On 1/4/21 7:28 PM, Bruno Haible wrote:
Yes, there is the potential for redefinition warnings here. If they occur,
we should consider where in the compilation unit to include standard headers
like <stdio.h> and where to include <libc-config.h>. And maybe add a header
<libc-config-end.h> which undefines all of <libc-config.h> ?
I'm hoping we don't need to go down that path, as I want to minimize
differences from glibc. We've talked glibc into putting this into glibc
source files:
#ifndef _LIBC
# include <libc-config.h>
#endif
and I'd rather not have to talk glibc into putting more stuff like that
in, if it can be avoided.
I think I see a way to do that: include glibc <cdefs.h> only on
platforms where <sys/cdefs.h> is not good enough for Gnulib. This should
give us some time to update our cdefs.h after Glibc does. Had we done
this before, we would have had eight years grace period instead of no
years. I installed the attached patch to try to do that. A good chunk of
it is simple reindenting, and you can use "git diff -w" to narrow it down.
>From 7fcdb8f9f2f568b48e8b4d7beab344a735cc2b9a Mon Sep 17 00:00:00 2001
From: Paul Eggert <egg...@cs.ucla.edu>
Date: Tue, 5 Jan 2021 13:12:39 -0800
Subject: [PATCH] libc-config: merge from glibc
Use a better way of keeping glibc <sys/cdefs.h> and gnulib
lib/cdefs.h mostly in sync, by using lib/cdefs.h only on platforms
where <sys/cdefs.h> does not work well enough for Gnulib.
* lib/cdefs.h: Go back to using _SYS_CDEFS_H rather than
_GL_DEFS_H as an include guard.
(__THROW, __THROWNL, __NTH, __NTHNL):
Define to noexcept for C++11 and later.
(__glibc_objsize, __glibc_objsize0): New, for _FORTIFY_SOURCE=3.
(__warndecl): Remove.
(__attribute_copy__): New macro, for GCC 9 support.
(__LDBL_REDIR, __LDBL_REDIR_DECL, __LDBL_REDIR1)
(__LDBL_REDIR1_DECL, __LDBL_REDIR1_NTH, __REDIRECT_NTH_LDBL)
(__REDIRECT_LDBL, __LDBL_REDIR_NTH):
Redirections for IEEE long double on powerpc64le.
(__LDBL_REDIR2_DECL): New macro.
(__attr_access): New macro, for GCC 10 bounds checking.
(__attribute_returns_twice__): New macro, for setjmp etc.
* lib/libc-config.h: Include <cdefs.h> only if __glibc_likely is
undefined. The following changes apply only if __glibc_likely
is not defined.
(__LDBL_REDIR2_DECL, __attr_access, __attribute_returns_twice__)
(__glibc_clang_has_attribute, __glibc_clang_has_extension)
(__glibc_objsize, __glibc_objsize0):
Undef these new (or newer) <cdefs.h> macros.
(__P, __PMT, __always_inline): Do not undef, since cdefs.h does that.
(__glibc_likely): Do not undef, since this is inside
ifndef __glibc_likely.
(__warndecl): Do not undef; no longer defined.
---
ChangeLog | 32 +++++++++
lib/cdefs.h | 115 ++++++++++++++++++++++++-------
lib/libc-config.h | 171 ++++++++++++++++++++++++----------------------
3 files changed, 210 insertions(+), 108 deletions(-)
diff --git a/ChangeLog b/ChangeLog
index 893d9fd2a..3d4d5f260 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,35 @@
+2021-01-05 Paul Eggert <egg...@cs.ucla.edu>
+
+ libc-config: merge from glibc
+ Use a better way of keeping glibc <sys/cdefs.h> and gnulib
+ lib/cdefs.h mostly in sync, by using lib/cdefs.h only on platforms
+ where <sys/cdefs.h> does not work well enough for Gnulib.
+ * lib/cdefs.h: Go back to using _SYS_CDEFS_H rather than
+ _GL_DEFS_H as an include guard.
+ (__THROW, __THROWNL, __NTH, __NTHNL):
+ Define to noexcept for C++11 and later.
+ (__glibc_objsize, __glibc_objsize0): New, for _FORTIFY_SOURCE=3.
+ (__warndecl): Remove.
+ (__attribute_copy__): New macro, for GCC 9 support.
+ (__LDBL_REDIR, __LDBL_REDIR_DECL, __LDBL_REDIR1)
+ (__LDBL_REDIR1_DECL, __LDBL_REDIR1_NTH, __REDIRECT_NTH_LDBL)
+ (__REDIRECT_LDBL, __LDBL_REDIR_NTH):
+ Redirections for IEEE long double on powerpc64le.
+ (__LDBL_REDIR2_DECL): New macro.
+ (__attr_access): New macro, for GCC 10 bounds checking.
+ (__attribute_returns_twice__): New macro, for setjmp etc.
+ * lib/libc-config.h: Include <cdefs.h> only if __glibc_likely is
+ undefined. The following changes apply only if __glibc_likely
+ is not defined.
+ (__LDBL_REDIR2_DECL, __attr_access, __attribute_returns_twice__)
+ (__glibc_clang_has_attribute, __glibc_clang_has_extension)
+ (__glibc_objsize, __glibc_objsize0):
+ Undef these new (or newer) <cdefs.h> macros.
+ (__P, __PMT, __always_inline): Do not undef, since cdefs.h does that.
+ (__glibc_likely): Do not undef, since this is inside
+ ifndef __glibc_likely.
+ (__warndecl): Do not undef; no longer defined.
+
2021-01-05 Jim Meyering <meyer...@fb.com>
maintainer-makefile: correct preceding change
diff --git a/lib/cdefs.h b/lib/cdefs.h
index fd72b7b4d..4383e70f2 100644
--- a/lib/cdefs.h
+++ b/lib/cdefs.h
@@ -15,8 +15,8 @@
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
-#ifndef _GL_CDEFS_H
-#define _GL_CDEFS_H 1
+#ifndef _SYS_CDEFS_H
+#define _SYS_CDEFS_H 1
/* We are almost always included from features.h. */
#ifndef _FEATURES_H
@@ -25,7 +25,7 @@
/* The GNU libc does not support any K&R compilers or the traditional mode
of ISO C compilers anymore. Check for some of the combinations not
- anymore supported. */
+ supported anymore. */
#if defined __GNUC__ && !defined __STDC__
# error "You need a ISO C conforming compiler to use the glibc headers"
#endif
@@ -74,7 +74,7 @@
# endif
/* GCC can always grok prototypes. For C++ programs we add throw()
- to help it optimize the function calls. But this works only with
+ to help it optimize the function calls. But this only works with
gcc 2.8.x and egcs. For gcc 3.4 and up we even mark C functions
as non-throwing using a function attribute since programs can use
the -fexceptions options for C code as well. */
@@ -86,10 +86,14 @@
# define __NTHNL(fct) __attribute__ ((__nothrow__)) fct
# else
# if defined __cplusplus && (__GNUC_PREREQ (2,8) || __clang_major >= 4)
-# define __THROW throw ()
-# define __THROWNL throw ()
-# define __NTH(fct) __LEAF_ATTR fct throw ()
-# define __NTHNL(fct) fct throw ()
+# if __cplusplus >= 201103L
+# define __THROW noexcept (true)
+# else
+# define __THROW throw ()
+# endif
+# define __THROWNL __THROW
+# define __NTH(fct) __LEAF_ATTR fct __THROW
+# define __NTHNL(fct) fct __THROW
# else
# define __THROW
# define __THROWNL
@@ -142,24 +146,20 @@
#define __bos(ptr) __builtin_object_size (ptr, __USE_FORTIFY_LEVEL > 1)
#define __bos0(ptr) __builtin_object_size (ptr, 0)
+/* Use __builtin_dynamic_object_size at _FORTIFY_SOURCE=3 when available. */
+#if __USE_FORTIFY_LEVEL == 3 && __glibc_clang_prereq (9, 0)
+# define __glibc_objsize0(__o) __builtin_dynamic_object_size (__o, 0)
+# define __glibc_objsize(__o) __builtin_dynamic_object_size (__o, 1)
+#else
+# define __glibc_objsize0(__o) __bos0 (__o)
+# define __glibc_objsize(__o) __bos (__o)
+#endif
+
#if __GNUC_PREREQ (4,3)
-# define __warndecl(name, msg) \
- extern void name (void) __attribute__((__warning__ (msg)))
# define __warnattr(msg) __attribute__((__warning__ (msg)))
# define __errordecl(name, msg) \
extern void name (void) __attribute__((__error__ (msg)))
-#elif __glibc_clang_has_attribute (__diagnose_if__) && 0
-/* These definitions are not enabled, because they produce bogus warnings
- in the glibc Fortify functions. These functions are written in a style
- that works with GCC. In order to work with clang, these functions would
- need to be modified. */
-# define __warndecl(name, msg) \
- extern void name (void) __attribute__((__diagnose_if__ (1, msg, "warning")))
-# define __warnattr(msg) __attribute__((__diagnose_if__ (1, msg, "warning")))
-# define __errordecl(name, msg) \
- extern void name (void) __attribute__((__diagnose_if__ (1, msg, "error")))
#else
-# define __warndecl(name, msg) extern void name (void)
# define __warnattr(msg)
# define __errordecl(name, msg) extern void name (void)
#endif
@@ -285,8 +285,8 @@
/* Since version 4.5, gcc also allows one to specify the message printed
when a deprecated function is used. clang claims to be gcc 4.2, but
may also support this feature. */
-#if __GNUC_PREREQ (4,5) || \
- __glibc_clang_has_extension (__attribute_deprecated_with_message__)
+#if __GNUC_PREREQ (4,5) \
+ || __glibc_clang_has_extension (__attribute_deprecated_with_message__)
# define __attribute_deprecated_msg__(msg) \
__attribute__ ((__deprecated__ (msg)))
#else
@@ -467,6 +467,16 @@
# define __attribute_nonstring__
#endif
+/* Undefine (also defined in libc-symbols.h). */
+#undef __attribute_copy__
+#if __GNUC_PREREQ (9, 0)
+/* Copies attributes from the declaration or type referenced by
+ the argument. */
+# define __attribute_copy__(arg) __attribute__ ((__copy__ (arg)))
+#else
+# define __attribute_copy__(arg)
+#endif
+
#if (!defined _Static_assert && !defined __cplusplus \
&& (defined __STDC_VERSION__ ? __STDC_VERSION__ : 0) < 201112 \
&& (!(__GNUC_PREREQ (4, 6) || __clang_major__ >= 4) \
@@ -483,7 +493,37 @@
# include <bits/long-double.h>
#endif
-#if defined __LONG_DOUBLE_MATH_OPTIONAL && defined __NO_LONG_DOUBLE_MATH
+#if __LDOUBLE_REDIRECTS_TO_FLOAT128_ABI == 1
+# ifdef __REDIRECT
+
+/* Alias name defined automatically. */
+# define __LDBL_REDIR(name, proto) ... unused__ldbl_redir
+# define __LDBL_REDIR_DECL(name) \
+ extern __typeof (name) name __asm (__ASMNAME ("__" #name "ieee128"));
+
+/* Alias name defined automatically, with leading underscores. */
+# define __LDBL_REDIR2_DECL(name) \
+ extern __typeof (__##name) __##name \
+ __asm (__ASMNAME ("__" #name "ieee128"));
+
+/* Alias name defined manually. */
+# define __LDBL_REDIR1(name, proto, alias) ... unused__ldbl_redir1
+# define __LDBL_REDIR1_DECL(name, alias) \
+ extern __typeof (name) name __asm (__ASMNAME (#alias));
+
+# define __LDBL_REDIR1_NTH(name, proto, alias) \
+ __REDIRECT_NTH (name, proto, alias)
+# define __REDIRECT_NTH_LDBL(name, proto, alias) \
+ __LDBL_REDIR1_NTH (name, proto, __##alias##ieee128)
+
+/* Unused. */
+# define __REDIRECT_LDBL(name, proto, alias) ... unused__redirect_ldbl
+# define __LDBL_REDIR_NTH(name, proto) ... unused__ldbl_redir_nth
+
+# else
+_Static_assert (0, "IEEE 128-bits long double requires redirection on this platform");
+# endif
+#elif defined __LONG_DOUBLE_MATH_OPTIONAL && defined __NO_LONG_DOUBLE_MATH
# define __LDBL_COMPAT 1
# ifdef __REDIRECT
# define __LDBL_REDIR1(name, proto, alias) __REDIRECT (name, proto, alias)
@@ -492,6 +532,8 @@
# define __LDBL_REDIR1_NTH(name, proto, alias) __REDIRECT_NTH (name, proto, alias)
# define __LDBL_REDIR_NTH(name, proto) \
__LDBL_REDIR1_NTH (name, proto, __nldbl_##name)
+# define __LDBL_REDIR2_DECL(name) \
+ extern __typeof (__##name) __##name __asm (__ASMNAME ("__nldbl___" #name));
# define __LDBL_REDIR1_DECL(name, alias) \
extern __typeof (name) name __asm (__ASMNAME (#alias));
# define __LDBL_REDIR_DECL(name) \
@@ -502,11 +544,13 @@
__LDBL_REDIR1_NTH (name, proto, __nldbl_##alias)
# endif
#endif
-#if !defined __LDBL_COMPAT || !defined __REDIRECT
+#if (!defined __LDBL_COMPAT && __LDOUBLE_REDIRECTS_TO_FLOAT128_ABI == 0) \
+ || !defined __REDIRECT
# define __LDBL_REDIR1(name, proto, alias) name proto
# define __LDBL_REDIR(name, proto) name proto
# define __LDBL_REDIR1_NTH(name, proto, alias) name proto __THROW
# define __LDBL_REDIR_NTH(name, proto) name proto __THROW
+# define __LDBL_REDIR2_DECL(name)
# define __LDBL_REDIR_DECL(name)
# ifdef __REDIRECT
# define __REDIRECT_LDBL(name, proto, alias) __REDIRECT (name, proto, alias)
@@ -545,4 +589,23 @@
# define __HAVE_GENERIC_SELECTION 0
#endif
-#endif /* gnulib cdefs.h */
+#if __GNUC_PREREQ (10, 0)
+/* Designates a 1-based positional argument ref-index of pointer type
+ that can be used to access size-index elements of the pointed-to
+ array according to access mode, or at least one element when
+ size-index is not provided:
+ access (access-mode, <ref-index> [, <size-index>]) */
+#define __attr_access(x) __attribute__ ((__access__ x))
+#else
+# define __attr_access(x)
+#endif
+
+/* Specify that a function such as setjmp or vfork may return
+ twice. */
+#if __GNUC_PREREQ (4, 1)
+# define __attribute_returns_twice__ __attribute__ ((__returns_twice__))
+#else
+# define __attribute_returns_twice__ /* Ignore. */
+#endif
+
+#endif /* sys/cdefs.h */
diff --git a/lib/libc-config.h b/lib/libc-config.h
index fbea948e6..18fb722dc 100644
--- a/lib/libc-config.h
+++ b/lib/libc-config.h
@@ -71,102 +71,109 @@
# endif
#endif
-
-/* Prepare to include <cdefs.h>, which is our copy of glibc
- <sys/cdefs.h>. */
+#ifndef __glibc_likely
+/* <sys/cdefs.h> either does not exist, or predates glibc commit
+ 2012-12-28T06:33:01Z!siddh...@redhat.com
+ (91998e449e0ce758db55aecf2abc3ee510fcbc8f)
+ and so does not suffice for Gnulib. Prepare to include <cdefs.h>,
+ which is Gnulib's copy of a more-recent glibc <sys/cdefs.h>. */
/* Define _FEATURES_H so that <cdefs.h> does not include <features.h>. */
-#ifndef _FEATURES_H
-# define _FEATURES_H 1
-#endif
+# ifndef _FEATURES_H
+# define _FEATURES_H 1
+# endif
/* Define __WORDSIZE so that <cdefs.h> does not attempt to include
nonexistent files. Make it a syntax error, since Gnulib does not
use __WORDSIZE now, and if Gnulib uses it later the syntax error
will let us know that __WORDSIZE needs configuring. */
-#ifndef __WORDSIZE
-# define __WORDSIZE %%%
-#endif
+# ifndef __WORDSIZE
+# define __WORDSIZE %%%
+# endif
/* Undef the macros unconditionally defined by our copy of glibc
<sys/cdefs.h>, so that they do not clash with any system-defined
versions. */
-#undef _GL_CDEFS_H
-#undef __ASMNAME
-#undef __ASMNAME2
-#undef __BEGIN_DECLS
-#undef __CONCAT
-#undef __END_DECLS
-#undef __HAVE_GENERIC_SELECTION
-#undef __LDBL_COMPAT
-#undef __LDBL_REDIR
-#undef __LDBL_REDIR1
-#undef __LDBL_REDIR1_DECL
-#undef __LDBL_REDIR1_NTH
-#undef __LDBL_REDIR_DECL
-#undef __LDBL_REDIR_NTH
-#undef __LEAF
-#undef __LEAF_ATTR
-#undef __NTH
-#undef __NTHNL
-#undef __P
-#undef __PMT
-#undef __REDIRECT
-#undef __REDIRECT_LDBL
-#undef __REDIRECT_NTH
-#undef __REDIRECT_NTHNL
-#undef __REDIRECT_NTH_LDBL
-#undef __STRING
-#undef __THROW
-#undef __THROWNL
-#undef __always_inline
-#undef __attribute__
-#undef __attribute_alloc_size__
-#undef __attribute_artificial__
-#undef __attribute_const__
-#undef __attribute_deprecated__
-#undef __attribute_deprecated_msg__
-#undef __attribute_format_arg__
-#undef __attribute_format_strfmon__
-#undef __attribute_malloc__
-#undef __attribute_noinline__
-#undef __attribute_nonstring__
-#undef __attribute_pure__
-#undef __attribute_used__
-#undef __attribute_warn_unused_result__
-#undef __bos
-#undef __bos0
-#undef __errordecl
-#undef __extension__
-#undef __extern_always_inline
-#undef __extern_inline
-#undef __flexarr
-#undef __fortify_function
-#undef __glibc_c99_flexarr_available
-#undef __glibc_clang_has_extension
-#undef __glibc_likely
-#undef __glibc_macro_warning
-#undef __glibc_macro_warning1
-#undef __glibc_unlikely
-#undef __inline
-#undef __ptr_t
-#undef __restrict
-#undef __restrict_arr
-#undef __va_arg_pack
-#undef __va_arg_pack_len
-#undef __warnattr
-#undef __warndecl
+# undef _SYS_CDEFS_H
+# undef __ASMNAME
+# undef __ASMNAME2
+# undef __BEGIN_DECLS
+# undef __CONCAT
+# undef __END_DECLS
+# undef __HAVE_GENERIC_SELECTION
+# undef __LDBL_COMPAT
+# undef __LDBL_REDIR
+# undef __LDBL_REDIR1
+# undef __LDBL_REDIR1_DECL
+# undef __LDBL_REDIR1_NTH
+# undef __LDBL_REDIR2_DECL
+# undef __LDBL_REDIR_DECL
+# undef __LDBL_REDIR_NTH
+# undef __LEAF
+# undef __LEAF_ATTR
+# undef __NTH
+# undef __NTHNL
+# undef __REDIRECT
+# undef __REDIRECT_LDBL
+# undef __REDIRECT_NTH
+# undef __REDIRECT_NTHNL
+# undef __REDIRECT_NTH_LDBL
+# undef __STRING
+# undef __THROW
+# undef __THROWNL
+# undef __attr_access
+# undef __attribute__
+# undef __attribute_alloc_size__
+# undef __attribute_artificial__
+# undef __attribute_const__
+# undef __attribute_deprecated__
+# undef __attribute_deprecated_msg__
+# undef __attribute_format_arg__
+# undef __attribute_format_strfmon__
+# undef __attribute_malloc__
+# undef __attribute_noinline__
+# undef __attribute_nonstring__
+# undef __attribute_pure__
+# undef __attribute_returns_twice__
+# undef __attribute_used__
+# undef __attribute_warn_unused_result__
+# undef __bos
+# undef __bos0
+# undef __errordecl
+# undef __extension__
+# undef __extern_always_inline
+# undef __extern_inline
+# undef __flexarr
+# undef __fortify_function
+# undef __glibc_c99_flexarr_available
+# undef __glibc_clang_has_attribute
+# undef __glibc_clang_has_builtin
+# undef __glibc_clang_has_extension
+# undef __glibc_macro_warning
+# undef __glibc_macro_warning1
+# undef __glibc_objsize
+# undef __glibc_objsize0
+# undef __glibc_unlikely
+# undef __inline
+# undef __ptr_t
+# undef __restrict
+# undef __restrict_arr
+# undef __va_arg_pack
+# undef __va_arg_pack_len
+# undef __warnattr
/* Include our copy of glibc <sys/cdefs.h>. */
-#include <cdefs.h>
+# include <cdefs.h>
/* <cdefs.h> __inline is too pessimistic for non-GCC. */
-#undef __inline
-#ifndef HAVE___INLINE
-# if 199901 <= __STDC_VERSION__ || defined inline
-# define __inline inline
-# else
-# define __inline
+# undef __inline
+# ifndef HAVE___INLINE
+# if 199901 <= __STDC_VERSION__ || defined inline
+# define __inline inline
+# else
+# define __inline
+# endif
# endif
-#endif
+
+#endif /* defined __glibc_likely */
/* A substitute for glibc <libc-symbols.h>, good enough for Gnulib. */
--
2.27.0
