zturner added inline comments.
================
Comment at: lib/ASTMatchers/Dynamic/Registry.cpp:77
+ internal::MatcherDescriptor *matchDescriptor, StringRef MatcherName) {
+ auto K = ast_type_traits::ASTNodeKind::getFromNodeKind<
+ typename
ast_matchers::internal::VariadicAllOfMatcher<ResultT>::Type>();
----------------
steveire wrote:
> aaron.ballman wrote:
> > zturner wrote:
> > > steveire wrote:
> > > > aaron.ballman wrote:
> > > > > steveire wrote:
> > > > > > aaron.ballman wrote:
> > > > > > > Mildly not keen on the use of `auto` here. It's a factory
> > > > > > > function, so it kind of names the resulting type, but it also
> > > > > > > looks like the type will be
> > > > > > > `ast_matchers::internal::VariadicAllOfMatcher<ResultT>::Type`
> > > > > > > from the template argument, which is incorrect.
> > > > > > There is no reason to assume that taking a template argument means
> > > > > > that type is result.
> > > > > >
> > > > > > The method is `getFrom` which decreases the ambiguity still further.
> > > > > >
> > > > > > Spelling out the type doesn't add anything useful. This should be
> > > > > > ok.
> > > > > > There is no reason to assume that taking a template argument means
> > > > > > that type is result.
> > > > >
> > > > > Aside from all the other places that do exactly that (getAs<>,
> > > > > cast<>, dyn_cast<>, castAs<>, and so on). Generally, when we have a
> > > > > function named get that takes a template type argument, the result
> > > > > when seen in proximity to auto is the template type.
> > > > >
> > > > > > Spelling out the type doesn't add anything useful. This should be
> > > > > > ok.
> > > > >
> > > > > I slept on this one and fall on the other side of it; using auto
> > > > > hides information that tripped up at least one person when reading
> > > > > the code, so don't use auto. It's not clear enough what the resulting
> > > > > type will be.
> > > > I put this in the category of requiring
> > > >
> > > > SomeType ST = SomeType::create();
> > > >
> > > > instead of
> > > >
> > > > auto ST = SomeType::create();
> > > >
> > > > `ast_type_traits::ASTNodeKind` is already on that line and you want to
> > > > see it again.
> > > >
> > > FWIW I'm with Aaron here. Im' not familiar at all with this codebase,
> > > and looking at the code, my first instinct is "the result type is
> > > probably `ast_matchers::internal::VariadicAllOfMatcher<ResultT>::Type`".
> > > According to Aaron's earlier comment, that is incorrect, so there's at
> > > least 1 data point that it hinders readability.
> > >
> > > So, honest question. What *is* the return type here?
> > > So, honest question. What *is* the return type here?
> >
> > Much to my surprise, it's `ASTNodeKind`. It was entirely unobvious to me
> > that this was a factory function.
> @zturner Quoting myself:
>
> > `ast_type_traits::ASTNodeKind` is already on that line and you want to see
> > it again.
>
> The expression is `getFromNodeKind`. There is a pattern of
> `SomeType::fromFooKind<FooKind>()` returning a `SomeType`. This is not so
> unusual.
>
>
Note that at the top of this file there's already a `using namespace
clang::ast_type_traits;` So if you're worried about verbosity, then you can
remove the `ast_type_traits::`, remove the `auto`, and the net effect is that
the overall line will end up being shorter.
Repository:
rC Clang
https://reviews.llvm.org/D54405
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