Re: AC_PROG_CC_C99

[Noah Misch]

On Thu, Dec 02, 2004 at 10:54:36AM -0800, Paul Eggert wrote:
> Can you test Autoconf with 'gcc -std=c99 -pedantic-errors -Werror'?
> That might catch some of the problems we're worried about.

Very interesting.  I just tried that on the meaty configure script of net-snmp.

$ gcc -v
Reading specs from 
/data2/nm/sw/gcc341/bin/../lib/gcc/i686-pc-linux-gnu/3.4.1/specs
Configured with: ../gcc-3.4.1/configure --prefix=/home/nm/sw/gcc341 
--enable-languages=c --with-system-zlib
Thread model: posix
gcc version 3.4.1

Notable misbehavior:

configure:10244: checking for asin in -lm
configure:10275: gcc -std=c99 -pedantic-errors -Werror -o conftest -g -O2 
-Dlinux   conftest.c -lm   >&5
configure:10296: warning: conflicting types for built-in function 'asin'

The `conflicting types for built-in function FOO' warning also arises for
strchr, memcpy, memmove, vsnprintf, and snprintf.

configure:18609: checking for working memcmp
configure:18658: gcc -std=c99 -pedantic-errors -Werror -o conftest -g -O2 
-Dlinux   conftest.c -lcrypto -lelf  >&5
configure: In function `main':
configure:18743: warning: overflow in implicit constant conversion
configure:18743: warning: overflow in implicit constant conversion
configure:18744: error: implicit declaration of function `memcmp'
configure:18745: error: implicit declaration of function `exit'
configure:18758: error: implicit declaration of function `strcpy'
configure:18661: $? = 1
configure: program exited with status 1
configure: failed program was:
<snipped>
configure:18680: result: no

I posted the full log at http://www.cs.caltech.edu/~noah/net-snmp-config-log.gz
for the time being.