fix linker args for lld-link + clang-cl + flang

[lucascolley]

Closes scipy/scipy#24925 (in combination with conda-forge/flang-activation-feedstock#51).

I have been unable to find a way to craft LDFLAGS such that both clang-cl and flang ingest them without warnings when using lld-link. This PR aims to fix that by stripping -Wl, when the ninja backend grabs LINK_ARGS.

[lucascolley]

This fix is for the following rule:

rule c_LINKER
 command = "lld-link" $ARGS /MACHINE:x64 /OUT:$out $in $LINK_ARGS
 description = Linking target $out

On this PR:

build scipy/_cyutility.cp314-win_amd64.pyd | scipy/_cyutility.cp314-win_amd64.pdb: c_LINKER scipy/_cyutility.cp314-win_amd64.pyd.p/meson-generated_..__cyutility.c.obj | C$:/Users/lucas/ghq/github.com/scipy/scipy/.pixi/envs/build/libs/python314.lib
 LINK_ARGS = "/nologo" "/DEBUG" "/PDB:scipy\_cyutility.cp314-win_amd64.pdb" "/DLL" "/IMPLIB:scipy\_cyutility.cp314-win_amd64.lib" "/DEFAULTLIB:C:/Users/lucas/ghq/github.com/scipy/scipy/.pixi/envs/build/lib/clang/21/lib/windows/clang_rt.builtins-x86_64.lib" "C:\Users\lucas\ghq\github.com\scipy\scipy\.pixi\envs\build\libs\python314.lib" "kernel32.lib" "user32.lib" "gdi32.lib" "winspool.lib" "shell32.lib" "ole32.lib" "oleaut32.lib" "uuid.lib" "comdlg32.lib" "advapi32.lib"

On the latest release:

[76/1160] Linking target scipy/_cyutility.cp314-win_amd64.pyd
lld-link: warning: ignoring unknown argument '-Wl,/DEFAULTLIB:C:/Users/lucas/ghq/github.com/scipy/scipy/.pixi/envs/build/lib/clang/21/lib/windows/clang_rt.builtins-x86_64.lib'

build scipy/_cyutility.cp314-win_amd64.pyd | scipy/_cyutility.cp314-win_amd64.pdb: c_LINKER scipy/_cyutility.cp314-win_amd64.pyd.p/meson-generated_..__cyutility.c.obj | C$:/Users/lucas/ghq/github.com/scipy/scipy/.pixi/envs/build/libs/python314.lib
 LINK_ARGS = "/nologo" "/DEBUG" "/PDB:scipy\_cyutility.cp314-win_amd64.pdb" "/DLL" "/IMPLIB:scipy\_cyutility.cp314-win_amd64.lib" "-Wl,/DEFAULTLIB:C:/Users/lucas/ghq/github.com/scipy/scipy/.pixi/envs/build/lib/clang/21/lib/windows/clang_rt.builtins-x86_64.lib" "C:\Users\lucas\ghq\github.com\scipy\scipy\.pixi\envs\build\libs\python314.lib" "kernel32.lib" "user32.lib" "gdi32.lib" "winspool.lib" "shell32.lib" "ole32.lib" "oleaut32.lib" "uuid.lib" "comdlg32.lib" "advapi32.lib"

[lucascolley]

this is called at

meson/mesonbuild/backend/ninjabackend.py

Line 3793 in 2ab0228

commands += linker.get_build_link_args(target, self.build)

where the linker is (bare) lld-link when using it with clang-cl. Hence, we want the same stripping of -Wl, as occurs at

meson/mesonbuild/compilers/mixins/clike.py

Line 404 in 2ab0228

largs += [l for l in self.linker_to_compiler_args(la) if l != '/link']

in build_wrapper_args.

[lucascolley]

cc @bonzini I see you have worked on this file recently :)