Compiler detection is incorrect for native LLVM/Clang install on Windows

[MarkIngramUK]

ClangCompiler.get_soname_args assumes that Clang on Windows is running under MINGW. It then tries to generate -Wl,-soname options, which are incompatible with Clang 5.0.0.0 running natively on Windows.

CompilerArgs.to_native adds groups via -Wl,--start-group and -Wl,--end-group (as get_compiler_uses_gnuld returns true for Clang on Windows).

CCompiler.gen_import_library_args adds the -Wl,--out-implib option.

CCompiler.build_rpath_args adds the -Wl,-rpath option.

Related options -Wl,--as-needed and -Wl,--no-undefined aren't supported either, but they can be disabled via the b_asneeded and b_lundef flags, respectively.

[jibsen]

Native Clang on Windows can target both MSVC and mingw-w64 (I think they started out targeting MinGW, then added support for MSVC, and now MSVC is the default). Clang also supplies clang-cl, a cli that is compatible with MSVC cl.exe.

I've had some issues getting both options to work with CMake on AppVeyor (see for instance the squash AppVeyor script).

So I would love if meson were able to support both.

[xgalaxy]

Yes. Support for this would be great. Preferably with an option to choose either the GNU compatible (clang/clang++) or the msvc adapter (clang-cl).

[XVilka]

Ping?

[nirbheek]

Ping?

That only really works for pull requests, not issues. See also, "help wanted" label. ;)

We'd be happy to review a PR that fixes this and adds a test for it so we can properly support GNU clang (easy) and clang-cl (harder).

[barcharcraz]

fwiw, on windows it looks like both "clang" and "clang++" always compile using the msvc abi, the difference is in how they parse arguments and how good they are at figuring out how to link the C library.

You can see this by taking the following program

namespace test {
    void testfunction(int t) {

    }
}
int main(int argc, char** argv) {
    test::testfunction(4);
}

and compiling it with clang++ -c test.cpp on windows. then looking at test.o in dumpbin or similar, if you see ?testfunction@test@@YAXH@Z then clang is compiling with MSVC ABI

if you compile with clang++ -c -target x86_64-pc-windows-gnu test.cpp you should instead see _ZN4test12testfunctionEi

[barcharcraz]

note that it's likely that if you configure/build clang with gcc on windows or with gcc on unix targeting windows then you'll get a clang.exe that defaults to x86_64-pc-windows-gnu!

[barcharcraz]

AND if you have visual studio installed you may have a version of clang that's neither of these and that is the clang parser with C2 (microsoft's backend) output!!!! For all intents this should be similar to clang with x86_64-pc-windows-msvc

[dcbaker]

@jon-turney, is this closable now?

[jon-turney]

Not yet fixed. Possibly a duplicate of #4232, though.