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Re: New attribute: returns_nonnull
- From: David Malcolm <dmalcolm at redhat dot com>
- To: Marc Glisse <marc dot glisse at inria dot fr>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Mon, 07 Oct 2013 13:18:42 -0400
- Subject: Re: New attribute: returns_nonnull
- Authentication-results: sourceware.org; auth=none
- References: <alpine dot DEB dot 2 dot 02 dot 1310071600430 dot 22663 at stedding dot saclay dot inria dot fr>
On Mon, 2013-10-07 at 16:17 +0200, Marc Glisse wrote:
> Hello,
>
> this patch adds an attribute to let the compiler know that a function
> never returns NULL. I saw some ECF_* flags, but the attribute seems
> sufficient. I considered using nonnull(0), but then it would have been
> confusing that the version of nonnull without arguments applies only to
> parameters and not the return value.
I can't comment on the patch itself, but could there also be an
attribute "returns_null", for functions that *always* return NULL?
This may sound weird, but I know of at least one API that exposes such
functions: CPython's exception-handling API: see e.g.
http://docs.python.org/2/c-api/exceptions.html#PyErr_NoMemory
and various other functions that have "Return value: Always NULL."
This allows the user to write one-liners like:
return PyErr_NoMemory();
Hope this is helpful
Dave