[PATCH] D141954: Forbid implicit conversion of constraint expression to bool
Erich Keane via Phabricator via cfe-commits
cfe-commits at lists.llvm.org
Wed Jan 18 05:50:32 PST 2023
erichkeane marked an inline comment as done.
erichkeane added a comment.
In D141954#4060647 <https://reviews.llvm.org/D141954#4060647>, @philnik wrote:
> In D141954#4060246 <https://reviews.llvm.org/D141954#4060246>, @erichkeane wrote:
>
>> In D141954#4060244 <https://reviews.llvm.org/D141954#4060244>, @philnik wrote:
>>
>>> In D141954#4060212 <https://reviews.llvm.org/D141954#4060212>, @erichkeane wrote:
>>>
>>>> @ldionne @Mordante The libcxx failure isn't clear what it is complaining about, but I thought this fix might end up breaking a libcxx test, since it would be easy to fall into the trap of having an implicit conversion here.
>>>>
>>>> Any chance you could prod at that test a little and see whose fault it is?
>>>>
>>>> ALSO: NOTE TO SELF: need release note!
>>>
>>> I think the problem is that `__type_traits/common_reference.h` doesn't re-export `__type_traits/common_type.h` in the modulemap. It //should// be enough to add `export common_type` to `module common_reference` (`libcxx/include/module.modulemap.in:1399`). See `module is_arithmetic` for an example. This is just a guess though, this stuff can be very weird.
>>
>> Oh man, I hope the others know what you're talking about :) I don't really know how I caused this though :/
>
> I've applied your patch locally and this diff fixes the issue:
>
> diff --git a/libcxx/include/module.modulemap.in b/libcxx/include/module.modulemap.in
> index 5d4cf53aa334..30209b353d6b 100644
> --- a/libcxx/include/module.modulemap.in
> +++ b/libcxx/include/module.modulemap.in
> @@ -747,7 +747,10 @@ module std [system] {
> module assignable { private header "__concepts/assignable.h" }
> module boolean_testable { private header "__concepts/boolean_testable.h" }
> module class_or_enum { private header "__concepts/class_or_enum.h" }
> - module common_reference_with { private header "__concepts/common_reference_with.h" }
> + module common_reference_with {
> + private header "__concepts/common_reference_with.h"
> + export type_traits.common_reference
> + }
> module common_with { private header "__concepts/common_with.h" }
> module constructible { private header "__concepts/constructible.h" }
> module convertible_to { private header "__concepts/convertible_to.h" }
>
> I don't know why your patch changes the behaviour of clang here, but I wouldn't worry too much about it. There is a lot of weirdness around modules and dependent type names resulting in pretty much useless error messages. I hope the work on C++ modules reduces this weirdness, but I don't really know how that stuff works.
Thanks! I'll apply that patch here and see if it makes the bot happy.
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https://reviews.llvm.org/D141954/new/
https://reviews.llvm.org/D141954
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