Allow comments in {% match %} and remove panic!()

askama_shared/src/parser.rs

@@ -804,7 +804,7 @@ fn block_match<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, Node<'a>> {
             opt(char('-')),
             |i| tag_block_end(i, s),
             cut(tuple((
-                opt(|i| take_content(i, s)),
+                ws(many0(ws(value((), |i| block_comment(i, s))))),
                 many1(|i| when_block(i, s)),
                 cut(tuple((
                     opt(|i| match_else_block(i, s)),
@@ -818,30 +818,13 @@ fn block_match<'a>(i: &'a str, s: &State<'_>) -> IResult<&'a str, Node<'a>> {
             ))),
         ))),
     ));
-    let (i, (pws1, _, (expr, nws1, _, (inter, arms, (else_arm, (_, pws2, _, nws2)))))) = p(i)?;
+    let (i, (pws1, _, (expr, nws1, _, (_, arms, (else_arm, (_, pws2, _, nws2)))))) = p(i)?;
 
     let mut arms = arms;
     if let Some(arm) = else_arm {
         arms.push(arm);
     }
 
-    match inter {
-        Some(Node::Lit(_, val, rws)) => {
-            assert!(
-                val.is_empty(),
-                "only whitespace allowed between match and first when, found {}",
-                val
-            );
-            assert!(
-                rws.is_empty(),
-                "only whitespace allowed between match and first when, found {}",
-                rws
-            );
-        }
-        None => {}
-        _ => panic!("only literals allowed between match and first when"),
-    }
-
     Ok((
         i,
         Node::Match(

testing/tests/matches.rs

@@ -172,3 +172,28 @@ fn test_match_option_result_option() {
     };
     assert_eq!(s.render().unwrap(), "num=4711");
 }
+
+#[derive(Template)]
+#[template(
+    ext = "txt",
+    source = r#"
+{%- match good -%}
+    {#- when good, then good -#}
+    {%- when true -%}
+        good
+    {%- when _ -%}
+        bad
+{%- endmatch -%}"#
+)]
+struct MatchWithComment {
+    good: bool,
+}
+
+#[test]
+fn test_match_with_comment() {
+    let s = MatchWithComment { good: true };
+    assert_eq!(s.render().unwrap(), "good");
+
+    let s = MatchWithComment { good: false };
+    assert_eq!(s.render().unwrap(), "bad");
+}

testing/tests/ui/match_with_extra.rs

@@ -0,0 +1,20 @@
+use askama::Template;
+
+#[derive(Template)]
+#[template(
+    ext = "txt",
+    source = r#"
+{%- match good -%}
+    // Help, I forgot how to write comments!
+    {%- when true %}
+        good
+    {%- when _ -%}
+        bad
+{%- endmatch -%}"#
+)]
+struct MatchWithExtra {
+    good: bool,
+}
+
+fn main() {
+}

testing/tests/ui/match_with_extra.stderr

@@ -0,0 +1,8 @@
+error: problems parsing template source at row 3, column 4 near:
+       "// Help, I forgot how to write comments!"...
+ --> tests/ui/match_with_extra.rs:3:10
+  |
+3 | #[derive(Template)]
+  |          ^^^^^^^^
+  |
+  = note: this error originates in the derive macro `Template` (in Nightly builds, run with -Z macro-backtrace for more info)