Support multiple severity levels for diags from a single checker

[tauchris]

I have a checker that flags differences in parameter type declaration spelling between the prototype and definition for C functions. Some differences (for example, inconsistent use of 'const' qualifier) are purely questions of STYLE. But it can be argued that some (for example, inconsistent use of 'restrict' qualifier) have real risk, even though the difference in declaration spelling is meaningless to the compiler. So, I'd like to set the severity for some of the diagnostics differently than for the purely-STYLE findings.

As things stand, with CodeChecker settings, I don't see a way for distinct diagnostics from a single checker to have different severity levels. I think it might be possible to do something like this with regular expressions in the codechecker config, though. Perhaps, instead of

"mychecker": [ "doc_url:https://blah-blah-blah/blah-blah", "severity:STYLE" ],

we might have:

"mychecker": [ "doc_url:https://blah-blah-blah/blah-blah", "conditional-severity": [ "match-regex:.*restrict.*", "severity:LOW" ], "severity:STYLE" ],

Not sure what would make the most sense for the config parser, as this format looks like JSON at the top, but values in the JSON look like they are further broken into key/value pairs with some additional custom syntax expectations...

The only other alternative is for me to break the checker into multiple checkers with different severity levels, which costs extra runtime, and also can generate redundant diagnostics (consider a single declaration where both 'const' and 'restrict' are used inconsistently between prototype and definition, for example -- a single checker can emit one diagnostic and one fixit covering both conditions, but multiple checkers cannot). Breaking up the checker also increases code complexity and/or maintenance risk for the checker implementation.

I've had similar cases before that forced me to break checkers up into multiple checkers. Since this came up for me a second time, I thought I might ask...

[bruntib]

Hi,
As you say, currently the severity levels belong to checkers. This is reflected in the database schema design and some other conceptual decisions. I understand the motivation behind this feature request. We had another question earlier about the possibility of assigning severity to reports individually. Unfortunately, these behaviors would bring more complexity and error prone queries, and for this reason we haven't started in this direction. I'm not fully against this request, but I can't see if the current behavior could change in the future. I'll bring this topic up in the team, though.