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PostgreSQL/config/ax_pthread.m4
Tom Lane df303aff66 Update config/ax_pthread.m4 to latest upstream version. 
This change doesn't fix any bugs that we've heard about, but it seems
like a good idea on general principles to track upstream occasionally.

Discussion: https://postgr.es/m/3320.1542647565@sss.pgh.pa.us
2018-11-19 15:05:33 -05:00

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# ===========================================================================
# https://www.gnu.org/software/autoconf-archive/ax_pthread.html
# ===========================================================================
#
# SYNOPSIS
#
# AX_PTHREAD([ACTION-IF-FOUND[, ACTION-IF-NOT-FOUND]])
#
# DESCRIPTION
#
# This macro figures out how to build C programs using POSIX threads. It
# sets the PTHREAD_LIBS output variable to the threads library and linker
# flags, and the PTHREAD_CFLAGS output variable to any special C compiler
# flags that are needed. (The user can also force certain compiler
# flags/libs to be tested by setting these environment variables.)
#
# Also sets PTHREAD_CC to any special C compiler that is needed for
# multi-threaded programs (defaults to the value of CC otherwise). (This
# is necessary on AIX to use the special cc_r compiler alias.)
#
# NOTE: You are assumed to not only compile your program with these flags,
# but also to link with them as well. For example, you might link with
# $PTHREAD_CC $CFLAGS $PTHREAD_CFLAGS $LDFLAGS ... $PTHREAD_LIBS $LIBS
#
# If you are only building threaded programs, you may wish to use these
# variables in your default LIBS, CFLAGS, and CC:
#
# LIBS="$PTHREAD_LIBS $LIBS"
# CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
# CC="$PTHREAD_CC"
#
# In addition, if the PTHREAD_CREATE_JOINABLE thread-attribute constant
# has a nonstandard name, this macro defines PTHREAD_CREATE_JOINABLE to
# that name (e.g. PTHREAD_CREATE_UNDETACHED on AIX).
#
# Also HAVE_PTHREAD_PRIO_INHERIT is defined if pthread is found and the
# PTHREAD_PRIO_INHERIT symbol is defined when compiling with
# PTHREAD_CFLAGS.
#
# ACTION-IF-FOUND is a list of shell commands to run if a threads library
# is found, and ACTION-IF-NOT-FOUND is a list of commands to run it if it
# is not found. If ACTION-IF-FOUND is not specified, the default action
# will define HAVE_PTHREAD.
#
# Please let the authors know if this macro fails on any platform, or if
# you have any other suggestions or comments. This macro was based on work
# by SGJ on autoconf scripts for FFTW (http://www.fftw.org/) (with help
# from M. Frigo), as well as ac_pthread and hb_pthread macros posted by
# Alejandro Forero Cuervo to the autoconf macro repository. We are also
# grateful for the helpful feedback of numerous users.
#
# Updated for Autoconf 2.68 by Daniel Richard G.
#
# LICENSE
#
# Copyright (c) 2008 Steven G. Johnson <stevenj@alum.mit.edu>
# Copyright (c) 2011 Daniel Richard G. <skunk@iSKUNK.ORG>
#
# This program is free software: you can redistribute it and/or modify it
# under the terms of the GNU General Public License as published by the
# Free Software Foundation, either version 3 of the License, or (at your
# option) any later version.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
# Public License for more details.
#
# You should have received a copy of the GNU General Public License along
# with this program. If not, see <https://www.gnu.org/licenses/>.
#
# As a special exception, the respective Autoconf Macro's copyright owner
# gives unlimited permission to copy, distribute and modify the configure
# scripts that are the output of Autoconf when processing the Macro. You
# need not follow the terms of the GNU General Public License when using
# or distributing such scripts, even though portions of the text of the
# Macro appear in them. The GNU General Public License (GPL) does govern
# all other use of the material that constitutes the Autoconf Macro.
#
# This special exception to the GPL applies to versions of the Autoconf
# Macro released by the Autoconf Archive. When you make and distribute a
# modified version of the Autoconf Macro, you may extend this special
# exception to the GPL to apply to your modified version as well.
#serial 24
AU_ALIAS([ACX_PTHREAD], [AX_PTHREAD])
AC_DEFUN([AX_PTHREAD], [
AC_REQUIRE([AC_CANONICAL_HOST])
AC_REQUIRE([AC_PROG_CC])
AC_REQUIRE([AC_PROG_SED])
AC_LANG_PUSH([C])
ax_pthread_ok=no
# We used to check for pthread.h first, but this fails if pthread.h
# requires special compiler flags (e.g. on Tru64 or Sequent).
# It gets checked for in the link test anyway.
# First of all, check if the user has set any of the PTHREAD_LIBS,
# etcetera environment variables, and if threads linking works using
# them:
if test "x$PTHREAD_CFLAGS$PTHREAD_LIBS" != "x"; then
ax_pthread_save_CC="$CC"
ax_pthread_save_CFLAGS="$CFLAGS"
ax_pthread_save_LIBS="$LIBS"
AS_IF([test "x$PTHREAD_CC" != "x"], [CC="$PTHREAD_CC"])
CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
LIBS="$PTHREAD_LIBS $LIBS"
AC_MSG_CHECKING([for pthread_join using $CC $PTHREAD_CFLAGS $PTHREAD_LIBS])
AC_LINK_IFELSE([AC_LANG_CALL([], [pthread_join])], [ax_pthread_ok=yes])
AC_MSG_RESULT([$ax_pthread_ok])
if test "x$ax_pthread_ok" = "xno"; then
PTHREAD_LIBS=""
PTHREAD_CFLAGS=""
fi
CC="$ax_pthread_save_CC"
CFLAGS="$ax_pthread_save_CFLAGS"
LIBS="$ax_pthread_save_LIBS"
fi
# We must check for the threads library under a number of different
# names; the ordering is very important because some systems
# (e.g. DEC) have both -lpthread and -lpthreads, where one of the
# libraries is broken (non-POSIX).
# Create a list of thread flags to try. Items starting with a "-" are
# C compiler flags, and other items are library names, except for "none"
# which indicates that we try without any flags at all, and "pthread-config"
# which is a program returning the flags for the Pth emulation library.
ax_pthread_flags="pthreads none -Kthread -pthread -pthreads -mthreads pthread --thread-safe -mt pthread-config"
# The ordering *is* (sometimes) important. Some notes on the
# individual items follow:
# pthreads: AIX (must check this before -lpthread)
# none: in case threads are in libc; should be tried before -Kthread and
# other compiler flags to prevent continual compiler warnings
# -Kthread: Sequent (threads in libc, but -Kthread needed for pthread.h)
# -pthread: Linux/gcc (kernel threads), BSD/gcc (userland threads), Tru64
# (Note: HP C rejects this with "bad form for `-t' option")
# -pthreads: Solaris/gcc (Note: HP C also rejects)
# -mt: Sun Workshop C (may only link SunOS threads [-lthread], but it
# doesn't hurt to check since this sometimes defines pthreads and
# -D_REENTRANT too), HP C (must be checked before -lpthread, which
# is present but should not be used directly; and before -mthreads,
# because the compiler interprets this as "-mt" + "-hreads")
# -mthreads: Mingw32/gcc, Lynx/gcc
# pthread: Linux, etcetera
# --thread-safe: KAI C++
# pthread-config: use pthread-config program (for GNU Pth library)
case $host_os in
freebsd*)
# -kthread: FreeBSD kernel threads (preferred to -pthread since SMP-able)
# lthread: LinuxThreads port on FreeBSD (also preferred to -pthread)
ax_pthread_flags="-kthread lthread $ax_pthread_flags"
;;
hpux*)
# From the cc(1) man page: "[-mt] Sets various -D flags to enable
# multi-threading and also sets -lpthread."
ax_pthread_flags="-mt -pthread pthread $ax_pthread_flags"
;;
openedition*)
# IBM z/OS requires a feature-test macro to be defined in order to
# enable POSIX threads at all, so give the user a hint if this is
# not set. (We don't define these ourselves, as they can affect
# other portions of the system API in unpredictable ways.)
AC_EGREP_CPP([AX_PTHREAD_ZOS_MISSING],
[
# if !defined(_OPEN_THREADS) && !defined(_UNIX03_THREADS)
AX_PTHREAD_ZOS_MISSING
# endif
],
[AC_MSG_WARN([IBM z/OS requires -D_OPEN_THREADS or -D_UNIX03_THREADS to enable pthreads support.])])
;;
solaris*)
# On Solaris (at least, for some versions), libc contains stubbed
# (non-functional) versions of the pthreads routines, so link-based
# tests will erroneously succeed. (N.B.: The stubs are missing
# pthread_cleanup_push, or rather a function called by this macro,
# so we could check for that, but who knows whether they'll stub
# that too in a future libc.) So we'll check first for the
# standard Solaris way of linking pthreads (-mt -lpthread).
ax_pthread_flags="-mt,pthread pthread $ax_pthread_flags"
;;
esac
# GCC generally uses -pthread, or -pthreads on some platforms (e.g. SPARC)
AS_IF([test "x$GCC" = "xyes"],
[ax_pthread_flags="-pthread -pthreads $ax_pthread_flags"])
# The presence of a feature test macro requesting re-entrant function
# definitions is, on some systems, a strong hint that pthreads support is
# correctly enabled
case $host_os in
darwin* | hpux* | linux* | osf* | solaris*)
ax_pthread_check_macro="_REENTRANT"
;;
aix*)
ax_pthread_check_macro="_THREAD_SAFE"
;;
*)
ax_pthread_check_macro="--"
;;
esac
AS_IF([test "x$ax_pthread_check_macro" = "x--"],
[ax_pthread_check_cond=0],
[ax_pthread_check_cond="!defined($ax_pthread_check_macro)"])
# Are we compiling with Clang?
AC_CACHE_CHECK([whether $CC is Clang],
[ax_cv_PTHREAD_CLANG],
[ax_cv_PTHREAD_CLANG=no
# Note that Autoconf sets GCC=yes for Clang as well as GCC
if test "x$GCC" = "xyes"; then
AC_EGREP_CPP([AX_PTHREAD_CC_IS_CLANG],
[/* Note: Clang 2.7 lacks __clang_[a-z]+__ */
# if defined(__clang__) && defined(__llvm__)
AX_PTHREAD_CC_IS_CLANG
# endif
],
[ax_cv_PTHREAD_CLANG=yes])
fi
])
ax_pthread_clang="$ax_cv_PTHREAD_CLANG"
ax_pthread_clang_warning=no
# Clang needs special handling, because older versions handle the -pthread
# option in a rather... idiosyncratic way
if test "x$ax_pthread_clang" = "xyes"; then
# Clang takes -pthread; it has never supported any other flag
# (Note 1: This will need to be revisited if a system that Clang
# supports has POSIX threads in a separate library. This tends not
# to be the way of modern systems, but it's conceivable.)
# (Note 2: On some systems, notably Darwin, -pthread is not needed
# to get POSIX threads support; the API is always present and
# active. We could reasonably leave PTHREAD_CFLAGS empty. But
# -pthread does define _REENTRANT, and while the Darwin headers
# ignore this macro, third-party headers might not.)
PTHREAD_CFLAGS="-pthread"
PTHREAD_LIBS=
ax_pthread_ok=yes
# However, older versions of Clang make a point of warning the user
# that, in an invocation where only linking and no compilation is
# taking place, the -pthread option has no effect ("argument unused
# during compilation"). They expect -pthread to be passed in only
# when source code is being compiled.
#
# Problem is, this is at odds with the way Automake and most other
# C build frameworks function, which is that the same flags used in
# compilation (CFLAGS) are also used in linking. Many systems
# supported by AX_PTHREAD require exactly this for POSIX threads
# support, and in fact it is often not straightforward to specify a
# flag that is used only in the compilation phase and not in
# linking. Such a scenario is extremely rare in practice.
#
# Even though use of the -pthread flag in linking would only print
# a warning, this can be a nuisance for well-run software projects
# that build with -Werror. So if the active version of Clang has
# this misfeature, we search for an option to squash it.
AC_CACHE_CHECK([whether Clang needs flag to prevent "argument unused" warning when linking with -pthread],
[ax_cv_PTHREAD_CLANG_NO_WARN_FLAG],
[ax_cv_PTHREAD_CLANG_NO_WARN_FLAG=unknown
# Create an alternate version of $ac_link that compiles and
# links in two steps (.c -> .o, .o -> exe) instead of one
# (.c -> exe), because the warning occurs only in the second
# step
ax_pthread_save_ac_link="$ac_link"
ax_pthread_sed='s/conftest\.\$ac_ext/conftest.$ac_objext/g'
ax_pthread_link_step=`$as_echo "$ac_link" | sed "$ax_pthread_sed"`
ax_pthread_2step_ac_link="($ac_compile) && (echo ==== >&5) && ($ax_pthread_link_step)"
ax_pthread_save_CFLAGS="$CFLAGS"
for ax_pthread_try in '' -Qunused-arguments -Wno-unused-command-line-argument unknown; do
AS_IF([test "x$ax_pthread_try" = "xunknown"], [break])
CFLAGS="-Werror -Wunknown-warning-option $ax_pthread_try -pthread $ax_pthread_save_CFLAGS"
ac_link="$ax_pthread_save_ac_link"
AC_LINK_IFELSE([AC_LANG_SOURCE([[int main(void){return 0;}]])],
[ac_link="$ax_pthread_2step_ac_link"
AC_LINK_IFELSE([AC_LANG_SOURCE([[int main(void){return 0;}]])],
[break])
])
done
ac_link="$ax_pthread_save_ac_link"
CFLAGS="$ax_pthread_save_CFLAGS"
AS_IF([test "x$ax_pthread_try" = "x"], [ax_pthread_try=no])
ax_cv_PTHREAD_CLANG_NO_WARN_FLAG="$ax_pthread_try"
])
case "$ax_cv_PTHREAD_CLANG_NO_WARN_FLAG" in
no | unknown) ;;
*) PTHREAD_CFLAGS="$ax_cv_PTHREAD_CLANG_NO_WARN_FLAG $PTHREAD_CFLAGS" ;;
esac
fi # $ax_pthread_clang = yes
if test "x$ax_pthread_ok" = "xno"; then
for ax_pthread_try_flag in $ax_pthread_flags; do
case $ax_pthread_try_flag in
none)
AC_MSG_CHECKING([whether pthreads work without any flags])
;;
-mt,pthread)
AC_MSG_CHECKING([whether pthreads work with -mt -lpthread])
PTHREAD_CFLAGS="-mt"
PTHREAD_LIBS="-lpthread"
;;
-*)
AC_MSG_CHECKING([whether pthreads work with $ax_pthread_try_flag])
PTHREAD_CFLAGS="$ax_pthread_try_flag"
;;
pthread-config)
AC_CHECK_PROG([ax_pthread_config], [pthread-config], [yes], [no])
AS_IF([test "x$ax_pthread_config" = "xno"], [continue])
PTHREAD_CFLAGS="`pthread-config --cflags`"
PTHREAD_LIBS="`pthread-config --ldflags` `pthread-config --libs`"
;;
*)
AC_MSG_CHECKING([for the pthreads library -l$ax_pthread_try_flag])
PTHREAD_LIBS="-l$ax_pthread_try_flag"
;;
esac
ax_pthread_save_CFLAGS="$CFLAGS"
ax_pthread_save_LIBS="$LIBS"
CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
LIBS="$PTHREAD_LIBS $LIBS"
# Check for various functions. We must include pthread.h,
# since some functions may be macros. (On the Sequent, we
# need a special flag -Kthread to make this header compile.)
# We check for pthread_join because it is in -lpthread on IRIX
# while pthread_create is in libc. We check for pthread_attr_init
# due to DEC craziness with -lpthreads. We check for
# pthread_cleanup_push because it is one of the few pthread
# functions on Solaris that doesn't have a non-functional libc stub.
# We try pthread_create on general principles.
AC_LINK_IFELSE([AC_LANG_PROGRAM([#include <pthread.h>
# if $ax_pthread_check_cond
# error "$ax_pthread_check_macro must be defined"
# endif
static void routine(void *a) { a = 0; }
static void *start_routine(void *a) { return a; }],
[pthread_t th; pthread_attr_t attr;
pthread_create(&th, 0, start_routine, 0);
pthread_join(th, 0);
pthread_attr_init(&attr);
pthread_cleanup_push(routine, 0);
pthread_cleanup_pop(0) /* ; */])],
[ax_pthread_ok=yes],
[])
CFLAGS="$ax_pthread_save_CFLAGS"
LIBS="$ax_pthread_save_LIBS"
AC_MSG_RESULT([$ax_pthread_ok])
AS_IF([test "x$ax_pthread_ok" = "xyes"], [break])
PTHREAD_LIBS=""
PTHREAD_CFLAGS=""
done
fi
# Various other checks:
if test "x$ax_pthread_ok" = "xyes"; then
ax_pthread_save_CFLAGS="$CFLAGS"
ax_pthread_save_LIBS="$LIBS"
CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
LIBS="$PTHREAD_LIBS $LIBS"
# Detect AIX lossage: JOINABLE attribute is called UNDETACHED.
AC_CACHE_CHECK([for joinable pthread attribute],
[ax_cv_PTHREAD_JOINABLE_ATTR],
[ax_cv_PTHREAD_JOINABLE_ATTR=unknown
for ax_pthread_attr in PTHREAD_CREATE_JOINABLE PTHREAD_CREATE_UNDETACHED; do
AC_LINK_IFELSE([AC_LANG_PROGRAM([#include <pthread.h>],
[int attr = $ax_pthread_attr; return attr /* ; */])],
[ax_cv_PTHREAD_JOINABLE_ATTR=$ax_pthread_attr; break],
[])
done
])
AS_IF([test "x$ax_cv_PTHREAD_JOINABLE_ATTR" != "xunknown" && \
test "x$ax_cv_PTHREAD_JOINABLE_ATTR" != "xPTHREAD_CREATE_JOINABLE" && \
test "x$ax_pthread_joinable_attr_defined" != "xyes"],
[AC_DEFINE_UNQUOTED([PTHREAD_CREATE_JOINABLE],
[$ax_cv_PTHREAD_JOINABLE_ATTR],
[Define to necessary symbol if this constant
uses a non-standard name on your system.])
ax_pthread_joinable_attr_defined=yes
])
AC_CACHE_CHECK([whether more special flags are required for pthreads],
[ax_cv_PTHREAD_SPECIAL_FLAGS],
[ax_cv_PTHREAD_SPECIAL_FLAGS=no
case $host_os in
solaris*)
ax_cv_PTHREAD_SPECIAL_FLAGS="-D_POSIX_PTHREAD_SEMANTICS"
;;
esac
])
AS_IF([test "x$ax_cv_PTHREAD_SPECIAL_FLAGS" != "xno" && \
test "x$ax_pthread_special_flags_added" != "xyes"],
[PTHREAD_CFLAGS="$ax_cv_PTHREAD_SPECIAL_FLAGS $PTHREAD_CFLAGS"
ax_pthread_special_flags_added=yes])
AC_CACHE_CHECK([for PTHREAD_PRIO_INHERIT],
[ax_cv_PTHREAD_PRIO_INHERIT],
[AC_LINK_IFELSE([AC_LANG_PROGRAM([[#include <pthread.h>]],
[[int i = PTHREAD_PRIO_INHERIT;]])],
[ax_cv_PTHREAD_PRIO_INHERIT=yes],
[ax_cv_PTHREAD_PRIO_INHERIT=no])
])
AS_IF([test "x$ax_cv_PTHREAD_PRIO_INHERIT" = "xyes" && \
test "x$ax_pthread_prio_inherit_defined" != "xyes"],
[AC_DEFINE([HAVE_PTHREAD_PRIO_INHERIT], [1], [Have PTHREAD_PRIO_INHERIT.])
ax_pthread_prio_inherit_defined=yes
])
CFLAGS="$ax_pthread_save_CFLAGS"
LIBS="$ax_pthread_save_LIBS"
# More AIX lossage: compile with *_r variant
if test "x$GCC" != "xyes"; then
case $host_os in
aix*)
AS_CASE(["x/$CC"],
[x*/c89|x*/c89_128|x*/c99|x*/c99_128|x*/cc|x*/cc128|x*/xlc|x*/xlc_v6|x*/xlc128|x*/xlc128_v6],
[#handle absolute path differently from PATH based program lookup
AS_CASE(["x$CC"],
[x/*],
[AS_IF([AS_EXECUTABLE_P([${CC}_r])],[PTHREAD_CC="${CC}_r"])],
[AC_CHECK_PROGS([PTHREAD_CC],[${CC}_r],[$CC])])])
;;
esac
fi
fi
test -n "$PTHREAD_CC" || PTHREAD_CC="$CC"
AC_SUBST([PTHREAD_LIBS])
AC_SUBST([PTHREAD_CFLAGS])
AC_SUBST([PTHREAD_CC])
# Finally, execute ACTION-IF-FOUND/ACTION-IF-NOT-FOUND:
if test "x$ax_pthread_ok" = "xyes"; then
ifelse([$1],,[AC_DEFINE([HAVE_PTHREAD],[1],[Define if you have POSIX threads libraries and header files.])],[$1])
:
else
ax_pthread_ok=no
$2
fi
AC_LANG_POP
])dnl AX_PTHREAD
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