[lld] ld64.lld does not respect allowable-client field in .tbds

[bdash]

Apple's linker rejects linking to libraries with allowable client lists:

$ cc -framework vecLib -o test test.m         
ld: cannot link directly with 'vecLib' because product being built is not an allowed client of it
clang: error: linker command failed with exit code 1 (use -v to see invocation)

After #97639, not only does ld64.lld not reject linking to vecLib.framework, it links to the library despite the binary not being an allowed client:

$ cc -framework vecLib -fuse-ld=lld -Bllvm-build/Release+Asserts/bin -o test test.m
$ nm -m test | grep vecLib                                                                                               
                 (undefined) external _vvdiv (from vecLib)
$ grep ' clients:' $(xcrun --show-sdk-path)/System/Library/Frameworks/Accelerate.framework/Versions/Current/Frameworks/vecLib.framework/vecLib.tbd
    clients:         [ Accelerate ]
    clients:         [ vecLib ]
    clients:         [ vecLib ]
    clients:         [ vecLib ]
    clients:         [ vecLib ]
    clients:         [ Sparse, vecLib ]

Generating binaries that don't respect the allowable client list means applications will break if / when Apple moves symbols between libraries.

test.m:

#include <stdio.h>
#include <vecLib/vForce.h>

int main(int argc, char**argv) {
    fprintf(stderr, "%p\n", &vvdiv);
    return 0;
}

Originally posted by @bdash in #97639 (comment)

[bdash]

My apologies, I was too hasty in blaming #97639. The problem appears to predate that change.

[carlocab]

I have a branch that kind of fixes this for .dylibs (ld64.lld also does not respect it when dylibs are linked with -allowable_client flags).

It still needs polishing and tests, and I don't think it works for .tbds yet (haven't tested). I can open a PR if desired (unless someone's already done the work on this).

I also haven't tested if it works for frameworks too, but frameworks are just dylibs with different names so I suspect it should work.

[carlocab]

I opened #114638 to respect dylibs linked with -allowable_client. It doesn't support the same property for .tbds yet.

It can be added to #114638 with

diff --git a/lld/MachO/InputFiles.cpp b/lld/MachO/InputFiles.cpp
index c715169927e7..bb922a05cd2b 100644
--- a/lld/MachO/InputFiles.cpp
+++ b/lld/MachO/InputFiles.cpp
@@ -1899,6 +1899,11 @@ DylibFile::DylibFile(const InterfaceFile &interface, DylibFile *umbrella,
   exportingFile = (canBeImplicitlyLinked && isImplicitlyLinked(installName))
                       ? this
                       : umbrella;
+
+  if (!canBeImplicitlyLinked)
+    for (const auto &allowableClient : interface.allowableClients())
+      allowableClients.push_back(*make<std::string>(allowableClient.getInstallName().str()));
+
   auto addSymbol = [&](const llvm::MachO::Symbol &symbol,
                        const Twine &name) -> void {
     StringRef savedName = saver().save(name);

but doing this strikes me as a bit inefficient (and possibly very unidiomatic--unsure, I don't really write C++), so I'm wondering if there's a better way.

[llvmbot]

@llvm/issue-subscribers-lld-macho

Author: Mark Rowe (bdash)

Apple's linker rejects linking to libraries with allowable client lists:

$ cc -framework vecLib -o test test.m         
ld: cannot link directly with 'vecLib' because product being built is not an allowed client of it
clang: error: linker command failed with exit code 1 (use -v to see invocation)

After #97639, not only does ld64.lld not reject linking to vecLib.framework, it links to the library despite the binary not being an allowed client:

$ cc -framework vecLib -fuse-ld=lld -Bllvm-build/Release+Asserts/bin -o test test.m
$ nm -m test | grep vecLib                                                                                               
                 (undefined) external _vvdiv (from vecLib)
$ grep ' clients:' $(xcrun --show-sdk-path)/System/Library/Frameworks/Accelerate.framework/Versions/Current/Frameworks/vecLib.framework/vecLib.tbd
    clients:         [ Accelerate ]
    clients:         [ vecLib ]
    clients:         [ vecLib ]
    clients:         [ vecLib ]
    clients:         [ vecLib ]
    clients:         [ Sparse, vecLib ]

Generating binaries that don't respect the allowable client list means applications will break if / when Apple moves symbols between libraries.

test.m:

#include <stdio.h>
#include <vecLib/vForce.h>

int main(int argc, char**argv) {
    fprintf(stderr, "%p\n", &vvdiv);
    return 0;
}

Originally posted by @bdash in #97639 (comment)