Ralf Wildenhues wrote:
> > The reason is that the flag -Wl,-z,ignore is accepted by the C compiler
> > (cc), but
> > leads to an error with the C++ compiler (CC).
>
> Sun CC needs '-Qoption ld ' as prefix to linker flags (mind the trailing
> space) rather than '-Wl,'.
Thanks for this info.
So, a possible first step is to update the comments in lib-ignore.m4, like in
the proposed patch below.
But this does not fix the problem with coreutils, as long as it has some source
files in C++. I would therefore find it useful to change lib-ignore.m4 so that
it sets an AC_SUBSTed variable IGNORE_UNUSED_LIBS, and coreutils/Makefile.am
can then do
AM_LDFLAGS = $(IGNORE_UNUSED_LIBS)
What do you think?
Bruno
2010-03-14 Bruno Haible <br...@clisp.org>
* m4/lib-ignore.m4 (gl_IGNORE_UNUSED_LIBRARIES): Add comments.
--- m4/lib-ignore.m4.orig Sun Mar 14 17:06:37 2010
+++ m4/lib-ignore.m4 Sun Mar 14 16:20:31 2010
@@ -9,6 +9,30 @@
AC_DEFUN([gl_IGNORE_UNUSED_LIBRARIES],
[
+ # Determines the option to be passed to the C compiler, so that it
+ # omits unused libraries.
+ # Example (on Solaris):
+ # $ cc foo.c -lnsl; ldd ./a.out
+ # libnsl.so.1 => /lib/libnsl.so.1
+ # libc.so.1 => /lib/libc.so.1
+ # libmp.so.2 => /lib/libmp.so.2
+ # libmd.so.1 => /lib/libmd.so.1
+ # libscf.so.1 => /lib/libscf.so.1
+ # libdoor.so.1 => /lib/libdoor.so.1
+ # libuutil.so.1 => /lib/libuutil.so.1
+ # libgen.so.1 => /lib/libgen.so.1
+ # libm.so.2 => /lib/libm.so.2
+ # $ cc foo.c -lnsl -Wl,-z,ignore; ldd ./a.out
+ # libc.so.1 => /lib/libc.so.1
+ # libm.so.2 => /lib/libm.so.2
+
+ # Note that the options works only for the C compiler, not for the C++
+ # compiler:
+ # - Sun C likes '-Wl,-z,ignore'. '-Qoption ld -z,ignore' is not accepted.
+ # '-z ignore' is accepted but has no effect.
+ # - Sun C++ likes '-Qoption ld -z,ignore'. '-Wl,-z,ignore' is not accepted.
+ # '-z ignore' is accepted but has no effect.
+
AC_CACHE_CHECK([for flag to ignore unused libraries],
[gl_cv_ignore_unused_libraries],
[gl_cv_ignore_unused_libraries=none
@@ -21,7 +45,7 @@
# to forestall problems with linkers that have -z, -i, -g, -n, etc. flags.
# GCC + binutils likes '-Wl,--as-needed'.
# GCC + Solaris ld likes '-Wl,-z,ignore'.
- # Sun C likes '-z ignore'.
+ # Sun C likes '-Wl,-z,ignore'. '-z ignore' is accepted but has no effect.
# Don't try bare '--as-needed'; nothing likes it and the HP-UX 11.11
# native cc issues annoying warnings and then ignores it,
# which would cause us to incorrectly conclude that it worked.
@@ -38,6 +62,8 @@
done
LIBS=$gl_saved_libs])
+ # Note that adding this options to LDFLAGS unconditionally does not work in
+ # projects that are partially in C++.
test "$gl_cv_ignore_unused_libraries" != none &&
LDFLAGS="$LDFLAGS $gl_cv_ignore_unused_libraries"
])
