[PATCH] D146178: [Clang][Sema] Fix comparison of constraint expressions

[Erich Keane via Phabricator via cfe-commits]

erichkeane added a comment.

In D146178#4339561 <https://reviews.llvm.org/D146178#4339561>, @awson wrote:

> Now, this
>
>   #include <vector>
>   #include <ranges>
>   
>   auto drop1(const std::vector<int>& s){
>   	return s | std::views::drop(1);
>   }
>
> when compiled against gcc's-13.1 libstdc++ spits:
>
>   boro.cpp:5:11: error: invalid operands to binary expression ('const std::vector<int>' and '_Partial<_Drop, decay_t<int>>' (aka '_Partial<std::ranges::views::_Drop, int>'))
>           return s | std::views::drop(1);
>                  ~ ^ ~~~~~~~~~~~~~~~~~~~
>   C:\Progs\msys64\ucrt64\include\c++\13.1.0\cstddef:135:3: note: candidate function not viable: no known conversion from 'const std::vector<int>' to 'byte' for 1st argument
>     operator|(byte __l, byte __r) noexcept
>     ^
>   C:\Progs\msys64\ucrt64\include\c++\13.1.0\bits/ios_base.h:87:3: note: candidate function not viable: no known conversion from 'const std::vector<int>' to '_Ios_Fmtflags' for 1st argument
>     operator|(_Ios_Fmtflags __a, _Ios_Fmtflags __b)
>     ^
>   C:\Progs\msys64\ucrt64\include\c++\13.1.0\bits/ios_base.h:130:3: note: candidate function not viable: no known conversion from 'const std::vector<int>' to '_Ios_Openmode' for 1st argument
>     operator|(_Ios_Openmode __a, _Ios_Openmode __b)
>     ^
>   C:\Progs\msys64\ucrt64\include\c++\13.1.0\bits/ios_base.h:170:3: note: candidate function not viable: no known conversion from 'const std::vector<int>' to '_Ios_Iostate' for 1st argument
>     operator|(_Ios_Iostate __a, _Ios_Iostate __b)
>     ^
>   C:\Progs\msys64\ucrt64\include\c++\13.1.0\ranges:887:7: note: candidate template ignored: constraints not satisfied [with _Self = _Partial<_Drop, decay_t<int>>, _Range = const std::vector<int> &]
>         operator|(_Range&& __r, _Self&& __self)
>         ^
>   C:\Progs\msys64\ucrt64\include\c++\13.1.0\ranges:885:5: note: because '__adaptor_invocable<std::ranges::views::__adaptor::_Partial<std::ranges::views::_Drop, int>, const std::vector<int> &>' evaluated to false
>           && __adaptor_invocable<_Self, _Range>
>              ^
>   C:\Progs\msys64\ucrt64\include\c++\13.1.0\ranges:860:20: note: because 'std::declval<_Adaptor>()(declval<_Args>()...)' would be invalid: no matching function for call to object of type 'std::ranges::views::__adaptor::_Partial<std::ranges::views::_Drop, int>'
>         = requires { std::declval<_Adaptor>()(declval<_Args>()...); };
>                      ^
>   C:\Progs\msys64\ucrt64\include\c++\13.1.0\ranges:896:7: note: candidate template ignored: constraints not satisfied [with _Lhs = std::vector<int>, _Rhs = _Partial<_Drop, decay_t<int>>]
>         operator|(_Lhs __lhs, _Rhs __rhs)
>         ^
>   C:\Progs\msys64\ucrt64\include\c++\13.1.0\ranges:893:16: note: because 'derived_from<std::vector<int>, _RangeAdaptorClosure>' evaluated to false
>         requires derived_from<_Lhs, _RangeAdaptorClosure>
>                  ^
>   C:\Progs\msys64\ucrt64\include\c++\13.1.0\concepts:67:28: note: because '__is_base_of(std::ranges::views::__adaptor::_RangeAdaptorClosure, std::vector<int>)' evaluated to false
>       concept derived_from = __is_base_of(_Base, _Derived)
>                              ^
>   1 error generated.
>
> `transform` doesn't work either.

It isn't clear to me what the issue is here from looking at that.  @alexander-shaposhnikov : Any chance you have time soon to analyze this so we don't have to revert?  I'd very much like to not have to do that...


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