[rslifka]

Hi all,

I'm working at understand someone else's ancient Carbon code and have come across something I'm not quite sure how to address.

When utilizing the 'pascal' keyword in typedefs, Xcode gives me errors. For example:

typedef pascal FOO (SomeObject pObject);

Xcode says "Parse error before FOO" and if I remove the pascal keyword, everything builds... but I get an Illegal Instruction the very first time any of these 'pascal' typedefs are used. Granted it could be from another reason, but my first thought is that if they put 'pascal' there, it was for good reason.

I'm thinking this keyword for typedefs is some sort of compiler option? I can't even find examples of this on the web.

Rob

[Chuckit]

The "pascal" keyword isn't an actual type so much as a modifier, I think. It specifies how the stack should be handled for the function. Probably when the code was written, the compiler would infer a default type, but now it needs the type to be explicit. That's my guess.

[rslifka]

I came across this on /.

However, C and C++ compilers for the Mac all accept the "pascal" keyword, which is included in all the header files for the API. Besides that, you can ignore it, except in the special case where you need to pass a pointer to the API for a callback function. Then you need to declare your function as pascal, too. You have never had to declare all your functions pascal.

This is precisely the special case I'm in. Callback function pointers. Xcode/GCC/whatever is rejecting use of this 'pascal' keyword in creating the typedefs for the function pointers but it allows the use in function declarations.

Rob

[Thinine]

I'm fairly certain there are some build options regarding pascal, so you may want to look through those. Though they may only be pascal strings options.

[Dair Grant]

The Pascal calling convention has been a no-op since the PowerPC was introduced, and is a left-over from 68K - the crash will be down to something else.

However, even though it's a no-op, CodeWarrior has always recognised the 'pascal' keyword as a type qualifier - so will complain if you pass a non-pascal callback to a function expecting a function pointer declared as pascal (as it should: the types are different, so you can't mix them without an explicit cast).

Unfortunately gcc doesn't recognise the 'pascal' keyword, so if you have code that declares callbacks with 'pascal' directly rather than using the compiler-aware macros from ConditionalMacros.h then it won't compile. The simplest approach is either to take it out, or to -Dpascal= when using gcc to have it ignored.

Xcode's only Pascal support is to recognise "\pfoo" sequences as Pascal strings (e.g., a Str255 - rather than a C-style NULL terminated string, the initial byte holds the length of the string and there may not be a trailing NULL).