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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-15 19:37:10 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-15 19:37:10 +0000
commitc9addba5cc770d2d231b34f6739f32c6be8690f1 (patch)
treec643da154a95a1d163137135050bb47858a1654e /gl/m4/stdalign.m4
parentInitial commit. (diff)
downloadman-db-c9addba5cc770d2d231b34f6739f32c6be8690f1.tar.xz
man-db-c9addba5cc770d2d231b34f6739f32c6be8690f1.zip
Adding upstream version 2.12.0.upstream/2.12.0
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'gl/m4/stdalign.m4')
-rw-r--r--gl/m4/stdalign.m4200
1 files changed, 200 insertions, 0 deletions
diff --git a/gl/m4/stdalign.m4 b/gl/m4/stdalign.m4
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+# Check for alignas and alignof that conform to C23.
+
+dnl Copyright 2011-2023 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+dnl Written by Paul Eggert and Bruno Haible.
+
+# Prepare for substituting <stdalign.h> if it is not supported.
+
+AC_DEFUN([gl_ALIGNASOF],
+[
+ AC_CACHE_CHECK([for alignas and alignof],
+ [gl_cv_header_working_stdalign_h],
+ [gl_save_CFLAGS=$CFLAGS
+ for gl_working in "yes, keywords" "yes, <stdalign.h> macros"; do
+ AS_CASE([$gl_working],
+ [*stdalign.h*], [CFLAGS="$gl_save_CFLAGS -DINCLUDE_STDALIGN_H"])
+ AC_COMPILE_IFELSE(
+ [AC_LANG_PROGRAM(
+ [[#include <stdint.h>
+ #ifdef INCLUDE_STDALIGN_H
+ #include <stdalign.h>
+ #endif
+ #include <stddef.h>
+
+ /* Test that alignof yields a result consistent with offsetof.
+ This catches GCC bug 52023
+ <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52023>. */
+ #ifdef __cplusplus
+ template <class t> struct alignof_helper { char a; t b; };
+ # define ao(type) offsetof (alignof_helper<type>, b)
+ #else
+ # define ao(type) offsetof (struct { char a; type b; }, b)
+ #endif
+ char test_double[ao (double) % _Alignof (double) == 0 ? 1 : -1];
+ char test_long[ao (long int) % _Alignof (long int) == 0 ? 1 : -1];
+ char test_alignof[alignof (double) == _Alignof (double) ? 1 : -1];
+
+ /* Test alignas only on platforms where gnulib can help. */
+ #if \
+ ((defined __cplusplus && 201103 <= __cplusplus) \
+ || (__TINYC__ && defined __attribute__) \
+ || (defined __APPLE__ && defined __MACH__ \
+ ? 4 < __GNUC__ + (1 <= __GNUC_MINOR__) \
+ : __GNUC__) \
+ || (__ia64 && (61200 <= __HP_cc || 61200 <= __HP_aCC)) \
+ || __ICC || 0x590 <= __SUNPRO_C || 0x0600 <= __xlC__ \
+ || 1300 <= _MSC_VER)
+ struct alignas_test { char c; char alignas (8) alignas_8; };
+ char test_alignas[offsetof (struct alignas_test, alignas_8) == 8
+ ? 1 : -1];
+ #endif
+ ]])],
+ [gl_cv_header_working_stdalign_h=$gl_working],
+ [gl_cv_header_working_stdalign_h=no])
+
+ CFLAGS=$gl_save_CFLAGS
+ test "$gl_cv_header_working_stdalign_h" != no && break
+ done])
+
+ AS_CASE([$gl_cv_header_working_stdalign_h],
+ [yes*keyword*],
+ [AC_DEFINE([HAVE_C_ALIGNASOF], [1],
+ [Define to 1 if the alignas and alignof keywords work.])])
+
+ dnl The "zz" puts this toward config.h's end, to avoid potential
+ dnl collisions with other definitions.
+ AH_VERBATIM([zzalignas],
+[#if !defined HAVE_C_ALIGNASOF && __cplusplus < 201103 && !defined alignof
+# if HAVE_STDALIGN_H
+# include <stdalign.h>
+# endif
+
+/* ISO C23 alignas and alignof for platforms that lack it.
+
+ References:
+ ISO C23 (latest free draft
+ <http://www.open-std.org/jtc1/sc22/wg14/www/docs/n3047.pdf>)
+ sections 6.5.3.4, 6.7.5, 7.15.
+ C++11 (latest free draft
+ <http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2011/n3242.pdf>)
+ section 18.10. */
+
+/* alignof (TYPE), also known as _Alignof (TYPE), yields the alignment
+ requirement of a structure member (i.e., slot or field) that is of
+ type TYPE, as an integer constant expression.
+
+ This differs from GCC's and clang's __alignof__ operator, which can
+ yield a better-performing alignment for an object of that type. For
+ example, on x86 with GCC and on Linux/x86 with clang,
+ __alignof__ (double) and __alignof__ (long long) are 8, whereas
+ alignof (double) and alignof (long long) are 4 unless the option
+ '-malign-double' is used.
+
+ The result cannot be used as a value for an 'enum' constant, if you
+ want to be portable to HP-UX 10.20 cc and AIX 3.2.5 xlc. */
+
+/* GCC releases before GCC 4.9 had a bug in _Alignof. See GCC bug 52023
+ <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52023>.
+ clang versions < 8.0.0 have the same bug. */
+# if (!defined __STDC_VERSION__ || __STDC_VERSION__ < 201112 \
+ || (defined __GNUC__ && __GNUC__ < 4 + (__GNUC_MINOR__ < 9) \
+ && !defined __clang__) \
+ || (defined __clang__ && __clang_major__ < 8))
+# undef/**/_Alignof
+# ifdef __cplusplus
+# if (201103 <= __cplusplus || defined _MSC_VER)
+# define _Alignof(type) alignof (type)
+# else
+ template <class __t> struct __alignof_helper { char __a; __t __b; };
+# define _Alignof(type) offsetof (__alignof_helper<type>, __b)
+# define _GL_STDALIGN_NEEDS_STDDEF 1
+# endif
+# else
+# if (defined __GNUC__ && 4 <= __GNUC__) || defined __clang__
+# define _Alignof(type) __builtin_offsetof (struct { char __a; type __b; }, __b)
+# else
+# define _Alignof(type) offsetof (struct { char __a; type __b; }, __b)
+# define _GL_STDALIGN_NEEDS_STDDEF 1
+# endif
+# endif
+# endif
+# if ! (defined __cplusplus && (201103 <= __cplusplus || defined _MSC_VER))
+# undef/**/alignof
+# define alignof _Alignof
+# endif
+
+/* alignas (A), also known as _Alignas (A), aligns a variable or type
+ to the alignment A, where A is an integer constant expression. For
+ example:
+
+ int alignas (8) foo;
+ struct s { int a; int alignas (8) bar; };
+
+ aligns the address of FOO and the offset of BAR to be multiples of 8.
+
+ A should be a power of two that is at least the type's alignment
+ and at most the implementation's alignment limit. This limit is
+ 2**28 on typical GNUish hosts, and 2**13 on MSVC. To be portable
+ to MSVC through at least version 10.0, A should be an integer
+ constant, as MSVC does not support expressions such as 1 << 3.
+ To be portable to Sun C 5.11, do not align auto variables to
+ anything stricter than their default alignment.
+
+ The following C23 requirements are not supported here:
+
+ - If A is zero, alignas has no effect.
+ - alignas can be used multiple times; the strictest one wins.
+ - alignas (TYPE) is equivalent to alignas (alignof (TYPE)).
+
+ */
+# if !defined __STDC_VERSION__ || __STDC_VERSION__ < 201112
+# if defined __cplusplus && (201103 <= __cplusplus || defined _MSC_VER)
+# define _Alignas(a) alignas (a)
+# elif (!defined __attribute__ \
+ && ((defined __APPLE__ && defined __MACH__ \
+ ? 4 < __GNUC__ + (1 <= __GNUC_MINOR__) \
+ : __GNUC__ && !defined __ibmxl__) \
+ || (4 <= __clang_major__) \
+ || (__ia64 && (61200 <= __HP_cc || 61200 <= __HP_aCC)) \
+ || __ICC || 0x590 <= __SUNPRO_C || 0x0600 <= __xlC__))
+# define _Alignas(a) __attribute__ ((__aligned__ (a)))
+# elif 1300 <= _MSC_VER
+# define _Alignas(a) __declspec (align (a))
+# endif
+# endif
+# if !HAVE_STDALIGN_H
+# if ((defined _Alignas \
+ && !(defined __cplusplus \
+ && (201103 <= __cplusplus || defined _MSC_VER))) \
+ || (defined __STDC_VERSION__ && 201112 <= __STDC_VERSION__))
+# define alignas _Alignas
+# endif
+# endif
+
+# if _GL_STDALIGN_NEEDS_STDDEF
+# include <stddef.h>
+# endif
+#endif])
+])
+
+AC_DEFUN([gl_STDALIGN_H],
+[
+ AC_REQUIRE([gl_ALIGNASOF])
+ if test "$gl_cv_header_working_stdalign_h" = no; then
+ GL_GENERATE_STDALIGN_H=true
+ else
+ GL_GENERATE_STDALIGN_H=false
+ fi
+
+ gl_CHECK_NEXT_HEADERS([stdalign.h])
+ if test $ac_cv_header_stdalign_h = yes; then
+ HAVE_STDALIGN_H=1
+ else
+ HAVE_STDALIGN_H=0
+ fi
+ AC_SUBST([HAVE_STDALIGN_H])
+])