compiler: propagate array length error marker farther

Fixes golang/go#53639

Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/415936

gcc/go/gofrontend/MERGE

@@ -1,4 +1,4 @@
-a209dca9ec918535977dcab99fd9bb60986ffacd
+d295a0a2c96c0f7c3abd94fea3aa4e2303bf2af2
 
 The first line of this file holds the git revision number of the last
 merge done from the gofrontend repository.

gcc/go/gofrontend/expressions.cc

@@ -8486,6 +8486,11 @@ Builtin_call_expression::do_flatten(Gogo* gogo, Named_object* function,
 	     pa != this->args()->end();
 	     ++pa)
 	  {
+	    if ((*pa)->is_error_expression())
+	      {
+		go_assert(saw_errors());
+		return Expression::make_error(loc);
+	      }
 	    if ((*pa)->is_nil_expression())
 	      {
 		Expression* nil = Expression::make_nil(loc);
@@ -13391,6 +13396,7 @@ Array_index_expression::do_check_types(Gogo*)
   if (array_type == NULL)
     {
       go_assert(this->array_->type()->is_error());
+      this->set_is_error();
       return;
     }
 

gcc/go/gofrontend/types.cc

@@ -7429,7 +7429,10 @@ bool
 Array_type::do_verify()
 {
   if (this->element_type()->is_error_type())
-    return false;
+    {
+      this->set_is_error();
+      return false;
+    }
   if (!this->verify_length())
     {
       this->length_ = Expression::make_error(this->length_->location());