Re: [PATCH] libstdc++: Fix up <complex> for extended floating point types [PR107649]

[Jonathan Wakely <jwakely@redhat.com>]

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On Wed, 16 Nov 2022 at 13:42, Jonathan Wakely <jwakely@redhat.com> wrote:

>
>
> On Mon, 14 Nov 2022 at 13:57, Jakub Jelinek <jakub@redhat.com> wrote:
>
>> Hi!
>>
>> As filed by Jonathan in the PR, I've screwed up the requires syntax
>> in the extended floating point specialization:
>> -    requires(__complex_type<_Tp>::type)
>> +    requires requires { typename __complex_type<_Tp>::type; }
>> and doing this change resulted in lots of errors because
>> __complex_whatever
>> overfloads from extended floating point types were declared after the
>> templates which used them.
>>
>> The following patch fixes that.
>>
>> Bootstrapped/regtested on x86_64-linux and i686-linux, additionally
>> I've tested that with _GLIBCXX_HAVE_FLOAT128_MATH not being defined
>> while __STDCPP_FLOAT128_T__ defined one can still use
>> std::complex<std::float128_t> for basic arithmetic etc., just one can't
>> expect std::sin etc. to work in that case (because we don't have any
>> implementation).
>>
>> Ok for trunk?
>>
>
> OK, thanks for the quick fix.
>

Oh, also no released version of Clang can handle the C++20 rules about
'typename' yet, so we get this error:

complex:1843:15: error: no template named 'type' in '__complex_ty
pe<_Tp>'; did you mean 'ctype'?
     typedef std::__complex_type<_Tp>::type _ComplexT;
             ^~~~~~~~~~~~~~~~~~~~~~~~~~
It needs a 'typename' after 'typedef'.

I can add that if you want though.

(It's fixed on Clang trunk, so will be in 16.0.0)