Give right hand type higher priority on errors

gcc/rust/ChangeLog:

	* typecheck/rust-unify.cc (UnifyRules::Resolve): Return right hand type
	on error.

Signed-off-by: Pierre-Emmanuel Patry <[email protected]>

Author: P-E-P

gcc/rust/typecheck/rust-unify.cc

@@ -50,7 +50,10 @@ UnifyRules::Resolve (TyTy::TyWithLocation lhs, TyTy::TyWithLocation rhs,
 
   bool failed = result->get_kind () == TyTy::TypeKind::ERROR;
   if (failed && r.emit_error)
-    r.emit_type_mismatch ();
+    {
+      r.emit_type_mismatch ();
+      return lhs.get_ty ()->clone ();
+    }
 
   return result;
 }