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Libstdc++: Fix bootstrap failure for cross without tm.tm_zone [PR119550]

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In r15-8491-g778c28c70f8573 I added a use of the Autoconf macro
AC_STRUCT_TIMEZONE, but that requires a link-test for the global tzname
object if tm.tm_zone isn't supported. That link-test isn't allowed for
cross-compilation, so bootstrap fails if tm.tm_zone isn't supported.

Since libstdc++ only cares about tm.tm_zone and won't use tzname anyway,
we don't need the link-test. Replace AC_STRUCT_TIMEZONE with a custom
macro that only checks for tm.tm_zone. We can improve on the Autoconf
macro by checking it's a suitable type, which isn't actually checked by
AC_STRUCT_TIMEZONE.

libstdc++-v3/ChangeLog:

	PR libstdc++/119550
	* acinclude.m4 (GLIBCXX_STRUCT_TM_TM_ZONE): New macro.
	* config.h.in: Regenerate.
	* configure: Regenerate.
	* configure.ac: Use GLIBCXX_STRUCT_TM_TM_ZONE.
	* include/bits/chrono_io.h (__formatter_chrono::_M_c): Check
	_GLIBCXX_USE_STRUCT_TM_TM_ZONE instead of
	_GLIBCXX_HAVE_STRUCT_TM_TM_ZONE.
This commit is contained in:
Jonathan Wakely 2025-03-31 15:07:12 +01:00 committed by Jonathan Wakely
parent 0cb8889e51
commit 97cbe3cd5f
No known key found for this signature in database
5 changed files with 109 additions and 192 deletions
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35
libstdc++-v3/acinclude.m4
View File

@ -5744,6 +5744,41 @@ AC_DEFUN([GLIBCXX_ZONEINFO_DIR], [
fi
])
dnl
dnl Check for a tm_zone member in struct tm.
dnl
dnl This member is defined as const char* in Glibc, newlib, POSIX.1-2024,
dnl and as char* in BSD (including macOS).
dnl
dnl Defines:
dnl _GLIBCXX_USE_STRUCT_TM_TM_ZONE if struct tm has a tm_zone member.
dnl
AC_DEFUN([GLIBCXX_STRUCT_TM_TM_ZONE], [
AC_LANG_SAVE
AC_LANG_CPLUSPLUS
ac_save_CXXFLAGS="$CXXFLAGS"
CXXFLAGS="$CXXFLAGS -std=c++20"
AC_CACHE_CHECK([for tm_zone member of struct tm], glibcxx_cv_tm_zone, [
AC_COMPILE_IFELSE([AC_LANG_PROGRAM([#include <time.h>
],
[struct tm t{}; t.tm_zone = (char*)0;]
)],
[glibcxx_cv_tm_zone=yes],
[glibcxx_cv_tm_zone=no]
)
])
if test $glibcxx_cv_tm_zone = yes; then
AC_DEFINE(_GLIBCXX_USE_STRUCT_TM_TM_ZONE, 1,
[Define if struct tm has a tm_zone member.])
fi
CXXFLAGS="$ac_save_CXXFLAGS"
AC_LANG_RESTORE
])
dnl
dnl Check whether lock tables can be aligned to avoid false sharing.
dnl

21
libstdc++-v3/config.h.in
View File

@ -74,10 +74,6 @@
don't. */
#undef HAVE_DECL_STRNLEN
/* Define to 1 if you have the declaration of `tzname', and to 0 if you don't.
*/
#undef HAVE_DECL_TZNAME
/* Define to 1 if you have the <dirent.h> header file. */
#undef HAVE_DIRENT_H
@ -412,9 +408,6 @@
/* Define to 1 if `d_type' is a member of `struct dirent'. */
#undef HAVE_STRUCT_DIRENT_D_TYPE
/* Define to 1 if `tm_zone' is a member of `struct tm'. */
#undef HAVE_STRUCT_TM_TM_ZONE
/* Define if strxfrm_l is available in <string.h>. */
#undef HAVE_STRXFRM_L
@ -506,17 +499,9 @@
/* Define to 1 if the target supports thread-local storage. */
#undef HAVE_TLS
/* Define to 1 if your `struct tm' has `tm_zone'. Deprecated, use
`HAVE_STRUCT_TM_TM_ZONE' instead. */
#undef HAVE_TM_ZONE
/* Define if truncate is available in <unistd.h>. */
#undef HAVE_TRUNCATE
/* Define to 1 if you don't have `tm_zone' but do have the external array
`tzname'. */
#undef HAVE_TZNAME
/* Define to 1 if you have the <uchar.h> header file. */
#undef HAVE_UCHAR_H
@ -605,9 +590,6 @@
/* Define to 1 if you have the ANSI C header files. */
#undef STDC_HEADERS
/* Define to 1 if your <sys/time.h> declares `struct tm'. */
#undef TM_IN_SYS_TIME
/* Version number of package */
#undef VERSION
@ -906,6 +888,9 @@
/* Define to restrict std::__basic_file<> to stdio APIs. */
#undef _GLIBCXX_USE_STDIO_PURE
/* Define if struct tm has a tm_zone member. */
#undef _GLIBCXX_USE_STRUCT_TM_TM_ZONE
/* Define if struct stat has timespec members. */
#undef _GLIBCXX_USE_ST_MTIM

238
libstdc++-v3/configure vendored
View File

@ -2731,63 +2731,6 @@ $as_echo "$ac_res" >&6; }
eval $as_lineno_stack; ${as_lineno_stack:+:} unset as_lineno
} # ac_fn_c_check_decl
# ac_fn_c_check_member LINENO AGGR MEMBER VAR INCLUDES
# ----------------------------------------------------
# Tries to find if the field MEMBER exists in type AGGR, after including
# INCLUDES, setting cache variable VAR accordingly.
ac_fn_c_check_member ()
{
as_lineno=${as_lineno-"$1"} as_lineno_stack=as_lineno_stack=$as_lineno_stack
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for $2.$3" >&5
$as_echo_n "checking for $2.$3... " >&6; }
if eval \${$4+:} false; then :
$as_echo_n "(cached) " >&6
else
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
/* end confdefs.h. */
$5
int
main ()
{
static $2 ac_aggr;
if (ac_aggr.$3)
return 0;
;
return 0;
}
_ACEOF
if ac_fn_c_try_compile "$LINENO"; then :
eval "$4=yes"
else
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
/* end confdefs.h. */
$5
int
main ()
{
static $2 ac_aggr;
if (sizeof ac_aggr.$3)
return 0;
;
return 0;
}
_ACEOF
if ac_fn_c_try_compile "$LINENO"; then :
eval "$4=yes"
else
eval "$4=no"
fi
rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
fi
rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
fi
eval ac_res=\$$4
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
$as_echo "$ac_res" >&6; }
eval $as_lineno_stack; ${as_lineno_stack:+:} unset as_lineno
} # ac_fn_c_check_member
cat >config.log <<_ACEOF
This file contains any messages produced by compilers while
running configure, to aid debugging if configure makes a mistake.
@ -12337,7 +12280,7 @@ else
lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
lt_status=$lt_dlunknown
cat > conftest.$ac_ext <<_LT_EOF
#line 12340 "configure"
#line 12283 "configure"
#include "confdefs.h"
#if HAVE_DLFCN_H
@ -12443,7 +12386,7 @@ else
lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
lt_status=$lt_dlunknown
cat > conftest.$ac_ext <<_LT_EOF
#line 12446 "configure"
#line 12389 "configure"
#include "confdefs.h"
#if HAVE_DLFCN_H
@ -16239,7 +16182,7 @@ $as_echo "$glibcxx_cv_atomic_long_long" >&6; }
# Fake what AC_TRY_COMPILE does.
cat > conftest.$ac_ext << EOF
#line 16242 "configure"
#line 16185 "configure"
int main()
{
typedef bool atomic_type;
@ -16274,7 +16217,7 @@ $as_echo "$glibcxx_cv_atomic_bool" >&6; }
rm -f conftest*
cat > conftest.$ac_ext << EOF
#line 16277 "configure"
#line 16220 "configure"
int main()
{
typedef short atomic_type;
@ -16309,7 +16252,7 @@ $as_echo "$glibcxx_cv_atomic_short" >&6; }
rm -f conftest*
cat > conftest.$ac_ext << EOF
#line 16312 "configure"
#line 16255 "configure"
int main()
{
// NB: _Atomic_word not necessarily int.
@ -16345,7 +16288,7 @@ $as_echo "$glibcxx_cv_atomic_int" >&6; }
rm -f conftest*
cat > conftest.$ac_ext << EOF
#line 16348 "configure"
#line 16291 "configure"
int main()
{
typedef long long atomic_type;
@ -16501,7 +16444,7 @@ $as_echo "mutex" >&6; }
# unnecessary for this test.
cat > conftest.$ac_ext << EOF
#line 16504 "configure"
#line 16447 "configure"
int main()
{
_Decimal32 d1;
@ -16543,7 +16486,7 @@ ac_compiler_gnu=$ac_cv_cxx_compiler_gnu
# unnecessary for this test.
cat > conftest.$ac_ext << EOF
#line 16546 "configure"
#line 16489 "configure"
template<typename T1, typename T2>
struct same
{ typedef T2 type; };
@ -54482,6 +54425,65 @@ _ACEOF
fi
# For std::chrono formatters to use tm::tm_zone
ac_ext=cpp
ac_cpp='$CXXCPP $CPPFLAGS'
ac_compile='$CXX -c $CXXFLAGS $CPPFLAGS conftest.$ac_ext >&5'
ac_link='$CXX -o conftest$ac_exeext $CXXFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
ac_compiler_gnu=$ac_cv_cxx_compiler_gnu
ac_save_CXXFLAGS="$CXXFLAGS"
CXXFLAGS="$CXXFLAGS -std=c++20"
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for tm_zone member of struct tm" >&5
$as_echo_n "checking for tm_zone member of struct tm... " >&6; }
if ${glibcxx_cv_tm_zone+:} false; then :
$as_echo_n "(cached) " >&6
else
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
/* end confdefs.h. */
#include <time.h>
int
main ()
{
struct tm t{}; t.tm_zone = (char*)0;
;
return 0;
}
_ACEOF
if ac_fn_cxx_try_compile "$LINENO"; then :
glibcxx_cv_tm_zone=yes
else
glibcxx_cv_tm_zone=no
fi
rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $glibcxx_cv_tm_zone" >&5
$as_echo "$glibcxx_cv_tm_zone" >&6; }
if test $glibcxx_cv_tm_zone = yes; then
$as_echo "#define _GLIBCXX_USE_STRUCT_TM_TM_ZONE 1" >>confdefs.h
fi
CXXFLAGS="$ac_save_CXXFLAGS"
ac_ext=c
ac_cpp='$CPP $CPPFLAGS'
ac_compile='$CC -c $CFLAGS $CPPFLAGS conftest.$ac_ext >&5'
ac_link='$CC -o conftest$ac_exeext $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
ac_compiler_gnu=$ac_cv_c_compiler_gnu
# For src/c++11/shared_ptr.cc alignment.
@ -54697,112 +54699,6 @@ ac_compiler_gnu=$ac_cv_c_compiler_gnu
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether struct tm is in sys/time.h or time.h" >&5
$as_echo_n "checking whether struct tm is in sys/time.h or time.h... " >&6; }
if ${ac_cv_struct_tm+:} false; then :
$as_echo_n "(cached) " >&6
else
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
/* end confdefs.h. */
#include <sys/types.h>
#include <time.h>
int
main ()
{
struct tm tm;
int *p = &tm.tm_sec;
return !p;
;
return 0;
}
_ACEOF
if ac_fn_c_try_compile "$LINENO"; then :
ac_cv_struct_tm=time.h
else
ac_cv_struct_tm=sys/time.h
fi
rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_struct_tm" >&5
$as_echo "$ac_cv_struct_tm" >&6; }
if test $ac_cv_struct_tm = sys/time.h; then
$as_echo "#define TM_IN_SYS_TIME 1" >>confdefs.h
fi
ac_fn_c_check_member "$LINENO" "struct tm" "tm_zone" "ac_cv_member_struct_tm_tm_zone" "#include <sys/types.h>
#include <$ac_cv_struct_tm>
"
if test "x$ac_cv_member_struct_tm_tm_zone" = xyes; then :
cat >>confdefs.h <<_ACEOF
#define HAVE_STRUCT_TM_TM_ZONE 1
_ACEOF
fi
if test "$ac_cv_member_struct_tm_tm_zone" = yes; then
$as_echo "#define HAVE_TM_ZONE 1" >>confdefs.h
else
ac_fn_c_check_decl "$LINENO" "tzname" "ac_cv_have_decl_tzname" "#include <time.h>
"
if test "x$ac_cv_have_decl_tzname" = xyes; then :
ac_have_decl=1
else
ac_have_decl=0
fi
cat >>confdefs.h <<_ACEOF
#define HAVE_DECL_TZNAME $ac_have_decl
_ACEOF
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for tzname" >&5
$as_echo_n "checking for tzname... " >&6; }
if ${ac_cv_var_tzname+:} false; then :
$as_echo_n "(cached) " >&6
else
if test x$gcc_no_link = xyes; then
as_fn_error $? "Link tests are not allowed after GCC_NO_EXECUTABLES." "$LINENO" 5
fi
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
/* end confdefs.h. */
#include <time.h>
#if !HAVE_DECL_TZNAME
extern char *tzname[];
#endif
int
main ()
{
return tzname[0][0];
;
return 0;
}
_ACEOF
if ac_fn_c_try_link "$LINENO"; then :
ac_cv_var_tzname=yes
else
ac_cv_var_tzname=no
fi
rm -f core conftest.err conftest.$ac_objext \
conftest$ac_exeext conftest.$ac_ext
fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_var_tzname" >&5
$as_echo "$ac_cv_var_tzname" >&6; }
if test $ac_cv_var_tzname = yes; then
$as_echo "#define HAVE_TZNAME 1" >>confdefs.h
fi
fi
# Define documentation rules conditionally.
# See if makeinfo has been installed and is modern enough

5
libstdc++-v3/configure.ac
View File

@ -572,6 +572,9 @@ GLIBCXX_EMERGENCY_EH_ALLOC
# For src/c++20/tzdb.cc defaults.
GLIBCXX_ZONEINFO_DIR
# For std::chrono formatters to use tm::tm_zone
GLIBCXX_STRUCT_TM_TM_ZONE
# For src/c++11/shared_ptr.cc alignment.
GLIBCXX_CHECK_ALIGNAS_CACHELINE
@ -584,8 +587,6 @@ GLIBCXX_CHECK_FILEBUF_NATIVE_HANDLES
# For std::text_encoding
GLIBCXX_CHECK_TEXT_ENCODING
AC_STRUCT_TIMEZONE
# Define documentation rules conditionally.
# See if makeinfo has been installed and is modern enough

2
libstdc++-v3/include/bits/chrono_io.h
View File

@ -905,7 +905,7 @@ namespace __format
// time zone info available for the time in __tm.
__tm.tm_isdst = -1;
#ifdef _GLIBCXX_HAVE_STRUCT_TM_TM_ZONE
#ifdef _GLIBCXX_USE_STRUCT_TM_TM_ZONE
// POSIX.1-2024 adds tm.tm_zone which will be used for %Z.
// BSD has had tm_zone since 1987 but as char* so cast away const.
if constexpr (__is_time_point_v<_Tp>)