GHA: Integrate Alpine musl job in main workflow

[kinke]

Incl. prebuilt package etc.

[JohanEngelen]

cool that you are working on this!

[kinke]

Okay, should be ready now, after lots of trial & error runs, as usual for these CI MRs. I guess adding a musl AArch64 job as follow-up would be pretty trivial.

Some notes:

• Preliminary runs with Alpine v3.21 and LLVM 19 exhibited LTO problems IIRC. So sticking with v3.20 / LLVM 17 for now.
• I couldn't find an Alpine package with static LLD libs. So no LDC_WITH_LLD / -link-internally support.
• The bundled ldc-prof{data,gen} tools aren't linked with -static, so depend on musl .so. That would require more CMake fiddling.
• std.net.curl support depends on loading libcurl dynamically, so doesn't work (at runtime) with fully static executables. So bundled dub and reggae depend on musl .so as well (not linked with -Xcc=-static).
  • The bundled ldc-build-runtime tool is fully static, so won't be able to download the source zip automatically. Again, would require more CMake fiddling.

[JohanEngelen]

Very cool! Let's fix the static linking later.

[JohanEngelen]

nitpick, replace darwin with OSX because it is more common throughout the source code.

[kinke]

Yeah I know it's deprecated (unfortunately), but it's more convenient than the usual

ldc/runtime/druntime/src/core/demangle.d

Lines 15 to 22 in 9de21fd

	version (OSX)
	version = Darwin;
	else version (iOS)
	version = Darwin;
	else version (TVOS)
	version = Darwin;
	else version (WatchOS)
	version = Darwin;

which would be required for the other Apple platforms too. There are 3 existing version (darwin) usages for this shared druntime integration test, so I added the 4th one, out of laziness of course. ;)

[JohanEngelen]

perhaps it is as simple as -DCMAKE_EXE_LINKER_FLAGS="-static-libstdc++;-static" to get fully statically linked ldc_profgen (cpp-only executables) ? I'm OK to leave as is for now.

[kinke]

Yes that would include the 2 pure C++ LLVM tools, but unfortunately also the static Phobos test runner, where the std.net.curl unittests then fail...

[kinke]

And D_LINKER_ARGS apply to all D executables built via build_d_executable() (now for LDC_LINK_MANUALLY=OFF too, where it was previously ignored). And that unfortunately also includes the ldc-build-runtime tool. Edit: But no druntime/Phobos test runners, they are pure C executables (in CMake terms).

So I think we need a dedicated CMake option for fully-static linking (on Posix), adding -static for suited executables only (no ldc-build-runtime, but the PGO LLVM tools).

[kinke]

Okay I've pushed a commit to that effect, and now all but dub/reggae/ldc-build-runtime executables are fully static.

[kinke]

Btw, I was surprised that I could link & run a Phobos-hello-world on my Ubuntu 24 box - with the bundled compiler, druntime and Phobos targeting a musl triple (edit: and my system cc for linking targeting glibc). No idea if that's just lucky or whether musl is a strict compatible subset of glibc API-wise (edit: well, the libc API required from druntime and Phobos at least).