C Compiler errors

I’ve got to know and love the random C compiler errors.
But I just got one of my favourites:

Error missing newline before EOF – inserted

I always wondered why you need a newline at the end of a C source file, does anyone know why – or is it just there purely for my amusement?

Error missing newline before EOF – inserted

Surely if the compiler notices that there was no newline and inserts one, this should become a warning and not an error?

Technically every line of input must end with a newline – it is part of the C spec – perhaps because some systems have difficulty reading the last line of data from files (treated as text not binary) if the newline isn’t present.

Update: It is part of the standard, here: http://c0x.coding-guidelines.com/5.1.1.2.html#123

The reasoning is as follows:

File “one.h” is this, it does not end with a newline:

// this file is now unused

File “two.h” is this, it ends with a newline:

#include <stdio.h>

File “meh.c” is this (ending with a newline):

#include "one.h"
#include "two.h"

int main(void)
{
   printf("Meh!\n");
   return 0;
}

It would probably fail to build, complaining about printf not being recognised. How is this possible? Simple – if the compiler did not raise an error for missing newlines, after preprocessing, the compiler would see this:

// this file is now unused#include <stdio.h>

int main(void)
{
   printf("Meh!\n");
   return 0;
}

Do you see what happened there?

It is part of the standard,

Shame that objasm doesn’t auto insert the newline when it throws up an error in similar circumstances

Thanks Rick, that explains it!
“// this file is now unused”
That should through an error anyway:

“ERROR: Detestable language detected” ;-)