Uninitialized variables check not working well at the moment

[Daniel Marjamäki]

I am rewriting a part of the check for the uninitialized variables and believe that it will be noisy in the near future.

I would prefer that you relax a bit with reporting problems for a week or so.. fixes are on the way.

[Daniel Marjamäki]

I would prefer that you relax a bit with reporting problems for a week or so.. fixes are on the way.

Feel free to report problems that you see now.

It seems to me that most false positives currently in daca@home are caused by;
* variable is initialized in function call. https://trac.cppcheck.net/ticket/10279
* XtSetArg was not configured properly. Should be fixed in git HEAD.

[Paul Fultz]

We should just get rid of checkUninitVar and move all the logic to valueflow.

I created a PR at least to fix the valueFlowUninit tests:

https://github.com/danmar/cppcheck/pull/3262

These tests are useful in checking changes to valueflow. I have a possible fix for #10263 but I want to make sure it wont break the valueFlowUninit tests(as the change might affect them).

[Daniel Marjamäki]

I wanted to rewrite CheckUninitVar::isVariableUsage. It did not rely on AST properly and it was a mess. I think it's so much better now.

I would be happy to get rid of the data flow logic from checkUninitVar.. when we feel that valueFlowUninit is enough. I feel that we should primarily fix false negatives by updating the valueflow.

[Daniel Marjamäki]

there are a lot of false positives in such reports:
http://cppcheck1.osuosl.org:8000/difftoday-uninitvar
http://cppcheck1.osuosl.org:8000/diff-uninitvar

I am looking at these false positives. But help is appreciated.

[Daniel Marjamäki]

There are many bugs that valueFlowUninit fails to detect, for instance for arrays and structs.

[Paul Fultz]

Yea, we shouldn't delete the checkUninit but rather move it to valueflow. Instead of warning about a uninit var, just set valueflow value to uninit.

Although, it would be nice to use the analyzers to find struct members and arrays, but this is quite a bit more work. If we can just move what we currently have, this can help simplify the uninit checking and testing.

[orbitcowboy]

Here is a wrap up of the actual open tickets addressing uninitvar, tested with (https://github.com/danmar/cppcheck/commit/e2d9aaf23b680b17280c3de17d76b117f5c62115 ). I hope this overview complements the rewriting of the checker a bit ...

https://trac.cppcheck.net/ticket/4791 False negative: uninitialized nested struct not detected
--language=c++ works, but --language=c is not working

https://trac.cppcheck.net/ticket/9313 false negative: uninitvar
- False negative still present

https://trac.cppcheck.net/ticket/9735 false negative: uninitvar (bit field)
- False negative still present

https://trac.cppcheck.net/ticket/4526 false negative: usage of uninitialized pointer with std::cin
- False negative still present

https://trac.cppcheck.net/ticket/6325 false negative: uninitialized variable usage (write, posix)
- False negative still present

https://trac.cppcheck.net/ticket/6475 false negative: uninitialized variable usage not detected - uninitialized int passed via reference
- False negative still present

https://trac.cppcheck.net/ticket/6517 false negative: (error) Uninitialized variable - conditional intialization in if-clause
- False negative still present

https://trac.cppcheck.net/ticket/6577 Detect pointer to uninitialised memory with clock_settime() reopened
- False negative still present

https://trac.cppcheck.net/ticket/6597 false negative: uninitialized variable usage not detected (ValueFlow , multi variables)
- False negative still present for sample from comment:4

https://trac.cppcheck.net/ticket/6987 false negative: (error) Uninitialized variable (std::setiosflags)
- False negative still present

https://trac.cppcheck.net/ticket/6621 false negative: uninitialized variable usage not detected (std::pair)
- False negative still present

https://trac.cppcheck.net/ticket/6633 false negative: uninitialized variable usage not detected new uninitvar
- False negative still present

https://trac.cppcheck.net/ticket/6933 false negative: (error) Uninitialized variable (using uninitialized variable in class instantiation)
- More info needed due to open discussion

https://trac.cppcheck.net/ticket/8046 false negative: uninitalized variable (union) new uninitvar valueflow
- False negative still present

https://trac.cppcheck.net/ticket/8048 Missing type declaration in C triggers uninitvar new uninitvar
- More info needed due to open discussion

https://trac.cppcheck.net/ticket/8134 Uninitialized variable is not caught when variable not assigned any value in if condition
- False negative still present

https://trac.cppcheck.net/ticket/8135 Uninitialized variable is not caught when variable not assigned any value in switch/case condition
- False negative still present

https://trac.cppcheck.net/ticket/8163 Unitialized variable not caught by CPPCheck if function arguments used in comparison
- False negative still present

https://trac.cppcheck.net/ticket/8446 false negative: (error) Uninitialized variable: s.x
- False negative still present

https://trac.cppcheck.net/ticket/9107 false negative: conditional uninitvar (subfunction call) - False negative still present

https://trac.cppcheck.net/ticket/9303 FP: "uninitvar" reported after lambda expression
- False positive still present

https://trac.cppcheck.net/ticket/9316 false negative: uninitvar (local array) new uninitvar
- False negative still present

https://trac.cppcheck.net/ticket/9346 False negative due to missing configuration for struct timeval
- False negative still present

https://trac.cppcheck.net/ticket/9455 false negative: uninit iterator not detected
- False negative still present

https://trac.cppcheck.net/ticket/9484 false negative: uninitvar (passing address of uninitialized buffer to subfunction that reads buffer)
- False negative still present

https://trac.cppcheck.net/ticket/9772 FP uninitvar: in cppcheck 2.1
- False positive still present

https://trac.cppcheck.net/ticket/9924 false negative: uninitvar
- False negative still present

https://trac.cppcheck.net/ticket/9953 false positive: uninitvar
- False positive still present

https://trac.cppcheck.net/ticket/9970 false negative: uninitvar
- False negative still present

https://trac.cppcheck.net/ticket/10291 false negative: uninitvar
- False negative still present

https://trac.cppcheck.net/ticket/10292 false negative: uninitvar
- False negative still present