Auto merge of rust-lang#122822 - matthiaskrgr:rollup-rjgmnbe, r=matth…

…iaskrgr

Rollup of 8 pull requests

Successful merges:

 - rust-lang#122222 (deref patterns: bare-bones feature gate and typechecking)
 - rust-lang#122358 (Don't ICE when encountering bound regions in generator interior type)
 - rust-lang#122696 (Add bare metal riscv32 target.)
 - rust-lang#122773 (make "expected paren or brace" error translatable)
 - rust-lang#122795 (Inherit `RUSTC_BOOTSTRAP` when testing wasm)
 - rust-lang#122799 (Replace closures with `_` when suggesting fully qualified path for method call)
 - rust-lang#122801 (Fix misc printing issues in emit=stable_mir)
 - rust-lang#122806 (Make `type_ascribe!` not a built-in)

Failed merges:

 - rust-lang#122771 (add some comments to hir::ModuleItems)

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

compiler/rustc_ast_passes/src/feature_gate.rs

@@ -413,7 +413,10 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
                 }
             }
             PatKind::Box(..) => {
-                gate!(&self, box_patterns, pattern.span, "box pattern syntax is experimental");
+                if !self.features.deref_patterns {
+                    // Allow box patterns under `deref_patterns`.
+                    gate!(&self, box_patterns, pattern.span, "box pattern syntax is experimental");
+                }
             }
             PatKind::Range(_, Some(_), Spanned { node: RangeEnd::Excluded, .. }) => {
                 gate!(
@@ -607,13 +610,16 @@ pub fn check_crate(krate: &ast::Crate, sess: &Session, features: &Features) {
         };
     }
 
+    if !visitor.features.deref_patterns {
+        // Allow box patterns under `deref_patterns`.
+        gate_all_legacy_dont_use!(box_patterns, "box pattern syntax is experimental");
+    }
     gate_all_legacy_dont_use!(trait_alias, "trait aliases are experimental");
     // Despite being a new feature, `where T: Trait<Assoc(): Sized>`, which is RTN syntax now,
     // used to be gated under associated_type_bounds, which are right above, so RTN needs to
     // be too.
     gate_all_legacy_dont_use!(return_type_notation, "return type notation is experimental");
     gate_all_legacy_dont_use!(decl_macro, "`macro` is experimental");
-    gate_all_legacy_dont_use!(box_patterns, "box pattern syntax is experimental");
     gate_all_legacy_dont_use!(
         exclusive_range_pattern,
         "exclusive range pattern syntax is experimental"

compiler/rustc_builtin_macros/src/lib.rs

@@ -49,7 +49,6 @@ mod log_syntax;
 mod source_util;
 mod test;
 mod trace_macros;
-mod type_ascribe;
 mod util;
 
 pub mod asm;
@@ -99,7 +98,6 @@ pub fn register_builtin_macros(resolver: &mut dyn ResolverExpand) {
         std_panic: edition_panic::expand_panic,
         stringify: source_util::expand_stringify,
         trace_macros: trace_macros::expand_trace_macros,
-        type_ascribe: type_ascribe::expand_type_ascribe,
         unreachable: edition_panic::expand_unreachable,
         // tidy-alphabetical-end
     }

compiler/rustc_expand/messages.ftl

@@ -33,6 +33,9 @@ expand_duplicate_matcher_binding = duplicate matcher binding
 expand_expected_comma_in_list =
     expected token: `,`
 
+expand_expected_paren_or_brace =
+    expected `(` or `{"{"}`, found `{$token}`
+
 expand_explain_doc_comment_inner =
     inner doc comments expand to `#![doc = "..."]`, which is what this macro attempted to match
 

compiler/rustc_expand/src/errors.rs

@@ -448,3 +448,11 @@ pub struct InvalidFragmentSpecifier {
     pub fragment: Ident,
     pub help: String,
 }
+
+#[derive(Diagnostic)]
+#[diag(expand_expected_paren_or_brace)]
+pub struct ExpectedParenOrBrace<'a> {
+    #[primary_span]
+    pub span: Span,
+    pub token: Cow<'a, str>,
+}

compiler/rustc_expand/src/mbe/quoted.rs

@@ -194,9 +194,11 @@ fn parse_tree<'a>(
                             }
                             Delimiter::Parenthesis => {}
                             _ => {
-                                let tok = pprust::token_kind_to_string(&token::OpenDelim(delim));
-                                let msg = format!("expected `(` or `{{`, found `{tok}`");
-                                sess.dcx().span_err(delim_span.entire(), msg);
+                                let token = pprust::token_kind_to_string(&token::OpenDelim(delim));
+                                sess.dcx().emit_err(errors::ExpectedParenOrBrace {
+                                    span: delim_span.entire(),
+                                    token,
+                                });
                             }
                         }
                     }

compiler/rustc_feature/src/unstable.rs

@@ -436,6 +436,8 @@ declare_features! (
     (unstable, deprecated_safe, "1.61.0", Some(94978)),
     /// Allows having using `suggestion` in the `#[deprecated]` attribute.
     (unstable, deprecated_suggestion, "1.61.0", Some(94785)),
+    /// Allows deref patterns.
+    (incomplete, deref_patterns, "CURRENT_RUSTC_VERSION", Some(87121)),
     /// Controls errors in trait implementations.
     (unstable, do_not_recommend, "1.67.0", Some(51992)),
     /// Tells rustdoc to automatically generate `#[doc(cfg(...))]`.

compiler/rustc_hir_analysis/src/astconv/bounds.rs

@@ -565,7 +565,7 @@ fn check_assoc_const_binding_type<'tcx>(
     let mut guar = ty.visit_with(&mut collector).break_value();
 
     let ty_note = ty
-        .make_suggestable(tcx, false)
+        .make_suggestable(tcx, false, None)
         .map(|ty| crate::errors::TyOfAssocConstBindingNote { assoc_const, ty });
 
     let enclosing_item_owner_id = tcx

compiler/rustc_hir_analysis/src/collect.rs

@@ -1371,7 +1371,7 @@ fn infer_return_ty_for_fn_sig<'tcx>(
             // recursive function definition to leak out into the fn sig.
             let mut should_recover = false;
 
-            if let Some(ret_ty) = ret_ty.make_suggestable(tcx, false) {
+            if let Some(ret_ty) = ret_ty.make_suggestable(tcx, false, None) {
                 diag.span_suggestion(
                     ty.span,
                     "replace with the correct return type",
@@ -1449,7 +1449,7 @@ fn suggest_impl_trait<'tcx>(
             let ty::Tuple(types) = *args_tuple.kind() else {
                 return None;
             };
-            let types = types.make_suggestable(tcx, false)?;
+            let types = types.make_suggestable(tcx, false, None)?;
             let maybe_ret =
                 if item_ty.is_unit() { String::new() } else { format!(" -> {item_ty}") };
             Some(format!(
@@ -1507,7 +1507,7 @@ fn suggest_impl_trait<'tcx>(
         // FIXME(compiler-errors): We may benefit from resolving regions here.
         if ocx.select_where_possible().is_empty()
             && let item_ty = infcx.resolve_vars_if_possible(item_ty)
-            && let Some(item_ty) = item_ty.make_suggestable(tcx, false)
+            && let Some(item_ty) = item_ty.make_suggestable(tcx, false, None)
             && let Some(sugg) = formatter(
                 tcx,
                 infcx.resolve_vars_if_possible(args),

compiler/rustc_hir_analysis/src/collect/type_of.rs

@@ -47,7 +47,7 @@ fn anon_const_type_of<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> Ty<'tcx> {
             let ty = tcx.fold_regions(ty, |r, _| {
                 if r.is_erased() { ty::Region::new_error_misc(tcx) } else { r }
             });
-            let (ty, opt_sugg) = if let Some(ty) = ty.make_suggestable(tcx, false) {
+            let (ty, opt_sugg) = if let Some(ty) = ty.make_suggestable(tcx, false, None) {
                 (ty, Some((span, Applicability::MachineApplicable)))
             } else {
                 (ty, None)
@@ -587,7 +587,7 @@ fn infer_placeholder_type<'a>(
                     suggestions.clear();
                 }
 
-                if let Some(ty) = ty.make_suggestable(tcx, false) {
+                if let Some(ty) = ty.make_suggestable(tcx, false, None) {
                     err.span_suggestion(
                         span,
                         format!("provide a type for the {kind}"),
@@ -606,7 +606,7 @@ fn infer_placeholder_type<'a>(
             let mut diag = bad_placeholder(tcx, vec![span], kind);
 
             if !ty.references_error() {
-                if let Some(ty) = ty.make_suggestable(tcx, false) {
+                if let Some(ty) = ty.make_suggestable(tcx, false, None) {
                     diag.span_suggestion(
                         span,
                         "replace with the correct type",

compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs

@@ -809,7 +809,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 return true;
             }
             &hir::FnRetTy::DefaultReturn(span) if expected.is_unit() => {
-                if let Some(found) = found.make_suggestable(self.tcx, false) {
+                if let Some(found) = found.make_suggestable(self.tcx, false, None) {
                     err.subdiagnostic(
                         self.dcx(),
                         errors::AddReturnTypeSuggestion::Add { span, found: found.to_string() },

compiler/rustc_hir_typeck/src/op.rs

@@ -601,8 +601,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                                             if let Some(output_def_id) = output_def_id
                                                 && let Some(trait_def_id) = trait_def_id
                                                 && self.tcx.parent(output_def_id) == trait_def_id
-                                                && let Some(output_ty) =
-                                                    output_ty.make_suggestable(self.tcx, false)
+                                                && let Some(output_ty) = output_ty
+                                                    .make_suggestable(self.tcx, false, None)
                                             {
                                                 Some(("Output", output_ty))
                                             } else {

compiler/rustc_hir_typeck/src/pat.rs

@@ -18,8 +18,7 @@ use rustc_span::edit_distance::find_best_match_for_name;
 use rustc_span::hygiene::DesugaringKind;
 use rustc_span::source_map::Spanned;
 use rustc_span::symbol::{kw, sym, Ident};
-use rustc_span::Span;
-use rustc_span::{BytePos, DUMMY_SP};
+use rustc_span::{BytePos, Span, DUMMY_SP};
 use rustc_target::abi::FieldIdx;
 use rustc_trait_selection::traits::{ObligationCause, Pattern};
 use ty::VariantDef;
@@ -211,6 +210,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             PatKind::Tuple(elements, ddpos) => {
                 self.check_pat_tuple(pat.span, elements, ddpos, expected, pat_info)
             }
+            PatKind::Box(inner) if self.tcx.features().deref_patterns => {
+                self.check_pat_deref(pat.span, inner, expected, pat_info)
+            }
             PatKind::Box(inner) => self.check_pat_box(pat.span, inner, expected, pat_info),
             PatKind::Ref(inner, mutbl) => self.check_pat_ref(pat, inner, mutbl, expected, pat_info),
             PatKind::Slice(before, slice, after) => {
@@ -1975,6 +1977,28 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         box_ty
     }
 
+    fn check_pat_deref(
+        &self,
+        span: Span,
+        inner: &'tcx Pat<'tcx>,
+        expected: Ty<'tcx>,
+        pat_info: PatInfo<'tcx, '_>,
+    ) -> Ty<'tcx> {
+        let tcx = self.tcx;
+        // FIXME(deref_patterns): use `DerefPure` for soundness
+        // FIXME(deref_patterns): use `DerefMut` when required
+        // <expected as Deref>::Target
+        let ty = Ty::new_projection(
+            tcx,
+            tcx.require_lang_item(hir::LangItem::DerefTarget, Some(span)),
+            [expected],
+        );
+        let ty = self.normalize(span, ty);
+        let ty = self.try_structurally_resolve_type(span, ty);
+        self.check_pat(inner, ty, pat_info);
+        expected
+    }
+
     // Precondition: Pat is Ref(inner)
     fn check_pat_ref(
         &self,

compiler/rustc_infer/src/infer/error_reporting/need_type_info.rs

@@ -546,40 +546,55 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                 }
             }
             InferSourceKind::FullyQualifiedMethodCall { receiver, successor, args, def_id } => {
-                let mut printer = fmt_printer(self, Namespace::ValueNS);
-                printer.print_def_path(def_id, args).unwrap();
-                let def_path = printer.into_buffer();
-
-                // We only care about whether we have to add `&` or `&mut ` for now.
-                // This is the case if the last adjustment is a borrow and the
-                // first adjustment was not a builtin deref.
-                let adjustment = match typeck_results.expr_adjustments(receiver) {
-                    [
-                        Adjustment { kind: Adjust::Deref(None), target: _ },
-                        ..,
-                        Adjustment { kind: Adjust::Borrow(AutoBorrow::Ref(..)), target: _ },
-                    ] => "",
-                    [
-                        ..,
-                        Adjustment { kind: Adjust::Borrow(AutoBorrow::Ref(_, mut_)), target: _ },
-                    ] => hir::Mutability::from(*mut_).ref_prefix_str(),
-                    _ => "",
-                };
+                let placeholder = Some(self.next_ty_var(TypeVariableOrigin {
+                    span: rustc_span::DUMMY_SP,
+                    kind: TypeVariableOriginKind::MiscVariable,
+                }));
+                if let Some(args) = args.make_suggestable(self.infcx.tcx, true, placeholder) {
+                    let mut printer = fmt_printer(self, Namespace::ValueNS);
+                    printer.print_def_path(def_id, args).unwrap();
+                    let def_path = printer.into_buffer();
+
+                    // We only care about whether we have to add `&` or `&mut ` for now.
+                    // This is the case if the last adjustment is a borrow and the
+                    // first adjustment was not a builtin deref.
+                    let adjustment = match typeck_results.expr_adjustments(receiver) {
+                        [
+                            Adjustment { kind: Adjust::Deref(None), target: _ },
+                            ..,
+                            Adjustment { kind: Adjust::Borrow(AutoBorrow::Ref(..)), target: _ },
+                        ] => "",
+                        [
+                            ..,
+                            Adjustment {
+                                kind: Adjust::Borrow(AutoBorrow::Ref(_, mut_)),
+                                target: _,
+                            },
+                        ] => hir::Mutability::from(*mut_).ref_prefix_str(),
+                        _ => "",
+                    };
 
-                multi_suggestions.push(SourceKindMultiSuggestion::new_fully_qualified(
-                    receiver.span,
-                    def_path,
-                    adjustment,
-                    successor,
-                ));
+                    multi_suggestions.push(SourceKindMultiSuggestion::new_fully_qualified(
+                        receiver.span,
+                        def_path,
+                        adjustment,
+                        successor,
+                    ));
+                }
             }
             InferSourceKind::ClosureReturn { ty, data, should_wrap_expr } => {
-                let ty_info = ty_to_string(self, ty, None);
-                multi_suggestions.push(SourceKindMultiSuggestion::new_closure_return(
-                    ty_info,
-                    data,
-                    should_wrap_expr,
-                ));
+                let placeholder = Some(self.next_ty_var(TypeVariableOrigin {
+                    span: rustc_span::DUMMY_SP,
+                    kind: TypeVariableOriginKind::MiscVariable,
+                }));
+                if let Some(ty) = ty.make_suggestable(self.infcx.tcx, true, placeholder) {
+                    let ty_info = ty_to_string(self, ty, None);
+                    multi_suggestions.push(SourceKindMultiSuggestion::new_closure_return(
+                        ty_info,
+                        data,
+                        should_wrap_expr,
+                    ));
+                }
             }
         }
         match error_code {

compiler/rustc_middle/src/thir.rs

@@ -647,6 +647,7 @@ impl<'tcx> Pat<'tcx> {
             AscribeUserType { subpattern, .. }
             | Binding { subpattern: Some(subpattern), .. }
             | Deref { subpattern }
+            | DerefPattern { subpattern }
             | InlineConstant { subpattern, .. } => subpattern.walk_(it),
             Leaf { subpatterns } | Variant { subpatterns, .. } => {
                 subpatterns.iter().for_each(|field| field.pattern.walk_(it))
@@ -762,6 +763,11 @@ pub enum PatKind<'tcx> {
         subpattern: Box<Pat<'tcx>>,
     },
 
+    /// Deref pattern, written `box P` for now.
+    DerefPattern {
+        subpattern: Box<Pat<'tcx>>,
+    },
+
     /// One of the following:
     /// * `&str` (represented as a valtree), which will be handled as a string pattern and thus
     ///   exhaustiveness checking will detect if you use the same string twice in different
@@ -1172,6 +1178,9 @@ impl<'tcx> fmt::Display for Pat<'tcx> {
                 }
                 write!(f, "{subpattern}")
             }
+            PatKind::DerefPattern { ref subpattern } => {
+                write!(f, "k#deref {subpattern}")
+            }
             PatKind::Constant { value } => write!(f, "{value}"),
             PatKind::InlineConstant { def: _, ref subpattern } => {
                 write!(f, "{} (from inline const)", subpattern)

compiler/rustc_middle/src/thir/visit.rs

@@ -229,6 +229,7 @@ pub fn walk_pat<'thir, 'tcx: 'thir, V: Visitor<'thir, 'tcx>>(
     match &pat.kind {
         AscribeUserType { subpattern, ascription: _ }
         | Deref { subpattern }
+        | DerefPattern { subpattern }
         | Binding {
             subpattern: Some(subpattern),
             mutability: _,