[PATCH] D71795: [ELF] Delete an unused special rule from isStaticLinkTimeConstant. NFC

[Peter Collingbourne via Phabricator via llvm-commits]

pcc added a comment.

> Weak undefined symbols are preemptible after D71794 <https://reviews.llvm.org/D71794>.

What about hidden weak undefined symbols? We now reject the following input:

  cat foo.cpp
  __attribute__((weak, visibility("hidden"))) void f();
  
  void g() {
    if (f) f();
  }
  $ clang -shared -fuse-ld=lld foo.cpp
  ld.lld: error: relocation R_X86_64_PLT32 cannot refer to absolute symbol: f()
  >>> defined in /tmp/foo-014d89.o
  >>> referenced by foo.cpp
  >>>               /tmp/foo-014d89.o:(g())
  clang: error: linker command failed with exit code 1 (use -v to see invocation)

This seems like a reasonable thing to want to do. I actually hit this problem in a slightly different case (`--exclude-libs` demoted the weak undef to hidden) which we could fix like so:

  diff --git a/lld/ELF/Driver.cpp b/lld/ELF/Driver.cpp
  index 19598f52cd4..54c033303f6 100644
  --- a/lld/ELF/Driver.cpp
  +++ b/lld/ELF/Driver.cpp
  @@ -1374,7 +1374,7 @@ static void excludeLibs(opt::InputArgList &args) {
       if (!file->archiveName.empty())
         if (all || libs.count(path::filename(file->archiveName)))
           for (Symbol *sym : file->getSymbols())
  -          if (!sym->isLocal() && sym->file == file)
  +          if (!sym->isUndefined() && !sym->isLocal() && sym->file == file)
               sym->versionId = VER_NDX_LOCAL;
     };
   

But I'm somewhat more concerned about the explicit hidden case.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D71795/new/

https://reviews.llvm.org/D71795