| Issue |
121969
|
| Summary |
Hierarchical .clang-tidy HeaderFilterRegex Settings Ignored in Clang-Tidy 19
|
| Labels |
clang-tidy
|
| Assignees |
|
| Reporter |
sfc-gh-mheimel
|
# Summary
Our project uses a hierarchical `.clang-tidy` files to selectively enable checks for specific folders. Previously (in Clang-Tidy 18.1.x), we could rely on `HeaderFilterRegex` to exclude headers in other directories from checks that were only enabled in certain subfolders. After updating to Clang-Tidy 19.1.x, the subfolder’s `HeaderFilterRegex` seems to be ignored, causing unwanted warnings for headers outside the subfolder.
We traced this regression to [PR #91400](https://github.com/llvm/llvm-project/pull/91400); reverting that PR makes Clang-Tidy 19 behave like 18 again.
# Steps to Reproduce
## Folder Structure
```
.clang-tidy
test.hpp
a/
├─ .clang-tidy
└─ main.cpp
```
## File Contents
1. Root `.clang-tidy`:
```yaml
HeaderFilterRegex: '.*'
Checks: -.*
```
2. Root `test.hpp`:
```c++
int test() {
return (int)4.0; // violates google-readability-casting
}
```
3. Subfolder `a/.clang-tidy`:
```yaml
InheritParentConfig: true
HeaderFilterRegex: '.*a/.*'
Checks: google-readability-casting
```
4. Subfolder `a/main.cpp`:
```c++
#include "test.hpp"
int main() {
return test();
}
```
## Steps to reproduce
### With clang-18 (Expected Behavior)
```
> clang-tidy-18 a/main.cpp --quiet -- -I.
1 warning generated.
```
### With clang-19 (Regression)
```
> clang-tidy-19 a/main.cpp --quiet -- -I.
1 warning generated.
./test.hpp:2:10: error: C-style casts are discouraged; use static_cast [google-readability-casting,-warnings-as-errors]
2 | return (int)4.0;
| ^~~~~
| static_cast<int>( )
```
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