[GCC-XML] default argument namespace

[Brad King]

Gerd v. Egidy wrote:
> Hi,
> 
> I'm using gccxml within our libt2n-project (a C++ IPC library, 
> http://www.intra2net.com/de/produkte/opensource/libt2n/)
> and it has helped us very much to avoid needing an IDL-file: you just 
> mark a function within the source and that is parsed by gccxml to 
> gather the information usually found within an IDL.
> 
> I'm now adding support for default arguments and I'm unsure 
> about the details of the gccxml-output:
> 
> when I write 
> 
> void testb(std::string a=std::string())
> {
>     return;
> }
> 
> I'll get
> 
> <Function id="_8" name="testb" returns="_334" context="_1" mangled="_Z5testbSs" 
>    demangled="testb(std::string)" location="f0:23" file="f0" line="23" endline="25">
>   <Argument name="a" type="_951" location="f0:23" file="f0" line="23" default="string()"/>
> </Function>
> 
> So the default argument is returned without namespace.
> 
> But in this code:
> 
> namespace foo
> {
> 
>     class bar
>     {
>         public:
>             static const std::string other;
>     };
> 
>     const std::string bar::other="secret";
> }
>  
> void testc(std::string a=foo::bar::other)
> {
>     return;
> }
> 
> <Function id="_7" name="testc" returns="_334" context="_1" mangled="_Z5testcSs" 
>   demangled="testc(std::string)" location="f0:28" file="f0" line="28" endline="30">
>   <Argument name="a" type="_951" location="f0:28" file="f0" line="28" default="foo::bar::other"/>
> </Function>
> 
> I get the full namespace of the default argument.
> 
> I always need the full namespace of the default argument to be able 
> to add it to the headers of my stubs.
> 
> Would anyone mind to help me understand the logic behind the
> default attribute and where to get the namespace from in my
> first example?

The default argument string is just an expression->string conversion
done by the internal GCC parser (which is there for production of error
messages from the compiler).  It is mostly for human reference, and I
doubt it can be parsed/used reliably for something automated.

True support for default arguments will require support for dumping
expressions, which in turn is part of the missing support for function
bodies.  A contributor is working on support for bodies, though:

  http://gccxml-bodies.sourceforge.net/

-Brad