Dear locale maintainers,

fix the glibc bug 12031 "iconv -t ascii//translit with Greek characters" [1]
add Greek transliteration rows to locale/C-translit.h.in.

This work is done on the heels of the successfully committed patch for the 

virtually the same bug [BZ #2872] but concerning Cyrillic characters. [2] 


AFAIK there are many versions of transcription tables for Greek to ASCII 

transcription. Given that current iconv logic can only translit one to many 

but not many to many symbols we take the "Standard" part of 

the Romanization_of_Greek#Modern_Greek table [3]

and only keep the one letter Greek graphems. That "standard" seems to be close to 

the ELOT 743 indeed but not the same. 


So we omit things like M and Μπ being transliterated as M and B accordingly. 

Rather Μπ will be treated like two separate graphems and transliterated as Mp. 


Here is the list of some standards I have collected so far. There doesn't seem 

a way to harmonize them all into one. But if anyone want to propose a solution - 

please do.

* ΕΛΟΤ 743 https://www.teicrete.gr/users/kutrulis/Ergalia/ELOT743.htm Passports.
* ISO 843 https://en.wikipedia.org/wiki/ISO_843
* ALA-LC https://www.loc.gov/catdir/cpso/romanization/greek.pdf Book titles.
* BGN/PCGN http://libraries.ucsd.edu/bib/fed/USBGN_romanization.pdf 

* http://geonames.nga.mil/gns/html/Romanization/Romanization_Greek.pdf Geographical names.

Furthermore to cover the whole U0370-U03FF Greek/Coptic Unicode range I have 

asked around and made a best effort transliteration for the rest of characters 

not covered in above standards. 


Should you have better sources for the actual translit entries please make sure to 

send your feedback!

The patch is attached. 


Best regards,
Egor Kobylkin

https://sourceware.org/bugzilla/show_bug.cgi?id=12031 [1]
https://sourceware.org/ml/libc-alpha/2019-07/msg00477.html [2]
https://en.wikipedia.org/wiki/Romanization_of_Greek#Modern_Greek [3]