[pushed] c++: -fconcepts and __cpp_concepts

[Jason Merrill <jason@redhat.com>]

Tested x86_64-pc-linux-gnu, applying to trunk.

-- 8< --

Since -fconcepts no longer implies -fconcepts-ts, we shouldn't advertise TS
support with __cpp_concepts=201507L.  Also fix one case where -std=c++14
-fconcepts wasn't working (as found by range-v3 calendar).  Fixing other
cases is not a priority, probably better to reject that flag combination if
there are further issues.

gcc/c-family/ChangeLog:

	* c-cppbuiltin.cc (c_cpp_builtins): Adjust __cpp_concepts.

gcc/cp/ChangeLog:

	* parser.cc (cp_parser_simple_type_specifier): Handle -std=c++14
	-fconcepts.
---
 gcc/c-family/c-cppbuiltin.cc | 2 +-
 gcc/cp/parser.cc             | 5 +++--
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/gcc/c-family/c-cppbuiltin.cc b/gcc/c-family/c-cppbuiltin.cc
index 6bd4c1261a7..f2b12fd63db 100644
--- a/gcc/c-family/c-cppbuiltin.cc
+++ b/gcc/c-family/c-cppbuiltin.cc
@@ -1089,7 +1089,7 @@ c_cpp_builtins (cpp_reader *pfile)
 	}
       if (flag_concepts)
         {
-	  if (cxx_dialect >= cxx20)
+	  if (cxx_dialect >= cxx20 || !flag_concepts_ts)
 	    cpp_define (pfile, "__cpp_concepts=202002L");
           else
             cpp_define (pfile, "__cpp_concepts=201507L");
diff --git a/gcc/cp/parser.cc b/gcc/cp/parser.cc
index 2d27376d988..7f646704d3f 100644
--- a/gcc/cp/parser.cc
+++ b/gcc/cp/parser.cc
@@ -20017,12 +20017,13 @@ cp_parser_simple_type_specifier (cp_parser* parser,
       /* Otherwise, look for a type-name.  */
       if (!type)
 	{
-	  if (cxx_dialect >= cxx17)
+	  if (cxx_dialect >= cxx17 || flag_concepts)
 	    cp_parser_parse_tentatively (parser);
 
 	  type = cp_parser_type_name (parser, (qualified_p && typename_p));
 
-	  if (cxx_dialect >= cxx17 && !cp_parser_parse_definitely (parser))
+	  if ((cxx_dialect >= cxx17 || flag_concepts)
+	      && !cp_parser_parse_definitely (parser))
 	    type = NULL_TREE;
 	}
 

base-commit: 2d2b05f0691799f03062bf5c436462f14cad3e7c
-- 
2.39.3