* lib/stddef.in.h: Do nothing if _@GUARD_PREFIX@_STDDEF_H is
defined, as stddef.h has already been included. This works
around GCC bug 114870.
(_GCC_NULLPTR_T): Define if needed to work around GCC bug 114869.
* m4/stddef_h.m4 (gl_STDDEF_H, gl_STDDEF_H_DEFAULTS):
* modules/stddef (stddef.h):
Detect the two bugs.
---
ChangeLog | 11 +++++++++++
doc/posix-headers/stddef.texi | 5 +++++
lib/stddef.in.h | 23 +++++++++++++++++------
m4/stddef_h.m4 | 32 +++++++++++++++++++++++++++++++-
modules/stddef | 1 +
5 files changed, 65 insertions(+), 7 deletions(-)
diff --git a/ChangeLog b/ChangeLog
index dacf6892b1..b30238f934 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,14 @@
+2024-04-27 Paul Eggert <egg...@cs.ucla.edu>
+
+ stddef: work around GCC 14 stddef.h bugs
+ * lib/stddef.in.h: Do nothing if _@GUARD_PREFIX@_STDDEF_H is
+ defined, as stddef.h has already been included. This works
+ around GCC bug 114870.
+ (_GCC_NULLPTR_T): Define if needed to work around GCC bug 114869.
+ * m4/stddef_h.m4 (gl_STDDEF_H, gl_STDDEF_H_DEFAULTS):
+ * modules/stddef (stddef.h):
+ Detect the two bugs.
+
2024-04-27 Bruno Haible <br...@clisp.org>
bootstrap: Support checking out a recent GNULIB_REVISION.
diff --git a/doc/posix-headers/stddef.texi b/doc/posix-headers/stddef.texi
index 33ad48244c..0e331481aa 100644
--- a/doc/posix-headers/stddef.texi
+++ b/doc/posix-headers/stddef.texi
@@ -45,6 +45,11 @@ Some platforms fail to provide @code{nullptr_t},
which Gnulib cannot usefully emulate:
GCC 12, Clang 15, and other pre-2023 C compilers.
+@item
+Some platforms define @code{nullptr_t} even when @code{<stddef.h>} is
+not included:
+GCC 14.0.
+
@item
Some platforms provide an @code{offsetof} macro that cannot be used in
arbitrary expressions:
diff --git a/lib/stddef.in.h b/lib/stddef.in.h
index fa8998d9b7..fa249259cd 100644
--- a/lib/stddef.in.h
+++ b/lib/stddef.in.h
@@ -27,13 +27,18 @@
#endif
@PRAGMA_COLUMNS@
-#if defined __need_wchar_t || defined __need_size_t \
- || defined __need_ptrdiff_t || defined __need_NULL \
- || defined __need_wint_t
+#if (!defined _@GUARD_PREFIX@_STDDEF_H \
+ && (defined __need_wchar_t || defined __need_size_t \
+ || defined __need_ptrdiff_t || defined __need_NULL \
+ || defined __need_wint_t))
/* Special invocation convention inside gcc header files. In
- particular, gcc provides a version of <stddef.h> that blindly
- redefines NULL even when __need_wint_t was defined, even though
- wint_t is not normally provided by <stddef.h>. Hence, we must
+ particular, <stddef.h> in some ancient versions of GCC blindly
+ redefined NULL when __need_wint_t was defined, even though wint_t
+ is not normally provided by <stddef.h>.
+ (FIXME: It's not clear what GCC versions those were - perhaps so
+ ancient that we can stop worrying about this?)
+ Although glibc 2.26 (2017) and later do not use __need_wint_t,
+ for portability to older Glibc + GCC,
remember if special invocation has ever been used to obtain wint_t,
in which case we need to clean up NULL yet again. */
@@ -74,6 +79,12 @@ typedef long max_align_t;
# endif
# endif
+# if !defined _GCC_NULLPTR_T && !@NULLPTR_T_NEEDS_STDDEF@
+ /* Suppress unwanted nullptr_t typedef. See
+ <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114869>. */
+# define _GCC_NULLPTR_T
+# endif
+
/* The include_next requires a split double-inclusion guard. */
# @INCLUDE_NEXT@ @NEXT_STDDEF_H@
diff --git a/m4/stddef_h.m4 b/m4/stddef_h.m4
index 84d3bae801..0d4ddf8fcb 100644
--- a/m4/stddef_h.m4
+++ b/m4/stddef_h.m4
@@ -1,5 +1,5 @@
# stddef_h.m4
-# serial 14
+# serial 15
dnl Copyright (C) 2009-2024 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
@@ -84,6 +84,35 @@ AC_DEFUN_ONCE([gl_STDDEF_H],
GL_GENERATE_STDDEF_H=true
fi
+ dnl https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114869
+ AC_CACHE_CHECK([whether nullptr_t needs <stddef.h>],
+ [gl_cv_nullptr_t_needs_stddef],
+ [AC_COMPILE_IFELSE([AC_LANG_DEFINES_PROVIDED[nullptr_t x;]],
+ [gl_cv_nullptr_t_needs_stddef=no],
+ [gl_cv_nullptr_t_needs_stddef=yes])])
+ if test "$gl_cv_nullptr_t_needs_stddef" = no; then
+ NULLPTR_T_NEEDS_STDDEF=0
+ GL_GENERATE_STDDEF_H=true
+ fi
+
+ AC_CACHE_CHECK([for clean definition of __STDC_VERSION_STDDEF_H__],
+ [gl_cv_clean_version_stddef],
+ [AC_PREPROC_IFELSE(
+ [AC_LANG_SOURCE(
+ [[/* https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114870 */
+ #include <stddef.h>
+ #undef __STDC_VERSION_STDDEF_H__
+ #include <time.h>
+ #ifdef __STDC_VERSION_STDDEF_H__
+ # error "<time.h> defines __STDC_VERSION_STDDEF_H__"
+ #endif
+ ]])],
+ [gl_cv_clean_version_stddef=yes],
+ [gl_cv_clean_version_stddef=no])])
+ if test "$gl_cv_clean_version_stddef" = no; then
+ GL_GENERATE_STDDEF_H=true
+ fi
+
if $GL_GENERATE_STDDEF_H; then
gl_NEXT_HEADERS([stddef.h])
fi
@@ -114,6 +143,7 @@ AC_DEFUN([gl_STDDEF_H_REQUIRE_DEFAULTS],
AC_DEFUN([gl_STDDEF_H_DEFAULTS],
[
dnl Assume proper GNU behavior unless another module says otherwise.
+ NULLPTR_T_NEEDS_STDDEF=1; AC_SUBST([NULLPTR_T_NEEDS_STDDEF])
REPLACE_NULL=0; AC_SUBST([REPLACE_NULL])
HAVE_MAX_ALIGN_T=1; AC_SUBST([HAVE_MAX_ALIGN_T])
HAVE_WCHAR_T=1; AC_SUBST([HAVE_WCHAR_T])
diff --git a/modules/stddef b/modules/stddef
index fb7214138e..4096ab955d 100644
--- a/modules/stddef
+++ b/modules/stddef
@@ -33,6 +33,7 @@ stddef.h: stddef.in.h $(top_builddir)/config.status
-e 's|@''NEXT_STDDEF_H''@|$(NEXT_STDDEF_H)|g' \
-e 's|@''HAVE_MAX_ALIGN_T''@|$(HAVE_MAX_ALIGN_T)|g' \
-e 's|@''HAVE_WCHAR_T''@|$(HAVE_WCHAR_T)|g' \
+ -e 's|@''NULLPTR_T_NEEDS_STDDEF''@|$(NULLPTR_T_NEEDS_STDDEF)|g' \
-e 's|@''REPLACE_NULL''@|$(REPLACE_NULL)|g' \
$(srcdir)/stddef.in.h > $@-t
$(AM_V_at)mv $@-t $@
--
2.44.0
