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UselessCode FP #91

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mebigfatguy opened this issue Dec 23, 2016 · 1 comment
Open

UselessCode FP #91

mebigfatguy opened this issue Dec 23, 2016 · 1 comment
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@mebigfatguy
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the useless code detector fires when a condition is known only from an assert. It should ignore asserts as pre-conditions.

ie

       assert cmp <= 0;

        if (cmp < 0)
        {
            break; 
        }
        else if (cmp == 0)   // <-- UC Fires here
        {
             ....
        }
@jsotuyod jsotuyod added the bug label Dec 23, 2016
KengoTODA added a commit to KengoTODA/spotbugs that referenced this issue Feb 4, 2017
@KengoTODA
refs spotbugs#91: reproduce reported prooblem
b89e914
KengoTODA added a commit to KengoTODA/spotbugs that referenced this issue Feb 4, 2017
@KengoTODA
close spotbugs#91: assume assertions are disabled to fix problem
b5b03c1
KengoTODA added a commit to KengoTODA/spotbugs that referenced this issue Feb 5, 2017
@KengoTODA
refs spotbugs#91: extract logic to share logic
e0b7519
KengoTODA added a commit to KengoTODA/spotbugs that referenced this issue Feb 5, 2017
@KengoTODA
refs spotbugs#91: create CFGIgnoringAssert to let specific detector…
362c9fb 
… to ignore assert

but this approach failed due to AnalysisCache problem:
that cache expect that we have only one CFG for each descriptor
so this branch has failed tests like below:

```
  Error pruning normal return edges for unconditionally throwing methods for UselessCode.method(I)V
    edu.umd.cs.findbugs.ba.DataflowAnalysisException: not enough values on stack: access=1, avail=0
      At edu.umd.cs.findbugs.ba.Frame.getStackValue(Frame.java:247)
```
@Maaartinus
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I slightly disagree.

With assert, two versions of the code to be analyzed at the same time. When something makes sense in either version, then it's not redundant.

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@mebigfatguy @jsotuyod @Maaartinus