Spurious uninitialized variable warning

[llvmbot]

Bugzilla Link	9079
Resolution	WONTFIX
Resolved on	Jan 31, 2011 13:51
Version	trunk
OS	MacOS X
Attachments	example
Reporter	LLVM Bugzilla Contributor
CC	@tkremenek

Extended Description

If a local is initialized within some 'if' guarded by a condition and later is accessed only if that same condition is true, clang emits a warning.

The case I just hit in my code has structure similar to this:

int x(int y)
{
int value;
if (y != 0) {
value = 0;
}

switch (y) {
case 0:
return 1; // handles the uninitialized case
default:
return value; // can only get here if the value=0 line was executed
}
}

This is probably a duplicate, but this test case may be different enough.

[tkremenek]

This is a control-dependency, which is not modeled by the dataflow analysis.

[lattner]

The compilers uninitialized variable stuff should never catch this case. It should be simple, predictable, and stable across revisions of the compiler. The static analyzer is where the intelligence should go.