Don't produce "comparison is always (true|false)" warnings when the
comparison itself is a constant expression. Fixes PR7536.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@126057 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaChecking.cpp b/lib/Sema/SemaChecking.cpp
index 2cddac5..5566654 100644
--- a/lib/Sema/SemaChecking.cpp
+++ b/lib/Sema/SemaChecking.cpp
@@ -2581,7 +2581,11 @@
   // We don't do anything special if this isn't an unsigned integral
   // comparison:  we're only interested in integral comparisons, and
   // signed comparisons only happen in cases we don't care to warn about.
-  if (!T->hasUnsignedIntegerRepresentation())
+  //
+  // We also don't care about value-dependent expressions or expressions
+  // whose result is a constant.
+  if (!T->hasUnsignedIntegerRepresentation()
+      || E->isValueDependent() || E->isIntegerConstantExpr(S.Context))
     return AnalyzeImpConvsInComparison(S, E);
 
   Expr *lex = E->getLHS()->IgnoreParenImpCasts();