ahatanak added inline comments.
================
Comment at: clang/lib/Sema/SemaInit.cpp:4506
!S.Context.hasSameUnqualifiedType(E->getType(), DestType) &&
- (E->getType()->isIntegralOrEnumerationType() ||
+ (E->getType()->isIntegralOrUnscopedEnumerationType() ||
E->getType()->isFloatingType())) {
----------------
ahatanak wrote:
> aaron.ballman wrote:
> > ahatanak wrote:
> > > aaron.ballman wrote:
> > > > This doesn't match the comments immediately above here and I don't
> > > > think is the correct fix.
> > > >
> > > > We're handling this case: http://eel.is/c++draft/dcl.init.list#3.8
> > > >
> > > > A scoped enumeration has a fixed underlying type
> > > > (https://eel.is/c++draft/dcl.enum#5.sentence-5). The initializer list
> > > > has a single element and that element can be implicitly converted to
> > > > the underlying type (`int` in all of the test cases changed in this
> > > > patch). And this is a direct initialization case, so I think we should
> > > > be performing the conversion here rather than skipping to the next
> > > > bullet.
> > > Can scoped enums be implicitly converted to integer types? Unscoped enums
> > > can be converted to an integer type, but I don't see any mention of
> > > scoped enums here: https://eel.is/c++draft/conv.integral
> > >
> > > It seems that the original paper was trying to change the rules about
> > > conversions from the underlying type to a scoped enum. It doesn't look
> > > like it's allowing conversion from a scope enum to another scope enum.
> > >
> > > https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/p0138r2.pdf
> > > Can scoped enums be implicitly converted to integer types? Unscoped enums
> > > can be converted to an integer type, but I don't see any mention of
> > > scoped enums here: https://eel.is/c++draft/conv.integral
> >
> > Correct, they cannot be implicitly converted to an integer.
> >
> > > It seems that the original paper was trying to change the rules about
> > > conversions from the underlying type to a scoped enum. It doesn't look
> > > like it's allowing conversion from a scope enum to another scope enum.
> >
> > Agreed, however, I think where we want this to fail is below in the attempt
> > at conversion. "v can be implicitly converted to U" is the part that should
> > be failing here, and we're now skipping over the bit of code that's
> > checking whether the implicit conversion is valid.
> Is the code below checking whether the implicit conversion is valid? It looks
> like it's assuming the implicit conversion is valid and adding an implicit
> conversion sequence based on that assumption. If the source is an integer,
> unscoped enum, or floating type, the implicit conversion that is performed
> later should succeed except when there is narrowing.
>
> Or are you suggesting we should add a check to
> `Sema::PerformImplicitConversion` that rejects conversions from scoped enums
> to other types? It seems to me that it's better to detect the error earlier.
Alternatively, we can emit a diagnostic in the code below that specifically
calls out conversion from scoped enums to integer types.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D126084/new/
https://reviews.llvm.org/D126084
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