Link time checking for incompatible flags

[Jim Wilson]

Rahul Joshi wrote:
> Would it be possible to add such link-time
> checking for incompatible compiler options?

It is possible in theory.  You can set flags in object files, and then 
check the flags at link time.  However, this requires coordinated 
compiler, assembler, and linker changes, and may also require ABI 
changes to reserve the flags.  Generally, it is only done when ABIs 
specify incompatible alternatives, for instance some targets support 
multiple ABIs such as 32-bit and 64-bit code, and you will get a linker 
error if you mix them.  In this case, the ABI will reserve flags in the 
object files for this purpose.

Since -fshort-enums is not part of any ABI, there are no standard flags 
to use for it.

An alternative to use flags would be to use comment sections, but that 
likely has other problems.  For instance, comment sections can be 
stripped, and then you don't get the warnings anymore.  This is easier 
in the sense that we don't have to worry about ABI problems with object 
file flags.

Most gcc work is done by volunteers, so this won't get done unless a 
volunteer submits a patch for it, and it is unlikely anyone will 
volunteer to do this, unless you want to try.
-- 
Jim Wilson, GNU Tools Support, http://www.SpecifixInc.com