Re: BUG: %lc in printf fails with transliteration

[Ulrich Drepper <drepper at redhat dot com>]

Markus Kuhn <Markus.Kuhn@cl.cam.ac.uk> writes:

> The standard (§7.20) only says that
> 
>        "MB_CUR_MAX [..]
>        expands to a positive integer expression with type
>        size_t  that  is  the maximum number of bytes in a multibyte
>        character for the extended character set  specified  by  the
>        current  locale  (category LC_CTYPE), which is never greater
>        than MB_LEN_MAX.
> 
> If a locale contains a transliteration L"ü" -> "ue", then for this
> locale the implementation will have to make sure that MB_CUR_MAX >=
> strlen("ue").

First of all, this is everything but practical.  Many programs assume
MB_CUR_MAX to be an attribute of the charset which is used to trigger
certain handling.  This all would break.  Second, I deliberately
didn't enable the transliteration for the wc*tomb* functions since in
the contexts they are used they have to be exact.  THere is even an
error number defined for the case an invalid character is found.  This
is different from the stream handling where this is keft
implementation defined.  Also, iconv() also does not enable
transliteration by default for the same reason.

It is a bad idea to do this since it is greatly reducing portability
and the ability to develop programs on Linux for other architectures.
Stdio is used for output which might also lead to some
incompatibilities but the standard says so and the most problematic
situations (e.g., compilers converting input to multibyte) is done
using wc*tomb and iconv().

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