[PATCH] D106577: [clang] Define __STDC_ISO_10646__

[James Y Knight via Phabricator via cfe-commits]

jyknight added a comment.

In D106577#2897588 <https://reviews.llvm.org/D106577#2897588>, @aaron.ballman wrote:

> In D106577#2897522 <https://reviews.llvm.org/D106577#2897522>, @jyknight wrote:
>
>> I'm not sure we should be populating this.
>>
>> The _value_ is determined by what libc supports, so it probably needs to be left up to libc to define it.
>
> Why is the value determined by what libc supports? The definition from the standard is:
>
>   If this symbol is defined, then every character in the Unicode required set, when stored in an
>   object of type wchar_t, has the same value as the short identifier of that character.
>
> That doesn't seem to imply anything about the library, just the size of `wchar_t`.

Huh. So it doesn't! Not sure why I got that idea. Disregard my comment then -- I agree that just setting it to some arbitrary unicode version ought to be OK, and there's probably no need to ever change it, since the set of possible unicode values isn't ever going to change.

And if the C library also defines this macro in its headers, that's ok, since -Wmacro-redefinition is suppressed by system headers.


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