CODEWITHSUNDEEP
c++c
vehomzzz
vehomzzz

Reputation: 44578

C++ expected type specifier error

I am trying to write a wrapper function to figure out who is calling a specific function. So in .h file I added the following: (and implementation in the .cc file)

extern int foo(/*some arguments*/);

extern void call_log(const char*file,const char*function,const int line,const char*args);

#define foo(...) (call_log(__FILE__, __FUNCTION__, __LINE__, "" #__VA_ARGS__), foo(__VA_ARGS__))

However, I get the following error:

 error: expected a type specifier
    (call_log(__FILE__, __FUNCTION__, __LINE__, "" #__VA_ARGS__),foo(__VA_ARGS__)

Assume that the foo function is called with some parameters and returns an int.

the compiler is gcc 3.4

Thanks

EDIT

removed "." and extra spaced, yet problem still there. Can anyone see what can cause it. Also notice that I am using variadic macros -- supported by my compiler (c99)

Edit 2 Just to get the claims about my illegal use of some c/c++ constructs. The following code below works, and I am trying to adapt it to my current (above function)

#include <stdio.h> 

int funcA( int a, int b ){ return a+b; }

// instrumentation

void call_log(const char*file,const char*function,const int line,const char*args){
  printf("file:%s line: %i function: %s args: %s\n",file,line,function,args);
}

#define funcA(...) \
  (call_log(__FILE__, __FUNCTION__, __LINE__, "" #__VA_ARGS__), funcA(__VA_ARGS__)) 

// testing

void funcB()
{
  funcA(7,8);
}


int main(void){
  int x = funcA(1,2)+

          funcA(3,4);

  printf( "x: %i (==10)\n", x );

  funcA(5,6);

  funcB();
}

Edit 3

As litb pointed out, the problem is, in fact, due to macro substitutions. I also noticed that foo is not only a function call but also used as ptr->foo[] in some cases. Any ides how to resolve this sort of issues, without breaking more code

Upvotes: 1

Views: 10071

Answers (2)

Reputation:

If I'm not mistaken I believe you have a number of syntax errors in the definition and declaration of call_log.

In the definition I am pretty sure you need a space between the const char* and the variable name. ie...

extern void call_log(const char* file,const char* function,const int line,const char* args);

In addition, in the declaration, I don't think you can append #__VA_ARGS__ to "" in the manner you are doing. The macro will resolved this as:

(call_log(file_name, function_name, line_#, "" arg1, arg2...), foo(args[])

which is not a valid function call. On a side-note you are also missing a semicolon after the macro definition.

Finally, I do not see a reference to foo(args) in your macro definition; It's possible I'm missing some context but you may wish to look at that as well.

Hope this helps...

CJ

Upvotes: 0

xtofl
xtofl

Reputation: 41509

The best way to find out what's wrong would be to make the compiler show the preprocessed code. You can then easier spot the problem in the offending line.

Upvotes: 1

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