aaron.ballman added subscribers: sbenza, klimek.
aaron.ballman added inline comments.
================
Comment at: test/clang-tidy/hicpp-exception-baseclass.cpp:9
+class deep_hierarchy : public derived_exception {};
class non_derived_exception {};
----------------
JonasToth wrote:
> aaron.ballman wrote:
> > JonasToth wrote:
> > > aaron.ballman wrote:
> > > > JonasToth wrote:
> > > > > aaron.ballman wrote:
> > > > > > Can you add a test that uses multiple inheritance? e.g.,
> > > > > > ```
> > > > > > class terrible_idea : public non_derived_exception, public
> > > > > > derived_exception {};
> > > > > > ```
> > > > > > Also, is private inheritance also acceptable, or does it need to be
> > > > > > public inheritance? I kind of get the impression it needs to be
> > > > > > public, because the goal appears to be that you should always be
> > > > > > able to catch a `std::exception` instance, and you can't do that if
> > > > > > it's privately inherited. That should have a test as well.
> > > > > The rules do not state directly, that it must be inherited public,
> > > > > but i dont see a good reason to allow non-public inheritance.
> > > > > Another thing is, that you can always call `e.what()` on public
> > > > > derived exceptions.
> > > > >
> > > > > Multiple inheritance is harder, since the type is still a
> > > > > `std::exception`. One could catch it and use its interface, so these
> > > > > reasons are gone to disallow it.
> > > > > The rules do not state directly, that it must be inherited public,
> > > > > but i dont see a good reason to allow non-public inheritance.
> > > >
> > > > Agreed.
> > > >
> > > > > Another thing is, that you can always call e.what() on public derived
> > > > > exceptions.
> > > >
> > > > Agreed.
> > > >
> > > > > Multiple inheritance is harder, since the type is still a
> > > > > std::exception. One could catch it and use its interface, so these
> > > > > reasons are gone to disallow it.
> > > >
> > > > I think the multiple inheritance case should not diagnose because it
> > > > meets the HIC++ requirement of being derived from `std::exception`.
> > > I have a problem with implementing the inheritance rules.
> > >
> > > From the Matchers, there seems to be no way to test, if the inheritance
> > > is public. Should i work a new matcher for that, or rather move the
> > > tests, if the type holds all conditions into the callback function. This
> > > would mean, that every `throw` gets matched.
> > I would say you can handle private inheritance in a follow-up patch. I
> > would look into changing the `isPublic()` (and related) matchers to handle
> > inheritance (might as well handle `isVirtual()` at the same time, too),
> > though I've not given this interface a ton of thought.
> Ok. I will commit this one with according FIXME: sections and will `#if 0`
> the currently offending check-messages.
>
> from the usability, something like:
> `isSameOrDerivedFrom("std::exception", isPublic())` would be nice, but i dont
> know if this is even possible.
> In that sense, the other modifiers could be used as well (`isVirtual()`,
> `isProtected()`...).
I'm not too certain (maybe @klimek or @sbenza knows more), but I think you can
modify `isDerivedFrom()` to accept an additional matcher so that could can
write `isDerivedFrom(hasName("X"), allOf(isPublic(), isVirtual()))` and then
thread that change through to the other derived matchers. I would guess this
means `isPublic()` (et al) would need to accept a `CXXBaseSpecifier` as well as
the declarations they currently accept.
https://reviews.llvm.org/D37060
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