<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/63963>63963</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            -Wconstant-logical-operand should not fire for expressions involving macros
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            quality-of-implementation,
            clang:diagnostics
      </td>
    </tr>

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

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

<pre>
    Clang currently issues this diagnostic when the constant in question is a macro, as in ([live example](https://godbolt.org/z/M13cx7hPY)):
```
#ifndef X
#define X 0
#endif

#ifndef Y
#define Y 2
#endif

bool foo() {
  return X || Y;
}
```
I think any use of a macro should suppress the diagnostic on the assumption that the macro value is constant for one configuration but may not be constant in all configurations. However, I can also see why we might want to still diagnose macro uses, such as cases like:
```
void func(int error) {
  if (ENOMEM || error == 12)
    ...
}
```
where the user could have forgotten to add `error ==` to the expression. So it might be that we want to split this off into separate diagnostic groups.

Relates to discussion in https://reviews.llvm.org/D142609
</pre>
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