Re: WCHAR_MAX question

[Jeff Johnston <jjohnstn at redhat dot com>]

Artem B. Bityuckiy wrote:
> > The correct way it should be done is to have the compiler generate a 
> > macro for it.  As it turns out, the gcc compiler has __WCHAR_MAX__ as 
> > one of it's default builtins which is why the code is defined as it 
> > is.  See c-cppbuiltin.c in the gcc directory.
> >
> > For non-gcc compilers, we are defaulting the maximum value which I do 
> > not think a bad thing as most wchar_t implementations use 4-byte 
> > values for obvious reasons.
>
>
> I agree that the most right way is to use GCC's predefined macro like 
> __WCHAR_MAX__. BUT! There is no such macro in gcc-3.2! What version of 
> gcc did you mention? I did 'grep -r WCHAR_MAX gcc-3.2/*' and didn't 
> found anything interesting...

I actually have a newer compiler: 3.4.0.  I could find no sign of the 
--with-short-wchar configuration option in my sources.

This really should be done by the compiler.  The macro has to be a constant so 
it cannot use sizeof() or make a function call (ala errno).  Now, an end-user 
can always specify the -fshort-wchar option on a compilation.  As you can see, 
this means that the macro should be dynamically defined by the compiler.  The 
newest gcc compiler has managed to do this right.

Even without the -fshort-wchar problem, calculating at configuration time is 
going to be inaccurate.  For a cross-target, an execution test would be 
required, but we can't do that when we are in the stages of building the C 
library.  I guess we could check for the configuration option and set a flag in 
newlib.h to handle the case you have mentioned.

-- Jeff J.