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Re: restrict keyword [was: expalin this syntax pls]
- From: "Joseph S. Myers" <jsm28 at cam dot ac dot uk>
- To: Joe Buck <jbuck at synopsys dot com>
- Cc: <gcc at gcc dot gnu dot org>
- Date: Sat, 19 Oct 2002 01:23:01 +0100 (BST)
- Subject: Re: restrict keyword [was: expalin this syntax pls]
On Fri, 18 Oct 2002, Joe Buck wrote:
> This means that we can't issue a hard error for it, but a warning may well
> still be appropriate. Errors are for code that is wrong, warnings are for
> code that is likely to be wrong. If you insist on not issuing warnings for
> such code, we have the problem that we can't use similar mechanisms to
> warn about possible misuse of memcpy, whose specification implies
> "restrict" even for C++, which doesn't have the keyword.
You can't issue a hard error for it anyway, since the code might never be
executed. The key questions for issuing a warning (under its own option,
possibly included in -Wall) are:
* Does anyone write real (broken) code the warning would detect? (The
relevant question for having the warning at all.)
* Does anyone write real (working) code the warning would wrongly trigger
on?
* How common are these?
* Can working code wrongly triggering the warning be easily changed, even
if automatically generated, so as not to trigger it? (The relevant
question for -Wall inclusion.)
In the case of memcpy, we have more information to tell whether a call
*is* a problem (rather than might be).
--
Joseph S. Myers
jsm28@cam.ac.uk