Auto merge of #125593 - workingjubilee:rollup-67qk7di, r=workingjubilee

Rollup of 8 pull requests

Successful merges:

 - #124048 (Support C23's Variadics Without a Named Parameter)
 - #125046 (Only allow immutable statics with #[linkage])
 - #125466 (Don't continue probing for method if in suggestion and autoderef hits ambiguity)
 - #125469 (Don't skip out of inner const when looking for body for suggestion)
 - #125544 (Also mention my-self for other check-cfg docs changes)
 - #125559 (Simplify the `unchecked_sh[lr]` ub-checks a bit)
 - #125566 (Notify T-rustdoc for beta-accepted and stable-accepted too)
 - #125582 (Avoid a `FieldIdx::from_usize` in InstSimplify)

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

8 files changed, 33 insertions, 30 deletions

diff --git a/compiler/rustc_ast_passes/messages.ftl b/compiler/rustc_ast_passes/messages.ftl
index 31a184fe921..3a4c95b250c 100644
--- a/compiler/rustc_ast_passes/messages.ftl
+++ b/compiler/rustc_ast_passes/messages.ftl
@@ -92,9 +92,6 @@ ast_passes_fn_body_extern = incorrect function inside `extern` block
 ast_passes_fn_param_c_var_args_not_last =
     `...` must be the last argument of a C-variadic function
 
-ast_passes_fn_param_c_var_args_only =
-    C-variadic function must be declared with at least one named argument
-
 ast_passes_fn_param_doc_comment =
     documentation comments cannot be applied to function parameters
     .label = doc comments are not allowed here
diff --git a/compiler/rustc_ast_passes/src/ast_validation.rs b/compiler/rustc_ast_passes/src/ast_validation.rs
index c57be3cdf35..598a3ec2d3c 100644
--- a/compiler/rustc_ast_passes/src/ast_validation.rs
+++ b/compiler/rustc_ast_passes/src/ast_validation.rs
@@ -364,7 +364,7 @@ impl<'a> AstValidator<'a> {
 
     fn check_fn_decl(&self, fn_decl: &FnDecl, self_semantic: SelfSemantic) {
         self.check_decl_num_args(fn_decl);
-        self.check_decl_cvaradic_pos(fn_decl);
+        self.check_decl_cvariadic_pos(fn_decl);
         self.check_decl_attrs(fn_decl);
         self.check_decl_self_param(fn_decl, self_semantic);
     }
@@ -379,13 +379,11 @@ impl<'a> AstValidator<'a> {
         }
     }
 
-    fn check_decl_cvaradic_pos(&self, fn_decl: &FnDecl) {
+    /// Emits an error if a function declaration has a variadic parameter in the
+    /// beginning or middle of parameter list.
+    /// Example: `fn foo(..., x: i32)` will emit an error.
+    fn check_decl_cvariadic_pos(&self, fn_decl: &FnDecl) {
         match &*fn_decl.inputs {
-            [Param { ty, span, .. }] => {
-                if let TyKind::CVarArgs = ty.kind {
-                    self.dcx().emit_err(errors::FnParamCVarArgsOnly { span: *span });
-                }
-            }
             [ps @ .., _] => {
                 for Param { ty, span, .. } in ps {
                     if let TyKind::CVarArgs = ty.kind {
diff --git a/compiler/rustc_ast_passes/src/errors.rs b/compiler/rustc_ast_passes/src/errors.rs
index a95a7bdaf6d..c07fbe5b016 100644
--- a/compiler/rustc_ast_passes/src/errors.rs
+++ b/compiler/rustc_ast_passes/src/errors.rs
@@ -93,13 +93,6 @@ pub struct FnParamTooMany {
 }
 
 #[derive(Diagnostic)]
-#[diag(ast_passes_fn_param_c_var_args_only)]
-pub struct FnParamCVarArgsOnly {
-    #[primary_span]
-    pub span: Span,
-}
-
-#[derive(Diagnostic)]
 #[diag(ast_passes_fn_param_c_var_args_not_last)]
 pub struct FnParamCVarArgsNotLast {
     #[primary_span]
diff --git a/compiler/rustc_codegen_ssa/src/codegen_attrs.rs b/compiler/rustc_codegen_ssa/src/codegen_attrs.rs
index 9bf055b1739..e3e513084ea 100644
--- a/compiler/rustc_codegen_ssa/src/codegen_attrs.rs
+++ b/compiler/rustc_codegen_ssa/src/codegen_attrs.rs
@@ -327,6 +327,18 @@ fn codegen_fn_attrs(tcx: TyCtxt<'_>, did: LocalDefId) -> CodegenFnAttrs {
                     } else {
                         codegen_fn_attrs.linkage = linkage;
                     }
+                    if tcx.is_mutable_static(did.into()) {
+                        let mut diag = tcx.dcx().struct_span_err(
+                            attr.span,
+                            "mutable statics are not allowed with `#[linkage]`",
+                        );
+                        diag.note(
+                            "making the static mutable would allow changing which symbol the \
+                             static references rather than make the target of the symbol \
+                             mutable",
+                        );
+                        diag.emit();
+                    }
                 }
             }
             sym::link_section => {
diff --git a/compiler/rustc_hir_typeck/src/coercion.rs b/compiler/rustc_hir_typeck/src/coercion.rs
index 11a1c65b749..ebdc558282a 100644
--- a/compiler/rustc_hir_typeck/src/coercion.rs
+++ b/compiler/rustc_hir_typeck/src/coercion.rs
@@ -1871,11 +1871,8 @@ impl<'tcx, 'exprs, E: AsCoercionSite> CoerceMany<'tcx, 'exprs, E> {
         // If this is due to a block, then maybe we forgot a `return`/`break`.
         if due_to_block
             && let Some(expr) = expression
-            && let Some((parent_fn_decl, parent_id)) = fcx
-                .tcx
-                .hir()
-                .parent_iter(block_or_return_id)
-                .find_map(|(_, node)| Some((node.fn_decl()?, node.associated_body()?.0)))
+            && let Some(parent_fn_decl) =
+                fcx.tcx.hir().fn_decl_by_hir_id(fcx.tcx.local_def_id_to_hir_id(fcx.body_id))
         {
             fcx.suggest_missing_break_or_return_expr(
                 &mut err,
@@ -1884,7 +1881,7 @@ impl<'tcx, 'exprs, E: AsCoercionSite> CoerceMany<'tcx, 'exprs, E> {
                 expected,
                 found,
                 block_or_return_id,
-                parent_id,
+                fcx.body_id,
             );
         }
 
diff --git a/compiler/rustc_hir_typeck/src/method/probe.rs b/compiler/rustc_hir_typeck/src/method/probe.rs
index e0a60337c3b..820fe97afb5 100644
--- a/compiler/rustc_hir_typeck/src/method/probe.rs
+++ b/compiler/rustc_hir_typeck/src/method/probe.rs
@@ -395,8 +395,15 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         // ambiguous.
         if let Some(bad_ty) = &steps.opt_bad_ty {
             if is_suggestion.0 {
-                // Ambiguity was encountered during a suggestion. Just keep going.
-                debug!("ProbeContext: encountered ambiguity in suggestion");
+                // Ambiguity was encountered during a suggestion. There's really
+                // not much use in suggesting methods in this case.
+                return Err(MethodError::NoMatch(NoMatchData {
+                    static_candidates: Vec::new(),
+                    unsatisfied_predicates: Vec::new(),
+                    out_of_scope_traits: Vec::new(),
+                    similar_candidate: None,
+                    mode,
+                }));
             } else if bad_ty.reached_raw_pointer
                 && !self.tcx.features().arbitrary_self_types
                 && !self.tcx.sess.at_least_rust_2018()
diff --git a/compiler/rustc_mir_transform/src/dataflow_const_prop.rs b/compiler/rustc_mir_transform/src/dataflow_const_prop.rs
index 53a016f01ec..e5bce30398d 100644
--- a/compiler/rustc_mir_transform/src/dataflow_const_prop.rs
+++ b/compiler/rustc_mir_transform/src/dataflow_const_prop.rs
@@ -142,10 +142,10 @@ impl<'tcx> ValueAnalysis<'tcx> for ConstAnalysis<'_, 'tcx> {
                     _ => return,
                 };
                 if let Some(variant_target_idx) = variant_target {
-                    for (field_index, operand) in operands.iter().enumerate() {
+                    for (field_index, operand) in operands.iter_enumerated() {
                         if let Some(field) = self.map().apply(
                             variant_target_idx,
-                            TrackElem::Field(FieldIdx::from_usize(field_index)),
+                            TrackElem::Field(field_index),
                         ) {
                             self.assign_operand(state, field, operand);
                         }
diff --git a/compiler/rustc_mir_transform/src/instsimplify.rs b/compiler/rustc_mir_transform/src/instsimplify.rs
index f1adeab3f88..5e70b300f33 100644
--- a/compiler/rustc_mir_transform/src/instsimplify.rs
+++ b/compiler/rustc_mir_transform/src/instsimplify.rs
@@ -9,7 +9,6 @@ use rustc_middle::ty::layout::ValidityRequirement;
 use rustc_middle::ty::{self, GenericArgsRef, ParamEnv, Ty, TyCtxt};
 use rustc_span::sym;
 use rustc_span::symbol::Symbol;
-use rustc_target::abi::FieldIdx;
 use rustc_target::spec::abi::Abi;
 
 pub struct InstSimplify;
@@ -217,11 +216,11 @@ impl<'tcx> InstSimplifyContext<'tcx, '_> {
                     && let Some(place) = operand.place()
                 {
                     let variant = adt_def.non_enum_variant();
-                    for (i, field) in variant.fields.iter().enumerate() {
+                    for (i, field) in variant.fields.iter_enumerated() {
                         let field_ty = field.ty(self.tcx, args);
                         if field_ty == *cast_ty {
                             let place = place.project_deeper(
-                                &[ProjectionElem::Field(FieldIdx::from_usize(i), *cast_ty)],
+                                &[ProjectionElem::Field(i, *cast_ty)],
                                 self.tcx,
                             );
                             let operand = if operand.is_move() {