| Issue |
71397
|
| Summary |
`-Wimplicit-fallthrough` suggests to use a macro from a random third-party library instead of `[[fallthrough]]`
|
| Labels |
new issue
|
| Assignees |
|
| Reporter |
HolyBlackCat
|
Here's the code:
```cpp
#define FMT_FALLTHROUGH [[fallthrough]]
void a();
void b(int x)
{
switch (x)
{
case 1:
a();
case 2:
a();
}
}
```
When compiled with Clang 17 (or trunk), it says:
```none
<source>:11:7: warning: unannotated fall-through between switch labels [-Wimplicit-fallthrough]
11 | case 2:
| ^
<source>:11:7: note: insert 'FMT_FALLTHROUGH;' to silence this warning
11 | case 2:
| ^
| FMT_FALLTHROUGH;
<source>:11:7: note: insert 'break;' to avoid fall-through
11 | case 2:
| ^
| break;
```
Notice how it suggests using `FMT_FALLTHROUGH` instead of `[[fallthrough]]`, presumably because it finds a macro that expands to this attribute.
Now this is clever in theory, but in my case, the macro comes from a third-party library (libfmt in this case), and I wouldn't want to use their internal macro in my code.
I suggest that this warning should suggest always suggest `[[fallthrough]]`, never a macro.
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