Rollup of 8 pull requests

compiler/rustc_expand/src/mbe/macro_rules.rs

@@ -223,7 +223,8 @@ fn expand_macro<'cx>(
             let arm_span = rhses[i].span();
 
             // rhs has holes ( `$id` and `$(...)` that need filled)
-            let tts = match transcribe(cx, &named_matches, rhs, rhs_span, transparency) {
+            let id = cx.current_expansion.id;
+            let tts = match transcribe(psess, &named_matches, rhs, rhs_span, transparency, id) {
                 Ok(tts) => tts,
                 Err(err) => {
                     let guar = err.emit();

compiler/rustc_expand/src/mbe/transcribe.rs

@@ -1,4 +1,3 @@
-use crate::base::ExtCtxt;
 use crate::errors::{
     CountRepetitionMisplaced, MetaVarExprUnrecognizedVar, MetaVarsDifSeqMatchers, MustRepeatOnce,
     NoSyntaxVarsExprRepeat, VarStillRepeating,
@@ -9,12 +8,13 @@ use rustc_ast::mut_visit::{self, MutVisitor};
 use rustc_ast::token::{self, Delimiter, Token, TokenKind};
 use rustc_ast::tokenstream::{DelimSpacing, DelimSpan, Spacing, TokenStream, TokenTree};
 use rustc_data_structures::fx::FxHashMap;
-use rustc_errors::{pluralize, Diag, PResult};
+use rustc_errors::{pluralize, Diag, DiagCtxt, PResult};
 use rustc_parse::parser::ParseNtResult;
 use rustc_span::hygiene::{LocalExpnId, Transparency};
 use rustc_span::symbol::{sym, Ident, MacroRulesNormalizedIdent};
 use rustc_span::{with_metavar_spans, Span, SyntaxContext};
 
+use rustc_session::parse::ParseSess;
 use smallvec::{smallvec, SmallVec};
 use std::mem;
 
@@ -99,11 +99,12 @@ impl<'a> Iterator for Frame<'a> {
 ///
 /// Along the way, we do some additional error checking.
 pub(super) fn transcribe<'a>(
-    cx: &ExtCtxt<'a>,
+    psess: &'a ParseSess,
     interp: &FxHashMap<MacroRulesNormalizedIdent, NamedMatch>,
     src: &mbe::Delimited,
     src_span: DelimSpan,
     transparency: Transparency,
+    expand_id: LocalExpnId,
 ) -> PResult<'a, TokenStream> {
     // Nothing for us to transcribe...
     if src.tts.is_empty() {
@@ -137,8 +138,9 @@ pub(super) fn transcribe<'a>(
     // again, and we are done transcribing.
     let mut result: Vec<TokenTree> = Vec::new();
     let mut result_stack = Vec::new();
-    let mut marker = Marker(cx.current_expansion.id, transparency, Default::default());
+    let mut marker = Marker(expand_id, transparency, Default::default());
 
+    let dcx = &psess.dcx;
     loop {
         // Look at the last frame on the stack.
         // If it still has a TokenTree we have not looked at yet, use that tree.
@@ -201,19 +203,17 @@ pub(super) fn transcribe<'a>(
             seq @ mbe::TokenTree::Sequence(_, seq_rep) => {
                 match lockstep_iter_size(seq, interp, &repeats) {
                     LockstepIterSize::Unconstrained => {
-                        return Err(cx
-                            .dcx()
-                            .create_err(NoSyntaxVarsExprRepeat { span: seq.span() }));
+                        return Err(dcx.create_err(NoSyntaxVarsExprRepeat { span: seq.span() }));
                     }
 
                     LockstepIterSize::Contradiction(msg) => {
                         // FIXME: this really ought to be caught at macro definition time... It
                         // happens when two meta-variables are used in the same repetition in a
                         // sequence, but they come from different sequence matchers and repeat
                         // different amounts.
-                        return Err(cx
-                            .dcx()
-                            .create_err(MetaVarsDifSeqMatchers { span: seq.span(), msg }));
+                        return Err(
+                            dcx.create_err(MetaVarsDifSeqMatchers { span: seq.span(), msg })
+                        );
                     }
 
                     LockstepIterSize::Constraint(len, _) => {
@@ -227,9 +227,7 @@ pub(super) fn transcribe<'a>(
                                 // FIXME: this really ought to be caught at macro definition
                                 // time... It happens when the Kleene operator in the matcher and
                                 // the body for the same meta-variable do not match.
-                                return Err(cx
-                                    .dcx()
-                                    .create_err(MustRepeatOnce { span: sp.entire() }));
+                                return Err(dcx.create_err(MustRepeatOnce { span: sp.entire() }));
                             }
                         } else {
                             // 0 is the initial counter (we have done 0 repetitions so far). `len`
@@ -274,7 +272,7 @@ pub(super) fn transcribe<'a>(
                         MatchedSingle(ParseNtResult::Tt(tt)) => {
                             // `tt`s are emitted into the output stream directly as "raw tokens",
                             // without wrapping them into groups.
-                            maybe_use_metavar_location(cx, &stack, sp, tt, &mut marker)
+                            maybe_use_metavar_location(psess, &stack, sp, tt, &mut marker)
                         }
                         MatchedSingle(ParseNtResult::Ident(ident, is_raw)) => {
                             marker.visit_span(&mut sp);
@@ -295,7 +293,7 @@ pub(super) fn transcribe<'a>(
                         }
                         MatchedSeq(..) => {
                             // We were unable to descend far enough. This is an error.
-                            return Err(cx.dcx().create_err(VarStillRepeating { span: sp, ident }));
+                            return Err(dcx.create_err(VarStillRepeating { span: sp, ident }));
                         }
                     };
                     result.push(tt)
@@ -314,7 +312,7 @@ pub(super) fn transcribe<'a>(
 
             // Replace meta-variable expressions with the result of their expansion.
             mbe::TokenTree::MetaVarExpr(sp, expr) => {
-                transcribe_metavar_expr(cx, expr, interp, &mut marker, &repeats, &mut result, sp)?;
+                transcribe_metavar_expr(dcx, expr, interp, &mut marker, &repeats, &mut result, sp)?;
             }
 
             // If we are entering a new delimiter, we push its contents to the `stack` to be
@@ -374,7 +372,7 @@ pub(super) fn transcribe<'a>(
 ///   combine with each other and not with tokens outside of the sequence.
 /// - The metavariable span comes from a different crate, then we prefer the more local span.
 fn maybe_use_metavar_location(
-    cx: &ExtCtxt<'_>,
+    psess: &ParseSess,
     stack: &[Frame<'_>],
     mut metavar_span: Span,
     orig_tt: &TokenTree,
@@ -412,7 +410,7 @@ fn maybe_use_metavar_location(
                 && insert(mspans, dspan.entire(), metavar_span)
         }),
     };
-    if no_collision || cx.source_map().is_imported(metavar_span) {
+    if no_collision || psess.source_map().is_imported(metavar_span) {
         return orig_tt.clone();
     }
 
@@ -573,7 +571,7 @@ fn lockstep_iter_size(
 /// * `[ $( ${count(foo, 1)} ),* ]` will return an error because `${count(foo, 1)}` is
 ///   declared inside a single repetition and the index `1` implies two nested repetitions.
 fn count_repetitions<'a>(
-    cx: &ExtCtxt<'a>,
+    dcx: &'a DiagCtxt,
     depth_user: usize,
     mut matched: &NamedMatch,
     repeats: &[(usize, usize)],
@@ -610,7 +608,7 @@ fn count_repetitions<'a>(
         .and_then(|el| el.checked_sub(repeats.len()))
         .unwrap_or_default();
     if depth_user > depth_max {
-        return Err(out_of_bounds_err(cx, depth_max + 1, sp.entire(), "count"));
+        return Err(out_of_bounds_err(dcx, depth_max + 1, sp.entire(), "count"));
     }
 
     // `repeats` records all of the nested levels at which we are currently
@@ -626,15 +624,15 @@ fn count_repetitions<'a>(
     }
 
     if let MatchedSingle(_) = matched {
-        return Err(cx.dcx().create_err(CountRepetitionMisplaced { span: sp.entire() }));
+        return Err(dcx.create_err(CountRepetitionMisplaced { span: sp.entire() }));
     }
 
     count(depth_user, depth_max, matched)
 }
 
 /// Returns a `NamedMatch` item declared on the LHS given an arbitrary [Ident]
 fn matched_from_ident<'ctx, 'interp, 'rslt>(
-    cx: &ExtCtxt<'ctx>,
+    dcx: &'ctx DiagCtxt,
     ident: Ident,
     interp: &'interp FxHashMap<MacroRulesNormalizedIdent, NamedMatch>,
 ) -> PResult<'ctx, &'rslt NamedMatch>
@@ -643,12 +641,12 @@ where
 {
     let span = ident.span;
     let key = MacroRulesNormalizedIdent::new(ident);
-    interp.get(&key).ok_or_else(|| cx.dcx().create_err(MetaVarExprUnrecognizedVar { span, key }))
+    interp.get(&key).ok_or_else(|| dcx.create_err(MetaVarExprUnrecognizedVar { span, key }))
 }
 
 /// Used by meta-variable expressions when an user input is out of the actual declared bounds. For
 /// example, index(999999) in an repetition of only three elements.
-fn out_of_bounds_err<'a>(cx: &ExtCtxt<'a>, max: usize, span: Span, ty: &str) -> Diag<'a> {
+fn out_of_bounds_err<'a>(dcx: &'a DiagCtxt, max: usize, span: Span, ty: &str) -> Diag<'a> {
     let msg = if max == 0 {
         format!(
             "meta-variable expression `{ty}` with depth parameter \
@@ -660,11 +658,11 @@ fn out_of_bounds_err<'a>(cx: &ExtCtxt<'a>, max: usize, span: Span, ty: &str) ->
              must be less than {max}"
         )
     };
-    cx.dcx().struct_span_err(span, msg)
+    dcx.struct_span_err(span, msg)
 }
 
 fn transcribe_metavar_expr<'a>(
-    cx: &ExtCtxt<'a>,
+    dcx: &'a DiagCtxt,
     expr: &MetaVarExpr,
     interp: &FxHashMap<MacroRulesNormalizedIdent, NamedMatch>,
     marker: &mut Marker,
@@ -679,8 +677,8 @@ fn transcribe_metavar_expr<'a>(
     };
     match *expr {
         MetaVarExpr::Count(original_ident, depth) => {
-            let matched = matched_from_ident(cx, original_ident, interp)?;
-            let count = count_repetitions(cx, depth, matched, repeats, sp)?;
+            let matched = matched_from_ident(dcx, original_ident, interp)?;
+            let count = count_repetitions(dcx, depth, matched, repeats, sp)?;
             let tt = TokenTree::token_alone(
                 TokenKind::lit(token::Integer, sym::integer(count), None),
                 visited_span(),
@@ -689,7 +687,7 @@ fn transcribe_metavar_expr<'a>(
         }
         MetaVarExpr::Ignore(original_ident) => {
             // Used to ensure that `original_ident` is present in the LHS
-            let _ = matched_from_ident(cx, original_ident, interp)?;
+            let _ = matched_from_ident(dcx, original_ident, interp)?;
         }
         MetaVarExpr::Index(depth) => match repeats.iter().nth_back(depth) {
             Some((index, _)) => {
@@ -698,7 +696,7 @@ fn transcribe_metavar_expr<'a>(
                     visited_span(),
                 ));
             }
-            None => return Err(out_of_bounds_err(cx, repeats.len(), sp.entire(), "index")),
+            None => return Err(out_of_bounds_err(dcx, repeats.len(), sp.entire(), "index")),
         },
         MetaVarExpr::Len(depth) => match repeats.iter().nth_back(depth) {
             Some((_, length)) => {
@@ -707,7 +705,7 @@ fn transcribe_metavar_expr<'a>(
                     visited_span(),
                 ));
             }
-            None => return Err(out_of_bounds_err(cx, repeats.len(), sp.entire(), "len")),
+            None => return Err(out_of_bounds_err(dcx, repeats.len(), sp.entire(), "len")),
         },
     }
     Ok(())

compiler/rustc_lint/messages.ftl

@@ -233,6 +233,7 @@ lint_drop_trait_constraints =
 lint_dropping_copy_types = calls to `std::mem::drop` with a value that implements `Copy` does nothing
     .label = argument has type `{$arg_ty}`
     .note = use `let _ = ...` to ignore the expression or result
+    .suggestion = use `let _ = ...` to ignore the expression or result
 
 lint_dropping_references = calls to `std::mem::drop` with a reference instead of an owned value does nothing
     .label = argument has type `{$arg_ty}`

compiler/rustc_lint/src/drop_forget_useless.rs

@@ -1,12 +1,12 @@
-use rustc_hir::{Arm, Expr, ExprKind, Node};
+use rustc_hir::{Arm, Expr, ExprKind, Node, StmtKind};
 use rustc_middle::ty;
 use rustc_session::{declare_lint, declare_lint_pass};
 use rustc_span::sym;
 
 use crate::{
     lints::{
-        DropCopyDiag, DropRefDiag, ForgetCopyDiag, ForgetRefDiag, UndroppedManuallyDropsDiag,
-        UndroppedManuallyDropsSuggestion,
+        DropCopyDiag, DropCopySuggestion, DropRefDiag, ForgetCopyDiag, ForgetRefDiag,
+        UndroppedManuallyDropsDiag, UndroppedManuallyDropsSuggestion,
     },
     LateContext, LateLintPass, LintContext,
 };
@@ -164,10 +164,23 @@ impl<'tcx> LateLintPass<'tcx> for DropForgetUseless {
                     );
                 }
                 sym::mem_drop if is_copy && !drop_is_single_call_in_arm => {
+                    let sugg = if let Some((_, node)) = cx.tcx.hir().parent_iter(expr.hir_id).nth(0)
+                        && let Node::Stmt(stmt) = node
+                        && let StmtKind::Semi(e) = stmt.kind
+                        && e.hir_id == expr.hir_id
+                    {
+                        DropCopySuggestion::Suggestion {
+                            start_span: expr.span.shrink_to_lo().until(arg.span),
+                            end_span: arg.span.shrink_to_hi().until(expr.span.shrink_to_hi()),
+                        }
+                    } else {
+                        DropCopySuggestion::Note
+                    };
+
                     cx.emit_span_lint(
                         DROPPING_COPY_TYPES,
                         expr.span,
-                        DropCopyDiag { arg_ty, label: arg.span },
+                        DropCopyDiag { arg_ty, label: arg.span, sugg },
                     );
                 }
                 sym::mem_forget if is_copy => {

compiler/rustc_lint/src/lints.rs

@@ -677,11 +677,25 @@ pub struct DropRefDiag<'a> {
 
 #[derive(LintDiagnostic)]
 #[diag(lint_dropping_copy_types)]
-#[note]
 pub struct DropCopyDiag<'a> {
     pub arg_ty: Ty<'a>,
     #[label]
     pub label: Span,
+    #[subdiagnostic]
+    pub sugg: DropCopySuggestion,
+}
+
+#[derive(Subdiagnostic)]
+pub enum DropCopySuggestion {
+    #[note(lint_note)]
+    Note,
+    #[multipart_suggestion(lint_suggestion, style = "verbose", applicability = "maybe-incorrect")]
+    Suggestion {
+        #[suggestion_part(code = "let _ = ")]
+        start_span: Span,
+        #[suggestion_part(code = "")]
+        end_span: Span,
+    },
 }
 
 #[derive(LintDiagnostic)]

compiler/rustc_mir_transform/src/sroa.rs

@@ -70,6 +70,11 @@ fn escaping_locals<'tcx>(
                 // Exclude #[repr(simd)] types so that they are not de-optimized into an array
                 return true;
             }
+            if Some(def.did()) == tcx.lang_items().dyn_metadata() {
+                // codegen wants to see the `DynMetadata<T>`,
+                // not the inner reference-to-opaque-type.
+                return true;
+            }
             // We already excluded unions and enums, so this ADT must have one variant
             let variant = def.variant(FIRST_VARIANT);
             if variant.fields.len() > 1 {