[PATCH] D152504: [clang][ThreadSafety] Analyze cleanup functions

[Aaron Puchert via Phabricator via cfe-commits]

aaronpuchert added inline comments.


================
Comment at: clang/lib/Analysis/ThreadSafety.cpp:2436
+                                    CF.getVarDecl()->getLocation());
+          break;
+        }
----------------
aaronpuchert wrote:
> tbaeder wrote:
> > This handles the function call, but without the instance parameter. I was wondering how to best do that.
> Should you not simply pass `SxBuilder.createVariable(CF.getVarDecl())` as third parameter in analogy with the `AutomaticObjectDtor` case? It might also make sense to copy the attribute check.
Can you write a test case that relies on passing the variable? Here is an idea:
```
void unlock_scope(Mutex **mu) __attribute__((release_capability(*mu))) {
  mutex_exclusive_unlock(*mu);
}

Mutex* const CLEANUP(unlock_scope) scope = &mu1;
mutex_exclusive_lock(*scope);
// Unlock should happen automatically.
```
I think this is mildly more interesting than the cleanup function with an unused parameter.

Unfortunately this is not quite as powerful as a scoped lock in C++, as we don't track the identity `scope == &mu1`. So `guarded_by` won't work with this. But we can at least see warnings on balanced locking/unlocking.

As for proper scoped locking, we could treat some variable initializations like construction of a C++ scoped lock. But let's discuss this separately.


================
Comment at: clang/test/Sema/warn-thread-safety-analysis.c:76-77
 
+void cleanup_int(int *unused) __attribute__((release_capability(mu1))) {
+  (void)unused;
+  mutex_exclusive_unlock(&mu1);
----------------
tbaeder wrote:
> aaronpuchert wrote:
> > 
> > omitting the parameter name in a function definition is a C2x extension
Ah, I didn't know that C gained this only recently.


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  https://reviews.llvm.org/D152504/new/

https://reviews.llvm.org/D152504