Amaury Forgeot d'Arc wrote:
> 
> Amaury Forgeot d'Arc <amauryfa@gmail.com> added the comment:
> 
>> No, but changing the APIs from 16-bit integers to 32-bit integers
>> does require a recompile of all code using it.
> 
> Is it acceptable between 3.1 and 3.2 for example? ISTM that other
> changes already require recompilation of extension modules.

With the proposed approach, we'll keep binary compatibility, so
this is not much of an issue.

Note: Changes to the binary interface can be done in minor releases,
but we should make sure that it's not possible to load an extension
compiled with 3.1 in 3.2 to prevent segfaults and buffer overruns.

>> Also, the Unicode type database itself uses Py_UNICODE, so
>> case mapping would fail for non-BMP code points.
> 
> Where, please? in unicodedata.c, getuchar and _getrecord_ex use Py_UCS4.

The change affects the Unicode type database which is implemented
in unicodectype.c, not the Unicode database, which already uses UCS4.