diff options
Diffstat (limited to '')
| -rw-r--r-- | m4/ax_pthread.m4 | 219 |
1 files changed, 117 insertions, 102 deletions
diff --git a/m4/ax_pthread.m4 b/m4/ax_pthread.m4 index 0300e4ed..1598d077 100644 --- a/m4/ax_pthread.m4 +++ b/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 @@ -82,7 +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. -#serial 26 +#serial 27 AU_ALIAS([ACX_PTHREAD], [AX_PTHREAD]) AC_DEFUN([AX_PTHREAD], [ @@ -123,10 +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" @@ -194,36 +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,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], @@ -242,83 +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 @@ -328,10 +269,10 @@ 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"]) ;; -*) @@ -399,6 +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" |