This is a pity: efforts were invested in computing correctly the
number of screen columns consumed by multibyte characters, but the
routines that do that were fed by single-byte inputs...
As a consequence Bison never displayed correctly locations when there
are multibyte characters.
* src/scan-gram.l (mbchar): New.
Use it instead of . in the catch-all clause.
* tests/diagnostics.at (Tabulations): Enhance into...
(Tabulations and multibyte characters): this.
afe7dfd3b9