From bd7aebb8b002f0706bfa771f22c01f243fa7fbcf Mon Sep 17 00:00:00 2001
From: Akim Demaille <akim.demaille@gmail.com>
Date: Tue, 30 Oct 2018 19:09:46 +0100
Subject: [PATCH] c: update the definition of _Noreturn

Does not work on Solaris 11.3 x86/64:

    479. c++.at:1293: testing C++ GLR parser identifier shadowing ...
    ======== Testing with C++ standard flags: '-std=c++17'
    ./c++.at:1332: $BISON_CXX_WORKS
    stderr:
    stdout:
    ./c++.at:1332: $CXX $CXXFLAGS $CPPFLAGS  $LDFLAGS -o input input.cc $LIBS
    stderr:
    input.cc:837:8: error: '_Noreturn' does not name a type
     static _Noreturn void
            ^~~~~~~~~
    input.cc:845:8: error: '_Noreturn' does not name a type
     static _Noreturn void
            ^~~~~~~~~

Reported by Kiyoshi Kanazawa.
http://lists.gnu.org/archive/html/bug-bison/2018-10/msg00051.html

* data/c.m4 (b4_attribute_define): Use the snippet which is currently
in gnulib's m4/gnulib-common.m4 (which seems a little more advanced
than lib/_Noreturn.h).
---
 data/c.m4 | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/data/c.m4 b/data/c.m4
index 2df76e77..04df3ffc 100644
--- a/data/c.m4
+++ b/data/c.m4
@@ -227,12 +227,16 @@ m4_define([b4_attribute_define],
 # define YY_ATTRIBUTE_UNUSED YY_ATTRIBUTE ((__unused__))
 #endif
 
-]m4_bmatch([$1], [\bnoreturn\b], [[#if !defined _Noreturn \
-     && (!defined __STDC_VERSION__ || __STDC_VERSION__ < 201112)
-# if defined _MSC_VER && 1200 <= _MSC_VER
+]m4_bmatch([$1], [\bnoreturn\b], [[/* The _Noreturn keyword of C11.  */
+#if ! (defined _Noreturn \
+       || (defined __STDC_VERSION__ && 201112 <= __STDC_VERSION__))
+# if (3 <= __GNUC__ || (__GNUC__ == 2 && 8 <= __GNUC_MINOR__) \
+      || 0x5110 <= __SUNPRO_C)
+#  define _Noreturn __attribute__ ((__noreturn__))
+# elif defined _MSC_VER && 1200 <= _MSC_VER
 #  define _Noreturn __declspec (noreturn)
 # else
-#  define _Noreturn YY_ATTRIBUTE ((__noreturn__))
+#  define _Noreturn
 # endif
 #endif