[PATCH] D116203: [clang] adds unary type transformations as compiler built-ins

[Christopher Di Bella via Phabricator via cfe-commits]

cjdb added inline comments.


================
Comment at: clang/test/SemaCXX/type-traits.cpp:3495-3496
+
+  { int a[T(__is_same(make_signed_t<Enum>, int))]; }
+  { int a[T(__is_same(make_signed_t<SignedEnum>, int))]; }
+  { int a[T(__is_same(make_signed_t<const SignedEnum>, const int))]; }
----------------
cjdb wrote:
> rsmith wrote:
> > It'd be useful to test enums with different underlying types. However, this test is not portable: if `short` and `int` are the same size, this is required to produce `short`, not `int`. It'd be good to have some test coverage of that quirk too. Perhaps this is easiest to see with a test like:
> > 
> > ```
> > enum E : long long {};
> > static_assert(__is_same(__make_signed(E), long));
> > ```
> > 
> > ... which should hold in cases where `long` and `long long` are the same size and are larger than `int`.
> I agree, but what about when `long` is smaller than `int`?
Bleh, this is impossible. What I meant to ask is what happens when `long` and `int` are the same size, I think?


Repository:
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  https://reviews.llvm.org/D116203/new/

https://reviews.llvm.org/D116203