Render fn defs with target_features attrs with the attribute [second site]

Author: oli-obk

compiler/rustc_trait_selection/src/error_reporting/infer/nice_region_error/trait_impl_difference.rs

@@ -3,7 +3,7 @@
 use rustc_errors::ErrorGuaranteed;
 use rustc_hir as hir;
 use rustc_hir::def::{Namespace, Res};
-use rustc_hir::def_id::DefId;
+use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_hir::intravisit::Visitor;
 use rustc_middle::hir::nested_filter;
 use rustc_middle::traits::ObligationCauseCode;
@@ -33,14 +33,21 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
             _,
         ) = error.clone()
             && let (Subtype(sup_trace), Subtype(sub_trace)) = (&sup_origin, &sub_origin)
-            && let &ObligationCauseCode::CompareImplItem { trait_item_def_id, .. } =
-                sub_trace.cause.code()
+            && let &ObligationCauseCode::CompareImplItem {
+                trait_item_def_id, impl_item_def_id, ..
+            } = sub_trace.cause.code()
             && sub_trace.values == sup_trace.values
             && let ValuePairs::PolySigs(ExpectedFound { expected, found }) = sub_trace.values
         {
             // FIXME(compiler-errors): Don't like that this needs `Ty`s, but
             // all of the region highlighting machinery only deals with those.
-            let guar = self.emit_err(var_origin.span(), expected, found, trait_item_def_id);
+            let guar = self.emit_err(
+                var_origin.span(),
+                expected,
+                found,
+                trait_item_def_id,
+                impl_item_def_id,
+            );
             return Some(guar);
         }
         None
@@ -52,6 +59,7 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
         expected: ty::PolyFnSig<'tcx>,
         found: ty::PolyFnSig<'tcx>,
         trait_item_def_id: DefId,
+        impl_item_def_id: LocalDefId,
     ) -> ErrorGuaranteed {
         let trait_sp = self.tcx().def_span(trait_item_def_id);
 
@@ -82,18 +90,25 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
 
         let expected_highlight = HighlightBuilder::build(expected);
         let tcx = self.cx.tcx;
-        let expected = Highlighted {
+        let mut expected = Highlighted {
             highlight: expected_highlight,
             ns: Namespace::TypeNS,
             tcx,
             value: expected,
         }
         .to_string();
+        if tcx.codegen_fn_attrs(trait_item_def_id).safe_target_features {
+            expected = format!("#[target_features] {expected}");
+        }
         let found_highlight = HighlightBuilder::build(found);
-        let found =
+        let mut found =
             Highlighted { highlight: found_highlight, ns: Namespace::TypeNS, tcx, value: found }
                 .to_string();
 
+        if tcx.codegen_fn_attrs(impl_item_def_id).safe_target_features {
+            found = format!("#[target_features] {found}");
+        }
+
         // Get the span of all the used type parameters in the method.
         let assoc_item = self.tcx().associated_item(trait_item_def_id);
         let mut visitor = TypeParamSpanVisitor { tcx: self.tcx(), types: vec![] };