[LLVMbugs] [Bug 15985] New: false positive logic error with float variable

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=15985

            Bug ID: 15985
           Summary: false positive logic error with float variable
           Product: clang
           Version: trunk
          Hardware: Macintosh
                OS: MacOS X
            Status: NEW
          Severity: normal
          Priority: P
         Component: Static Analyzer
          Assignee: kremenek at apple.com
          Reporter: bugzilla at jwwalker.com
                CC: llvmbugs at cs.uiuc.edu
    Classification: Unclassified

Overview:

The static analyzer reports that a variable is used uninitialized, in a
situation where it can't be.


Steps to reproduce:

Analyze this C++ code:

-------------------------------
#include <vector>

static int Foo( std::vector<int>& things )
{
    int result = 0;
    int blah;

    float maxDist = -10000;

    if (things.empty())
    {
        maxDist = 1;
        blah = 9;
    }

    if (maxDist > 0)
    {
        result = blah + 2;
    }

    return result;
}
-------------------------------


Actual results:

warning: The left operand of '+' is a garbage value
(pointing to the assignment result = blah + 2)


Expected results:

No warnings.


Build date:

clang version 3.4 (trunk 181711)
Target: x86_64-apple-darwin11.4.2
Thread model: posix

Additional information:

Note that if the vector is empty, then blah will have a value assigned to it,
whereas if the vector is not empty, the assignment to result will not be
reached.

If I change the type of maxDist from float to int, the warning goes away.

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