[cfe-dev] Constant CF/NSString and Unicode

[Matthew Jimenez]

On Jul 10, 2008, at 1:50 AM, Jean-Daniel Dupas wrote:

>
> Le 10 juil. 08 à 07:56, Chris Lattner a écrit :
>
>>
>> On Jul 9, 2008, at 4:10 PM, Jean-Daniel Dupas wrote:
>>> I just wonder if there is some kind of unicode support in
>>> __builtin___CFStringMakeConstantString.
>>
>> In GCC or clang?  Clang doesn't have any unicode support yet.
>>
>>> In the current GCC version, when you compile an objc file, constant
>>> strings that contains non-ascii chars are converted into utf-16
>>> strings and a flag is set into the generated CFString.
>>
>> Ok.  Fariborz implemented that fwiw.
>>
>>> The fact that it works only for objc file look more like a design
>>> decision than a technical limit, and this feature can easily be
>>> extended to c files. In fact, I managed to implement this feature in
>>> cc1 and it look like it works. (if I'm wrong, feel free to correct
>>> me).
>>>
>>> And what about clang and unicode CFString ?
>>
>> I'm not sure what you mean, can you explain a bit more?
>>
>> -Chris
>
>
> Yep,
> put this simple code snippet in cfstring.c :
>
> #include <CoreFoundation/CoreFoundation.h>
>
> int main(int argc, char **argv) {
>   CFShowStr(CFSTR("hé hé hé"));
>   CFShow(CFSTR("hé hé hé"));
>   return 0;
> }
>
> if you compile this file using "gcc -o cfstring cfstring.c -framework
> CoreFoundation" and run it  you got:
>
> Length 11
> IsEightBit 1
> HasLengthByte 0
> HasNullByte 1
> InlineContents 0
> Allocator SystemDefault
> Mutable 0
> Contents 0x1ff2
> h\u221a\u00a9 h\u221a\u00a9 h\u221a\u00a9
>
> Now, if you compile this same file using
>
> gcc -x objective-c -o cfstring cfstring.c -framework CoreFoundation
>
> the output is:
>
> Length 8
> IsEightBit 0
> HasLengthByte 0
> HasNullByte 0
> InlineContents 0
> Allocator SystemDefault
> Mutable 0
> Contents 0x1fee
> h\u00e9 h\u00e9 h\u00e9
>
> Maybe I miss something, but I really do not understand the current
> limitation.
> As clang will probably implements this feature some day, I just wonder
> if it should duplicate the GCC behavior (emitting a warning and
> generating an ascii based CFString) or if it can be extended to
> support also UTF-16 CFString generation in plain C file.
>

Now I'm curious. Does this behavior change using -fconstant-cfstrings
instead of defining the language as ObjC? According to the  
documentation,
it looks like that is the flag to enable  
__builtin__CFStringMakeConstantString.

-Matthew