www.digitalmars.com         C & C++   DMDScript  

D.gnu - [Issue 983] New: constant cfstrings for Darwin

reply d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=983

           Summary: constant cfstrings for Darwin
           Product: DGCC aka GDC
           Version: unspecified
          Platform: Macintosh
        OS/Version: Mac OS X
            Status: NEW
          Severity: enhancement
          Priority: P2
         Component: glue layer
        AssignedTo: dvdfrdmn users.sf.net
        ReportedBy: afb algonet.se


When doing Carbon programming for Mac OS X, there are two possible ways to
create constant strings for CoreFoundation - both use the CFSTR() macro from
CFString.h. It would be nice if the __CFStringMakeConstantString built-in could
be made available to D (same as for C/C++), to avoid having to do the runtime
call.

I've introduced a version(GNU_Constant_CFStrings) that matches the macro
__CONSTANT_CFSTRINGS__ that C/C++ uses to check the current setting. But we
still need the built-in function for __CFStringMakeConstantString, and I assume
that GCC also needs the type somehow (it's a struct pointer, maybe a void* will
do)


darwin.c:

  /* struct __builtin_CFString {
       const int *isa;          (will point at
       int flags;                __CFConstantStringClassReference)
       const char *str;
       int length;
     };  */

  /* const struct __builtin_CFstring *
     __builtin___CFStringMakeConstantString (const char *); */


-- 
Feb 19 2007
next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=983





------- Comment #1 from afb algonet.se  2007-02-19 08:11 -------
Created an attachment (id=104)
 --> (http://d.puremagic.com/issues/attachment.cgi?id=104&action=view)
gdc-0.23-constant-cfstrings.patch

tested OK with gcc-5363


-- 
Feb 19 2007
prev sibling next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=983





------- Comment #2 from afb algonet.se  2007-02-19 08:13 -------

Suggested usage of the built-in would be something like this:


/* Macro to allow creation of compile-time constant strings; the argument
should be a constant string.

CFSTR(), not being a "Copy" or "Create" function, does not return a new
reference for you. So, you should not release the return value. This is
much like constant C or Pascal strings --- when you use "hello world"
in a program, you do not free it.

However, strings returned from CFSTR() can be retained and released in a
properly nested fashion, just like any other CF type. That is, if you pass
a CFSTR() return value to a function such as SetMenuItemWithCFString(), the
function can retain it, then later, when it's done with it, it can release it.

At this point non-7 bit characters (that is, characters > 127) in CFSTR() are
not 
supported and using them will lead to unpredictable results. This includes
escaped
(\nnn) characters whose values are > 127. Even if it works for you in testing, 
it might not work for a user with a different language preference.
*/

/+
#ifdef __CONSTANT_CFSTRINGS__
#define CFSTR(cStr)  ((CFStringRef) __builtin___CFStringMakeConstantString (""
cStr ""))
#else
#define CFSTR(cStr)  __CFStringMakeConstantString("" cStr "")
#endif
+/
version (GNU_Constant_CFStrings) {
    private import gcc.builtins;
    alias __builtin___CFStringMakeConstantString CFSTR;
} else {
    extern(C) CFStringRef __CFStringMakeConstantString(char *cStr);
    alias __CFStringMakeConstantString CFSTR;
}


GCC toggles which version it uses with -fconstant-cfstrings (default)
or -fno-constant-cfstrings (default in earlier versions of Mac OS X)


-- 
Feb 19 2007
prev sibling next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=983


dvdfrdmn users.sf.net changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED




------- Comment #3 from dvdfrdmn users.sf.net  2007-03-08 21:12 -------
Targeted to release 0.24.  This should already work, but I neglected to add
target builtins to the gcc.builtins module.  

It may not be a good idea to simply alias to CFSTR in Phobos.  The original C
CFSTR macro casts the result of the builtin function to CFStringRef, which is
defined in the Core Foundation headers. 


-- 
Mar 08 2007
prev sibling next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=983





------- Comment #4 from afb algonet.se  2007-03-09 02:04 -------
You mean it would be better to make it an inline function ?

CFStringRef CFSTR(char *cStr)
{
    return __builtin___CFStringMakeConstantString(cStr);
}

Just for type safety, or was there some other reason too ?


-- 
Mar 09 2007
prev sibling next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=983





------- Comment #5 from dvdfrdmn users.sf.net  2007-03-10 06:37 -------
Yes, for type safety (compatibility, really).  Presumably, a D interface to
CoreFoundation is going to define CFString itself, so the wrapper around
__CFStringMakeConstantString would also have to be defined in that interface.


-- 
Mar 10 2007
prev sibling next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=983





------- Comment #6 from afb algonet.se  2007-03-10 07:10 -------
The D wrappers I've made so far only used the opaque CFStringRef type,
which could be a "typedef void*" or use the struct that C header uses.

Will the D inlining work for making data section constants like this ?
(I usually try to avoid the inlines, because of the extra object code)


-- 
Mar 10 2007
prev sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=983


dvdfrdmn users.sf.net changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED




------- Comment #7 from dvdfrdmn users.sf.net  2007-09-23 20:22 -------
A inline function will not work because the non-inlined original will pass a
non-constant char* to __builtin___CFStringMakeConstantString (and fail to
compile).  Making CFString a void*...

    alias __builtin___CFStringMakeConstantString CFSTR;
    alias void * CFStringRef;

... is probably okay except that it becomes possible to this:

    CFString x = <pointer to something that is not a CFString....>

This is another possibility...

  static if ( is( typeof(__builtin___CFStringMakeConstantString) ret == return
) ) {
    alias ret CFStringRef;
    alias typeof(*CFStringRef) CFString;
    alias __builtin___CFStringMakeConstantString CFSTR;
  } else {
    struct CFString;
    alias CFString * CFStringRef;
  }

... but typeid(CFStringRef) could differ across object modules depending on the
compiler version, flags, etc.

We may just have to wait for AST macros to get the perfect solution.

(Closing the issue since CFStringMakeConstantString now works.)


-- 
Sep 23 2007