SonOfFlyingPig SonOfFlyingPig - 1 month ago 21
C++ Question

Why is clang++ linking to gcc?

I have a simple "Hello, world" style program that I'm compiling with clang++ on FreeBSD:

#include <cstdlib>
#include <iostream>

using namespace std;

int main(int argc, char* argv[]) {
cout << "Oh, hello" << endl;
return EXIT_SUCCESS;
}


Which I compile with clang++ and its libc++:

$ clang++ -stdlib=libc++ -v ohhello.cpp
FreeBSD clang version 3.8.0 (tags/RELEASE_380/final 262564) (based on LLVM 3.8.0)
Target: x86_64-unknown-freebsd11.0
Thread model: posix
InstalledDir: /usr/bin
"/usr/bin/clang++" -cc1 -triple x86_64-unknown-freebsd11.0 -emit-obj -mrelax-all -disable-free -disable-llvm-verifier -main-file-name ohhello.cpp -mrelocation-model static -mthread-model posix -mdisable-fp-elim -masm-verbose -mconstructor-aliases -munwind-tables -target-cpu x86-64 -v -dwarf-column-info -debugger-tuning=gdb -resource-dir /usr/bin/../lib/clang/3.8.0 -internal-isystem /usr/include/c++/v1 -fdeprecated-macro -fdebug-compilation-dir /usr/home/mike/projects/ohhello -ferror-limit 19 -fmessage-length 80 -fobjc-runtime=gnustep -fcxx-exceptions -fexceptions -fdiagnostics-show-option -fcolor-diagnostics -o /tmp/ohhello-050a75.o -x c++ ohhello.cpp
clang -cc1 version 3.8.0 based upon LLVM 3.8.0 default target x86_64-unknown-freebsd11.0
#include "..." search starts here:
#include <...> search starts here:
/usr/include/c++/v1
/usr/bin/../lib/clang/3.8.0/include
/usr/include
End of search list.
"/usr/bin/ld" --eh-frame-hdr -dynamic-linker /libexec/ld-elf.so.1 --hash-style=both --enable-new-dtags -o a.out /usr/lib/crt1.o /usr/lib/crti.o /usr/lib/crtbegin.o -L/usr/lib /tmp/ohhello-050a75.o -lc++ -lm -lgcc --as-needed -lgcc_s --no-as-needed -lc -lgcc --as-needed -lgcc_s --no-as-needed /usr/lib/crtend.o /usr/lib/crtn.o


In the linker step I see "-lgcc" and "-lgcc_s" multiple times. Why is clang++ trying to link against gcc if it's using libc++ (not libstdc++)?

Thanks

Answer

libgcc is not gcc. It is a small, non compiler-specific C library. It is provided by gcc, but it is not specific to the compiler.