Re: [C++ Patch/RFC] PR 71169 ("[7/8 Regression] ICE on invalid C++ code in pop_nested_class"), PR 71832 and more

[Jason Merrill <jason@redhat.com>]

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On Wed, Mar 7, 2018 at 12:18 PM, Paolo Carlini <paolo.carlini@oracle.com> wrote:
> Hi,
>
> [snip the various clarifications]
>
> Il 7 Marzo 2018 17:57:07 CET, Jason Merrill <jason@redhat.com> ha scritto:
>>My thought was that this patch adds a lot of managing of the flag in
>>different places in the parser, whereas looking for error_mark_node in
>>the template parms here would be just in one place.  But if you prefer
>>the current approach, that's fine, it's straightforward enough.
>
> Thanks a lot for the various clarifications above, where essentially turns out that some details of my patch are correct essentially by chance ;) Seriously, I'm thinking the following: since 8 is getting real close, what if, for 8, for the known mild regressions, we go ahead with my super safe Plan B which I mentioned at beginning of the thread, then as soon as trunk branches we immediately apply my patch and we give it a serious spin, say we rebuild distros with it, and see what happens?

This is what I was suggesting, what do you think?

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commit 706f372b52e65694161b9dff0272481d23fa898a
Author: Jason Merrill <jason@redhat.com>
Date:   Wed Mar 7 14:45:19 2018 -0500

            PR c++/71832 - ICE with ill-formed template parameter.
    
            * pt.c (any_erroneous_template_args_p): New.
            * parser.c (cp_parser_class_specifier_1): Use it.

diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index 268be0fd543..8f3ec86e8ce 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -6558,6 +6558,7 @@ extern int processing_template_parmlist;
 extern bool dependent_type_p			(tree);
 extern bool dependent_scope_p			(tree);
 extern bool any_dependent_template_arguments_p  (const_tree);
+extern bool any_erroneous_template_args_p	(const_tree);
 extern bool dependent_template_p		(tree);
 extern bool dependent_template_id_p		(tree, tree);
 extern bool type_dependent_expression_p		(tree);
diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index a19bbe1e1d0..f7a8be50b79 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -22682,6 +22682,8 @@ cp_parser_class_specifier_1 (cp_parser* parser)
       FOR_EACH_VEC_SAFE_ELT (unparsed_funs_with_default_args, ix, e)
 	{
 	  decl = e->decl;
+	  if (any_erroneous_template_args_p (decl))
+	    continue;
 	  /* If there are default arguments that have not yet been processed,
 	     take care of them now.  */
 	  if (class_type != e->class_type)
@@ -22704,6 +22706,8 @@ cp_parser_class_specifier_1 (cp_parser* parser)
       save_ccr = current_class_ref;
       FOR_EACH_VEC_SAFE_ELT (unparsed_nsdmis, ix, decl)
 	{
+	  if (any_erroneous_template_args_p (decl))
+	    continue;
 	  if (class_type != DECL_CONTEXT (decl))
 	    {
 	      if (pushed_scope)
@@ -27642,6 +27646,9 @@ cp_parser_late_parsing_for_member (cp_parser* parser, tree member_function)
   if (DECL_FUNCTION_TEMPLATE_P (member_function))
     member_function = DECL_TEMPLATE_RESULT (member_function);
 
+  if (any_erroneous_template_args_p (member_function))
+    return;
+
   /* There should not be any class definitions in progress at this
      point; the bodies of members are only parsed outside of all class
      definitions.  */
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 89024c10fe2..1ce04aaabc7 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -25048,6 +25048,38 @@ any_dependent_template_arguments_p (const_tree args)
   return false;
 }
 
+/* Returns true if ARGS contains any errors.  */
+
+bool
+any_erroneous_template_args_p (const_tree args)
+{
+  int i;
+  int j;
+
+  if (args && TREE_CODE (args) != TREE_VEC)
+    {
+      if (tree ti = get_template_info (args))
+	args = TI_ARGS (ti);
+      else
+	args = NULL_TREE;
+    }
+
+  if (!args)
+    return false;
+  if (args == error_mark_node)
+    return true;
+
+  for (i = 0; i < TMPL_ARGS_DEPTH (args); ++i)
+    {
+      const_tree level = TMPL_ARGS_LEVEL (args, i + 1);
+      for (j = 0; j < TREE_VEC_LENGTH (level); ++j)
+	if (error_operand_p (TREE_VEC_ELT (level, j)))
+	  return true;
+    }
+
+  return false;
+}
+
 /* Returns TRUE if the template TMPL is type-dependent.  */
 
 bool