New upstream version 1.10

[debian/gzip] / m4 / threadlib.m4

diff --git a/m4/threadlib.m4 b/m4/threadlib.m4
index 1f7b1341c1e3fc2360171bdb4a1cf4fb433299a7..ed6ebd51175f3a9d4b0f1277831364311f22edd1 100644 (file)
--- a/m4/threadlib.m4
+++ b/m4/threadlib.m4
@@ -1,4 +1,4 @@
-# threadlib.m4 serial 13
+# threadlib.m4 serial 15
 dnl Copyright (C) 2005-2018 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -6,6 +6,8 @@ dnl with or without modifications, as long as this notice is preserved.
 
 dnl From Bruno Haible.
 
+AC_PREREQ([2.60])
+
 dnl gl_THREADLIB
 dnl ------------
 dnl Tests for a multithreading library to be used.
@@ -43,11 +45,7 @@ AC_DEFUN([gl_THREADLIB_EARLY_BODY],
 
   AC_REQUIRE([AC_CANONICAL_HOST])
   dnl _GNU_SOURCE is needed for pthread_rwlock_t on glibc systems.
-  dnl AC_USE_SYSTEM_EXTENSIONS was introduced in autoconf 2.60 and obsoletes
-  dnl AC_GNU_SOURCE.
-  m4_ifdef([AC_USE_SYSTEM_EXTENSIONS],
-    [AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])],
-    [AC_REQUIRE([AC_GNU_SOURCE])])
+  AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
   dnl Check for multithreading.
   m4_ifdef([gl_THREADLIB_DEFAULT_NO],
     [m4_divert_text([DEFAULTS], [gl_use_threads_default=no])],
@@ -153,6 +151,36 @@ int main ()
          *" -static "*) gl_cv_have_weak=no ;;
        esac
       ])
+    dnl Check whether the linker supports the --as-needed/--no-as-needed options.
+    dnl Assume GCC, so that we can use the -Wl option.
+    AC_CACHE_CHECK([whether the linker supports --as-needed],
+      [gl_cv_linker_have_as_needed],
+      [if test -n "$GCC"; then
+         gl_saved_ldflags="$LDFLAGS"
+         LDFLAGS="$gl_saved_ldflags -Wl,--as-needed -Wl,--no-as-needed"
+         AC_LINK_IFELSE([AC_LANG_PROGRAM()],
+           [gl_cv_linker_have_as_needed=yes],
+           [gl_cv_linker_have_as_needed=no])
+         LDFLAGS="$gl_saved_ldflags"
+       else
+         gl_cv_linker_have_as_needed=no
+       fi
+      ])
+    dnl Check whether the linker supports the --push-state/--pop-state options.
+    dnl Assume GCC, so that we can use the -Wl option.
+    AC_CACHE_CHECK([whether the linker supports --push-state],
+      [gl_cv_linker_have_push_state],
+      [if test -n "$GCC"; then
+         gl_saved_ldflags="$LDFLAGS"
+         LDFLAGS="$gl_saved_ldflags -Wl,--push-state -Wl,--pop-state"
+         AC_LINK_IFELSE([AC_LANG_PROGRAM()],
+           [gl_cv_linker_have_push_state=yes],
+           [gl_cv_linker_have_push_state=no])
+         LDFLAGS="$gl_saved_ldflags"
+       else
+         gl_cv_linker_have_push_state=no
+       fi
+      ])
     if test "$gl_use_threads" = yes || test "$gl_use_threads" = posix; then
       # On OSF/1, the compiler needs the flag -pthread or -D_REENTRANT so that
       # it groks <pthread.h>. It's added above, in gl_THREADLIB_EARLY_BODY.
@@ -231,6 +259,32 @@ int main ()
                 [Define if references to the POSIX multithreading library should be made weak.])
               LIBTHREAD=
               LTLIBTHREAD=
+              dnl On platforms where GCC enables --as-needed by default, attempt
+              dnl to make sure that LIBMULTITHREAD really links with -lpthread.
+              dnl Otherwise linking with LIBMULTITHREAD has no effect; then
+              dnl the weak symbols are not defined and thus evaluate to NULL.
+              case "$LIBMULTITHREAD" in
+                "") ;;
+                -pthread)
+                  if test $gl_cv_linker_have_as_needed = yes; then
+                    if test $gl_cv_linker_have_push_state = yes; then
+                      LIBMULTITHREAD="$LIBMULTITHREAD -Wl,--push-state -Wl,--no-as-needed -lpthread -Wl,--pop-state"
+                    else
+                      LIBMULTITHREAD="$LIBMULTITHREAD -Wl,--no-as-needed -lpthread"
+                    fi
+                  fi
+                  ;;
+                *)
+                  if test $gl_cv_linker_have_as_needed = yes; then
+                    if test $gl_cv_linker_have_push_state = yes; then
+                      LIBMULTITHREAD="-Wl,--push-state -Wl,--no-as-needed $LIBMULTITHREAD -Wl,--pop-state"
+                    else
+                      LIBMULTITHREAD="-Wl,--no-as-needed $LIBMULTITHREAD"
+                    fi
+                  fi
+                  ;;
+              esac
+              # TODO: May need to modify LTLIBMULTITHREAD similarly.
             fi
           fi
         fi
@@ -263,6 +317,18 @@ int main ()
               [Define if references to the old Solaris multithreading library should be made weak.])
             LIBTHREAD=
             LTLIBTHREAD=
+            dnl On platforms where GCC enables --as-needed by default, attempt
+            dnl to make sure that LIBMULTITHREAD really links with -lthread.
+            dnl Otherwise linking with LIBMULTITHREAD has no effect; then
+            dnl the weak symbols are not defined and thus evaluate to NULL.
+            if test $gl_cv_linker_have_as_needed = yes; then
+              if test $gl_cv_linker_have_push_state = yes; then
+                LIBMULTITHREAD="-Wl,--push-state -Wl,--no-as-needed $LIBMULTITHREAD -Wl,--pop-state"
+              else
+                LIBMULTITHREAD="-Wl,--no-as-needed $LIBMULTITHREAD"
+              fi
+            fi
+            # TODO: May need to modify LTLIBMULTITHREAD similarly.
           fi
         fi
       fi
@@ -291,6 +357,18 @@ int main ()
               [Define if references to the GNU Pth multithreading library should be made weak.])
             LIBTHREAD=
             LTLIBTHREAD=
+            dnl On platforms where GCC enables --as-needed by default, attempt
+            dnl to make sure that LIBMULTITHREAD really links with -lpth.
+            dnl Otherwise linking with LIBMULTITHREAD has no effect; then
+            dnl the weak symbols are not defined and thus evaluate to NULL.
+            if test $gl_cv_linker_have_as_needed = yes; then
+              if test $gl_cv_linker_have_push_state = yes; then
+                LIBMULTITHREAD="-Wl,--push-state -Wl,--no-as-needed $LIBMULTITHREAD -Wl,--pop-state"
+              else
+                LIBMULTITHREAD="-Wl,--no-as-needed $LIBMULTITHREAD"
+              fi
+            fi
+            # TODO: May need to modify LTLIBMULTITHREAD similarly.
           fi
         fi
       else