#
# 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
# modified version of the Autoconf Macro, you may extend this special
# exception to the GPL to apply to your modified version as well.
-#serial 26
+#serial 27
AU_ALIAS([ACX_PTHREAD], [AX_PTHREAD])
AC_DEFUN([AX_PTHREAD], [
# (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"
# 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"
+ 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 -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 $CC is Clang],
])
ax_pthread_clang="$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
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"
+ *,*)
+ 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 "$PTHREAD_LIBS"])
;;
-*)
done
fi
+
+# Clang needs special handling, because older versions handle the -pthread
+# option in a rather... idiosyncratic way
+
+if test "x$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"
projects / lttng-tools.git / commitdiff
