Support using 'auto' in a function parameter list to introduce an implicit template parameter.

gcc/cp/
	* cp-tree.h (type_uses_auto_or_concept): Declare.
	(is_auto_or_concept): Declare.
	* decl.c (grokdeclarator): Allow 'auto' parameters in lambdas with
	-std=gnu++1y or -std=c++1y or, as a GNU extension, in plain functions.
	* type-utils.h: New header defining ...
	(find_type_usage): ... this new function based on pt.c (type_uses_auto)
	for searching a type tree given a predicate.
	* pt.c (type_uses_auto): Reimplement via type-utils.h (find_type_usage).
	(is_auto_or_concept): New function.
	(type_uses_auto_or_concept): New function.
	* parser.h (struct cp_parser): Add fully_implicit_function_template_p.
	* parser.c (cp_parser_new): Initialize fully_implicit_function_template_p.
	(cp_parser_new): Initialize fully_implicit_function_template_p.
	(cp_parser_lambda_expression): Copy and restore value of
	fully_implicit_function_template_p as per other parser fields.
	(cp_parser_parameter_declaration_list): Count generic
	parameters and call ...
	(add_implicit_template_parms): ... this new function to synthesize them
	with help from type-utils.h (find_type_usage), ...
	(tree_type_is_auto_or_concept): ... this new static function and ...
	(make_generic_type_name): ... this new static function.
	(cp_parser_direct_declarator): Account for implicit template parameters.
	(cp_parser_lambda_declarator_opt): Finish fully implicit template if
	necessary by calling ...
	(finish_fully_implicit_template): ... this new function.
	(cp_parser_init_declarator): Likewise.
	(cp_parser_function_definition_after_declarator): Likewise.
	(cp_parser_member_declaration): Likewise.
	* Make-lang.in (cp/pt.o): Add dependency on type-utils.h.
	(cp/parser.o): Likewise.

gcc/testsuite/
	g++.dg/cpp0x/auto9.C: Downgrade two previously expected errors (now
	interpreted as implicit templates) to be expected pedwarns instead.

From-SVN: r202612

1 files changed, 6 insertions, 0 deletions

diff --git a/gcc/cp/parser.h b/gcc/cp/parser.h
index 3d8bb74..ffdddaf 100644
--- a/gcc/cp/parser.h
+++ b/gcc/cp/parser.h
@@ -341,6 +341,12 @@ typedef struct GTY(()) cp_parser {
   /* The number of template parameter lists that apply directly to the
      current declaration.  */
   unsigned num_template_parameter_lists;
+
+  /* TRUE if the function being declared was made a template due to its
+     parameter list containing generic type specifiers (`auto' or concept
+     identifiers) rather than an explicit template parameter list.  */
+  bool fully_implicit_function_template_p;
+
 } cp_parser;
 
 /* In parser.c  */