[PATCH] D85256: Add -Wtautological-value-range-compare warning.

[Richard Smith - zygoloid via Phabricator via cfe-commits]

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This warning diagnoses cases where an expression is compared to a
constant, and the comparison is tautological due to the form of the
expression (but not merely due to its type). This applies in cases such
as comparisons of bit-fields and the result of bit-masks.

The new warning is added to the Clang diagnostic group
-Wtautological-constant-in-range-compare but not to the
formerly-equivalent GCC-compatibility diagnostic group -Wtype-limits,
which retains its old meaning of diagnosing only tautological
comparisons to extremal values of a type (eg, int > INT_MAX).


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D85256

Files:
  clang/include/clang/Basic/DiagnosticGroups.td
  clang/include/clang/Basic/DiagnosticSemaKinds.td
  clang/lib/Sema/SemaChecking.cpp
  clang/test/Sema/tautological-constant-compare.c

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