Fix duplicated function generation on higher ranked trait bounds

Deuplicate function elimination can fail when we compile helpers during
higher ranked trait bound monomorphization. This because the
TyTy::BaseType info can be lost/reset during the compilation process. This
adds a second mechanism to match based on the manged names which is a bit
more reliable. This patch is required since the query based refactor of
the type system so this issue was likely hidden to to using duplicated type
info for higher ranked trait bounds.

1 files changed, 20 insertions, 1 deletions

diff --git a/gcc/rust/backend/rust-compile-context.h b/gcc/rust/backend/rust-compile-context.h
index 096b65f..415b13e 100644
--- a/gcc/rust/backend/rust-compile-context.h
+++ b/gcc/rust/backend/rust-compile-context.h
@@ -148,7 +148,8 @@ public:
   }
 
   bool lookup_function_decl (HirId id, tree *fn, DefId dId = UNKNOWN_DEFID,
-			     const TyTy::BaseType *ref = nullptr)
+			     const TyTy::BaseType *ref = nullptr,
+			     const std::string &asm_name = std::string ())
   {
     // for for any monomorphized fns
     if (ref != nullptr)
@@ -163,11 +164,29 @@ public:
 	  {
 	    const TyTy::BaseType *r = e.first;
 	    tree f = e.second;
+
 	    if (ref->is_equal (*r))
 	      {
 		*fn = f;
 		return true;
 	      }
+
+	    if (DECL_ASSEMBLER_NAME_SET_P (f) && !asm_name.empty ())
+	      {
+		tree raw = DECL_ASSEMBLER_NAME_RAW (f);
+		const char *rptr = IDENTIFIER_POINTER (raw);
+
+		bool lengths_match_p
+		  = IDENTIFIER_LENGTH (raw) == asm_name.size ();
+		if (lengths_match_p
+		    && strncmp (rptr, asm_name.c_str (),
+				IDENTIFIER_LENGTH (raw))
+			 == 0)
+		  {
+		    *fn = f;
+		    return true;
+		  }
+	      }
 	  }
 	return false;
       }