GC/GTY and Coverity "resource leaks" (was Re: Daily Coverity analysis on gcc)

[David Malcolm]

On Mon, 2017-06-26 at 06:36 -0700, Sylvestre Ledru wrote:
> Over the last few weeks, working with Jonathan, I have been running
> daily analysis of Coverity (a proprietary static analyzer tool)
> It is running on a Debian amd64 with the options:
> --with-gnu-as --with-gnu-ld --disable-bootstrap 
> --enable-languages=jit,c,c++,fortran,lto,objc  --enable-host-shared
> 
> Coverity finds about 4300 defects. The defect density is 1.67 for 2.5
> millions line of code.
> 
> As a comparison, the llvm toolchain (llvm, clang, lldb, etc) has 3223
> defects (0.62 of defect density for 5.1M loc).
> 
> Most of the defect are detected as resource leaks (1681 defects). I
> had
> a quick look and many of them are actual issues (in many cases
> minor), I
> took the
> opportunity to fix some of them.
> 
> To access to the list of results, you can apply
> https://scan.coverity.com/projects/gcc, please try to prove that you
> are
> a gcc contributor.
> 
> Thanks,
> Sylvestre

Thanks.

The most recent one, and thus the first one I looked at (CID=1412982)
was a supposed "Resource Leak" in the get_cast_suggestion function I
introduced in r249461, where the local variable "trial" is supposedly
leaked (leading to 3 issues within Coverity overall, if I'm reading
things right, for the 3 ways in which a non-NULL value can be generated
and then fall out of scope).

But this is a tree, and will eventually be GC-ed.

So is there a way to teach Coverity about GTY and our garbage
collector?  I'm wondering how many of the resource leak defects are
similar false positives.

Dave