macOS "<function> was used with no prototype before its definition" error

[kainjow]

I am getting this error in a file with C functions. The function is implemented like so:

static OSStatus installCustomMenu() {
 ...
}

and is defined in the header like so:

static OSStatus installCustomMenu();

It is being called from a function above it, and I'm still seeing this error (warning actually).

Anyone know how to get rid of it? The .m file is #import-ing the .h file normally, so it should see that it's defined in the header.

 

[robbieduncan]

Note sure about this but #import is very Obj-C based. Can you #import instead #include straight C based stuff. I don't see why it would make any difference at a .h level as the header files would look the same.

Although now I've read that a bit more carefully: you are defining code in the .h. I'd certainly try #include instead of #import then. I seem to remember code headers does not work when #import ed

 

[kainjow]

#include doesn't remove the warning. I think #import doesn't do anything special for non-Objective-C files, but I didn't write the original files

 

[robbieduncan]

#include doesn't remove the warning. I think #import doesn't do anything special for non-Objective-C files, but I didn't write the original files

#import removes the need for protective #defines and the like. It should do that for all headers (obj-c or otherwise).

Clearly something is compiler "noticing" the function definition exists. It should clearly pick up the forward declaration if nothing else so that's very weird. Have you tried creating a simple .h file and defining a function of your own to see if it works?

 

[lazydog]

Hi,

I'm not entirely sure about this but perhaps it has something to do with the fact that it is a static function? Since it is static there is no need to prototype it in a seperate .h file as it can't be called from any other file other than the one it is defined in.

b e n

 

[kainjow]

I changed the parameter to (void) from just (), and that made it work. I have no idea why.

 

[gnasher729]

Why do you have the prototype for a static function in a header file?

 

[kainjow]

Why do you have the prototype for a static function in a header file?

No idea, the code wasn't written by me, I'm just trying to get rid of the warning.