Re: Warn when returning the address of a temporary (middle-end)

[Marc Glisse <marc dot glisse at inria dot fr>]

On Mon, 7 Apr 2014, Jeff Law wrote:

> > I am also afraid we may get more false positives, but maybe not.
> The only false positives should come from paths which are unexecutable.  One 
> could argue that if we find any that we should warn, then isolate the path so 
> that we get an immediate runtime trap rather than letting the address of the 
> local escape through the return value.
>
> That in turn would argue for dumping it into gimple-isolate-erroneous-paths 
> ;-)

I wonder if trapping may be too strong? If a function sometimes returns a 
pointer to a local variable but the caller always ignores the return value 
in those cases, we can warn, but maybe we don't want to introduce a trap? 
Replacing the address with a null pointer seemed like a compromise, it 
will trap when you try to read it, but not if you ignore it. But if you 
think we can trap, ok.

--
Marc Glisse