Auto merge of rust-lang#136248 - matthiaskrgr:rollup-leaxgfd, r=matthiaskrgr

Rollup of 8 pull requests

Successful merges:

 - rust-lang#133382 (Suggest considering casting fn item as fn pointer in more cases)
 - rust-lang#136092 (Test pipes also when not running on Windows and Linux simultaneously)
 - rust-lang#136190 (Remove duplicated code in RISC-V asm bad-reg test)
 - rust-lang#136192 (ci: remove unused windows runner)
 - rust-lang#136205 (Properly check that array length is valid type during built-in unsizing in index)
 - rust-lang#136211 (Update mdbook to 0.4.44)
 - rust-lang#136212 (Tweak `&mut self` suggestion span)
 - rust-lang#136214 (Make crate AST mutation accessible for driver callback)

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

Author: bors

compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs

@@ -1140,10 +1140,9 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
 
         let amp_mut_sugg = match *local_decl.local_info() {
             LocalInfo::User(mir::BindingForm::ImplicitSelf(_)) => {
-                let suggestion = suggest_ampmut_self(self.infcx.tcx, decl_span);
-                let additional =
-                    local_trait.map(|span| (span, suggest_ampmut_self(self.infcx.tcx, span)));
-                Some(AmpMutSugg { has_sugg: true, span: decl_span, suggestion, additional })
+                let (span, suggestion) = suggest_ampmut_self(self.infcx.tcx, decl_span);
+                let additional = local_trait.map(|span| suggest_ampmut_self(self.infcx.tcx, span));
+                Some(AmpMutSugg { has_sugg: true, span, suggestion, additional })
             }
 
             LocalInfo::User(mir::BindingForm::Var(mir::VarBindingForm {
@@ -1202,10 +1201,11 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
                                     opt_ty_info: None,
                                     ..
                                 })) => {
-                                    let sugg = suggest_ampmut_self(self.infcx.tcx, decl_span);
+                                    let (span, sugg) =
+                                        suggest_ampmut_self(self.infcx.tcx, decl_span);
                                     Some(AmpMutSugg {
                                         has_sugg: true,
-                                        span: decl_span,
+                                        span,
                                         suggestion: sugg,
                                         additional: None,
                                     })
@@ -1461,17 +1461,12 @@ fn mut_borrow_of_mutable_ref(local_decl: &LocalDecl<'_>, local_name: Option<Symb
     }
 }
 
-fn suggest_ampmut_self<'tcx>(tcx: TyCtxt<'tcx>, span: Span) -> String {
+fn suggest_ampmut_self(tcx: TyCtxt<'_>, span: Span) -> (Span, String) {
     match tcx.sess.source_map().span_to_snippet(span) {
-        Ok(snippet) => {
-            let lt_pos = snippet.find('\'');
-            if let Some(lt_pos) = lt_pos {
-                format!("&{}mut self", &snippet[lt_pos..snippet.len() - 4])
-            } else {
-                "&mut self".to_string()
-            }
+        Ok(snippet) if snippet.ends_with("self") => {
+            (span.with_hi(span.hi() - BytePos(4)).shrink_to_hi(), "mut ".to_string())
         }
-        _ => "&mut self".to_string(),
+        _ => (span, "&mut self".to_string()),
     }
 }
 

compiler/rustc_driver_impl/src/lib.rs

@@ -160,7 +160,7 @@ pub trait Callbacks {
     fn after_crate_root_parsing(
         &mut self,
         _compiler: &interface::Compiler,
-        _queries: &ast::Crate,
+        _krate: &mut ast::Crate,
     ) -> Compilation {
         Compilation::Continue
     }
@@ -311,7 +311,7 @@ pub fn run_compiler(at_args: &[String], callbacks: &mut (dyn Callbacks + Send))
 
         // Parse the crate root source code (doesn't parse submodules yet)
         // Everything else is parsed during macro expansion.
-        let krate = passes::parse(sess);
+        let mut krate = passes::parse(sess);
 
         // If pretty printing is requested: Figure out the representation, print it and exit
         if let Some(pp_mode) = sess.opts.pretty {
@@ -328,7 +328,7 @@ pub fn run_compiler(at_args: &[String], callbacks: &mut (dyn Callbacks + Send))
             return early_exit();
         }
 
-        if callbacks.after_crate_root_parsing(compiler, &krate) == Compilation::Stop {
+        if callbacks.after_crate_root_parsing(compiler, &mut krate) == Compilation::Stop {
             return early_exit();
         }
 

compiler/rustc_hir_typeck/src/place_op.rs

@@ -1,6 +1,7 @@
 use rustc_errors::Applicability;
 use rustc_hir_analysis::autoderef::Autoderef;
 use rustc_infer::infer::InferOk;
+use rustc_infer::traits::{Obligation, ObligationCauseCode};
 use rustc_middle::span_bug;
 use rustc_middle::ty::adjustment::{
     Adjust, Adjustment, AllowTwoPhase, AutoBorrow, AutoBorrowMutability, OverloadedDeref,
@@ -136,8 +137,14 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             let mut self_ty = adjusted_ty;
             if unsize {
                 // We only unsize arrays here.
-                if let ty::Array(element_ty, _) = adjusted_ty.kind() {
-                    self_ty = Ty::new_slice(self.tcx, *element_ty);
+                if let ty::Array(element_ty, ct) = *adjusted_ty.kind() {
+                    self.register_predicate(Obligation::new(
+                        self.tcx,
+                        self.cause(base_expr.span, ObligationCauseCode::ArrayLen(adjusted_ty)),
+                        self.param_env,
+                        ty::ClauseKind::ConstArgHasType(ct, self.tcx.types.usize),
+                    ));
+                    self_ty = Ty::new_slice(self.tcx, element_ty);
                 } else {
                     continue;
                 }

compiler/rustc_middle/src/traits/mod.rs

@@ -194,6 +194,9 @@ pub enum ObligationCauseCode<'tcx> {
     /// A slice or array is WF only if `T: Sized`.
     SliceOrArrayElem,
 
+    /// An array `[T; N]` can only be indexed (and is only well-formed if) `N` has type usize.
+    ArrayLen(Ty<'tcx>),
+
     /// A tuple is WF only if its middle elements are `Sized`.
     TupleElem,
 

compiler/rustc_trait_selection/messages.ftl

@@ -165,6 +165,8 @@ trait_selection_explicit_lifetime_required_with_param_type = explicit lifetime r
 
 trait_selection_fn_consider_casting = consider casting the fn item to a fn pointer: `{$casting}`
 
+trait_selection_fn_consider_casting_both = consider casting both fn items to fn pointers using `as {$sig}`
+
 trait_selection_fn_uniq_types = different fn items have unique types, even if their signatures are the same
 trait_selection_fps_cast = consider casting to a fn pointer
 trait_selection_fps_cast_both = consider casting both fn items to fn pointers using `as {$expected_sig}`

compiler/rustc_trait_selection/src/error_reporting/infer/mod.rs

@@ -1844,7 +1844,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                 self.suggest_tuple_pattern(cause, &exp_found, diag);
                 self.suggest_accessing_field_where_appropriate(cause, &exp_found, diag);
                 self.suggest_await_on_expect_found(cause, span, &exp_found, diag);
-                self.suggest_function_pointers(cause, span, &exp_found, diag);
+                self.suggest_function_pointers(cause, span, &exp_found, terr, diag);
                 self.suggest_turning_stmt_into_expr(cause, &exp_found, diag);
             }
         }

compiler/rustc_trait_selection/src/error_reporting/infer/suggest.rs

@@ -12,6 +12,7 @@ use rustc_middle::traits::{
     IfExpressionCause, MatchExpressionArmCause, ObligationCause, ObligationCauseCode,
     StatementAsExpression,
 };
+use rustc_middle::ty::error::TypeError;
 use rustc_middle::ty::print::with_no_trimmed_paths;
 use rustc_middle::ty::{self as ty, GenericArgKind, IsSuggestable, Ty, TypeVisitableExt};
 use rustc_span::{Span, sym};
@@ -20,7 +21,7 @@ use tracing::debug;
 use crate::error_reporting::TypeErrCtxt;
 use crate::error_reporting::infer::hir::Path;
 use crate::errors::{
-    ConsiderAddingAwait, FnConsiderCasting, FnItemsAreDistinct, FnUniqTypes,
+    ConsiderAddingAwait, FnConsiderCasting, FnConsiderCastingBoth, FnItemsAreDistinct, FnUniqTypes,
     FunctionPointerSuggestion, SuggestAccessingField, SuggestRemoveSemiOrReturnBinding,
     SuggestTuplePatternMany, SuggestTuplePatternOne, TypeErrorAdditionalDiags,
 };
@@ -381,14 +382,12 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
         }
     }
 
-    pub(super) fn suggest_function_pointers(
+    pub fn suggest_function_pointers_impl(
         &self,
-        cause: &ObligationCause<'tcx>,
-        span: Span,
+        span: Option<Span>,
         exp_found: &ty::error::ExpectedFound<Ty<'tcx>>,
         diag: &mut Diag<'_>,
     ) {
-        debug!("suggest_function_pointers(cause={:?}, exp_found={:?})", cause, exp_found);
         let ty::error::ExpectedFound { expected, found } = exp_found;
         let expected_inner = expected.peel_refs();
         let found_inner = found.peel_refs();
@@ -411,6 +410,13 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                     return;
                 }
 
+                let Some(span) = span else {
+                    let casting = format!("{fn_name} as {sig}");
+                    diag.subdiagnostic(FnItemsAreDistinct);
+                    diag.subdiagnostic(FnConsiderCasting { casting });
+                    return;
+                };
+
                 let sugg = match (expected.is_ref(), found.is_ref()) {
                     (true, false) => FunctionPointerSuggestion::UseRef { span, fn_name },
                     (false, true) => FunctionPointerSuggestion::RemoveRef { span, fn_name },
@@ -445,6 +451,12 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                 }
 
                 let fn_name = self.tcx.def_path_str_with_args(*did2, args2);
+
+                let Some(span) = span else {
+                    diag.subdiagnostic(FnConsiderCastingBoth { sig: *expected_sig });
+                    return;
+                };
+
                 let sug = if found.is_ref() {
                     FunctionPointerSuggestion::CastBothRef {
                         span,
@@ -488,6 +500,23 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
         };
     }
 
+    pub(super) fn suggest_function_pointers(
+        &self,
+        cause: &ObligationCause<'tcx>,
+        span: Span,
+        exp_found: &ty::error::ExpectedFound<Ty<'tcx>>,
+        terr: TypeError<'tcx>,
+        diag: &mut Diag<'_>,
+    ) {
+        debug!("suggest_function_pointers(cause={:?}, exp_found={:?})", cause, exp_found);
+
+        if exp_found.expected.peel_refs().is_fn() && exp_found.found.peel_refs().is_fn() {
+            self.suggest_function_pointers_impl(Some(span), exp_found, diag);
+        } else if let TypeError::Sorts(exp_found) = terr {
+            self.suggest_function_pointers_impl(None, &exp_found, diag);
+        }
+    }
+
     pub fn should_suggest_as_ref_kind(
         &self,
         expected: Ty<'tcx>,

compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs

@@ -1969,6 +1969,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                             StringPart::highlighted(exp_found.found.to_string()),
                             StringPart::normal("`"),
                         ]);
+                        self.suggest_function_pointers_impl(None, &exp_found, err);
                     }
 
                     true

compiler/rustc_trait_selection/src/error_reporting/traits/suggestions.rs

@@ -2769,6 +2769,9 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
             ObligationCauseCode::SliceOrArrayElem => {
                 err.note("slice and array elements must have `Sized` type");
             }
+            ObligationCauseCode::ArrayLen(array_ty) => {
+                err.note(format!("the length of array `{array_ty}` must be type `usize`"));
+            }
             ObligationCauseCode::TupleElem => {
                 err.note("only the last element of a tuple may have a dynamically sized type");
             }

compiler/rustc_trait_selection/src/errors.rs

@@ -1496,6 +1496,12 @@ pub struct FnConsiderCasting {
     pub casting: String,
 }
 
+#[derive(Subdiagnostic)]
+#[help(trait_selection_fn_consider_casting_both)]
+pub struct FnConsiderCastingBoth<'a> {
+    pub sig: Binder<'a, FnSig<'a>>,
+}
+
 #[derive(Subdiagnostic)]
 pub enum SuggestAccessingField<'a> {
     #[suggestion(