balazske 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);
+ }};
----------------
aaron.ballman wrote:
> 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.
I think it is more convenient to merge the two checkers. The visitation of
called functions goes the same way, the support for C++ constructs should not
cause problems if used with C code. The handling of a detected function can be
different code for C and C++ mode but if there are similar parts code can be
reused.
Otherwise code of this checker would be a better starting point for
"SignalHandlerMustBePlainOldFunctionCheck" because it handles detection of the
`signal` function already better specially for C++.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D87449/new/
https://reviews.llvm.org/D87449
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