Auto merge of #143958 - samueltardieu:rollup-lh1s143, r=samueltardieu

Rollup of 13 pull requests

Successful merges:

 - rust-lang/rust#142301 (tests: Fix duplicated-path-in-error fail with musl)
 - rust-lang/rust#143630 (Drop `./x suggest`)
 - rust-lang/rust#143736 (Give all bytes of TypeId provenance)
 - rust-lang/rust#143752 (Don't panic if WASI_SDK_PATH not set when detecting compiler)
 - rust-lang/rust#143837 (Adjust `run_make_support::symbols` helpers)
 - rust-lang/rust#143878 (Port `#[pointee]` to the new attribute parsing infrastructure)
 - rust-lang/rust#143905 (Recover and suggest to use `;` to construct array type)
 - rust-lang/rust#143907 (core: make `str::split_at_unchecked()` inline)
 - rust-lang/rust#143910 (Add experimental `backtrace-trace-only` std feature)
 - rust-lang/rust#143927 (Preserve constness in trait objects up to hir ty lowering)
 - rust-lang/rust#143935 (rustc_type_ir/walk: move docstring to `TypeWalker` itself)
 - rust-lang/rust#143938 (Update books)
 - rust-lang/rust#143941 (update `cfg_select!` documentation)

Failed merges:

 - rust-lang/rust#143926 (Remove deprecated fields in bootstrap)

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

compiler/rustc_parse/src/parser/cfg_select.rs

@@ -7,7 +7,7 @@ use rustc_span::Span;
 use crate::exp;
 use crate::parser::Parser;
 
-pub enum CfgSelectRule {
+pub enum CfgSelectPredicate {
     Cfg(MetaItemInner),
     Wildcard(Token),
 }
@@ -20,7 +20,7 @@ pub struct CfgSelectBranches {
     pub wildcard: Option<(Token, TokenStream, Span)>,
     /// All branches after the first wildcard, including further wildcards.
     /// These branches are kept for formatting.
-    pub unreachable: Vec<(CfgSelectRule, TokenStream, Span)>,
+    pub unreachable: Vec<(CfgSelectPredicate, TokenStream, Span)>,
 }
 
 /// Parses a `TokenTree` that must be of the form `{ /* ... */ }`, and returns a `TokenStream` where
@@ -52,7 +52,7 @@ pub fn parse_cfg_select<'a>(p: &mut Parser<'a>) -> PResult<'a, CfgSelectBranches
             match branches.wildcard {
                 None => branches.wildcard = Some((underscore, tts, span)),
                 Some(_) => {
-                    branches.unreachable.push((CfgSelectRule::Wildcard(underscore), tts, span))
+                    branches.unreachable.push((CfgSelectPredicate::Wildcard(underscore), tts, span))
                 }
             }
         } else {
@@ -64,7 +64,9 @@ pub fn parse_cfg_select<'a>(p: &mut Parser<'a>) -> PResult<'a, CfgSelectBranches
 
             match branches.wildcard {
                 None => branches.reachable.push((meta_item, tts, span)),
-                Some(_) => branches.unreachable.push((CfgSelectRule::Cfg(meta_item), tts, span)),
+                Some(_) => {
+                    branches.unreachable.push((CfgSelectPredicate::Cfg(meta_item), tts, span))
+                }
             }
         }
     }

compiler/rustc_parse/src/parser/ty.rs

@@ -575,14 +575,69 @@ impl<'a> Parser<'a> {
                 self.expect(exp!(CloseBracket))?;
             }
             TyKind::Array(elt_ty, length)
-        } else {
-            self.expect(exp!(CloseBracket))?;
+        } else if self.eat(exp!(CloseBracket)) {
             TyKind::Slice(elt_ty)
+        } else {
+            self.maybe_recover_array_ty_without_semi(elt_ty)?
         };
 
         Ok(ty)
     }
 
+    /// Recover from malformed array type syntax.
+    ///
+    /// This method attempts to recover from cases like:
+    /// - `[u8, 5]` → suggests using `;`, return a Array type
+    /// - `[u8 5]` → suggests using `;`, return a Array type
+    /// Consider to add more cases in the future.
+    fn maybe_recover_array_ty_without_semi(&mut self, elt_ty: P<Ty>) -> PResult<'a, TyKind> {
+        let span = self.token.span;
+        let token_descr = super::token_descr(&self.token);
+        let mut err =
+            self.dcx().struct_span_err(span, format!("expected `;` or `]`, found {}", token_descr));
+        err.span_label(span, "expected `;` or `]`");
+        err.note("you might have meant to write a slice or array type");
+
+        // If we cannot recover, return the error immediately.
+        if !self.may_recover() {
+            return Err(err);
+        }
+
+        let snapshot = self.create_snapshot_for_diagnostic();
+
+        let suggestion_span = if self.eat(exp!(Comma)) || self.eat(exp!(Star)) {
+            // Consume common erroneous separators.
+            self.prev_token.span
+        } else {
+            self.token.span.shrink_to_lo()
+        };
+
+        // we first try to parse pattern like `[u8 5]`
+        let length = match self.parse_expr_anon_const() {
+            Ok(length) => length,
+            Err(e) => {
+                e.cancel();
+                self.restore_snapshot(snapshot);
+                return Err(err);
+            }
+        };
+
+        if let Err(e) = self.expect(exp!(CloseBracket)) {
+            e.cancel();
+            self.restore_snapshot(snapshot);
+            return Err(err);
+        }
+
+        err.span_suggestion_verbose(
+            suggestion_span,
+            "you might have meant to use `;` as the separator",
+            ";",
+            Applicability::MaybeIncorrect,
+        );
+        err.emit();
+        Ok(TyKind::Array(elt_ty, length))
+    }
+
     fn parse_borrowed_pointee(&mut self) -> PResult<'a, TyKind> {
         let and_span = self.prev_token.span;
         let mut opt_lifetime = self.check_lifetime().then(|| self.expect_lifetime());

compiler/rustc_parse/src/validate_attr.rs

@@ -297,6 +297,7 @@ pub fn check_builtin_meta_item(
                 | sym::align
                 | sym::deprecated
                 | sym::optimize
+                | sym::pointee
                 | sym::cold
                 | sym::target_feature
                 | sym::rustc_allow_const_fn_unstable