false positive: uninitialized variable (lack of linear constraints)

[llvmbot]

Bugzilla Link	4272
Version	unspecified
OS	MacOS X
Depends On	#2678
Attachments	false postive at while test
Reporter	LLVM Bugzilla Contributor
CC	@tkremenek

Extended Description

Given the attached code, a false positive is reported at the "while".

If the "while" is turned into "bool ignore = ++colnum < numColumns;", the false positive is not reported.

[llvmbot]

assigned to @tkremenek

[tkremenek]

Created an attachment (id=3037) [details]
false postive at while test

Given the attached code, a false positive is reported at the "while".

The problem here is that the analyzer is not tracking the linear constraint that 'i' is initially 'numCellsNeeded - 1'. This depends on implementing PR 2306.

If the "while" is turned into "bool ignore = ++colnum < numColumns;", the false
positive is not reported.

The uninitialized value is still here, it just hasn't been used for anything, so the analyzer isn't flagging a warning. We probably should be flagging an error for any loads of uninitialized values.

The problem here is that the analyzer is not tracking the linear constraint that 'i' is initially 'numCellsNeeded - 1'.