Auto merge of #129665 - matthiaskrgr:rollup-hy23k7d, r=matthiaskrgr

Rollup of 8 pull requests

Successful merges:

 - #129507 (make it possible to enable const_precise_live_drops per-function)
 - #129581 (exit: explain our expectations for the exit handlers registered in a Rust program)
 - #129634 (Fix tidy to allow `edition = "2024"` in `Cargo.toml`)
 - #129635 (Use unsafe extern blocks throughout the compiler)
 - #129645 (Fix typos in floating-point primitive type docs)
 - #129648 (More `unreachable_pub`)
 - #129649 (ABI compat check: detect unadjusted ABI mismatches)
 - #129652 (fix Pointer to reference conversion docs)

r? `@ghost`
`@rustbot` modify labels: rollup

compiler/rustc_abi/src/lib.rs

@@ -1700,7 +1700,9 @@ impl<FieldIdx: Idx, VariantIdx: Idx> LayoutS<FieldIdx, VariantIdx> {
 
     /// Checks if these two `Layout` are equal enough to be considered "the same for all function
     /// call ABIs". Note however that real ABIs depend on more details that are not reflected in the
-    /// `Layout`; the `PassMode` need to be compared as well.
+    /// `Layout`; the `PassMode` need to be compared as well. Also note that we assume
+    /// aggregates are passed via `PassMode::Indirect` or `PassMode::Cast`; more strict
+    /// checks would otherwise be required.
     pub fn eq_abi(&self, other: &Self) -> bool {
         // The one thing that we are not capturing here is that for unsized types, the metadata must
         // also have the same ABI, and moreover that the same metadata leads to the same size. The

compiler/rustc_codegen_llvm/src/lib.rs

@@ -6,6 +6,7 @@
 
 // tidy-alphabetical-start
 #![allow(internal_features)]
+#![cfg_attr(bootstrap, feature(unsafe_extern_blocks))]
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![doc(rust_logo)]
 #![feature(assert_matches)]

compiler/rustc_codegen_llvm/src/llvm/ffi.rs

@@ -564,12 +564,12 @@ pub enum ArchiveKind {
 }
 
 // LLVMRustThinLTOData
-extern "C" {
+unsafe extern "C" {
     pub type ThinLTOData;
 }
 
 // LLVMRustThinLTOBuffer
-extern "C" {
+unsafe extern "C" {
     pub type ThinLTOBuffer;
 }
 
@@ -621,7 +621,7 @@ pub enum MemoryEffects {
     InaccessibleMemOnly,
 }
 
-extern "C" {
+unsafe extern "C" {
     type Opaque;
 }
 #[repr(C)]
@@ -631,54 +631,54 @@ struct InvariantOpaque<'a> {
 }
 
 // Opaque pointer types
-extern "C" {
+unsafe extern "C" {
     pub type Module;
 }
-extern "C" {
+unsafe extern "C" {
     pub type Context;
 }
-extern "C" {
+unsafe extern "C" {
     pub type Type;
 }
-extern "C" {
+unsafe extern "C" {
     pub type Value;
 }
-extern "C" {
+unsafe extern "C" {
     pub type ConstantInt;
 }
-extern "C" {
+unsafe extern "C" {
     pub type Attribute;
 }
-extern "C" {
+unsafe extern "C" {
     pub type Metadata;
 }
-extern "C" {
+unsafe extern "C" {
     pub type BasicBlock;
 }
 #[repr(C)]
 pub struct Builder<'a>(InvariantOpaque<'a>);
 #[repr(C)]
 pub struct PassManager<'a>(InvariantOpaque<'a>);
-extern "C" {
+unsafe extern "C" {
     pub type Pass;
 }
-extern "C" {
+unsafe extern "C" {
     pub type TargetMachine;
 }
-extern "C" {
+unsafe extern "C" {
     pub type Archive;
 }
 #[repr(C)]
 pub struct ArchiveIterator<'a>(InvariantOpaque<'a>);
 #[repr(C)]
 pub struct ArchiveChild<'a>(InvariantOpaque<'a>);
-extern "C" {
+unsafe extern "C" {
     pub type Twine;
 }
-extern "C" {
+unsafe extern "C" {
     pub type DiagnosticInfo;
 }
-extern "C" {
+unsafe extern "C" {
     pub type SMDiagnostic;
 }
 #[repr(C)]
@@ -688,7 +688,7 @@ pub struct OperandBundleDef<'a>(InvariantOpaque<'a>);
 #[repr(C)]
 pub struct Linker<'a>(InvariantOpaque<'a>);
 
-extern "C" {
+unsafe extern "C" {
     pub type DiagnosticHandler;
 }
 
@@ -823,7 +823,7 @@ bitflags! {
     }
 }
 
-extern "C" {
+unsafe extern "C" {
     pub type ModuleBuffer;
 }
 
@@ -834,7 +834,7 @@ pub type SelfProfileAfterPassCallback = unsafe extern "C" fn(*mut c_void);
 pub type GetSymbolsCallback = unsafe extern "C" fn(*mut c_void, *const c_char) -> *mut c_void;
 pub type GetSymbolsErrorCallback = unsafe extern "C" fn(*const c_char) -> *mut c_void;
 
-extern "C" {
+unsafe extern "C" {
     // Create and destroy contexts.
     pub fn LLVMContextDispose(C: &'static mut Context);
     pub fn LLVMGetMDKindIDInContext(C: &Context, Name: *const c_char, SLen: c_uint) -> c_uint;
@@ -1518,7 +1518,7 @@ extern "C" {
 }
 
 #[link(name = "llvm-wrapper", kind = "static")]
-extern "C" {
+unsafe extern "C" {
     pub fn LLVMRustInstallErrorHandlers();
     pub fn LLVMRustDisableSystemDialogsOnCrash();
 

compiler/rustc_const_eval/src/check_consts/post_drop_elaboration.rs

@@ -9,13 +9,19 @@ use super::check::Qualifs;
 use super::ops::{self, NonConstOp};
 use super::qualifs::{NeedsNonConstDrop, Qualif};
 use super::ConstCx;
+use crate::check_consts::rustc_allow_const_fn_unstable;
 
 /// Returns `true` if we should use the more precise live drop checker that runs after drop
 /// elaboration.
 pub fn checking_enabled(ccx: &ConstCx<'_, '_>) -> bool {
-    // Const-stable functions must always use the stable live drop checker.
+    // Const-stable functions must always use the stable live drop checker...
     if ccx.is_const_stable_const_fn() {
-        return false;
+        // ...except if they have the feature flag set via `rustc_allow_const_fn_unstable`.
+        return rustc_allow_const_fn_unstable(
+            ccx.tcx,
+            ccx.body.source.def_id().expect_local(),
+            sym::const_precise_live_drops,
+        );
     }
 
     ccx.tcx.features().const_precise_live_drops

compiler/rustc_driver_impl/src/lib.rs

@@ -7,6 +7,7 @@
 // tidy-alphabetical-start
 #![allow(internal_features)]
 #![allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
+#![cfg_attr(bootstrap, feature(unsafe_extern_blocks))]
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![doc(rust_logo)]
 #![feature(decl_macro)]
@@ -15,6 +16,7 @@
 #![feature(panic_update_hook)]
 #![feature(result_flattening)]
 #![feature(rustdoc_internals)]
+#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 use std::cmp::max;

compiler/rustc_driver_impl/src/signal_handler.rs

@@ -6,7 +6,7 @@ use std::{fmt, mem, ptr};
 
 use rustc_interface::util::{DEFAULT_STACK_SIZE, STACK_SIZE};
 
-extern "C" {
+unsafe extern "C" {
     fn backtrace_symbols_fd(buffer: *const *mut libc::c_void, size: libc::c_int, fd: libc::c_int);
 }
 

compiler/rustc_error_codes/src/lib.rs

@@ -6,6 +6,7 @@
 #![deny(rustdoc::invalid_codeblock_attributes)]
 #![doc(rust_logo)]
 #![feature(rustdoc_internals)]
+#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 // This higher-order macro defines the error codes that are in use. It is used

compiler/rustc_error_messages/src/lib.rs

@@ -4,6 +4,7 @@
 #![feature(rustc_attrs)]
 #![feature(rustdoc_internals)]
 #![feature(type_alias_impl_trait)]
+#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 use std::borrow::Cow;

compiler/rustc_errors/src/diagnostic.rs

@@ -204,7 +204,7 @@ pub trait LintDiagnostic<'a, G: EmissionGuarantee> {
 }
 
 #[derive(Clone, Debug, Encodable, Decodable)]
-pub struct DiagLocation {
+pub(crate) struct DiagLocation {
     file: Cow<'static, str>,
     line: u32,
     col: u32,

compiler/rustc_errors/src/emitter.rs

@@ -2387,7 +2387,7 @@ enum DisplaySuggestion {
 impl FileWithAnnotatedLines {
     /// Preprocess all the annotations so that they are grouped by file and by line number
     /// This helps us quickly iterate over the whole message (including secondary file spans)
-    pub fn collect_annotations(
+    pub(crate) fn collect_annotations(
         emitter: &dyn Emitter,
         args: &FluentArgs<'_>,
         msp: &MultiSpan,

compiler/rustc_errors/src/lib.rs

@@ -25,6 +25,7 @@
 #![feature(trait_alias)]
 #![feature(try_blocks)]
 #![feature(yeet_expr)]
+#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 extern crate self as rustc_errors;
@@ -1701,7 +1702,7 @@ impl DiagCtxtInner {
     }
 
     /// Translate `message` eagerly with `args` to `SubdiagMessage::Eager`.
-    pub fn eagerly_translate<'a>(
+    fn eagerly_translate<'a>(
         &self,
         message: DiagMessage,
         args: impl Iterator<Item = DiagArg<'a>>,
@@ -1710,7 +1711,7 @@ impl DiagCtxtInner {
     }
 
     /// Translate `message` eagerly with `args` to `String`.
-    pub fn eagerly_translate_to_string<'a>(
+    fn eagerly_translate_to_string<'a>(
         &self,
         message: DiagMessage,
         args: impl Iterator<Item = DiagArg<'a>>,

compiler/rustc_errors/src/lock.rs

@@ -12,7 +12,7 @@
 use std::any::Any;
 
 #[cfg(windows)]
-pub fn acquire_global_lock(name: &str) -> Box<dyn Any> {
+pub(crate) fn acquire_global_lock(name: &str) -> Box<dyn Any> {
     use std::ffi::CString;
     use std::io;
 
@@ -80,6 +80,6 @@ pub fn acquire_global_lock(name: &str) -> Box<dyn Any> {
 }
 
 #[cfg(not(windows))]
-pub fn acquire_global_lock(_name: &str) -> Box<dyn Any> {
+pub(crate) fn acquire_global_lock(_name: &str) -> Box<dyn Any> {
     Box::new(())
 }

compiler/rustc_errors/src/markdown/parse.rs

@@ -74,7 +74,7 @@ enum ParseOpt {
 }
 
 /// Parse a buffer
-pub fn entrypoint(txt: &str) -> MdStream<'_> {
+pub(crate) fn entrypoint(txt: &str) -> MdStream<'_> {
     let ctx = Context { top_block: true, prev: Prev::Newline };
     normalize(parse_recursive(txt.trim().as_bytes(), ctx), &mut Vec::new())
 }

compiler/rustc_errors/src/markdown/term.rs

@@ -15,7 +15,7 @@ thread_local! {
 }
 
 /// Print to terminal output to a buffer
-pub fn entrypoint(stream: &MdStream<'_>, buf: &mut Buffer) -> io::Result<()> {
+pub(crate) fn entrypoint(stream: &MdStream<'_>, buf: &mut Buffer) -> io::Result<()> {
     #[cfg(not(test))]
     if let Some((w, _)) = termize::dimensions() {
         WIDTH.with(|c| c.set(std::cmp::min(w, DEFAULT_COLUMN_WIDTH)));
@@ -47,7 +47,7 @@ fn write_stream(
     Ok(())
 }
 
-pub fn write_tt(tt: &MdTree<'_>, buf: &mut Buffer, indent: usize) -> io::Result<()> {
+fn write_tt(tt: &MdTree<'_>, buf: &mut Buffer, indent: usize) -> io::Result<()> {
     match tt {
         MdTree::CodeBlock { txt, lang: _ } => {
             buf.set_color(ColorSpec::new().set_dimmed(true))?;