Bug 473947

Created attachment 325241 [details]
Reproducer source code for this bug

Description of problem:
This is actually an issue with the kernel-headers package, the file
/usr/include/asm-generic/ioctl.h
This has been resolved in the upstream kernel, see:
http://bugzilla.kernel.org/show_bug.cgi?id=11106
The Fedora10 kernel-headers already includes this commit.

Version-Release number of selected component (if applicable):
kernel-headers-2.6.18-92.el5

How reproducible:
always

Steps to Reproduce:

Building a program with debug (-g flag) can result in undefined reference to
"__invalid_size_argument_for_IOC".

This code from include/asm-generic/ioctl.h is the culprit:
     50 /* provoke compile error for invalid uses of size argument */
     51 extern unsigned int __invalid_size_argument_for_IOC;
     52 #define _IOC_TYPECHECK(t) \
     53         ((sizeof(t) == sizeof(t[1]) && \
     54           sizeof(t) < (1 << _IOC_SIZEBITS)) ? \
     55           sizeof(t) : __invalid_size_argument_for_IOC)
     ....
     61 #define _IOWR(type,nr,size)    
_IOC(_IOC_READ|_IOC_WRITE,(type),(nr),(_IOC_TYPECHECK(size)))

This gets used in the various _IO definitions.  The comment indicates this was
intended to throw a compiler error.  It doesn't - it will always compile and
end up generating a link-error for an undefined reference to
__invalid_size_argument_for_IOC.

In fact, lines 51-55 will only work *if* the compiler always optimizes away the
reference to __invalid_size_argument_for_IOC.  It turns out that gcc
(currently) actually does optimize this out in all cases (even -g -O0), and
never generates the undefined link reference.

This isn't true for Intel's compilers (icc and icpc).  If the -g flag is
asserted the reference is generated and the error *always* occurs.  It's hard
to generate a debug image;  The work-around hack is ugly - add a global def for
__invalid_size_argument_for_IOC.  This also disables the test.  The intel
compiler might not be the only one that has this behaviour.

Steps to reproduce:
I've attached a short reproducer program.

Build with:
(OK)      gcc    -Wall ioctl_broke.c
(OK)      gcc -g -Wall ioctl_broke.c
(OK)      icc    -Wall ioctl_broke.c
(Breaks)  icc -g -Wall ioctl_broke.c
          /tmp/iccRFH4Pa.o: In function `main':
          /home/rda/ioctl_test.c:23: undefined reference to '__invalid_size_argument_for_IOC'