[lld][macho] Add more skip platform check for libSystem re-exports

[bc-lee]

Summary

Xcode 13 comes with a mismatched platform in libcompiler_rt.dylib,
so this creates a linker error on mac catalyst.
Fix it by adding it to the skip list.

[int3]

Hmm, I would've loved to cross-check it with the latest ld64 code, but the source for version 711 hasn't dropped yet. I'll take your word for it :)

[bc-lee]

From what I understand, https://reviews.llvm.org/D100913 ( BZ https://llvm.org/bz49799 GH https://github.com/llvm/llvm-project/issues/49143 ) is for iphonesimulator cases. ld64 is also allowlisting those libraries.

This patch is for the catalyst case, where ld64 doesn't have a separate whitelist, but instead fully allows catalyst binary linking while linking with MacOS dynamic libraries.

The ld64 code related to this is https://github.com/apple-opensource/ld64/blob/e28c028b20af187a16a7161d89e91868a450cadc/src/ld/PlatformSupport.cpp#L177

Maybe we could also allow catalyst binary linking with the all MacOS dynamic libraries, but I don't think this is the best solution.

And I don't have a write access for LLVM, can you commit my changes on behalf of it?

[MaskRay]

lld/MachO/InputFiles.cpp

1274

const at a namespace scope is automatically internal linkage (unless some edge-case conditions) so static can be omitted.

[bc-lee]

lld/MachO/InputFiles.cpp

1274

Thanks!

[bc-lee]

Hi, int3. Can you commit my changes on behalf of it? I don't have a write access for LLVM.

[int3]

Yeah I can commit it. What name and email do you want it committed under?

[bc-lee]

In D117925#3297558, @int3 wrote:

Yeah I can commit it. What name and email do you want it committed under?

Byoungchan Lee <[e-mail]>. Thank you!

[thakis]

Should we revert this? Enough stuff is mismatched that ld64 (and, after D124336, ld64.lld) ignore platform mismatches when targeting catalyst for implicit reexports. libcompiler_rt.dylib is an implicit reexport of libSystem, so after D124336 this change here shouldn't have any effect.

[bc-lee]

@thakis It's okay to revert this. This patch was just a workaround. It's also a good idea to leave constexpr as it is.

[thakis]

Great, I made D124354 for that. Please stamp :)

lld/MachO/InputFiles.cpp

if (config->namespaceKind == NamespaceKind::flat &&
         error(Twine("unable to locate library '") + dylibPath +
               "' loaded from '" + toString(this) + "' for -flat_namespace");
     }
   }
 }
 
 // Some versions of XCode ship with .tbd files that don't have the right
 // platform settings.
-static constexpr std::array<StringRef, 3> skipPlatformChecks{
+static constexpr std::array<StringRef, 4> skipPlatformChecks{
     "/usr/lib/system/libsystem_kernel.dylib",
     "/usr/lib/system/libsystem_platform.dylib",
-    "/usr/lib/system/libsystem_pthread.dylib"};
+    "/usr/lib/system/libsystem_pthread.dylib",
+    "/usr/lib/system/libcompiler_rt.dylib"};
 
 DylibFile::DylibFile(const InterfaceFile &interface, DylibFile *umbrella,
                      bool isBundleLoader)
     : InputFile(DylibKind, interface), refState(RefState::Unreferenced),
       isBundleLoader(isBundleLoader) {
   // FIXME: Add test for the missing TBD code path.
 
   if (umbrella == nullptr)