What happens if the compiler doesn't support the -nostdlib flag? On Mon, Dec 20, 2010 at 12:16 AM, <liujisi@google.com> wrote: > Reviewers: kenton, > > > > Please review this at http://codereview.appspot.com/3772042/ > > Affected files: > M m4/acx_pthread.m4 > > > Index: m4/acx_pthread.m4 > diff --git a/m4/acx_pthread.m4 b/m4/acx_pthread.m4 > index > cb1a4bbe4d00d95e4658c347bad129700bdebbbb..81a1f667671cec9748bbe8a0a89bf85dd19ff49a > 100644 > --- a/m4/acx_pthread.m4 > +++ b/m4/acx_pthread.m4 > @@ -342,6 +342,40 @@ if test "x$acx_pthread_ok" = xyes; then > acx_pthread_ok=no > fi > > + AC_MSG_CHECKING([whether what we have so far is sufficient with > -nostdlib]) > + CFLAGS="-nostdlib $CFLAGS" > + # we need c with nostdlib > + LIBS="$LIBS -lc" > + AC_TRY_LINK([#include <pthread.h>], > + [pthread_t th; pthread_join(th, 0); > + pthread_attr_init(0); pthread_cleanup_push(0, 0); > + pthread_create(0,0,0,0); pthread_cleanup_pop(0); ], > + [done=yes],[done=no]) > + > + if test "x$done" = xyes; then > + AC_MSG_RESULT([yes]) > + else > + AC_MSG_RESULT([no]) > + fi > + > + if test x"$done" = xno; then > + AC_MSG_CHECKING([whether -lpthread saves the day]) > + LIBS="-lpthread $LIBS" > + AC_TRY_LINK([#include <pthread.h>], > + [pthread_t th; pthread_join(th, 0); > + pthread_attr_init(0); pthread_cleanup_push(0, 0); > + pthread_create(0,0,0,0); pthread_cleanup_pop(0); ], > + [done=yes],[done=no]) > + > + if test "x$done" = xyes; then > + AC_MSG_RESULT([yes]) > + PTHREAD_LIBS="$PTHREAD_LIBS -lpthread" > + else > + AC_MSG_RESULT([no]) > + AC_MSG_WARN([Impossible to determine how to use pthreads with > shared libraries and -nostdlib]) > + fi > + fi > + > CFLAGS="$save_CFLAGS" > LIBS="$save_LIBS" > CC="$save_CC" > > >
From the code, it seems the 2 tests will both fail, and no flag will be added. Should be a no-op for compiler that doesn't support the -nostdlib flag. On 2010/12/20 18:16:09, kenton wrote: > What happens if the compiler doesn't support the -nostdlib flag? > > On Mon, Dec 20, 2010 at 12:16 AM, <mailto:liujisi@google.com> wrote: > > > Reviewers: kenton, > > > > > > > > Please review this at http://codereview.appspot.com/3772042/ > > > > Affected files: > > M m4/acx_pthread.m4 > > > > > > Index: m4/acx_pthread.m4 > > diff --git a/m4/acx_pthread.m4 b/m4/acx_pthread.m4 > > index > > > cb1a4bbe4d00d95e4658c347bad129700bdebbbb..81a1f667671cec9748bbe8a0a89bf85dd19ff49a > > 100644 > > --- a/m4/acx_pthread.m4 > > +++ b/m4/acx_pthread.m4 > > @@ -342,6 +342,40 @@ if test "x$acx_pthread_ok" = xyes; then > > acx_pthread_ok=no > > fi > > > > + AC_MSG_CHECKING([whether what we have so far is sufficient with > > -nostdlib]) > > + CFLAGS="-nostdlib $CFLAGS" > > + # we need c with nostdlib > > + LIBS="$LIBS -lc" > > + AC_TRY_LINK([#include <pthread.h>], > > + [pthread_t th; pthread_join(th, 0); > > + pthread_attr_init(0); pthread_cleanup_push(0, 0); > > + pthread_create(0,0,0,0); pthread_cleanup_pop(0); ], > > + [done=yes],[done=no]) > > + > > + if test "x$done" = xyes; then > > + AC_MSG_RESULT([yes]) > > + else > > + AC_MSG_RESULT([no]) > > + fi > > + > > + if test x"$done" = xno; then > > + AC_MSG_CHECKING([whether -lpthread saves the day]) > > + LIBS="-lpthread $LIBS" > > + AC_TRY_LINK([#include <pthread.h>], > > + [pthread_t th; pthread_join(th, 0); > > + pthread_attr_init(0); pthread_cleanup_push(0, 0); > > + pthread_create(0,0,0,0); pthread_cleanup_pop(0); ], > > + [done=yes],[done=no]) > > + > > + if test "x$done" = xyes; then > > + AC_MSG_RESULT([yes]) > > + PTHREAD_LIBS="$PTHREAD_LIBS -lpthread" > > + else > > + AC_MSG_RESULT([no]) > > + AC_MSG_WARN([Impossible to determine how to use pthreads with > > shared libraries and -nostdlib]) > > + fi > > + fi > > + > > CFLAGS="$save_CFLAGS" > > LIBS="$save_LIBS" > > CC="$save_CC" > > > > > >
