Subj : Re: Non-strictly-conforming and unspecified versus undefined behavior
To   : comp.programming.threads,comp.std.c
From : Douglas A. Gwyn
Date : Fri Feb 18 2005 08:48 pm

David Schwartz wrote:
>     The standard does not say that output cannot depend upon
> implementation-defined behavior. If it did, then no useful POSIX strictly
> conforming program could be written.

The C standard certainly says that about a s.c. program.
I don't think POSIX uses the term "strictly conforming".
POSIX conformance is different from strict conformance
to the C standard.  Indeed, a strictly conforming C
program *cannot* use any POSIX extensions.  However,
not all programs need be s.c.  There is also the
useful category of a (plain) "conforming" program,
which is accepted by some conforming C implementation,
perhaps one that also supports POSIX extensions.

>     So then it *is* your position that virtually no useful POSIX
> multithreaded program is strictly conforming, since they will almost always
> have behavior that depends upon mutex acquisition order.

No program that uses *any* POSIX-specific feature
can be "strictly conforming" as the term is used by
the C standard.

I don't recall POSIX requiring invariance of output
for programs to conform to *its* standards.

.