#2496 function pointers to functions with struct pointer arguments do not work.

[Kio]

function pointers to functions with struct pointer arguments do not work.

compiling uploaded file foo.c with
sdcc foo.c
results in error:

foo.c:13: error 78: incompatible types
from type 'unsigned-int function ( struct Data generic* fixed) fixed'
  to type 'unsigned-int function ( struct Data generic* fixed) fixed'

tested in sdcc version 3.4 and in current nightly build.

[Ben Shi]

Your foo.c is wrong. Even gcc complaints with

$ gcc foo.c -c
foo.c:8:34: warning: ‘struct Data’ declared inside parameter list
 typedef unsigned int (*T)(struct Data*);
                                  ^
foo.c:8:34: warning: its scope is only this definition or declaration, which is probably not what you want
foo.c:13:9: warning: initialization from incompatible pointer type
 T bar = foo;
         ^

If you change it to

struct Data;
typedef unsigned int (*T)(struct Data*);

struct Data { unsigned int a; };

extern unsigned int foo(struct Data* f);
T bar = foo;

Both gcc and sdcc (the newest snapshot build) accept it.

The key reason is struct Data is neither defined nor declared before its reference in the definition of type T.

[Ben Shi]

Or you can delete the definition of struct Data, like

//struct Data;
typedef unsigned int (*T)(struct Data*);

//struct Data { unsigned int a; };

extern unsigned int foo(struct Data* f);
T bar = foo;

sdcc will treat the typedef unsigned int (*T)(struct Data*); as both definition of T and declaration of struct Data.

[Kio]

thanks for your explanations. the idea to test it with gcc didn't come to me, but the error message of gcc would have helped.
I understand the problem, but let's say, a standard which provides syntax to define functions which are impossible to call is a little bit silly then...
As i now understand why it did not work, i don't understand your last message and why sdcc accepts it. gcc rejects it and to my current understanding the compiler should reject it.

typedef unsigned int (*T)(struct Data*);

and

extern unsigned int foo(struct Data* f);

both define local data types which by that are different. (as gcc assures me.)
finally sdcc also rejects my code if i actually try to call the function pointer with a struct Data later:

typedef unsigned int (*T)(struct Data*); // local data type
extern unsigned int foo(struct Data* f); // local data type
T bar = foo;  // works in sdcc but shouldn't
struct Data { unsigned int a; };
int main() { struct Data d = {0}; foo(&d); } // rejected

never mind,

... Kio !

[Ben Shi]

sdcc should not accept

T bar = foo;  // works in sdcc but shouldn't

I will check it.

[Ben Shi]

Now sdcc revision #9578 rejects

T bar = foo;  // works in sdcc but shouldn't