[PATCH 2/2] assert-h: work around include confusion

[Paul Eggert]

* m4/assert_h.m4 (gl_ASSERT_H): Arrange for <config.h> to not
include <assert.h> if assert is already defined.  This works
around bugs in packages that mistakenly include <config.h> after
including <assert.h> (typically due to double-inclusion of
<config.h>).  Found in coreutils, which I plan to fix.
---
 ChangeLog      | 7 +++++++
 m4/assert_h.m4 | 2 +-
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/ChangeLog b/ChangeLog
index 1846e7c381..199b088200 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,12 @@
 2022-09-14  Paul Eggert  <eggert@cs.ucla.edu>
 
+       assert-h: work around include confusion
+       * m4/assert_h.m4 (gl_ASSERT_H): Arrange for <config.h> to not
+       include <assert.h> if assert is already defined.  This works
+       around bugs in packages that mistakenly include <config.h> after
+       including <assert.h> (typically due to double-inclusion of
+       <config.h>).  Found in coreutils, which I plan to fix.
+
        stdbool: depend on C99
        Record that stdbool depends on C99 these days.
        This matters only for ancient compilers that need special
diff --git a/m4/assert_h.m4 b/m4/assert_h.m4
index ec756a970b..43937869ec 100644
--- a/m4/assert_h.m4
+++ b/m4/assert_h.m4
@@ -47,7 +47,7 @@ AC_DEFUN([gl_ASSERT_H],
   dnl including assert.h.  Break the #undef apart with a comment
   dnl so that 'configure' does not comment it out.
   AH_VERBATIM([zzstatic_assert],
-[#if (!defined HAVE_C_STATIC_ASSERT \
+[#if (!defined HAVE_C_STATIC_ASSERT && !defined assert \
      && __cpp_static_assert < 201411 && __GNUG__ < 6)
  #include <assert.h>
  #undef/**/assert
-- 
2.37.2