[cfe-dev] How to create diff beetwen clang analyses?

Anna Zaks ganna at apple.com
Tue May 29 10:39:53 PDT 2012

On May 28, 2012, at 2:35 PM, Marcin Mirosław wrote:

> W dniu 22.05.2012 19:25, Anna Zaks pisze:
>> On May 21, 2012, at 3:46 AM, Marcin Mirosław wrote:
>>> Hello!
>>> I'm thinking about creating automatic tool to create clang analyse every
>>> commit/every period of time. I'd like to do comparising beetwen reports
>>> to know if new commits brings something unwanted in code. Ideally it
>>> would be to see what errors was fixed and what wrong appears with new
>>> commit. But id would be enough to see new warnings. I've got no idea how
>>> to parse html to create usefull diff.
> Hi Anna!
>> The clang analyzer can output plist files in addition to html. We have a python script which compares two plist files (See clang/utils/analyzer/CmpRuns.py). I've also started working on infrastructure to diff the analyzer warnings between different scan-build executions on the same project. We use this on an internal analyzer buildbot, which tests the analyzer using the same revision of analyzed projects.
>> The main issue is that we just compare the issues by file and line number, so if you have a change unrelated to a warning but in a file which does have a warning, the diff might change. This greatly limits the new issue detection; makes it noisy to the point it might not be very useful. So currently, the best workflow for a changing codebase is to ensure that the project does not have any analyzer issues and fix new issues as soon as they are reported.
>> We are very much interested in supporting the workflow you are talking about. The main challenge here is coming up with a smarter way of comparing issues and of cause implementing it. We envision this requiring support on the analyzer side.
> Fixing all issues is great but often is too hard:) Thank you for all
> information. CmpRuns.py is quiete usefull, it's easier to check 20
> issues than 200.

You can also take a look at SATest*.py, which use CmpRuns to compare results of two scan-build executions.

I also want to point that due to the mentioned limitations, we might not support the existing scripts, output formats forever.


> Regards,
> Marcin

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