[LifetimeSafety] Suppress dangling field warnings for RAII resetters in permissive mode
(#214212)
In `-Wlifetime-safety-permissive` mode, suppress dangling field warnings
(`-Wlifetime-safety-dangling-field`) when `this` or the escaping field
declaration is captured by a lambda within the function. This accounts
for common RAII field resetters that clean up dangling pointers on scope
exit.
### Motivating Example
Dangling field analysis can report false positives when an RAII field
resetter (such as `absl::MakeCleanup` or `absl::Cleanup`) captures
`this` or the field to reset the pointer before function exit:
```cpp
struct TimeServerInstance {
Handler* handler_;
void init() {
Handler local_handler;
handler_ = &local_handler;
// False positive: intra-procedural analysis does not evaluate RAII
// cleanup lambdas that reset dangling fields on scope exit.
absl::Cleanup cleanup = [this] {
handler_ = nullptr;
};
}
};
llvm-project
8b6f3dcd - [LifetimeSafety] Suppress dangling field warnings for RAII resetters in permissive mode
