aaron.ballman added inline comments.

================
Comment at: clang-tools-extra/clang-tidy/cert/SignalHandlerCheck.cpp:117-118
+    FunctionCallCollector Collector{[&CalledFunctions](const CallExpr *CE) {
+      if (isa<FunctionDecl>(CE->getCalleeDecl()))
+        CalledFunctions.push_back(CE);
+    }};
----------------
balazske wrote:
> aaron.ballman wrote:
> > aaron.ballman wrote:
> > > balazske wrote:
> > > > aaron.ballman wrote:
> > > > > For correctness, I think you need to handle more than just calls to 
> > > > > function declarations -- for instance, this should be just as 
> > > > > problematic:
> > > > > ```
> > > > > void some_signal_handler(int sig) {
> > > > >   []{ puts("this should not be an escape hatch for the check); }();
> > > > > }
> > > > > ```
> > > > > even though the call expression in the signal handler doesn't resolve 
> > > > > back to a function declaration. (Similar for blocks instead of 
> > > > > lambdas.) WDYT?
> > > > I do not know how many other cases could be there. Probably this can be 
> > > > left for future  improvement, the checker is mainly usable for C code 
> > > > then. There is a `clang::CallGraph` functionality that could be used 
> > > > instead of `FunctionCallCollector` but the `CallExpr` for the calls is 
> > > > not provided by it so it does not work for this case. Maybe there is 
> > > > other similar functionality that is usable?
> > > Given that we want it in the CERT module, we should try to ensure it 
> > > follows the rule as closely as we can. I went and checked what the C++ 
> > > rules say about this and... it was interesting to notice that SIG30-C is 
> > > not one of the C rules included by reference in C++ 
> > > (https://wiki.sei.cmu.edu/confluence/pages/viewpage.action?pageId=88046336).
> > > 
> > > It's not clear to me that this rule was accidentally tagged as 
> > > `not-for-cpp` or not, so I'd say it's fine to ignore lambdas for the 
> > > moment but we may have some follow-up work if CERT changes the rule to be 
> > > included in C++. My recommendation is: make the check a C-only check for 
> > > now, document it as such, and I'll ping the folks at CERT to see if this 
> > > rule was mistagged or not. WDYT?
> > Ah, this rule really is a C-only rule, because 
> > https://wiki.sei.cmu.edu/confluence/display/cplusplus/MSC54-CPP.+A+signal+handler+must+be+a+plain+old+function
> >  is the C++ rule. So I think the SIG30-C checker should be run in C-only 
> > mode and we can ignore the C++isms in it.
> > 
> > FWIW, we have an ongoing discussion about MSC54-CPP in 
> > https://reviews.llvm.org/D33825.
> Probably this checker can be merged with the other in D33825. According to 
> cppreference (https://en.cppreference.com/w/cpp/utility/program/signal) the 
> check for the called functions should be present for C++ too. And the other 
> checker should do a similar lookup of called functions as this checker, 
> including lambdas and C++ specific things.
While you would think that, it's a bit more complicated unfortunately. The C++ 
committee has been moving forward with this paper http://wg21.link/p0270 so 
that C++ is no longer tied to the same constraints as C. That may suggest that 
separate checks are appropriate, or it may still mean we want to merge the 
checks into one.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D87449/new/

https://reviews.llvm.org/D87449

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