comment return sites

src/librustc_trait_selection/traits/structural_match.rs

@@ -149,19 +149,19 @@ impl<'a, 'tcx> TypeVisitor<'tcx> for Search<'a, 'tcx> {
             }
             ty::Foreign(_) => {
                 self.found = Some(NonStructuralMatchTy::Foreign);
-                return true; // Stop visiting
+                return true; // Stop visiting.
             }
             ty::Opaque(..) => {
                 self.found = Some(NonStructuralMatchTy::Opaque);
-                return true;
+                return true; // Stop visiting.
             }
             ty::Projection(..) => {
                 self.found = Some(NonStructuralMatchTy::Projection);
-                return true;
+                return true; // Stop visiting.
             }
             ty::Generator(..) | ty::GeneratorWitness(..) => {
                 self.found = Some(NonStructuralMatchTy::Generator);
-                return true;
+                return true; // Stop visiting.
             }
             ty::RawPtr(..) => {
                 // structural-match ignores substructure of
@@ -179,31 +179,36 @@ impl<'a, 'tcx> TypeVisitor<'tcx> for Search<'a, 'tcx> {
                 // structural equality on `T` does not recur into the raw
                 // pointer. Therefore, one can still use `C` in a pattern.
 
-                // (But still tell caller to continue search.)
+                // (But still tell the caller to continue search.)
                 return false;
             }
             ty::FnDef(..) | ty::FnPtr(..) => {
                 // Types of formals and return in `fn(_) -> _` are also irrelevant;
                 // so we do not recur into them via `super_visit_with`
                 //
-                // (But still tell caller to continue search.)
+                // (But still tell the caller to continue search.)
                 return false;
             }
             ty::Array(_, n)
                 if { n.try_eval_usize(self.tcx(), ty::ParamEnv::reveal_all()) == Some(0) } =>
             {
                 // rust-lang/rust#62336: ignore type of contents
                 // for empty array.
+                //
+                // (But still tell the caller to continue search.)
                 return false;
             }
             ty::Bool | ty::Char | ty::Int(_) | ty::Uint(_) | ty::Float(_) | ty::Str | ty::Never => {
                 // These primitive types are always structural match.
                 //
                 // `Never` is kind of special here, but as it is not inhabitable, this should be fine.
+                //
+                // (But still tell the caller to continue search.)
                 return false;
             }
 
             ty::Array(..) | ty::Slice(_) | ty::Ref(..) | ty::Tuple(..) => {
+                // First check all contained types and then tell the caller to continue searching.
                 ty.super_visit_with(self);
                 return false;
             }
@@ -214,13 +219,15 @@ impl<'a, 'tcx> TypeVisitor<'tcx> for Search<'a, 'tcx> {
                 self.tcx().sess.delay_span_bug(self.span, "ty::Error in structural-match check");
                 // We still want to check other types after encountering an error,
                 // as this may still emit relevant errors.
+                //
+                // So we continue searching here.
                 return false;
             }
         };
 
         if !self.seen.insert(adt_def.did) {
             debug!("Search already seen adt_def: {:?}", adt_def);
-            // let caller continue its search
+            // Let caller continue its search.
             return false;
         }