[PATCH] D48714: [clang-tidy] fix PR37913, templated exception factory diagnosed correctly

Jonas Toth via Phabricator via cfe-commits cfe-commits at lists.llvm.org
Fri Aug 3 14:00:47 PDT 2018

JonasToth added inline comments.

Comment at: test/clang-tidy/hicpp-exception-baseclass.cpp:191
+void templated_thrower() { throw T{}(); }
+// CHECK-MESSAGES: [[@LINE-1]]:34: warning: throwing an exception whose type 'int' is not derived from 'std::exception'
JonasToth wrote:
> alexfh wrote:
> > hokein wrote:
> > > I think giving message on the template function here is confusing to users even it gets instantiated somewhere in this TU -- because users have to find the location that triggers the template instantiation.
> > > 
> > > Maybe 
> > > 1) Add a note which gives the instantiation location to the message, or
> > > 2) ignore template case (some clang-tidy checks do this)
> > In this particular case it seems to be useful to get warnings from template instantiations. But the message will indeed be confusing.
> > 
> > Ideally, the message should have "in instantiation of xxx requested here" notes attached, as clang warnings do. But this is not working automatically, and it's implemented in Sema (`Sema::PrintInstantiationStack()` in lib/Sema/SemaTemplateInstantiate.cpp).
> > 
> > I wonder whether it's feasible to produce similar notes after Sema is dead? Maybe not the whole instantiation stack, but at least it should be possible to figure out that the enclosing function is a template instantiation or is a member function of an type that is an instantiation of a template. That would be useful for other checks as well.
> It should be possible to figure out, that the type comes from template instantiation and that information could be added to the warning.
> I will take a look at Sema and think about something like this. Unfortunatly i dont have a lot of time :/
I did look further into the issue, i think it is non-trivial.

The newly added case is not a templated exception perse, but there is a exception-factory, which is templated, that creates a normal exception.

I did add another note for template instantiations, but i could not figure out a way to give better diagnostics for the new use-case.

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