isalpha man page - return value in case of argument equal to EOF

[Andreas Schwab]

On Jun 12 2023, Florian Weimer wrote:

> * Andreas Schwab via Libc-alpha:
>
>> On Jun 12 2023, Luigi Pellecchia via Libc-alpha wrote:
>>
>>> Even if there may be several reasons to accept EOF, it is not clear what
>>> the expected value should be in that case.
>>
>> Since EOF is not a character, it cannot be part of any of the character
>> classes.
>
> EOF can be equal to 'ÿ' (as in, have the same value and type).

No.  EOF is -1, (unsigned char) 'ÿ' is 255.

> It's unclear to me what we actually want to document in terms of C
> extensions.  I thought that is* was unspecified for EOF,

The classification functions are required to accept EOF.

-- 
Andreas Schwab, SUSE Labs, schwab@suse.de
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