Rollup of 6 pull requests

compiler/rustc_borrowck/src/diagnostics/region_errors.rs

@@ -1,17 +1,17 @@
 //! Error reporting machinery for lifetime errors.
 
-use rustc_errors::{Applicability, Diagnostic, DiagnosticBuilder, ErrorGuaranteed};
+use rustc_errors::{Diagnostic, DiagnosticBuilder, ErrorGuaranteed};
 use rustc_infer::infer::{
-    error_reporting::nice_region_error::NiceRegionError,
-    error_reporting::unexpected_hidden_region_diagnostic, NllRegionVariableOrigin,
-    RelateParamBound,
+    error_reporting::nice_region_error::{self, find_param_with_region, NiceRegionError},
+    error_reporting::unexpected_hidden_region_diagnostic,
+    NllRegionVariableOrigin, RelateParamBound,
 };
 use rustc_middle::hir::place::PlaceBase;
 use rustc_middle::mir::{ConstraintCategory, ReturnConstraint};
-use rustc_middle::ty::subst::{InternalSubsts, Subst};
+use rustc_middle::ty::subst::InternalSubsts;
 use rustc_middle::ty::{self, RegionVid, Ty};
-use rustc_span::symbol::{kw, sym};
-use rustc_span::{BytePos, Span};
+use rustc_span::symbol::sym;
+use rustc_span::Span;
 
 use crate::borrowck_errors;
 
@@ -651,82 +651,47 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
         fr_name: RegionName,
         outlived_fr: RegionVid,
     ) {
-        if let (Some(f), Some(ty::ReStatic)) =
-            (self.to_error_region(fr), self.to_error_region(outlived_fr).as_deref())
+        if let (Some(f), Some(outlived_f)) =
+            (self.to_error_region(fr), self.to_error_region(outlived_fr))
         {
-            if let Some(&ty::Opaque(did, substs)) = self
+            if *outlived_f != ty::ReStatic {
+                return;
+            }
+
+            let fn_returns = self
                 .infcx
                 .tcx
                 .is_suitable_region(f)
-                .map(|r| r.def_id)
-                .and_then(|id| self.infcx.tcx.return_type_impl_trait(id))
-                .map(|(ty, _)| ty.kind())
-            {
-                // Check whether or not the impl trait return type is intended to capture
-                // data with the static lifetime.
-                //
-                // eg. check for `impl Trait + 'static` instead of `impl Trait`.
-                let has_static_predicate = {
-                    let bounds = self.infcx.tcx.explicit_item_bounds(did);
-
-                    let mut found = false;
-                    for (bound, _) in bounds {
-                        if let ty::PredicateKind::TypeOutlives(ty::OutlivesPredicate(_, r)) =
-                            bound.kind().skip_binder()
-                        {
-                            let r = r.subst(self.infcx.tcx, substs);
-                            if r.is_static() {
-                                found = true;
-                                break;
-                            } else {
-                                // If there's already a lifetime bound, don't
-                                // suggest anything.
-                                return;
-                            }
-                        }
-                    }
-
-                    found
-                };
+                .map(|r| self.infcx.tcx.return_type_impl_or_dyn_traits(r.def_id))
+                .unwrap_or_default();
 
-                debug!(
-                    "add_static_impl_trait_suggestion: has_static_predicate={:?}",
-                    has_static_predicate
-                );
-                let static_str = kw::StaticLifetime;
-                // If there is a static predicate, then the only sensible suggestion is to replace
-                // fr with `'static`.
-                if has_static_predicate {
-                    diag.help(&format!("consider replacing `{fr_name}` with `{static_str}`"));
-                } else {
-                    // Otherwise, we should suggest adding a constraint on the return type.
-                    let span = self.infcx.tcx.def_span(did);
-                    if let Ok(snippet) = self.infcx.tcx.sess.source_map().span_to_snippet(span) {
-                        let suggestable_fr_name = if fr_name.was_named() {
-                            fr_name.to_string()
-                        } else {
-                            "'_".to_string()
-                        };
-                        let span = if snippet.ends_with(';') {
-                            // `type X = impl Trait;`
-                            span.with_hi(span.hi() - BytePos(1))
-                        } else {
-                            span
-                        };
-                        let suggestion = format!(" + {suggestable_fr_name}");
-                        let span = span.shrink_to_hi();
-                        diag.span_suggestion(
-                            span,
-                            &format!(
-                                "to allow this `impl Trait` to capture borrowed data with lifetime \
-                                 `{fr_name}`, add `{suggestable_fr_name}` as a bound",
-                            ),
-                            suggestion,
-                            Applicability::MachineApplicable,
-                        );
-                    }
-                }
+            if fn_returns.is_empty() {
+                return;
             }
+
+            let param = if let Some(param) = find_param_with_region(self.infcx.tcx, f, outlived_f) {
+                param
+            } else {
+                return;
+            };
+
+            let lifetime = if f.has_name() { fr_name.to_string() } else { "'_".to_string() };
+
+            let arg = match param.param.pat.simple_ident() {
+                Some(simple_ident) => format!("argument `{}`", simple_ident),
+                None => "the argument".to_string(),
+            };
+            let captures = format!("captures data from {}", arg);
+
+            return nice_region_error::suggest_new_region_bound(
+                self.infcx.tcx,
+                diag,
+                fn_returns,
+                lifetime,
+                Some(arg),
+                captures,
+                Some((param.param_ty_span, param.param_ty.to_string())),
+            );
         }
     }
 }

compiler/rustc_codegen_llvm/src/intrinsic.rs

@@ -816,6 +816,7 @@ fn generic_simd_intrinsic<'ll, 'tcx>(
     span: Span,
 ) -> Result<&'ll Value, ()> {
     // macros for error handling:
+    #[cfg_attr(not(bootstrap), allow(unused_macro_rules))]
     macro_rules! emit_error {
         ($msg: tt) => {
             emit_error!($msg, )
@@ -1144,6 +1145,7 @@ fn generic_simd_intrinsic<'ll, 'tcx>(
         span: Span,
         args: &[OperandRef<'tcx, &'ll Value>],
     ) -> Result<&'ll Value, ()> {
+        #[cfg_attr(not(bootstrap), allow(unused_macro_rules))]
         macro_rules! emit_error {
             ($msg: tt) => {
                 emit_error!($msg, )

compiler/rustc_expand/src/base.rs

@@ -711,6 +711,9 @@ pub struct SyntaxExtension {
     /// Built-in macros have a couple of special properties like availability
     /// in `#[no_implicit_prelude]` modules, so we have to keep this flag.
     pub builtin_name: Option<Symbol>,
+    /// Rule spans. Used for linting. If the macro is not made up of rules,
+    /// it's empty.
+    pub rule_spans: Vec<Span>,
 }
 
 impl SyntaxExtension {
@@ -740,6 +743,7 @@ impl SyntaxExtension {
             edition,
             builtin_name: None,
             kind,
+            rule_spans: Vec::new(),
         }
     }
 
@@ -753,6 +757,7 @@ impl SyntaxExtension {
         edition: Edition,
         name: Symbol,
         attrs: &[ast::Attribute],
+        rule_spans: Vec<Span>,
     ) -> SyntaxExtension {
         let allow_internal_unstable =
             attr::allow_internal_unstable(sess, &attrs).collect::<Vec<Symbol>>();
@@ -800,6 +805,7 @@ impl SyntaxExtension {
             helper_attrs,
             edition,
             builtin_name,
+            rule_spans,
         }
     }
 
@@ -887,6 +893,8 @@ pub trait ResolverExpand {
         force: bool,
     ) -> Result<Lrc<SyntaxExtension>, Indeterminate>;
 
+    fn record_macro_rule_usage(&mut self, mac_id: NodeId, rule_index: usize);
+
     fn check_unused_macros(&mut self);
 
     // Resolver interfaces for specific built-in macros.

compiler/rustc_expand/src/mbe/macro_rules.rs

@@ -156,6 +156,7 @@ impl<'a> ParserAnyMacro<'a> {
 }
 
 struct MacroRulesMacroExpander {
+    id: NodeId,
     name: Ident,
     span: Span,
     transparency: Transparency,
@@ -179,6 +180,7 @@ impl TTMacroExpander for MacroRulesMacroExpander {
             cx,
             sp,
             self.span,
+            self.id,
             self.name,
             self.transparency,
             input,
@@ -207,6 +209,7 @@ fn generic_extension<'cx, 'tt>(
     cx: &'cx mut ExtCtxt<'_>,
     sp: Span,
     def_span: Span,
+    id: NodeId,
     name: Ident,
     transparency: Transparency,
     arg: TokenStream,
@@ -297,6 +300,8 @@ fn generic_extension<'cx, 'tt>(
                 let mut p = Parser::new(sess, tts, false, None);
                 p.last_type_ascription = cx.current_expansion.prior_type_ascription;
 
+                cx.resolver.record_macro_rule_usage(id, i);
+
                 // Let the context choose how to interpret the result.
                 // Weird, but useful for X-macros.
                 return Box::new(ParserAnyMacro {
@@ -375,7 +380,7 @@ pub fn compile_declarative_macro(
     edition: Edition,
 ) -> SyntaxExtension {
     debug!("compile_declarative_macro: {:?}", def);
-    let mk_syn_ext = |expander| {
+    let mk_syn_ext = |expander, rule_spans| {
         SyntaxExtension::new(
             sess,
             SyntaxExtensionKind::LegacyBang(expander),
@@ -384,8 +389,10 @@ pub fn compile_declarative_macro(
             edition,
             def.ident.name,
             &def.attrs,
+            rule_spans,
         )
     };
+    let dummy_syn_ext = || mk_syn_ext(Box::new(macro_rules_dummy_expander), Vec::new());
 
     let diag = &sess.parse_sess.span_diagnostic;
     let lhs_nm = Ident::new(sym::lhs, def.span);
@@ -446,17 +453,17 @@ pub fn compile_declarative_macro(
             let s = parse_failure_msg(&token);
             let sp = token.span.substitute_dummy(def.span);
             sess.parse_sess.span_diagnostic.struct_span_err(sp, &s).span_label(sp, msg).emit();
-            return mk_syn_ext(Box::new(macro_rules_dummy_expander));
+            return dummy_syn_ext();
         }
         Error(sp, msg) => {
             sess.parse_sess
                 .span_diagnostic
                 .struct_span_err(sp.substitute_dummy(def.span), &msg)
                 .emit();
-            return mk_syn_ext(Box::new(macro_rules_dummy_expander));
+            return dummy_syn_ext();
         }
         ErrorReported => {
-            return mk_syn_ext(Box::new(macro_rules_dummy_expander));
+            return dummy_syn_ext();
         }
     };
 
@@ -531,6 +538,11 @@ pub fn compile_declarative_macro(
         None => {}
     }
 
+    // Compute the spans of the macro rules
+    // We only take the span of the lhs here,
+    // so that the spans of created warnings are smaller.
+    let rule_spans = lhses.iter().map(|lhs| lhs.span()).collect::<Vec<_>>();
+
     // Convert the lhses into `MatcherLoc` form, which is better for doing the
     // actual matching. Unless the matcher is invalid.
     let lhses = if valid {
@@ -550,17 +562,21 @@ pub fn compile_declarative_macro(
         vec![]
     };
 
-    mk_syn_ext(Box::new(MacroRulesMacroExpander {
-        name: def.ident,
-        span: def.span,
-        transparency,
-        lhses,
-        rhses,
-        valid,
-        // Macros defined in the current crate have a real node id,
-        // whereas macros from an external crate have a dummy id.
-        is_local: def.id != DUMMY_NODE_ID,
-    }))
+    mk_syn_ext(
+        Box::new(MacroRulesMacroExpander {
+            name: def.ident,
+            span: def.span,
+            id: def.id,
+            transparency,
+            lhses,
+            rhses,
+            valid,
+            // Macros defined in the current crate have a real node id,
+            // whereas macros from an external crate have a dummy id.
+            is_local: def.id != DUMMY_NODE_ID,
+        }),
+        rule_spans,
+    )
 }
 
 fn check_lhs_nt_follows(sess: &ParseSess, def: &ast::Item, lhs: &mbe::TokenTree) -> bool {

compiler/rustc_infer/src/infer/error_reporting/nice_region_error/mod.rs

@@ -15,6 +15,7 @@ mod trait_impl_difference;
 mod util;
 
 pub use static_impl_trait::suggest_new_region_bound;
+pub use util::find_param_with_region;
 
 impl<'cx, 'tcx> InferCtxt<'cx, 'tcx> {
     pub fn try_report_nice_region_error(&self, error: &RegionResolutionError<'tcx>) -> bool {