Re: why ld return with error?

[ali hagigat <hagigatali@gmail.com>]

Thank you for the reply. I think that GCC compiler collection has the
definitions and C code of some standard libraries. It means that the
code of printf exists inside the code of gcc and gcc does not need to
go to /usr/bin on hard disk to find libc.a and then find the defintion
and the body of printf.
Is that right? or I am mistaken?
If I am mistaken what will be the meaning of -fno-builtin then? I
think the code of built-in functions exist inside the code segment of
gcc when it is invoked.
Regards

On Mon, Jan 31, 2011 at 10:47 AM, Ian Lance Taylor <iant@google.com> wrote:
> ali hagigat <hagigatali@gmail.com> writes:
>
>> I have the following files:
>> prog3.c
>> #include <stdio.h>
>> main(){
>>       printf("uuuuuu\n");
>> }
>> prog3.ld
>> ASSERT(1,"there is not an error");
>> Then :
>> gcc -c prog3.c -o prog3.o
>> ld prog3.o prog3.ld -o prog3
>>
>> ld: warning: cannot find entry symbol _start; defaulting to 0000000008048074
>> prog3.o: In function `main':
>> prog3.c:(.text+0x11): undefined reference to `puts'
>> ------------------------------------------------------------------------
>> I want to force gcc (or ld) to use its built-in functions as printf
>> and puts(not to use the standard library functions like libc.a or
>> libc.so). how can i do it?
>
> gcc by default optimizes printf of a string constant ending in a newline
> to call puts instead.  To disable that, use -fno-builtin-printf when
> compiling.
>
> I don't understand what you mean when you say that you want gcc to use
> its built-in functions as printf rather than the standard library
> functions.  gcc has no built-in printf function.
>
> Ian
>