In D it's possible to use pragma(mangle) on a function to set the name
that will actually end up in the binary. This is useful if you need to
link to a C function that uses the same name as a keyword in D.
I think we need the same thing for types as well. This is important when
binding to C++ and Objective-C.
For C++ it's due the the types are mangled as part of function
signatures. Other than conflicting D keywords, it's also important for
another reason. In C, the name of structs live in their own namespace,
making it possible to have a struct and a function with the same name.
Since you always need to use "struct <name>" in C when referring to the
type it works.
This caused a problem [1]. There's a function called "stat", which also
accepts an argument of the type "stat". In D, the struct is declared
"stat_t" to avoid the conflict with the function. When using C functions
this works perfectly fine since no mangling is used. But when using a
C++ function taking an argument of the type "stat_t" this will generate
the wrong mangling since it's expected to be "stat" on the C++ side.
For Objective-C a similar scenario can occur. Because in Objective-C
protocols (what we call interfaces in D) and classes live in different
namespaces. In Objective-C there's a root class called "Object" just as
in D. But in Objective-C this class also conforms to a protocol called
"Object". For this to work properly from the D side, one needs to be
renamed in the D code and use pragma(mangle) to set the actual name that
would end up in the binary.
I suggest that we add support for using pragma(mangle) on types as well.
Thoughts?
I have already implemented the support for Objective-C classes in an old
branch several years ago.
[1] https://issues.dlang.org/show_bug.cgi?id=16650
--
/Jacob Carlborg
