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Assume that <stdbool.h> conforms to the C standard.

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Previously we checked "for <stdbool.h> that conforms to C99" using
autoconf's AC_HEADER_STDBOOL macro.  We've required C99 since PostgreSQL
12, so the test was redundant, and under C23 it was broken: autoconf
2.69's implementation doesn't understand C23's new empty header (the
macros it's looking for went away, replaced by language keywords).
Later autoconf versions fixed that, but let's just remove the
anachronistic test.

HAVE_STDBOOL_H and HAVE__BOOL will no longer be defined, but they
weren't directly tested in core or likely extensions (except in 11, see
below).  PG_USE_STDBOOL (or USE_STDBOOL in 11 and 12) is still defined
when sizeof(bool) is 1, which should be true on all modern systems.
Otherwise we define our own bool type and values of size 1, which would
fail to compile under C23 as revealed by the broken test.  (We'll
probably clean that dead code up in master, but here we want a minimal
back-patchable change.)

This came to our attention when GCC 15 recently started using using C23
by default and failed to compile the replacement code, as reported by
Sam James and build farm animal alligator.

Back-patch to all supported releases, and then two older versions that
also know about <stdbool.h>, per the recently-out-of-support policy[1].
12 requires C99 so it's much like the supported releases, but 11 only
assumes C89 so it now uses AC_CHECK_HEADERS instead of the overly picky
AC_HEADER_STDBOOL.  (I could find no discussion of which historical
systems had <stdbool.h> but failed the conformance test; if they ever
existed, they surely aren't relevant to that policy's goals.)

[1] https://wiki.postgresql.org/wiki/Committing_checklist#Policies

Reported-by: Sam James <sam@gentoo.org>
Reviewed-by: Peter Eisentraut <peter@eisentraut.org> (master version)
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us> (approach)
Discussion: https://www.postgresql.org/message-id/flat/87o72eo9iu.fsf%40gentoo.org
This commit is contained in:
Thomas Munro 2024-11-25 13:11:28 +13:00
parent d4d11940df
commit bc5a4dfcf7
5 changed files with 64 additions and 174 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

208
configure vendored
View File

@ -2094,60 +2094,6 @@ $as_echo "$ac_res" >&6; }
} # ac_fn_c_check_func
# ac_fn_c_check_type LINENO TYPE VAR INCLUDES
# -------------------------------------------
# Tests whether TYPE exists after having included INCLUDES, setting cache
# variable VAR accordingly.
ac_fn_c_check_type ()
{
as_lineno=${as_lineno-"$1"} as_lineno_stack=as_lineno_stack=$as_lineno_stack
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for $2" >&5
$as_echo_n "checking for $2... " >&6; }
if eval \${$3+:} false; then :
$as_echo_n "(cached) " >&6
else
eval "$3=no"
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
/* end confdefs.h. */
$4
int
main ()
{
if (sizeof ($2))
return 0;
;
return 0;
}
_ACEOF
if ac_fn_c_try_compile "$LINENO"; then :
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
/* end confdefs.h. */
$4
int
main ()
{
if (sizeof (($2)))
return 0;
;
return 0;
}
_ACEOF
if ac_fn_c_try_compile "$LINENO"; then :
else
eval "$3=yes"
fi
rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
fi
rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
fi
eval ac_res=\$$3
{ $as_echo "$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_type
# ac_fn_c_check_member LINENO AGGR MEMBER VAR INCLUDES
# ----------------------------------------------------
# Tries to find if the field MEMBER exists in type AGGR, after including
@ -2205,6 +2151,60 @@ $as_echo "$ac_res" >&6; }
} # ac_fn_c_check_member
# ac_fn_c_check_type LINENO TYPE VAR INCLUDES
# -------------------------------------------
# Tests whether TYPE exists after having included INCLUDES, setting cache
# variable VAR accordingly.
ac_fn_c_check_type ()
{
as_lineno=${as_lineno-"$1"} as_lineno_stack=as_lineno_stack=$as_lineno_stack
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for $2" >&5
$as_echo_n "checking for $2... " >&6; }
if eval \${$3+:} false; then :
$as_echo_n "(cached) " >&6
else
eval "$3=no"
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
/* end confdefs.h. */
$4
int
main ()
{
if (sizeof ($2))
return 0;
;
return 0;
}
_ACEOF
if ac_fn_c_try_compile "$LINENO"; then :
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
/* end confdefs.h. */
$4
int
main ()
{
if (sizeof (($2)))
return 0;
;
return 0;
}
_ACEOF
if ac_fn_c_try_compile "$LINENO"; then :
else
eval "$3=yes"
fi
rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
fi
rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
fi
eval ac_res=\$$3
{ $as_echo "$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_type
# ac_fn_c_compute_int LINENO EXPR VAR INCLUDES
# --------------------------------------------
# Tries to find the compile-time value of EXPR in a program that includes
@ -13227,100 +13227,6 @@ fi
## Header files
##
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for stdbool.h that conforms to C99" >&5
$as_echo_n "checking for stdbool.h that conforms to C99... " >&6; }
if ${ac_cv_header_stdbool_h+:} false; then :
$as_echo_n "(cached) " >&6
else
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
/* end confdefs.h. */
#include <stdbool.h>
#ifndef bool
"error: bool is not defined"
#endif
#ifndef false
"error: false is not defined"
#endif
#if false
"error: false is not 0"
#endif
#ifndef true
"error: true is not defined"
#endif
#if true != 1
"error: true is not 1"
#endif
#ifndef __bool_true_false_are_defined
"error: __bool_true_false_are_defined is not defined"
#endif
struct s { _Bool s: 1; _Bool t; } s;
char a[true == 1 ? 1 : -1];
char b[false == 0 ? 1 : -1];
char c[__bool_true_false_are_defined == 1 ? 1 : -1];
char d[(bool) 0.5 == true ? 1 : -1];
/* See body of main program for 'e'. */
char f[(_Bool) 0.0 == false ? 1 : -1];
char g[true];
char h[sizeof (_Bool)];
char i[sizeof s.t];
enum { j = false, k = true, l = false * true, m = true * 256 };
/* The following fails for
HP aC++/ANSI C B3910B A.05.55 [Dec 04 2003]. */
_Bool n[m];
char o[sizeof n == m * sizeof n[0] ? 1 : -1];
char p[-1 - (_Bool) 0 < 0 && -1 - (bool) 0 < 0 ? 1 : -1];
/* Catch a bug in an HP-UX C compiler. See
http://gcc.gnu.org/ml/gcc-patches/2003-12/msg02303.html
http://lists.gnu.org/archive/html/bug-coreutils/2005-11/msg00161.html
*/
_Bool q = true;
_Bool *pq = &q;
int
main ()
{
bool e = &s;
*pq |= q;
*pq |= ! q;
/* Refer to every declared value, to avoid compiler optimizations. */
return (!a + !b + !c + !d + !e + !f + !g + !h + !i + !!j + !k + !!l
+ !m + !n + !o + !p + !q + !pq);
;
return 0;
}
_ACEOF
if ac_fn_c_try_compile "$LINENO"; then :
ac_cv_header_stdbool_h=yes
else
ac_cv_header_stdbool_h=no
fi
rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_header_stdbool_h" >&5
$as_echo "$ac_cv_header_stdbool_h" >&6; }
ac_fn_c_check_type "$LINENO" "_Bool" "ac_cv_type__Bool" "$ac_includes_default"
if test "x$ac_cv_type__Bool" = xyes; then :
cat >>confdefs.h <<_ACEOF
#define HAVE__BOOL 1
_ACEOF
fi
if test $ac_cv_header_stdbool_h = yes; then
$as_echo "#define HAVE_STDBOOL_H 1" >>confdefs.h
fi
for ac_header in atomic.h copyfile.h execinfo.h getopt.h ifaddrs.h mbarrier.h sys/epoll.h sys/event.h sys/personality.h sys/prctl.h sys/procctl.h sys/signalfd.h sys/ucred.h termios.h ucred.h xlocale.h
do :
as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
@ -15061,9 +14967,7 @@ $as_echo_n "checking size of bool... " >&6; }
if ${ac_cv_sizeof_bool+:} false; then :
$as_echo_n "(cached) " >&6
else
if ac_fn_c_compute_int "$LINENO" "(long int) (sizeof (bool))" "ac_cv_sizeof_bool" "#ifdef HAVE_STDBOOL_H
#include <stdbool.h>
#endif
if ac_fn_c_compute_int "$LINENO" "(long int) (sizeof (bool))" "ac_cv_sizeof_bool" "#include <stdbool.h>
"; then :
else
@ -15089,7 +14993,7 @@ _ACEOF
if test "$ac_cv_header_stdbool_h" = yes -a "$ac_cv_sizeof_bool" = 1; then
if test "$ac_cv_sizeof_bool" = 1; then
$as_echo "#define PG_USE_STDBOOL 1" >>confdefs.h

13
configure.ac
View File

@ -1432,8 +1432,6 @@ AC_SUBST(UUID_LIBS)
## Header files
##
AC_HEADER_STDBOOL
AC_CHECK_HEADERS(m4_normalize([
atomic.h
copyfile.h
@ -1693,14 +1691,11 @@ if test "$ac_cv_sizeof_off_t" -lt 8; then
fi
fi
AC_CHECK_SIZEOF([bool], [],
[#ifdef HAVE_STDBOOL_H
#include <stdbool.h>
#endif])
AC_CHECK_SIZEOF([bool], [], [#include <stdbool.h>])
dnl We use <stdbool.h> if we have it and it declares type bool as having
dnl size 1. Otherwise, c.h will fall back to declaring bool as unsigned char.
if test "$ac_cv_header_stdbool_h" = yes -a "$ac_cv_sizeof_bool" = 1; then
dnl We use <stdbool.h> if bool has size 1 after including it. Otherwise, c.h
dnl will fall back to declaring bool as unsigned char.
if test "$ac_cv_sizeof_bool" = 1; then
AC_DEFINE([PG_USE_STDBOOL], 1,
[Define to 1 to use <stdbool.h> to define type bool.])
fi

9
meson.build
View File

@ -1755,12 +1755,9 @@ if cc.compiles('''
endif
# We use <stdbool.h> if we have it and it declares type bool as having
# size 1. Otherwise, c.h will fall back to declaring bool as unsigned char.
if cc.has_type('_Bool', args: test_c_args) \
and cc.has_type('bool', prefix: '#include <stdbool.h>', args: test_c_args) \
and cc.sizeof('bool', prefix: '#include <stdbool.h>', args: test_c_args) == 1
cdata.set('HAVE__BOOL', 1)
# We use <stdbool.h> if bool has size 1 after including it. Otherwise, c.h
# will fall back to declaring bool as unsigned char.
if cc.sizeof('bool', prefix: '#include <stdbool.h>', args: test_c_args) == 1
cdata.set('PG_USE_STDBOOL', 1)
endif

2
src/include/c.h
View File

@ -450,7 +450,7 @@ typedef void (*pg_funcptr_t) (void);
* bool
* Boolean value, either true or false.
*
* We use stdbool.h if available and its bool has size 1. That's useful for
* We use stdbool.h if bool has size 1 after including it. That's useful for
* better compiler and debugger output and for compatibility with third-party
* libraries. But PostgreSQL currently cannot deal with bool of other sizes;
* there are static assertions around the code to prevent that.

6
src/include/pg_config.h.in
View File

@ -367,9 +367,6 @@
/* Define to 1 if you have the `SSL_CTX_set_num_tickets' function. */
#undef HAVE_SSL_CTX_SET_NUM_TICKETS
/* Define to 1 if stdbool.h conforms to C99. */
#undef HAVE_STDBOOL_H
/* Define to 1 if you have the <stdint.h> header file. */
#undef HAVE_STDINT_H
@ -499,9 +496,6 @@
/* Define to 1 if you have XSAVE intrinsics. */
#undef HAVE_XSAVE_INTRINSICS
/* Define to 1 if the system has the type `_Bool'. */
#undef HAVE__BOOL
/* Define to 1 if your compiler understands __builtin_bswap16. */
#undef HAVE__BUILTIN_BSWAP16