[PATCH] D66397: [Diagnostics] Improve -Wxor-used-as-pow

[Aaron Ballman via Phabricator via cfe-commits]

aaron.ballman added inline comments.


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Comment at: lib/Sema/SemaExpr.cpp:11067
+
+  // Do not diagnose 2 ^ 64, but allow special case (2 ^ 64) - 1.
+  if (SubLHS && SubRHS && (LeftSideValue != 2 || RightSideValue != 64))
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aaron.ballman wrote:
> This comment explains what the code does, but not why it does it. Given that we're adding special cases, I think more comments here explaining why this is valuable would be appreciated.
Thank you, the comments helped! But they also raised another question for me. What's special about 2^64? Why not (2^16) - 1 or other common power-of-two values? I would have expected 8, 16, 32, and 64 to be handled similarly.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D66397/new/

https://reviews.llvm.org/D66397