| Issue |
166573
|
| Summary |
clang-tidy clang-analyzer-unix.BlockInCriticalSection false positive with std::defer_lock
|
| Labels |
clang-tidy,
false-positive
|
| Assignees |
|
| Reporter |
SRHMorris
|
I've run into this false positive when using std::unique_lock with std::defer_lock. This is using LLVM 21.1.4.
Minimum reproducible example, real code is more complex than this:
``` C++
#include <mutex>
#include <sys/socket.h>
int main()
{
std::mutex m;
std::unique_lock lock(m, std::defer_lock);
recv(0, nullptr, 0, 0);
}
```
Produces the following output:
```
.../main.cpp:8:3: error: Call to blocking function 'recv' inside of critical section [clang-analyzer-unix.BlockInCriticalSection,-warnings-as-errors]
8 | recv(0, nullptr, 0, 0);
| ^~~~~~~~~~~~~~~~~~~~~~
.../main.cpp:7:20: note: Entering critical section here
7 | std::unique_lock lock(m, std::defer_lock);
| ^~~~~~~~~~~~~~~~~~~~~~~~
.../main.cpp:8:3: note: Call to blocking function 'recv' inside of critical section
8 | recv(0, nullptr, 0, 0);
| ^~~~~~~~~~~~~~~~~~~~~~
```
Expected result is that this shouldn't produce a warning, as the mutex is unlocked at the point where recv is called.
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