On 7/26/24 8:32 PM, Stanislav Fomichev wrote:
On 07/26, Jakub Kicinski wrote:
On Fri, 26 Jul 2024 17:45:06 -0700 Andrii Nakryiko wrote:
or we could
#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#endif
(though we have 61 places with that...) so as to not have to update
every target in Makefile.
AFAIU we have -D_GNU_SOURCE= twice _in the command line args_ :(
One is from the Makefile which now always adds it to CFLAGS,
the other is "built-in" in g++ for some weird reason.
FWIW I have added this patch to the netdev "hack queue" so no
preference any more where the patch lands :)
Yeah, it can't be fixed with an ifdef because the conflict happens a bit
earlier:
$ echo "int main(int argc, char *argv[]){return 0;}" > test.cpp
$ clang++ -Wall -Werror -D_GNU_SOURCE= test.cpp
In file included from <built-in>:454:
<command line>:1:9: error: '_GNU_SOURCE' macro redefined [-Werror,-Wmacro-redefined]
1 | #define _GNU_SOURCE
| ^
<built-in>:445:9: note: previous definition is here
445 | #define _GNU_SOURCE 1
| ^
The above _GNU_SOURCE definition is defined by clang itself in the very beginning
of compilation.
See https://github.com/llvm/llvm-project/blob/main/clang/lib/Basic/Targets/OSTargets.h
// Linux target
template <typename Target>
class LLVM_LIBRARY_VISIBILITY LinuxTargetInfo : public OSTargetInfo<Target> {
protected:
void getOSDefines(const LangOptions &Opts, const llvm::Triple &Triple,
MacroBuilder &Builder) const override {
// Linux defines; list based off of gcc output
DefineStd(Builder, "unix", Opts);
DefineStd(Builder, "linux", Opts);
if (Triple.isAndroid()) {
Builder.defineMacro("__ANDROID__", "1");
this->PlatformName = "android";
this->PlatformMinVersion = Triple.getEnvironmentVersion();
const unsigned Maj = this->PlatformMinVersion.getMajor();
if (Maj) {
Builder.defineMacro("__ANDROID_MIN_SDK_VERSION__", Twine(Maj));
// This historical but ambiguous name for the minSdkVersion macro. Keep
// defined for compatibility.
Builder.defineMacro("__ANDROID_API__", "__ANDROID_MIN_SDK_VERSION__");
}
} else {
Builder.defineMacro("__gnu_linux__");
}
if (Opts.POSIXThreads)
Builder.defineMacro("_REENTRANT");
if (Opts.CPlusPlus)
Builder.defineMacro("_GNU_SOURCE");
if (this->HasFloat128)
Builder.defineMacro("__FLOAT128__");
}
...
This caused a conflict with -D_GNU_SOURCE= and hence compilation failure.
1 error generated.
