[committed] libstdc++: Move attributes that follow requires-clauses [PR101782]

[Jonathan Wakely]

On 05/08/21 15:40 +0100, Jonathan Wakely wrote:
>On 05/08/21 15:19 +0100, Jonathan Wakely wrote:
>>On 04/08/21 12:55 +0100, Jonathan Wakely wrote:
>>>This adds [[nodiscard]] throughout <iterator>, as proposed by P2377R0
>>>(with some minor corrections).
>>>
>>>The attribute is added for all modes from C++11 up, using
>>>[[__nodiscard__]] or _GLIBCXX_NODISCARD where C++17 [[nodiscard]] can't
>>>be used directly.
>>
>>This change causes errors when -fconcepts-ts is used. Fixed like so.
>>
>>Tested powerpc64le-linux, committed to trunk.
>>
>
>>commit 7b1de3eb9ed3f8dde54732d88520292c5ad1157d
>>Author: Jonathan Wakely <jwakely@redhat.com>
>>Date:   Thu Aug 5 13:34:00 2021
>>
>>   libstdc++: Move attributes that follow requires-clauses [PR101782]
>>   As explained in the PR, the grammar in the Concepts TS means that a [
>>   token following a requires-clause is parsed as part of the
>>   logical-or-expression rather than the start of an attribute. That makes
>>   the following ill-formed when using -fconcepts-ts:
>>     template<typename T> requires foo<T> [[nodiscard]] int f(T);
>>   This change moves all attributes that follow a requires-clause to the
>>   end of the function declarator.
>
>
>Except that as Jakub pointed out, putting it there doesn't work.
>
>It needs to be:
>
>  template<typename T> requires foo<T> int f [[nodiscard]] (T);
>
>At least the testsuite isn't failing now, but the attributes I moved
>have no effect. I'll fix it ... some time.

This should be correct now.

Tested powerpc64le-linux, pushed to trunk.


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