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Merge pull request #406 from fplll/update_ax_pthread

Updated m4/ax_pthread.m4 to latest autoconf-archive version
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malb committed Feb 7, 2020
2 parents 1e5fa48 + a6c32b9 commit 727fb592c2dde4796e1cd52909b84b6a64170913
Showing with 119 additions and 105 deletions.
  1. +119 −105 m4/ax_pthread.m4
@@ -55,6 +55,7 @@
#
# Copyright (c) 2008 Steven G. Johnson <stevenj@alum.mit.edu>
# Copyright (c) 2011 Daniel Richard G. <skunk@iSKUNK.ORG>
# Copyright (c) 2019 Marc Stevens <marc.stevens@cwi.nl>
#
# 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
@@ -82,8 +83,7 @@
# modified version of the Autoconf Macro, you may extend this special
# exception to the GPL to apply to your modified version as well.

# modified based on version serial 26
## serial 26
#serial 27

AU_ALIAS([ACX_PTHREAD], [AX_PTHREAD])
AC_DEFUN([AX_PTHREAD], [
@@ -124,10 +124,12 @@ fi
# (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.
# Create a list of thread flags to try. Items with a "," contain both
# C compiler flags (before ",") and linker flags (after ","). Other items
# starting with a "-" are C compiler flags, and remaining 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"
@@ -195,36 +197,10 @@ case $host_os in
# 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,-lpthread pthread $ax_pthread_flags"
ax_pthread_flags="-mt,-lpthread 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,-lpthread -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],
@@ -243,83 +219,47 @@ AC_CACHE_CHECK([whether $CC is Clang],
])
ax_pthread_clang="$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
# GCC generally uses -pthread, or -pthreads on some platforms (e.g. SPARC)
if test "x$ax_pthread_clang" = "xyes"; then
# Note that for GCC and Clang -pthread generally implies -lpthread,
# except when -nostdlib is passed.
# This is problematic using libtool to build C++ shared libraries with pthread:
# [1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=25460
# [2] https://bugzilla.redhat.com/show_bug.cgi?id=661333
# [3] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=468555
# To solve this, first try -pthread together with -lpthread for GCC
# Clang takes -pthread; it has never supported any other flag
AS_IF([test "x$GCC" = "xyes"],
[ax_pthread_flags="-pthread,-lpthread -pthread -pthreads $ax_pthread_flags"])
# (Note 1: This will need to be revisited if a system that Clang
# supports has POSIX threads in a separate library. This tends not
# to be the way of modern systems, but it's conceivable.)
# Clang takes -pthread (never supported any other flag), but we'll try with -lpthread first
# (Note 2: On some systems, notably Darwin, -pthread is not needed
# to get POSIX threads support; the API is always present and
# active. We could reasonably leave PTHREAD_CFLAGS empty. But
# -pthread does define _REENTRANT, and while the Darwin headers
# ignore this macro, third-party headers might not.)
AS_IF([test "x$ax_pthread_clang" = "xyes"],
[ax_pthread_flags="-pthread,-lpthread -pthread"])
PTHREAD_CFLAGS="-pthread"
PTHREAD_LIBS=
ax_pthread_ok=yes
# 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
# 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.
case $host_os in
darwin* | hpux* | linux* | osf* | solaris*)
ax_pthread_check_macro="_REENTRANT"
;;
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="$ax_pthread_try"
])
aix*)
ax_pthread_check_macro="_THREAD_SAFE"
;;
case "$ax_cv_PTHREAD_CLANG_NO_WARN_FLAG" in
no | unknown) ;;
*) PTHREAD_CFLAGS="$ax_cv_PTHREAD_CLANG_NO_WARN_FLAG $PTHREAD_CFLAGS" ;;
esac
*)
ax_pthread_check_macro="--"
;;
esac
AS_IF([test "x$ax_pthread_check_macro" = "x--"],
[ax_pthread_check_cond=0],
[ax_pthread_check_cond="!defined($ax_pthread_check_macro)"])
fi # $ax_pthread_clang = yes
if test "x$ax_pthread_ok" = "xno"; then
for ax_pthread_try_flag in $ax_pthread_flags; do
@@ -329,17 +269,17 @@ for ax_pthread_try_flag in $ax_pthread_flags; do
AC_MSG_CHECKING([whether pthreads work without any flags])
;;
*,*)
PTHREAD_CFLAGS=`echo $ax_pthread_try_flag | sed "s/^\(.*\),\(.*\)$/\1/"`
PTHREAD_LIBS=`echo $ax_pthread_try_flag | sed "s/^\(.*\),\(.*\)$/\2/"`
AC_MSG_CHECKING([whether pthreads work with "$PTHREAD_CFLAGS" and "$PTHREAD_LIBS"])
;;
-*)
AC_MSG_CHECKING([whether pthreads work with $ax_pthread_try_flag])
PTHREAD_CFLAGS="$ax_pthread_try_flag"
;;
,*)
PTHREAD_CFLAGS=`echo $ax_pthread_try_flag | sed "s/^,\(.*\),\(.*\)$/\1/"`
PTHREAD_LIBS=`echo $ax_pthread_try_flag | sed "s/^,\(.*\),\(.*\)$/\2/"`
AC_MSG_CHECKING([whether pthreads work with CFLAGS="$PTHREAD_CFLAGS" LIBS="$PTHREAD_LIBS"])
;;
pthread-config)
AC_CHECK_PROG([ax_pthread_config], [pthread-config], [yes], [no])
AS_IF([test "x$ax_pthread_config" = "xno"], [continue])
@@ -400,6 +340,80 @@ for ax_pthread_try_flag in $ax_pthread_flags; do
done
fi
# Clang needs special handling, because older versions handle the -pthread
# option in a rather... idiosyncratic way
if test "x$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.)
# 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 # $ax_pthread_clang = yes
# Various other checks:
if test "x$ax_pthread_ok" = "xyes"; then
ax_pthread_save_CFLAGS="$CFLAGS"

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