Re: Call the AC_CHECK_HEADER macro on a condition

[Paul Eggert]

On 04/12/2016 08:24 AM, Eric Blake wrote:
> Also, checking for <stdio.h> is pointless these days.  You can portably
> assume a C89 compiler (and these days, often a C99 compiler), which
> guarantees <stdio.h> is present.

Although it's safe to assume C89ish (or even C99ish) these days, there 
is the possibility that it's a freestanding C implementation, where the 
C standard does not require <stdio.h>. This might happen in a 
bootloader, say, where no operating system is available.