Why does Clang Make This Warning?

[SsageParuders]

I use mold for my project with clang.
But clang-15 make a warning like this:

clang-15: warning: argument unused during compilation: '-fuse-ld=mold' [-Wunused-command-line-argument]

And this is the result of readelf -p comment:

String dump of section '.comment':
  [     0]  clang version 15.0.6
  [    15]  mold 1.8.0 (a49a201695edd294ed4d97231c9dc5a994275dd2; compatible with GNU ld)
  [    63]  GCC: (Debian 12.2.0-9) 12.2.0

It looks like I had succeed to use mold.Should I ignore this warning?

---

Btw, I use clang for my project, but why the section of .comment had the info about GCC?

Thinks a lot ~

[rui314]

I think you added -fuse-ld=mold not only to the last clang invocation to create your executable but to every invocation of clang. When you are creating .o files, you don't need to add -fuse-ld=mold.

[SsageParuders]

You are right.
With target_link_options instead of set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fuse-ld=mold")

target_link_options(${PROJECT_NAME} PRIVATE
       -fuse-ld=mold
)

The warning losts, and the section of .comment had info about mold.
Thinks a lot.

[ZhongRuoyu]

Btw, I use clang for my project, but why the section of .comment had the info about GCC?

That may come from any library / object file that you link against. Like this one from GCC:

$ readelf -p .comment `gcc -print-file-name=crtendS.o`

String dump of section '.comment':
  [     1]  GCC: (Ubuntu 11.3.0-1ubuntu1~22.04) 11.3.0

[SsageParuders]

Yes, I think maybe I used libstdc++ from GCC.