http://llvm.org/bugs/show_bug.cgi?id=15891
Bug ID: 15891
Summary: False positives
Product: clang
Version: unspecified
Hardware: Macintosh
OS: MacOS X
Status: NEW
Severity: normal
Priority: P
Component: Static Analyzer
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected]
Classification: Unclassified
I'm not sure which version of clang is in Xcode 4.6.2. It generates two false
positives in the following:
#include <iostream>
int Test1(unsigned int x);
void Test2(int x, int y);
int main(int argc, const char * argv[])
{
Test2(0,100);
return Test1(51);
}
int Test1(unsigned int x)
{
int a;
switch (x & 0x3)
{
case 0: a = 1; break;
case 1: a = 2; break;
case 2: a = 3; break;
case 3: a = 4; break;
}
std::cout << "Test 1";
return a;
// False positive Undefined or garbage value returned to caller, but x&0x3 can
be only 0,1,2, or 3. Making case 3 default: eliminates the false positive.
}
void Test2(int x, int y)
{
int n = 10;
int a[100];
for (int i = 0; i < y; i++)
a[i] = 0;
for (int i = 0; i < 50; i++) {
int w = i;
if (w > a[x?0:(i / n)]) a[x?0:(i / n)] = w;
// The right operand of '>' is a garbage value
// moving the array index into a local or moving y into a local eliminates the
false positive.
}
std::cout << "Test 2\n";
}
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