tree 20f6b66320ee0e421f33e6e54eab73db57932762
parent 7decfe83555385bebac2e4bed35035f3b0f4d666
author Richard Trieu <rtrieu@google.com> 1571446643 +0000
committer Richard Trieu <rtrieu@google.com> 1571446643 +0000

New tautological warning for bitwise-or with non-zero constant always true.

Taking a value and the bitwise-or it with a non-zero constant will always
result in a non-zero value. In a boolean context, this is always true.

if (x | 0x4) {}  // always true, intended '&'

This patch creates a new warning group -Wtautological-bitwise-compare for this
warning. It also moves in the existing tautological bitwise comparisons into
this group. A few other changes were needed to the CFGBuilder so that all bool
contexts would be checked. The warnings in -Wtautological-bitwise-compare will
be off by default due to using the CFG.

Fixes: https://bugs.llvm.org/show_bug.cgi?id=42666
Differential Revision: https://reviews.llvm.org/D66046


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@375318 91177308-0d34-0410-b5e6-96231b3b80d8