Re: Compile Time Memory Leak Analyses

[Joern Rennecke <amylaar at redhat dot com>]

> Not at all.  Undecidability theorems mean only that an analysis routine
> that tries to establish whether property P is true must return a
> three-valued result (yes, no, and "I don't know").  gcc is full of
> such code.  If there are many cases where a definite answer can be
> given, the tool can be useful.
> 
> After all, reachability is also undecidable, but we still eliminate dead
> code.

Well, but that's an optimization.  We optimize only when we know that it
is safe (at least that's the theory ;-), so while we can't tolerate false
positives, we can tolerate false negatives.

However, for warnings, false positives are extremely annoying, while
false negatives mean that you can miss potential bugs while you are
lulled into a false security that the compiler will warn about problems.

So we set ourselves up for a warning that is likely to become as awkward as
the uninitialized warnings.