<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/64939>64939</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            clang: 'argument unused during compilation: '-rtlib=compiler-rt' warning when using -nostdlib
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            new issue
      </td>
    </tr>

    <tr>
      <th>Assignees</th>
      <td>
      </td>
    </tr>

    <tr>
      <th>Reporter</th>
      <td>
          nolange
      </td>
    </tr>
</table>

<pre>
    Hello,

I have a cmake project which includes some kinda plugins that need to be built with `-nostdlib`.
Using a toochain-file for clang which adds `-rtlib=compiler-rt` for linker steps will result in wrong warnings,
for the plugins as those 2 flags are then used together.

Small reproducer:

``` bash
echo "void foo() {}" > test.c
clang -c -o test.o test.c
clang -rtlib=compiler-rt -nostdlib --shared test.o
```

```
clang: warning: argument unused during compilation: '-rtlib=compiler-rt' [-Wunused-command-line-argument]
```

I believe this to be a bug, as

-   I want to use `-rtlib=compiler-rt` if an runtime is needed (defined in a toolchain file for the whole build),
    making this flag optional in regard to other options would be a compiler-specific mess.
- setting `-nostdlib++` and `-stdlib=libc++` is similar and doesnt result in a warning.

</pre>
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