> 	- we now ship with correct locale table, and lib/libc/locale/runeglue.c
> 	  converts it into _ctype_.  now _ctype_ can have correct locale bit
> 	  declarations and isprint() can behave strange.

I think we didn't ship _ctype_[] table with ((_ctype_+1)['\t'] & _B) != 0
in any release version. Is this right?
If so, because we don't have to keep bug-compatibility with -current, ...

> 	1c. don't change ctype.h declarations.
> 	    when we load locale declaration file, we make some trick about _B.
> 	    PROS: smallest amont of changes.
> 	    CONS: new binaries will have incorrect isprint() and isblank(),
> 		forever.

How about a variant of this?

e.g.

	1c1. don't change ctype.h declarations.
	  never define isblank() as macro, but allways define it as 
	  function as follows:
		isblank(int c) {
			return (c == '\t' || ((_ctype_ + 1)[c] & _B);
		}

	1c2. don't change ctype.h declarations.
	  isblank() may be defined as macro, but never use 0x80 (_B) bit
	  as blank bit. (i.e. reserve 0x80 bit for future extensions.)
	  we may have to find a way to make isblank() dynamic in future,
	  but current behaviour (hardcoded as ' ' and '\t') is ok for
	  some time.

The above 1c1 and 1c2 doesn't have problem of 1c.
--
soda