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| author | Richard Trieu <rtrieu@google.com> | 2019-10-19 00:57:23 +0000 |
|---|---|---|
| committer | Richard Trieu <rtrieu@google.com> | 2019-10-19 00:57:23 +0000 |
| commit | a27ae544f30bfd7dc765b8a6080190d39d893b99 (patch) | |
| tree | 20f6b66320ee0e421f33e6e54eab73db57932762 /docs | |
| parent | 7decfe83555385bebac2e4bed35035f3b0f4d666 (diff) | |
| download | clang-a27ae544f30bfd7dc765b8a6080190d39d893b99.tar.gz | |
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
Diffstat (limited to 'docs')
| -rw-r--r-- | docs/ReleaseNotes.rst | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/docs/ReleaseNotes.rst b/docs/ReleaseNotes.rst index 37dbac3090..41dea299e6 100644 --- a/docs/ReleaseNotes.rst +++ b/docs/ReleaseNotes.rst @@ -56,6 +56,11 @@ Improvements to Clang's diagnostics - -Wtautological-compare for self comparisons and -Wtautological-overlap-compare will now look through member and array access to determine if two operand expressions are the same. +- -Wtautological-bitwise-compare is a new warning group. This group has the + current warning which diagnoses the tautological comparison of a bitwise + operation and a constant. The group also has the new warning which diagnoses + when a bitwise-or with a non-negative value is converted to a bool, since + that bool will always be true. Non-comprehensive list of changes in this release ------------------------------------------------- |