Description
- Version: 12.12.0, 13.0.1
- Platform: macOS 10.13
- Subsystem:
node.gyp uses this code to decide whether to add the -latomic flag:
['OS in ("linux", "mac") and llvm_version != "0.0"', {
'libraries': ['-latomic'],
}],
This is exactly wrong. You want to add -latomic when not using llvm/clang. llvm_version is supposed to be 0.0 when not using llvm/clang. Therefore what I think you meant to write was 'OS in ("linux", "mac") and llvm_version == "0.0".
However, in fact, llvm_version ended up being 0.0 even when using llvm/clang on recent macOS versions because you're setting llvm_version wrong, or rather, it's wrong to assume that you can get the llvm version. It's set this way in configure.py:
o['variables']['llvm_version'] = get_llvm_version(CC) if is_clang else '0.0'
def get_llvm_version(cc):
return get_version_helper(
cc, r"(^(?:FreeBSD )?clang version|based on LLVM) ([0-9]+\.[0-9]+)")
This will only work with open-source versions of clang, and versions of Apple's Xcode clang prior to Xcode 7. As of Xcode 7, Apple no longer advertises its compiler as being "based on" a particular open source llvm version; Apple's llvm/clang has diverged too much from open source llvm/clang for any such association to be meaningful.
The consequence of the combination of these two errors is that it correctly omits -latomic with Xcode 7 and later, but incorrectly adds -latomic with any open source clang version and probably also with Xcode 6 and earlier.
You can try to get the clang version using the __clang_major__, __clang_minor__ and __clang_patchlevel__ preprocessor defines, which you do in try_check_compiler in configure.py, and you make decisions based on that number elsewhere, but note that Apple's clang uses a different version numbering scheme than open source clang. If there's a particular clang feature you need that you can't check for using the feature-checking macros, you can check if __apple_build_version__ is defined and if so you can compare that number with a known-good Apple build version; if it's not defined, you can compare __clang_major__.__clang_minor__.__clang_patchlevel__ with a known-good open source clang version.
For this situation, where you merely want to add -latomic when not using clang, it seems like you just need a variable based on the __clang__ preprocessor define that indicates whether you're using clang. It doesn't matter here what the specific llvm version is; it just matters whether or not clang is being used.