[PATCH] meson: Work around too strict lld
With its version 16.0, the LLVM's linker turned on --no-undefined-version by default [1]. This breaks how we detect --version-script= detection, because at the compile time there's no library built yet that we can use to make --version-script= happy. To cancel their choice of defaults, pass --undefined-version. Unfortunately, this flag is LLVM's invention and is not supported by GNU's ld. This all could be avoided if meson provided proper detection of supported linker arguments, but we are far away from that [2]. 1: https://reviews.llvm.org/D135402 2: https://github.com/mesonbuild/meson/issues/3047 Resolves: https://bugs.gentoo.org/902211 Signed-off-by: Michal Privoznik <mprivozn@redhat.com> --- Compile Libvirt? Absolutely Not Gonna. The choice of defaults for LLVM and related subprojects continues to surprise me. meson.build | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/meson.build b/meson.build index c35823a79a..df0d75449a 100644 --- a/meson.build +++ b/meson.build @@ -535,9 +535,13 @@ elif host_machine.system() == 'darwin' version_script_flags = '' else test_file = '@0@/src/libvirt_qemu.syms'.format(meson.project_source_root()) + version_script_flags = '' if cc.has_link_argument('-Wl,--version-script=@0@'.format(test_file)) version_script_flags = '-Wl,--version-script=' - else + elif cc.has_multi_link_arguments('-Wl,--undefined-version', '-Wl,--version-script=@0@'.format(test_file)) + version_script_flags = '-Wl,--version-script=' + endif + if version_script_flags == '' error('No supported version script link argument found.') endif endif -- 2.39.2
On Mon, Mar 20, 2023 at 02:54:11PM +0100, Michal Privoznik wrote:
With its version 16.0, the LLVM's linker turned on --no-undefined-version by default [1]. This breaks how we detect --version-script= detection, because at the compile time there's no library built yet that we can use to make --version-script= happy. To cancel their choice of defaults, pass --undefined-version. Unfortunately, this flag is LLVM's invention and is not supported by GNU's ld.
This all could be avoided if meson provided proper detection of supported linker arguments, but we are far away from that [2].
1: https://reviews.llvm.org/D135402 2: https://github.com/mesonbuild/meson/issues/3047
Resolves: https://bugs.gentoo.org/902211 Signed-off-by: Michal Privoznik <mprivozn@redhat.com> ---
Compile Libvirt? Absolutely Not Gonna.
The choice of defaults for LLVM and related subprojects continues to surprise me.
meson.build | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/meson.build b/meson.build index c35823a79a..df0d75449a 100644 --- a/meson.build +++ b/meson.build @@ -535,9 +535,13 @@ elif host_machine.system() == 'darwin' version_script_flags = '' else test_file = '@0@/src/libvirt_qemu.syms'.format(meson.project_source_root()) + version_script_flags = '' if cc.has_link_argument('-Wl,--version-script=@0@'.format(test_file)) version_script_flags = '-Wl,--version-script=' - else + elif cc.has_multi_link_arguments('-Wl,--undefined-version', '-Wl,--version-script=@0@'.format(test_file)) + version_script_flags = '-Wl,--version-script=' + endif + if version_script_flags == '' error('No supported version script link argument found.') endif endif
Should we bother probing for the argument at all ? if host_machine.system() == 'windows' version_script_flags = '-Wl,' elif host_machine.system() == 'darwin' # macOS libraries don't support symbol versioning version_script_flags = '' else test_file = '@0@/src/libvirt_qemu.syms'.format(meson.project_source_root()) if cc.has_link_argument('-Wl,--version-script=@0@'.format(test_file)) version_script_flags = '-Wl,--version-script=' else error('No supported version script link argument found.') endif endif In terms of our platforms, the 'else' clause is only impacting Linux and FreeBSD. Don't both of those platforms support -Wl,--version-script= since they both use ELF ? With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
On 3/20/23 15:19, Daniel P. Berrangé wrote:
On Mon, Mar 20, 2023 at 02:54:11PM +0100, Michal Privoznik wrote:
With its version 16.0, the LLVM's linker turned on --no-undefined-version by default [1]. This breaks how we detect --version-script= detection, because at the compile time there's no library built yet that we can use to make --version-script= happy. To cancel their choice of defaults, pass --undefined-version. Unfortunately, this flag is LLVM's invention and is not supported by GNU's ld.
This all could be avoided if meson provided proper detection of supported linker arguments, but we are far away from that [2].
1: https://reviews.llvm.org/D135402 2: https://github.com/mesonbuild/meson/issues/3047
Resolves: https://bugs.gentoo.org/902211 Signed-off-by: Michal Privoznik <mprivozn@redhat.com> ---
Compile Libvirt? Absolutely Not Gonna.
The choice of defaults for LLVM and related subprojects continues to surprise me.
meson.build | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/meson.build b/meson.build index c35823a79a..df0d75449a 100644 --- a/meson.build +++ b/meson.build @@ -535,9 +535,13 @@ elif host_machine.system() == 'darwin' version_script_flags = '' else test_file = '@0@/src/libvirt_qemu.syms'.format(meson.project_source_root()) + version_script_flags = '' if cc.has_link_argument('-Wl,--version-script=@0@'.format(test_file)) version_script_flags = '-Wl,--version-script=' - else + elif cc.has_multi_link_arguments('-Wl,--undefined-version', '-Wl,--version-script=@0@'.format(test_file)) + version_script_flags = '-Wl,--version-script=' + endif + if version_script_flags == '' error('No supported version script link argument found.') endif endif
Should we bother probing for the argument at all ?
if host_machine.system() == 'windows' version_script_flags = '-Wl,' elif host_machine.system() == 'darwin' # macOS libraries don't support symbol versioning version_script_flags = '' else test_file = '@0@/src/libvirt_qemu.syms'.format(meson.project_source_root()) if cc.has_link_argument('-Wl,--version-script=@0@'.format(test_file)) version_script_flags = '-Wl,--version-script=' else error('No supported version script link argument found.') endif endif
In terms of our platforms, the 'else' clause is only impacting Linux and FreeBSD. Don't both of those platforms support -Wl,--version-script= since they both use ELF ?
Yeah, I think we can drop the check completely and went with what you suggests. V2 on its way. Michal
participants (3)
-
Daniel P. Berrangé -
Michal Privoznik -
Michal Prívozník