan>
     <tspan x="10px" y="604px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan>           false =&gt; "</tspan>
 </tspan>
-    <tspan x="10px" y="622px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan>  </tspan><tspan class="fg-ansi256-009 bold">__________________^</tspan>
+    <tspan x="10px" y="622px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold"> __________________^</tspan>
 </tspan>
     <tspan x="10px" y="640px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">|</tspan>
 </tspan>
diff --git a/tests/ui/codemap_tests/huge_multispan_highlight.rs b/tests/ui/codemap_tests/huge_multispan_highlight.rs
index 28c595cca6425..7d7b757082350 100644
--- a/tests/ui/codemap_tests/huge_multispan_highlight.rs
+++ b/tests/ui/codemap_tests/huge_multispan_highlight.rs
@@ -1,4 +1,7 @@
-//@ compile-flags: --error-format=human --color=always
+//@ revisions: ascii unicode
+//@ compile-flags: --color=always
+//@[ascii] compile-flags: --error-format=human
+//@[unicode] compile-flags: -Zunstable-options=yes --error-format=human-unicode
 //@ ignore-windows
 fn main() {
     let _ = match true {
diff --git a/tests/ui/codemap_tests/huge_multispan_highlight.unicode.svg b/tests/ui/codemap_tests/huge_multispan_highlight.unicode.svg
new file mode 100644
index 0000000000000..4e1a8d14a28d7
--- /dev/null
+++ b/tests/ui/codemap_tests/huge_multispan_highlight.unicode.svg
@@ -0,0 +1,116 @@
+<svg width="743px" height="848px" xmlns="http://www.w3.org/2000/svg">
+  <style>
+    .fg { fill: #AAAAAA }
+    .bg { background: #000000 }
+    .fg-ansi256-009 { fill: #FF5555 }
+    .fg-ansi256-012 { fill: #5555FF }
+    .container {
+      padding: 0 10px;
+      line-height: 18px;
+    }
+    .bold { font-weight: bold; }
+    tspan {
+      font: 14px SFMono-Regular, Consolas, Liberation Mono, Menlo, monospace;
+      white-space: pre;
+      line-height: 18px;
+    }
+  </style>
+
+  <rect width="100%" height="100%" y="0" rx="4.5" class="bg" />
+
+  <text xml:space="preserve" class="container fg">
+    <tspan x="10px" y="28px"><tspan class="fg-ansi256-009 bold">error[E0308]</tspan><tspan class="bold">: `match` arms have incompatible types</tspan>
+</tspan>
+    <tspan x="10px" y="46px"><tspan>  </tspan><tspan class="fg-ansi256-012 bold"> ╭▸ </tspan><tspan>$DIR/huge_multispan_highlight.rs:99:18</tspan>
+</tspan>
+    <tspan x="10px" y="64px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">│</tspan>
+</tspan>
+    <tspan x="10px" y="82px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">│</tspan><tspan>       let _ = match true {</tspan>
+</tspan>
+    <tspan x="10px" y="100px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">│</tspan><tspan>               </tspan><tspan class="fg-ansi256-012 bold">──────────</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">`match` arms have incompatible types</tspan>
+</tspan>
+    <tspan x="10px" y="118px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">│</tspan><tspan>           true =&gt; (</tspan>
+</tspan>
+    <tspan x="10px" y="136px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">│</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">┌─────────────────┘</tspan>
+</tspan>
+    <tspan x="10px" y="154px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">│</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">│</tspan><tspan>             // last line shown in multispan header</tspan>
+</tspan>
+    <tspan x="10px" y="172px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">‡</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">│</tspan>
+</tspan>
+    <tspan x="10px" y="190px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">│</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">│</tspan>
+</tspan>
+    <tspan x="10px" y="208px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">│</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">│</tspan><tspan>         ),</tspan>
+</tspan>
+    <tspan x="10px" y="226px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">│</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">└─────────┘</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">this is found to be of type `()`</tspan>
+</tspan>
+    <tspan x="10px" y="244px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">│</tspan><tspan>           false =&gt; "</tspan>
+</tspan>
+    <tspan x="10px" y="262px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">│</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">┏━━━━━━━━━━━━━━━━━━┛</tspan>
+</tspan>
+    <tspan x="10px" y="280px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">‡</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">┃</tspan>
+</tspan>
+    <tspan x="10px" y="298px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">│</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">┃</tspan>
+</tspan>
+    <tspan x="10px" y="316px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">│</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">┃</tspan><tspan>         ",</tspan>
+</tspan>
+    <tspan x="10px" y="334px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">╰╴</tspan><tspan class="fg-ansi256-009 bold">┗━━━━━━━━━┛</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">expected `()`, found `&amp;str`</tspan>
+</tspan>
+    <tspan x="10px" y="352px">
+</tspan>
+    <tspan x="10px" y="370px"><tspan class="fg-ansi256-009 bold">error[E0308]</tspan><tspan class="bold">: `match` arms have incompatible types</tspan>
+</tspan>
+    <tspan x="10px" y="388px"><tspan>  </tspan><tspan class="fg-ansi256-012 bold"> ╭▸ </tspan><tspan>$DIR/huge_multispan_highlight.rs:216:18</tspan>
+</tspan>
+    <tspan x="10px" y="406px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">│</tspan>
+</tspan>
+    <tspan x="10px" y="424px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">│</tspan><tspan>       let _ = match true {</tspan>
+</tspan>
+    <tspan x="10px" y="442px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">│</tspan><tspan>               </tspan><tspan class="fg-ansi256-012 bold">──────────</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">`match` arms have incompatible types</tspan>
+</tspan>
+    <tspan x="10px" y="460px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">│</tspan><tspan>           true =&gt; (</tspan>
+</tspan>
+    <tspan x="10px" y="478px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">│</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">┌─────────────────┘</tspan>
+</tspan>
+    <tspan x="10px" y="496px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">│</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">│</tspan>
+</tspan>
+    <tspan x="10px" y="514px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">│</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">│</tspan><tspan>         1 // last line shown in multispan header</tspan>
+</tspan>
+    <tspan x="10px" y="532px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">‡</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">│</tspan>
+</tspan>
+    <tspan x="10px" y="550px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">│</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">│</tspan>
+</tspan>
+    <tspan x="10px" y="568px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">│</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">│</tspan><tspan>         ),</tspan>
+</tspan>
+    <tspan x="10px" y="586px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">│</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">└─────────┘</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">this is found to be of type `{integer}`</tspan>
+</tspan>
+    <tspan x="10px" y="604px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">│</tspan><tspan>           false =&gt; "</tspan>
+</tspan>
+    <tspan x="10px" y="622px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">│</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">┏━━━━━━━━━━━━━━━━━━┛</tspan>
+</tspan>
+    <tspan x="10px" y="640px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">│</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">┃</tspan>
+</tspan>
+    <tspan x="10px" y="658px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">│</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">┃</tspan>
+</tspan>
+    <tspan x="10px" y="676px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">│</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">┃</tspan><tspan>         1 last line shown in multispan</tspan>
+</tspan>
+    <tspan x="10px" y="694px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">‡</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">┃</tspan>
+</tspan>
+    <tspan x="10px" y="712px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">│</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">┃</tspan>
+</tspan>
+    <tspan x="10px" y="730px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">│</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">┃</tspan><tspan>         ",</tspan>
+</tspan>
+    <tspan x="10px" y="748px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">╰╴</tspan><tspan class="fg-ansi256-009 bold">┗━━━━━━━━━┛</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">expected integer, found `&amp;str`</tspan>
+</tspan>
+    <tspan x="10px" y="766px">
+</tspan>
+    <tspan x="10px" y="784px"><tspan class="fg-ansi256-009 bold">error</tspan><tspan class="bold">: aborting due to 2 previous errors</tspan>
+</tspan>
+    <tspan x="10px" y="802px">
+</tspan>
+    <tspan x="10px" y="820px"><tspan class="bold">For more information about this error, try `rustc --explain E0308`.</tspan>
+</tspan>
+    <tspan x="10px" y="838px">
+</tspan>
+  </text>
+
+</svg>
diff --git a/tests/ui/diagnostic-width/E0271.stderr b/tests/ui/diagnostic-width/E0271.ascii.stderr
similarity index 94%
rename from tests/ui/diagnostic-width/E0271.stderr
rename to tests/ui/diagnostic-width/E0271.ascii.stderr
index 31ec3fe366f4b..e276299e9e8ef 100644
--- a/tests/ui/diagnostic-width/E0271.stderr
+++ b/tests/ui/diagnostic-width/E0271.ascii.stderr
@@ -1,5 +1,5 @@
 error[E0271]: type mismatch resolving `<Result<Result<(), Result<Result<(), Result<Result<(), Option<{integer}>>, ...>>, ...>>, ...> as Future>::Error == Foo`
-  --> $DIR/E0271.rs:18:5
+  --> $DIR/E0271.rs:20:5
    |
 LL | /     Box::new(
 LL | |         Ok::<_, ()>(
@@ -11,7 +11,7 @@ LL | |     )
    | |_____^ type mismatch resolving `<Result<Result<(), Result<Result<(), ...>, ...>>, ...> as Future>::Error == Foo`
    |
 note: expected this to be `Foo`
-  --> $DIR/E0271.rs:8:18
+  --> $DIR/E0271.rs:10:18
    |
 LL |     type Error = E;
    |                  ^
diff --git a/tests/ui/diagnostic-width/E0271.rs b/tests/ui/diagnostic-width/E0271.rs
index d8cb24898ac30..ce41ad2952bc9 100644
--- a/tests/ui/diagnostic-width/E0271.rs
+++ b/tests/ui/diagnostic-width/E0271.rs
@@ -1,4 +1,6 @@
-//@ compile-flags: --diagnostic-width=40
+//@ revisions: ascii unicode
+//@[ascii] compile-flags: --diagnostic-width=40
+//@[unicode] compile-flags: -Zunstable-options=yes --error-format=human-unicode --diagnostic-width=40
 //@ normalize-stderr-test: "long-type-\d+" -> "long-type-hash"
 trait Future {
     type Error;
@@ -15,7 +17,7 @@ impl<T> Future for Option<T> {
 struct Foo;
 
 fn foo() -> Box<dyn Future<Error=Foo>> {
-    Box::new( //~ ERROR E0271
+    Box::new( //[ascii]~ ERROR E0271
         Ok::<_, ()>(
             Err::<(), _>(
                 Ok::<_, ()>(
diff --git a/tests/ui/diagnostic-width/E0271.unicode.stderr b/tests/ui/diagnostic-width/E0271.unicode.stderr
new file mode 100644
index 0000000000000..4a96ca36cd78d
--- /dev/null
+++ b/tests/ui/diagnostic-width/E0271.unicode.stderr
@@ -0,0 +1,22 @@
+error[E0271]: type mismatch resolving `<Result<Result<(), Result<Result<(), Result<Result<(), Option<{integer}>>, ...>>, ...>>, ...> as Future>::Error == Foo`
+   ╭▸ $DIR/E0271.rs:20:5
+   │
+LL │ ┏     Box::new(
+LL │ ┃         Ok::<_, ()>(
+LL │ ┃             Err::<(), _>(
+LL │ ┃                 Ok::<_, ()>(
+   ‡ ┃
+LL │ ┃         )
+LL │ ┃     )
+   │ ┗━━━━━┛ type mismatch resolving `<Result<Result<(), Result<Result<(), ...>, ...>>, ...> as Future>::Error == Foo`
+   ╰╴
+note: expected this to be `Foo`
+   ╭▸ $DIR/E0271.rs:10:18
+   │
+LL │     type Error = E;
+   │                  ━
+   ╰ note: required for the cast from `Box<Result<Result<(), Result<Result<(), Result<Result<(), Option<{integer}>>, ()>>, ()>>, ()>>` to `Box<(dyn Future<Error = Foo> + 'static)>`
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0271`.
diff --git a/tests/ui/diagnostic-width/flag-human.stderr b/tests/ui/diagnostic-width/flag-human.ascii.stderr
similarity index 89%
rename from tests/ui/diagnostic-width/flag-human.stderr
rename to tests/ui/diagnostic-width/flag-human.ascii.stderr
index eaa9684108069..4593304e087d2 100644
--- a/tests/ui/diagnostic-width/flag-human.stderr
+++ b/tests/ui/diagnostic-width/flag-human.ascii.stderr
@@ -1,5 +1,5 @@
 error[E0308]: mismatched types
-  --> $DIR/flag-human.rs:7:17
+  --> $DIR/flag-human.rs:9:17
    |
 LL | ..._: () = 42;
    |       --   ^^ expected `()`, found integer
diff --git a/tests/ui/diagnostic-width/flag-human.rs b/tests/ui/diagnostic-width/flag-human.rs
index a46122ed78350..1af4165914164 100644
--- a/tests/ui/diagnostic-width/flag-human.rs
+++ b/tests/ui/diagnostic-width/flag-human.rs
@@ -1,9 +1,11 @@
-//@ compile-flags: --diagnostic-width=20
+//@ revisions: ascii unicode
+//@[ascii] compile-flags: --diagnostic-width=20
+//@[unicode] compile-flags: -Zunstable-options=yes --error-format=human-unicode --diagnostic-width=20
 
 // This test checks that `-Z output-width` effects the human error output by restricting it to an
 // arbitrarily low value so that the effect is visible.
 
 fn main() {
     let _: () = 42;
-    //~^ ERROR mismatched types
+    //[ascii]~^ ERROR mismatched types
 }
diff --git a/tests/ui/diagnostic-width/flag-human.unicode.stderr b/tests/ui/diagnostic-width/flag-human.unicode.stderr
new file mode 100644
index 0000000000000..50176564786b1
--- /dev/null
+++ b/tests/ui/diagnostic-width/flag-human.unicode.stderr
@@ -0,0 +1,11 @@
+error[E0308]: mismatched types
+   ╭▸ $DIR/flag-human.rs:9:17
+   │
+LL │ …t _: () = 42;
+   │       ┬─   ━━ expected `()`, found integer
+   │       │
+   ╰╴      expected due to this
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/tests/ui/diagnostic-width/long-E0308.stderr b/tests/ui/diagnostic-width/long-E0308.ascii.stderr
similarity index 88%
rename from tests/ui/diagnostic-width/long-E0308.stderr
rename to tests/ui/diagnostic-width/long-E0308.ascii.stderr
index eb37da037e9d7..d45d6bf329bd3 100644
--- a/tests/ui/diagnostic-width/long-E0308.stderr
+++ b/tests/ui/diagnostic-width/long-E0308.ascii.stderr
@@ -1,5 +1,5 @@
 error[E0308]: mismatched types
-  --> $DIR/long-E0308.rs:44:9
+  --> $DIR/long-E0308.rs:46:9
    |
 LL |        let x: Atype<
    |  _____________-
@@ -20,11 +20,11 @@ LL |  |     ))))))))))))))))))))))))))))));
    |
    = note: expected struct `Atype<Btype<..., ...>, ...>`
                 found enum `Result<Result<..., ...>, ...>`
-   = note: the full type name has been written to '$TEST_BUILD_DIR/diagnostic-width/long-E0308/long-E0308.long-type-hash.txt'
+   = note: the full type name has been written to '$TEST_BUILD_DIR/diagnostic-width/long-E0308.ascii/long-E0308.long-type-hash.txt'
    = note: consider using `--verbose` to print the full type name to the console
 
 error[E0308]: mismatched types
-  --> $DIR/long-E0308.rs:57:26
+  --> $DIR/long-E0308.rs:59:26
    |
 LL |       ))))))))))))))))) == Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(O...
    |  __________________________^
@@ -36,11 +36,11 @@ LL | |     ))))))))))))))))))))))));
    |
    = note: expected enum `Option<Result<..., ...>>`
               found enum `Result<Result<..., ...>, ...>`
-   = note: the full type name has been written to '$TEST_BUILD_DIR/diagnostic-width/long-E0308/long-E0308.long-type-hash.txt'
+   = note: the full type name has been written to '$TEST_BUILD_DIR/diagnostic-width/long-E0308.ascii/long-E0308.long-type-hash.txt'
    = note: consider using `--verbose` to print the full type name to the console
 
 error[E0308]: mismatched types
-  --> $DIR/long-E0308.rs:88:9
+  --> $DIR/long-E0308.rs:90:9
    |
 LL |       let x: Atype<
    |  ____________-
@@ -56,11 +56,11 @@ LL | |     > = ();
    |
    = note: expected struct `Atype<Btype<..., ...>, ...>`
            found unit type `()`
-   = note: the full type name has been written to '$TEST_BUILD_DIR/diagnostic-width/long-E0308/long-E0308.long-type-hash.txt'
+   = note: the full type name has been written to '$TEST_BUILD_DIR/diagnostic-width/long-E0308.ascii/long-E0308.long-type-hash.txt'
    = note: consider using `--verbose` to print the full type name to the console
 
 error[E0308]: mismatched types
-  --> $DIR/long-E0308.rs:91:17
+  --> $DIR/long-E0308.rs:93:17
    |
 LL |       let _: () = Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(O...
    |  ____________--___^
@@ -74,7 +74,7 @@ LL | |     ))))))))))))))))))))))));
    |
    = note: expected unit type `()`
                    found enum `Result<Result<..., ...>, ...>`
-   = note: the full type name has been written to '$TEST_BUILD_DIR/diagnostic-width/long-E0308/long-E0308.long-type-hash.txt'
+   = note: the full type name has been written to '$TEST_BUILD_DIR/diagnostic-width/long-E0308.ascii/long-E0308.long-type-hash.txt'
    = note: consider using `--verbose` to print the full type name to the console
 
 error: aborting due to 4 previous errors
diff --git a/tests/ui/diagnostic-width/long-E0308.rs b/tests/ui/diagnostic-width/long-E0308.rs
index 150164ba21b4d..73f81f5872a64 100644
--- a/tests/ui/diagnostic-width/long-E0308.rs
+++ b/tests/ui/diagnostic-width/long-E0308.rs
@@ -1,4 +1,6 @@
-//@ compile-flags: --diagnostic-width=60 -Zwrite-long-types-to-disk=yes
+//@ revisions: ascii unicode
+//@[ascii] compile-flags: --diagnostic-width=60 -Zwrite-long-types-to-disk=yes
+//@[unicode] compile-flags: -Zunstable-options=yes --json=diagnostic-unicode --diagnostic-width=60 -Zwrite-long-types-to-disk=yes
 //@ normalize-stderr-test: "long-type-\d+" -> "long-type-hash"
 
 mod a {
diff --git a/tests/ui/diagnostic-width/long-E0308.unicode.stderr b/tests/ui/diagnostic-width/long-E0308.unicode.stderr
new file mode 100644
index 0000000000000..3e8d881d7a6b1
--- /dev/null
+++ b/tests/ui/diagnostic-width/long-E0308.unicode.stderr
@@ -0,0 +1,82 @@
+error[E0308]: mismatched types
+   ╭▸ $DIR/long-E0308.rs:46:9
+   │
+LL │        let x: Atype<
+   │ ┌─────────────┘
+LL │ │        Btype<
+LL │ │          Ctype<
+LL │ │            Atype<
+   ‡ │
+LL │ │        i32
+LL │ │      > = Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(O…
+   │ │┏━━━━━│━━━┛
+   │ └┃─────┤
+   │  ┃     expected due to this
+LL │  ┃         Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(O…
+LL │  ┃             Ok("")
+LL │  ┃         ))))))))))))))))))))))))))))))
+LL │  ┃     ))))))))))))))))))))))))))))));
+   │  ┗━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┛ expected `Atype<Btype<..., ...>, ...>`, found `Result<Result<..., ...>, ...>`
+   │
+   ├ note: expected struct `Atype<Btype<..., ...>, ...>`
+   │            found enum `Result<Result<..., ...>, ...>`
+   ├ note: the full type name has been written to '$TEST_BUILD_DIR/diagnostic-width/long-E0308.unicode/long-E0308.long-type-hash.txt'
+   ╰ note: consider using `--verbose` to print the full type name to the console
+
+error[E0308]: mismatched types
+   ╭▸ $DIR/long-E0308.rs:59:26
+   │
+LL │       ))))))))))))))))) == Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(…
+   │ ┏━━━━━━━━━━━━━━━━━━━━━━━━━━┛
+LL │ ┃         Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok…
+LL │ ┃             Ok(Ok(Ok(Ok(Ok(Ok(Ok("")))))))
+LL │ ┃         ))))))))))))))))))))))))))))))
+LL │ ┃     ))))))))))))))))))))))));
+   │ ┗━━━━━━━━━━━━━━━━━━━━━━━━━━━━┛ expected `Option<Result<..., ...>>`, found `Result<Result<..., ...>, ...>`
+   │
+   ├ note: expected enum `Option<Result<..., ...>>`
+   │          found enum `Result<Result<..., ...>, ...>`
+   ├ note: the full type name has been written to '$TEST_BUILD_DIR/diagnostic-width/long-E0308.unicode/long-E0308.long-type-hash.txt'
+   ╰ note: consider using `--verbose` to print the full type name to the console
+
+error[E0308]: mismatched types
+   ╭▸ $DIR/long-E0308.rs:90:9
+   │
+LL │       let x: Atype<
+   │ ┌────────────┘
+LL │ │       Btype<
+LL │ │         Ctype<
+LL │ │           Atype<
+   ‡ │
+LL │ │       i32
+LL │ │     > = ();
+   │ │     │   ━━ expected `Atype<Btype<..., ...>, ...>`, found `()`
+   │ └─────┤
+   │       expected due to this
+   │
+   ├ note: expected struct `Atype<Btype<..., ...>, ...>`
+   │       found unit type `()`
+   ├ note: the full type name has been written to '$TEST_BUILD_DIR/diagnostic-width/long-E0308.unicode/long-E0308.long-type-hash.txt'
+   ╰ note: consider using `--verbose` to print the full type name to the console
+
+error[E0308]: mismatched types
+   ╭▸ $DIR/long-E0308.rs:93:17
+   │
+LL │       let _: () = Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(…
+   │ ┏━━━━━━━━━━━━┬─━━━┛
+   │ ┃            │
+   │ ┃            expected due to this
+LL │ ┃         Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok(Ok…
+LL │ ┃             Ok(Ok(Ok(Ok(Ok(Ok(Ok("")))))))
+LL │ ┃         ))))))))))))))))))))))))))))))
+LL │ ┃     ))))))))))))))))))))))));
+   │ ┗━━━━━━━━━━━━━━━━━━━━━━━━━━━━┛ expected `()`, found `Result<Result<..., ...>, ...>`
+   │
+   ├ note: expected unit type `()`
+   │               found enum `Result<Result<..., ...>, ...>`
+   ├ note: the full type name has been written to '$TEST_BUILD_DIR/diagnostic-width/long-E0308.unicode/long-E0308.long-type-hash.txt'
+   ╰ note: consider using `--verbose` to print the full type name to the console
+
+error: aborting due to 4 previous errors
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/tests/ui/diagnostic-width/non-1-width-unicode-multiline-label.stderr b/tests/ui/diagnostic-width/non-1-width-unicode-multiline-label.ascii.stderr
similarity index 97%
rename from tests/ui/diagnostic-width/non-1-width-unicode-multiline-label.stderr
rename to tests/ui/diagnostic-width/non-1-width-unicode-multiline-label.ascii.stderr
index 8f200e15c64d8..4d8afb6f3ad9b 100644
--- a/tests/ui/diagnostic-width/non-1-width-unicode-multiline-label.stderr
+++ b/tests/ui/diagnostic-width/non-1-width-unicode-multiline-label.ascii.stderr
@@ -1,5 +1,5 @@
 error[E0369]: cannot add `&str` to `&str`
-  --> $DIR/non-1-width-unicode-multiline-label.rs:5:260
+  --> $DIR/non-1-width-unicode-multiline-label.rs:7:260
    |
 LL | ...ཽཾཿ྄ཱྀྀྂྃ྅྆྇ྈྉྊྋྌྍྎྏྐྑྒྒྷྔྕྖྗ྘ྙྚྛྜྜྷྞྟྠྡྡྷྣྤྥྦྦྷྨྩྪྫྫྷྭྮྯྰྱྲླྴྵྶྷྸྐྵྺྻྼ྽྾྿࿀࿁࿂࿃࿄࿅࿆࿇...࿋࿌࿍࿎࿏࿐࿑࿒࿓࿔࿕࿖࿗࿘࿙࿚"; let _a = unicode_is_fun + " really fun!";
    |                                                  -------------- ^ -------------- &str
diff --git a/tests/ui/diagnostic-width/non-1-width-unicode-multiline-label.rs b/tests/ui/diagnostic-width/non-1-width-unicode-multiline-label.rs
index 1989ea8863592..61c4b31e03a62 100644
--- a/tests/ui/diagnostic-width/non-1-width-unicode-multiline-label.rs
+++ b/tests/ui/diagnostic-width/non-1-width-unicode-multiline-label.rs
@@ -1,7 +1,9 @@
+//@ revisions: ascii unicode
+//@[unicode] compile-flags: -Zunstable-options=yes --error-format=human-unicode
 // ignore-tidy-linelength
 
 fn main() {
     let unicode_is_fun = "؁‱ஹ௸௵꧄.ဪ꧅⸻𒈙𒐫﷽𒌄𒈟𒍼𒁎𒀱𒌧𒅃 𒈓𒍙𒊎𒄡𒅌𒁏𒀰𒐪𒐩𒈙𒐫𪚥";
     let _ = "ༀ༁༂༃༄༅༆༇༈༉༊་༌།༎༏༐༑༒༓༔༕༖༗༘༙༚༛༜༝༞༟༠༡༢༣༤༥༦༧༨༩༪༫༬༭༮༯༰༱༲༳༴༵༶༷༸༹༺༻༼༽༾༿ཀཁགགྷངཅཆཇ཈ཉཊཋཌཌྷཎཏཐདདྷནཔཕབབྷམཙཚཛཛྷཝཞཟའཡརལཤཥསཧཨཀྵཪཫཬ཭཮཯཰ཱཱཱིིུུྲྀཷླྀཹེཻོཽཾཿ྄ཱྀྀྂྃ྅྆྇ྈྉྊྋྌྍྎྏྐྑྒྒྷྔྕྖྗ྘ྙྚྛྜྜྷྞྟྠྡྡྷྣྤྥྦྦྷྨྩྪྫྫྷྭྮྯྰྱྲླྴྵྶྷྸྐྵྺྻྼ྽྾྿࿀࿁࿂࿃࿄࿅࿆࿇࿈࿉࿊࿋࿌࿍࿎࿏࿐࿑࿒࿓࿔࿕࿖࿗࿘࿙࿚"; let _a = unicode_is_fun + " really fun!";
-    //~^ ERROR cannot add `&str` to `&str`
+    //[ascii]~^ ERROR cannot add `&str` to `&str`
 }
diff --git a/tests/ui/diagnostic-width/non-1-width-unicode-multiline-label.unicode.stderr b/tests/ui/diagnostic-width/non-1-width-unicode-multiline-label.unicode.stderr
new file mode 100644
index 0000000000000..ed8ce770bb7ea
--- /dev/null
+++ b/tests/ui/diagnostic-width/non-1-width-unicode-multiline-label.unicode.stderr
@@ -0,0 +1,18 @@
+error[E0369]: cannot add `&str` to `&str`
+   ╭▸ $DIR/non-1-width-unicode-multiline-label.rs:7:260
+   │
+LL │ …ཻོཽཾཿ྄ཱྀྀྂྃ྅྆྇ྈྉྊྋྌྍྎྏྐྑྒྒྷྔྕྖྗ྘ྙྚྛྜྜྷྞྟྠྡྡྷྣྤྥྦྦྷྨྩྪྫྫྷྭྮྯྰྱྲླྴྵྶྷྸྐྵྺྻྼ྽྾྿࿀࿁࿂࿃࿄࿅࿆࿇࿈࿉…࿋࿌࿍࿎࿏࿐࿑࿒࿓࿔࿕࿖࿗࿘࿙࿚"; let _a = unicode_is_fun + " really fun!";
+   │                                                  ┬───────────── ┯ ────────────── &str
+   │                                                  │              │
+   │                                                  │              `+` cannot be used to concatenate two `&str` strings
+   │                                                  &str
+   │
+   ╰ note: string concatenation requires an owned `String` on the left
+help: create an owned `String` from a string reference
+   ╭╴
+LL │     let _ = "ༀ༁༂༃༄༅༆༇༈༉༊་༌།༎༏༐༑༒༓༔༕༖༗༘༙༚༛༜༝༞༟༠༡༢༣༤༥༦༧༨༩༪༫༬༭༮༯༰༱༲༳༴༵༶༷༸༹༺༻༼༽༾༿ཀཁགགྷངཅཆཇ཈ཉཊཋཌཌྷཎཏཐདདྷནཔཕབབྷམཙཚཛཛྷཝཞཟའཡརལཤཥསཧཨཀྵཪཫཬ཭཮཯཰ཱཱཱིིུུྲྀཷླྀཹེཻོཽཾཿ྄ཱྀྀྂྃ྅྆྇ྈྉྊྋྌྍྎྏྐྑྒྒྷྔྕྖྗ྘ྙྚྛྜྜྷྞྟྠྡྡྷྣྤྥྦྦྷྨྩྪྫྫྷྭྮྯྰྱྲླྴྵྶྷྸྐྵྺྻྼ྽྾྿࿀࿁࿂࿃࿄࿅࿆࿇࿈࿉࿊࿋࿌࿍࿎࿏࿐࿑࿒࿓࿔࿕࿖࿗࿘࿙࿚"; let _a = unicode_is_fun.to_owned() + " really fun!";
+   ╰╴                                                                                                                                                                                        +++++++++++
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0369`.
diff --git a/tests/ui/diagnostic-width/non-whitespace-trimming-2.stderr b/tests/ui/diagnostic-width/non-whitespace-trimming-2.ascii.stderr
similarity index 91%
rename from tests/ui/diagnostic-width/non-whitespace-trimming-2.stderr
rename to tests/ui/diagnostic-width/non-whitespace-trimming-2.ascii.stderr
index a7d5c0bfb9415..70bd149545cfe 100644
--- a/tests/ui/diagnostic-width/non-whitespace-trimming-2.stderr
+++ b/tests/ui/diagnostic-width/non-whitespace-trimming-2.ascii.stderr
@@ -1,5 +1,5 @@
 error[E0308]: mismatched types
-  --> $DIR/non-whitespace-trimming-2.rs:4:311
+  --> $DIR/non-whitespace-trimming-2.rs:6:311
    |
 LL | ...13; let _: usize = 14; let _: usize = 15; let _: () = 42; let _: usize = 0; let _: usize = 1; let _: usize = 2; let _: usize = 3; let ...
    |                                                     --   ^^ expected `()`, found integer
diff --git a/tests/ui/diagnostic-width/non-whitespace-trimming-2.rs b/tests/ui/diagnostic-width/non-whitespace-trimming-2.rs
index abd9e189a7537..283506bd6c90d 100644
--- a/tests/ui/diagnostic-width/non-whitespace-trimming-2.rs
+++ b/tests/ui/diagnostic-width/non-whitespace-trimming-2.rs
@@ -1,6 +1,8 @@
+//@ revisions: ascii unicode
+//@[unicode] compile-flags: -Zunstable-options=yes --error-format=human-unicode
 // ignore-tidy-linelength
 
 fn main() {
     let _: usize = 0; let _: usize = 1; let _: usize = 2; let _: usize = 3; let _: usize = 4; let _: usize = 5; let _: usize = 6; let _: usize = 7; let _: usize = 8; let _: usize = 9; let _: usize = 10; let _: usize = 11; let _: usize = 12; let _: usize = 13; let _: usize = 14; let _: usize = 15; let _: () = 42; let _: usize = 0; let _: usize = 1; let _: usize = 2; let _: usize = 3; let _: usize = 4; let _: usize = 5; let _: usize = 6; let _: usize = 7; let _: usize = 8; let _: usize = 9; let _: usize = 10; let _: usize = 11; let _: usize = 12; let _: usize = 13; let _: usize = 14; let _: usize = 15;
-//~^ ERROR mismatched types
+//[ascii]~^ ERROR mismatched types
 }
diff --git a/tests/ui/diagnostic-width/non-whitespace-trimming-2.unicode.stderr b/tests/ui/diagnostic-width/non-whitespace-trimming-2.unicode.stderr
new file mode 100644
index 0000000000000..600d196de1673
--- /dev/null
+++ b/tests/ui/diagnostic-width/non-whitespace-trimming-2.unicode.stderr
@@ -0,0 +1,11 @@
+error[E0308]: mismatched types
+   ╭▸ $DIR/non-whitespace-trimming-2.rs:6:311
+   │
+LL │ …= 13; let _: usize = 14; let _: usize = 15; let _: () = 42; let _: usize = 0; let _: usize = 1; let _: usize = 2; let _: usize = 3; let _:…
+   │                                                     ┬─   ━━ expected `()`, found integer
+   │                                                     │
+   ╰╴                                                    expected due to this
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/tests/ui/error-emitter/highlighting.svg b/tests/ui/error-emitter/highlighting.svg
index be92c00c19bdc..a4019c78f4841 100644
--- a/tests/ui/error-emitter/highlighting.svg
+++ b/tests/ui/error-emitter/highlighting.svg
@@ -49,7 +49,7 @@
 </tspan>
     <tspan x="10px" y="262px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan>   fn query(_: fn(Box&lt;(dyn Any + Send + '_)&gt;) -&gt; Pin&lt;Box&lt;(</tspan>
 </tspan>
-    <tspan x="10px" y="280px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan>  </tspan><tspan class="fg-ansi256-012 bold">____</tspan><tspan class="fg-ansi256-010 bold">^^^^^</tspan><tspan class="fg-ansi256-012 bold">_-</tspan>
+    <tspan x="10px" y="280px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold"> ____</tspan><tspan class="fg-ansi256-010 bold">^^^^^</tspan><tspan class="fg-ansi256-012 bold">_-</tspan>
 </tspan>
     <tspan x="10px" y="298px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">|</tspan><tspan>     dyn Future&lt;Output = Result&lt;Box&lt;(dyn Any + 'static)&gt;, String&gt;&gt; + Send + 'static</tspan>
 </tspan>
diff --git a/tests/ui/error-emitter/highlighting.windows.svg b/tests/ui/error-emitter/highlighting.windows.svg
index 152245da9ddc1..c2378113b86f5 100644
--- a/tests/ui/error-emitter/highlighting.windows.svg
+++ b/tests/ui/error-emitter/highlighting.windows.svg
@@ -50,7 +50,7 @@
 </tspan>
     <tspan x="10px" y="262px"><tspan class="fg-ansi256-014 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-014 bold">|</tspan><tspan>   fn query(_: fn(Box&lt;(dyn Any + Send + '_)&gt;) -&gt; Pin&lt;Box&lt;(</tspan>
 </tspan>
-    <tspan x="10px" y="280px"><tspan>   </tspan><tspan class="fg-ansi256-014 bold">|</tspan><tspan>  </tspan><tspan class="fg-ansi256-014 bold">____</tspan><tspan class="fg-ansi256-010 bold">^^^^^</tspan><tspan class="fg-ansi256-014 bold">_-</tspan>
+    <tspan x="10px" y="280px"><tspan>   </tspan><tspan class="fg-ansi256-014 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-014 bold"> ____</tspan><tspan class="fg-ansi256-010 bold">^^^^^</tspan><tspan class="fg-ansi256-014 bold">_-</tspan>
 </tspan>
     <tspan x="10px" y="298px"><tspan class="fg-ansi256-014 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-014 bold">|</tspan><tspan> </tspan><tspan class="fg-ansi256-014 bold">|</tspan><tspan>     dyn Future&lt;Output = Result&lt;Box&lt;(dyn Any + 'static)&gt;, String&gt;&gt; + Send + 'static</tspan>
 </tspan>
diff --git a/tests/ui/error-emitter/unicode-output.rs b/tests/ui/error-emitter/unicode-output.rs
new file mode 100644
index 0000000000000..ba6db37b66c22
--- /dev/null
+++ b/tests/ui/error-emitter/unicode-output.rs
@@ -0,0 +1,21 @@
+//@ compile-flags: -Zunstable-options=yes --error-format=human-unicode --color=always
+//@ edition:2018
+//@ only-linux
+
+use core::pin::Pin;
+use core::future::Future;
+use core::any::Any;
+
+fn query(_: fn(Box<(dyn Any + Send + '_)>) -> Pin<Box<(
+    dyn Future<Output = Result<Box<(dyn Any + 'static)>, String>> + Send + 'static
+)>>) {}
+
+fn wrapped_fn<'a>(_: Box<(dyn Any + Send)>) -> Pin<Box<(
+    dyn Future<Output = Result<Box<(dyn Any + 'static)>, String>> + Send + 'static
+)>> {
+    Box::pin(async { Err("nope".into()) })
+}
+
+fn main() {
+    query(wrapped_fn);
+}
diff --git a/tests/ui/error-emitter/unicode-output.svg b/tests/ui/error-emitter/unicode-output.svg
new file mode 100644
index 0000000000000..f98fd8b74032b
--- /dev/null
+++ b/tests/ui/error-emitter/unicode-output.svg
@@ -0,0 +1,72 @@
+<svg width="785px" height="434px" xmlns="http://www.w3.org/2000/svg">
+  <style>
+    .fg { fill: #AAAAAA }
+    .bg { background: #000000 }
+    .fg-ansi256-009 { fill: #FF5555 }
+    .fg-ansi256-010 { fill: #55FF55 }
+    .fg-ansi256-012 { fill: #5555FF }
+    .fg-magenta { fill: #AA00AA }
+    .container {
+      padding: 0 10px;
+      line-height: 18px;
+    }
+    .bold { font-weight: bold; }
+    tspan {
+      font: 14px SFMono-Regular, Consolas, Liberation Mono, Menlo, monospace;
+      white-space: pre;
+      line-height: 18px;
+    }
+  </style>
+
+  <rect width="100%" height="100%" y="0" rx="4.5" class="bg" />
+
+  <text xml:space="preserve" class="container fg">
+    <tspan x="10px" y="28px"><tspan class="fg-ansi256-009 bold">error[E0308]</tspan><tspan class="bold">: mismatched types</tspan>
+</tspan>
+    <tspan x="10px" y="46px"><tspan>  </tspan><tspan class="fg-ansi256-012 bold"> ╭▸ </tspan><tspan>$DIR/unicode-output.rs:20:11</tspan>
+</tspan>
+    <tspan x="10px" y="64px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">│</tspan>
+</tspan>
+    <tspan x="10px" y="82px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">│</tspan><tspan>     query(wrapped_fn);</tspan>
+</tspan>
+    <tspan x="10px" y="100px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">│</tspan><tspan>     </tspan><tspan class="fg-ansi256-012 bold">┬────</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">━━━━━━━━━━</tspan><tspan> </tspan><tspan class="fg-ansi256-009 bold">one type is more general than the other</tspan>
+</tspan>
+    <tspan x="10px" y="118px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">│</tspan><tspan>     </tspan><tspan class="fg-ansi256-012 bold">│</tspan>
+</tspan>
+    <tspan x="10px" y="136px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">│</tspan><tspan>     </tspan><tspan class="fg-ansi256-012 bold">arguments to this function are incorrect</tspan>
+</tspan>
+    <tspan x="10px" y="154px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">│</tspan>
+</tspan>
+    <tspan x="10px" y="172px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">╰ </tspan><tspan class="bold">note</tspan><tspan>: expected fn pointer `</tspan><tspan class="fg-magenta bold">for&lt;'a&gt; </tspan><tspan>fn(Box&lt;</tspan><tspan class="fg-magenta bold">(dyn Any + Send + 'a)</tspan><tspan>&gt;) -&gt; Pin&lt;_&gt;`</tspan>
+</tspan>
+    <tspan x="10px" y="190px"><tspan>                 found fn item `fn(Box&lt;</tspan><tspan class="fg-magenta bold">(dyn Any + Send + 'static)</tspan><tspan>&gt;) -&gt; Pin&lt;_&gt; {wrapped_fn}`</tspan>
+</tspan>
+    <tspan x="10px" y="208px"><tspan class="fg-ansi256-010 bold">note</tspan><tspan>: function defined here</tspan>
+</tspan>
+    <tspan x="10px" y="226px"><tspan>  </tspan><tspan class="fg-ansi256-012 bold"> ╭▸ </tspan><tspan>$DIR/unicode-output.rs:9:4</tspan>
+</tspan>
+    <tspan x="10px" y="244px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">│</tspan>
+</tspan>
+    <tspan x="10px" y="262px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">│</tspan><tspan>   fn query(_: fn(Box&lt;(dyn Any + Send + '_)&gt;) -&gt; Pin&lt;Box&lt;(</tspan>
+</tspan>
+    <tspan x="10px" y="280px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">│</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">┌────</tspan><tspan class="fg-ansi256-010 bold">━━━━━</tspan><tspan class="fg-ansi256-012 bold">─┘</tspan>
+</tspan>
+    <tspan x="10px" y="298px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">│</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">│</tspan><tspan>     dyn Future&lt;Output = Result&lt;Box&lt;(dyn Any + 'static)&gt;, String&gt;&gt; + Send + 'static</tspan>
+</tspan>
+    <tspan x="10px" y="316px"><tspan class="fg-ansi256-012 bold">LL</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">│</tspan><tspan> </tspan><tspan class="fg-ansi256-012 bold">│</tspan><tspan> )&gt;&gt;) {}</tspan>
+</tspan>
+    <tspan x="10px" y="334px"><tspan>   </tspan><tspan class="fg-ansi256-012 bold">╰╴</tspan><tspan class="fg-ansi256-012 bold">└───┘</tspan>
+</tspan>
+    <tspan x="10px" y="352px">
+</tspan>
+    <tspan x="10px" y="370px"><tspan class="fg-ansi256-009 bold">error</tspan><tspan class="bold">: aborting due to 1 previous error</tspan>
+</tspan>
+    <tspan x="10px" y="388px">
+</tspan>
+    <tspan x="10px" y="406px"><tspan class="bold">For more information about this error, try `rustc --explain E0308`.</tspan>
+</tspan>
+    <tspan x="10px" y="424px">
+</tspan>
+  </text>
+
+</svg>
diff --git a/tests/ui/parser/bad-char-literals.stderr b/tests/ui/parser/bad-char-literals.stderr
index 1fb324a1b7e84..5a81ede0336ff 100644
--- a/tests/ui/parser/bad-char-literals.stderr
+++ b/tests/ui/parser/bad-char-literals.stderr
@@ -15,7 +15,7 @@ error: character constant must be escaped: `\n`
 LL |       '
    |  ______^
 LL | | ';
-   | |_
+   | |_^
    |
 help: escape the character
    |