[Bug c++/84588] [8/9 Regression] internal compiler error: Segmentation fault (contains_struct_check())

[paolo.carlini at oracle dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84588

--- Comment #12 from Paolo Carlini <paolo.carlini at oracle dot com> ---
What I'm finishing testing:

Index: cp/parser.c
===================================================================
--- cp/parser.c (revision 260280)
+++ cp/parser.c (working copy)
@@ -21308,7 +21308,7 @@ cp_parser_parameter_declaration_list (cp_parser* p
   while (true)
     {
       cp_parameter_declarator *parameter;
-      tree decl = error_mark_node;
+      tree decl;
       bool parenthesized_p = false;

       /* Parse the parameter.  */
@@ -21316,21 +21316,22 @@ cp_parser_parameter_declaration_list (cp_parser* p
        = cp_parser_parameter_declaration (parser,
                                           /*template_parm_p=*/false,
                                           &parenthesized_p);
+      if (!parameter)
+       {
+         *is_error = true;
+         parameters = error_mark_node;
+         break;
+       }

       /* We don't know yet if the enclosing context is deprecated, so wait
         and warn in grokparms if appropriate.  */
       deprecated_state = DEPRECATED_SUPPRESS;

-      if (parameter)
-       {
-         decl = grokdeclarator (parameter->declarator,
-                                &parameter->decl_specifiers,
-                                PARM,
-                                parameter->default_argument != NULL_TREE,
-                                &parameter->decl_specifiers.attributes);
-         if (decl != error_mark_node && parameter->loc != UNKNOWN_LOCATION)
-           DECL_SOURCE_LOCATION (decl) = parameter->loc;
-       }
+      decl = grokdeclarator (parameter->declarator,
+                            &parameter->decl_specifiers,
+                            PARM,
+                            parameter->default_argument != NULL_TREE,
+                            &parameter->decl_specifiers.attributes);

       deprecated_state = DEPRECATED_NORMAL;

@@ -21340,9 +21341,14 @@ cp_parser_parameter_declaration_list (cp_parser* p
        {
          *is_error = true;
          parameters = error_mark_node;
+         if (parser->fully_implicit_function_template_p)
+           abort_fully_implicit_template (parser);
          break;
        }

+      if (parameter->loc != UNKNOWN_LOCATION)
+       DECL_SOURCE_LOCATION (decl) = parameter->loc;
+
       if (parameter->decl_specifiers.attributes)
        cplus_decl_attributes (&decl,
                               parameter->decl_specifiers.attributes,
Index: testsuite/g++.dg/cpp1y/pr84588.C
===================================================================
--- testsuite/g++.dg/cpp1y/pr84588.C    (nonexistent)
+++ testsuite/g++.dg/cpp1y/pr84588.C    (working copy)
@@ -0,0 +1,10 @@
+// { dg-do compile { target c++14 } }
+// { dg-options "-w" }
+
+struct a {
+  void b() {}
+  void c(auto = [] {
+    if (a a(int auto){})  // { dg-error "two or more data types" }
+      ;
+  }) {}
+};