[PATCH] D66046: Add new tautological compare warning for bitwise-or with a non-zero constant

[Nico Weber via Phabricator via cfe-commits]

thakis added inline comments.


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Comment at: include/clang/Basic/DiagnosticSemaKinds.td:8161
+  "bitwise or with non-zero value always evaluates to true">,
+  InGroup<TautologicalBitwiseCompare>, DefaultIgnore;
 def warn_tautological_overlap_comparison : Warning<
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rtrieu wrote:
> jfb wrote:
> > rtrieu wrote:
> > > jfb wrote:
> > > > Why default ignore?
> > > This warning, like the tautological overlap warning, uses the CFG.  CFG-based analysis are typically excluded from being default warnings due to the extra work of construction the CFG.
> > Can you say so in the commit message?
> Updated patch description.
It addresses why it's not on-by-default, but not why it's not in -Wall. As I said 2 comments ago, we've kind of retconned -Wall to mean "needs CFG" at times.


Repository:
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  https://reviews.llvm.org/D66046/new/

https://reviews.llvm.org/D66046