GCC behavior when calling a function with too many arguments

Question

I just noticed GCC behavior that seems strange to me (not tested by other compilers).

If I compile this code:

#include <stdio.h>

void foo(int i)
{
  printf("Hello %d\n",i);
}

int main(){
  foo(1, 2);
  return 0;
}

I will get a compiler error:

test.c:9:5: error: too many arguments to function ‘foo’

But if I compile this code:

#include <stdio.h>

void foo()
{
  printf("Hello\n");
}

int main(){
  foo(1, 2);
  return 0;
}

I have no errors or warnings.

Can someone explain to me why?

I tested this with gcc 4.6.3 and arm-none-eabi-gcc 4.8.3

EDIT: I am compiling all warnings: gcc -Wall test.c

Answer 1

In C, the notation void foo()means that foo takes an indefinite number of arguments.

To indicate that the function foo()should not accept any arguments, you should writevoid foo(void)

int main(void).

Answer 2

!

void foo()

- ANSI C . , void foo(...) .

( ++ void foo() , ).

Answer 3

, gcc . Étienne , f extern, , (6.7.6.3§14 C11, 6.7.5.3§14 C99), ( ):

. , , , . , , .

clang (v3.4) (too many arguments in call to 'foo') , ( ) :

foo.c:

extern void foo();
int main(){
  foo(1, 2);
  return 0;
}

bar.c:

#include <stdio.h>
void foo (int x, int y, int z) { printf("Hello %d\n", z); }

:

$ clang -o foo bar.c foo.c
$ ./foo
Hello 1405669720