It also caused all the sanitizer builds to fail.  For example:

http://lab.llvm.org:8011/builders/sanitizer-ppc64le-linux/builds/3654

/home/buildbots/ppc64le-sanitizer/sanitizer-ppc64le/build/llvm/utils/TableGen/X86RecognizableInstr.cpp:789:21: error: comparison of constant -1 with expression of type 'llvm::X86Disassembler::OpcodeType' is always true [-Werror,-Wtautological-constant-out-of-range-compare]
  assert(opcodeType != (OpcodeType)-1 &&
         ~~~~~~~~~~ ^  ~~~~~~~~~~~~~~
/usr/include/assert.h:86:5: note: expanded from macro 'assert'
  ((expr)                                                               \
    ^~~~
1 error generated.
utils/TableGen/CMakeFiles/obj.llvm-tblgen.dir/build.make:1022: recipe for target 'utils/TableGen/CMakeFiles/obj.llvm-tblgen.dir/X86RecognizableInstr.cpp.o' failed make[3]: *** [utils/TableGen/CMakeFiles/obj.llvm-tblgen.dir/X86RecognizableInstr.cpp.o] Error 1



And there are lots more warnings (which are flagged as errors for the sanitizer builds) when I run a build by hand. For example:

[4001/4008] Building CXX object tools/clang/tools/libclang/CMakeFiles/libclang.dir/CIndex.cpp.o In file included from /home/seurer/llvm/llvm-test2/tools/clang/tools/libclang/CIndex.cpp:23: In file included from /home/seurer/llvm/llvm-test2/tools/clang/tools/libclang/CursorVisitor.h:16: In file included from /home/seurer/llvm/llvm-test2/tools/clang/include/clang/AST/DeclVisitor.h:19: In file included from /home/seurer/llvm/llvm-test2/tools/clang/include/clang/AST/DeclCXX.h:21: In file included from /home/seurer/llvm/llvm-test2/tools/clang/include/clang/AST/Attr.h:19: /home/seurer/llvm/llvm-test2/tools/clang/include/clang/AST/Expr.h:2745:17: warning: comparison of constant -1 with expression of type 'const clang::CastKind' is always true [-Wtautological-constant-out-of-range-compare]
    assert(kind != CK_Invalid && "creating cast with invalid cast kind");
           ~~~~ ^  ~~~~~~~~~~
/usr/include/assert.h:89:5: note: expanded from macro 'assert'
  ((expr)                                                               \
    ^~~~


On 12/08/2017 10:54 AM, Hans Wennborg via cfe-commits wrote:
Author: hans
Date: Fri Dec  8 08:54:08 2017
New Revision: 320162

URL: http://llvm.org/viewvc/llvm-project?rev=320162&view=rev
Log:
Revert "Unify implementation of our two different flavours of 
-Wtautological-compare."

Unify implementation of our two different flavours of -Wtautological-compare.

In so doing, fix a handful of remaining bugs where we would report false
positives or false negatives if we promote a signed value to an unsigned type
for the comparison.

This caused a new warning in Chromium:

../../base/trace_event/trace_log.cc:1545:29: error: comparison of constant 64
with expression of type 'unsigned int' is always true
[-Werror,-Wtautological-constant-out-of-range-compare]
   DCHECK(handle.event_index < TraceBufferChunk::kTraceBufferChunkSize);
          ~~~~~~~~~~~~~~~~~~ ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The 'unsigned int' is really a 6-bit bitfield, which is why it's always
less than 64.

I thought we didn't use to warn (with out-of-range-compare) when comparing
against the boundaries of a type?

Modified:
     cfe/trunk/lib/Sema/SemaChecking.cpp
     cfe/trunk/test/Sema/tautological-constant-compare.c
     cfe/trunk/test/Sema/tautological-constant-enum-compare.c
     cfe/trunk/test/SemaCXX/compare.cpp

Modified: cfe/trunk/lib/Sema/SemaChecking.cpp
URL: 
http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaChecking.cpp?rev=320162&r1=320161&r2=320162&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaChecking.cpp (original)
+++ cfe/trunk/lib/Sema/SemaChecking.cpp Fri Dec  8 08:54:08 2017
@@ -8662,113 +8662,54 @@ static bool isKnownToHaveUnsignedValue(E
  }
namespace {
-/// The promoted range of values of a type. In general this has the
-/// following structure:
-///
-///     |-----------| . . . |-----------|
-///     ^           ^       ^           ^
-///    Min       HoleMin  HoleMax      Max
-///
-/// ... where there is only a hole if a signed type is promoted to unsigned
-/// (in which case Min and Max are the smallest and largest representable
-/// values).
-struct PromotedRange {
-  // Min, or HoleMax if there is a hole.
-  llvm::APSInt PromotedMin;
-  // Max, or HoleMin if there is a hole.
-  llvm::APSInt PromotedMax;
-
-  PromotedRange(IntRange R, unsigned BitWidth, bool Unsigned) {
-    if (R.Width == 0)
-      PromotedMin = PromotedMax = llvm::APSInt(BitWidth, Unsigned);
-    else {
-      PromotedMin = llvm::APSInt::getMinValue(R.Width, R.NonNegative)
-                        .extOrTrunc(BitWidth);
-      PromotedMin.setIsUnsigned(Unsigned);
-
-      PromotedMax = llvm::APSInt::getMaxValue(R.Width, R.NonNegative)
-                        .extOrTrunc(BitWidth);
-      PromotedMax.setIsUnsigned(Unsigned);
-    }
-  }
- // Determine whether this range is contiguous (has no hole).
-  bool isContiguous() const { return PromotedMin <= PromotedMax; }
+enum class LimitType {
+  Max = 1U << 0U,  // e.g. 32767 for short
+  Min = 1U << 1U,  // e.g. -32768 for short
+  Both = Max | Min // When the value is both the Min and the Max limit at the
+                   // same time; e.g. in C++, A::a in enum A { a = 0 };
+};
- // Where a constant value is within the range.
-  enum ComparisonResult {
-    LT = 0x1,
-    LE = 0x2,
-    GT = 0x4,
-    GE = 0x8,
-    EQ = 0x10,
-    NE = 0x20,
-    InRangeFlag = 0x40,
-
-    Less = LE | LT | NE,
-    Min = LE | InRangeFlag,
-    InRange = InRangeFlag,
-    Max = GE | InRangeFlag,
-    Greater = GE | GT | NE,
+} // namespace
- OnlyValue = LE | GE | EQ | InRangeFlag,
-    InHole = NE
-  };
+/// Checks whether Expr 'Constant' may be the
+/// std::numeric_limits<>::max() or std::numeric_limits<>::min()
+/// of the Expr 'Other'. If true, then returns the limit type (min or max).
+/// The Value is the evaluation of Constant
+static llvm::Optional<LimitType> IsTypeLimit(Sema &S, Expr *Constant,
+                                             Expr *Other,
+                                             const llvm::APSInt &Value) {
+  if (IsEnumConstOrFromMacro(S, Constant))
+    return llvm::Optional<LimitType>();
- ComparisonResult compare(const llvm::APSInt &Value) const {
-    assert(Value.getBitWidth() == PromotedMin.getBitWidth() &&
-           Value.isUnsigned() == PromotedMin.isUnsigned());
-    if (!isContiguous()) {
-      assert(Value.isUnsigned() && "discontiguous range for signed compare");
-      if (Value.isMinValue()) return Min;
-      if (Value.isMaxValue()) return Max;
-      if (Value >= PromotedMin) return InRange;
-      if (Value <= PromotedMax) return InRange;
-      return InHole;
-    }
+  if (isKnownToHaveUnsignedValue(Other) && Value == 0)
+    return LimitType::Min;
- switch (llvm::APSInt::compareValues(Value, PromotedMin)) {
-    case -1: return Less;
-    case 0: return PromotedMin == PromotedMax ? OnlyValue : Min;
-    case 1:
-      switch (llvm::APSInt::compareValues(Value, PromotedMax)) {
-      case -1: return InRange;
-      case 0: return Max;
-      case 1: return Greater;
-      }
-    }
+  // TODO: Investigate using GetExprRange() to get tighter bounds
+  // on the bit ranges.
+  QualType OtherT = Other->IgnoreParenImpCasts()->getType();
+  if (const auto *AT = OtherT->getAs<AtomicType>())
+    OtherT = AT->getValueType();
- llvm_unreachable("impossible compare result");
-  }
+  IntRange OtherRange = IntRange::forValueOfType(S.Context, OtherT);
+  if (Other->isKnownToHaveBooleanValue())
+    OtherRange = IntRange::forBoolType();
- static llvm::Optional<bool> constantValue(BinaryOperatorKind Op,
-                                            ComparisonResult R,
-                                            bool ConstantOnRHS) {
-    ComparisonResult TrueFlag, FalseFlag;
-    if (Op == BO_EQ) {
-      TrueFlag = EQ;
-      FalseFlag = NE;
-    } else if (Op == BO_NE) {
-      TrueFlag = NE;
-      FalseFlag = EQ;
-    } else {
-      if ((Op == BO_LT || Op == BO_GE) ^ ConstantOnRHS) {
-        TrueFlag = LT;
-        FalseFlag = GE;
-      } else {
-        TrueFlag = GT;
-        FalseFlag = LE;
-      }
-      if (Op == BO_GE || Op == BO_LE)
-        std::swap(TrueFlag, FalseFlag);
-    }
-    if (R & TrueFlag)
-      return true;
-    if (R & FalseFlag)
-      return false;
-    return llvm::None;
-  }
-};
+  // Special-case for C++ for enum with one enumerator with value of 0.
+  if (OtherRange.Width == 0)
+    return Value == 0 ? LimitType::Both : llvm::Optional<LimitType>();
+
+  if (llvm::APSInt::isSameValue(
+          llvm::APSInt::getMaxValue(OtherRange.Width, OtherRange.NonNegative),
+          Value))
+    return LimitType::Max;
+
+  if (llvm::APSInt::isSameValue(
+          llvm::APSInt::getMinValue(OtherRange.Width, OtherRange.NonNegative),
+          Value))
+    return LimitType::Min;
+
+  return llvm::None;
  }
static bool HasEnumType(Expr *E) {
@@ -8806,47 +8747,29 @@ static bool CheckTautologicalComparison(
    if (S.inTemplateInstantiation() || !E->isRelationalOp())
      return false;
- if (IsEnumConstOrFromMacro(S, Constant))
-    return false;
-
-  Expr *OriginalOther = Other;
+  BinaryOperatorKind Op = E->getOpcode();
- Constant = Constant->IgnoreParenImpCasts();
-  Other = Other->IgnoreParenImpCasts();
-
-  // TODO: Investigate using GetExprRange() to get tighter bounds
-  // on the bit ranges.
-  QualType OtherT = Other->getType();
-  if (const auto *AT = OtherT->getAs<AtomicType>())
-    OtherT = AT->getValueType();
-  IntRange OtherRange = IntRange::forValueOfType(S.Context, OtherT);
-
-  // Whether we're treating Other as being a bool because of the form of
-  // expression despite it having another type (typically 'int' in C).
-  bool OtherIsBooleanDespiteType =
-      !OtherT->isBooleanType() && Other->isKnownToHaveBooleanValue();
-  if (OtherIsBooleanDespiteType)
-    OtherRange = IntRange::forBoolType();
-
-  if (FieldDecl *Bitfield = Other->getSourceBitField())
-    if (!Bitfield->getBitWidth()->isValueDependent())
-      OtherRange.Width =
-          std::min(Bitfield->getBitWidthValue(S.Context), OtherRange.Width);
-
-  // Check whether the constant value can be represented in OtherRange. Bail
-  // out if so; this isn't an out-of-range comparison.
-  PromotedRange OtherPromotedRange(OtherRange, Value.getBitWidth(),
-                                   Value.isUnsigned());
-
-  auto Cmp = OtherPromotedRange.compare(Value);
-  if (Cmp != PromotedRange::Min && Cmp != PromotedRange::Max &&
-      Cmp != PromotedRange::OnlyValue)
+  QualType OType = Other->IgnoreParenImpCasts()->getType();
+  if (!OType->isIntegerType())
      return false;
- auto Result = PromotedRange::constantValue(E->getOpcode(), Cmp, RhsConstant);
-  if (!Result)
+  // Determine which limit (min/max) the constant is, if either.
+  llvm::Optional<LimitType> ValueType = IsTypeLimit(S, Constant, Other, Value);
+  if (!ValueType)
      return false;
+ bool ConstIsLowerBound = (Op == BO_LT || Op == BO_LE) ^ RhsConstant;
+  bool ResultWhenConstEqualsOther = (Op == BO_LE || Op == BO_GE);
+  if (ValueType != LimitType::Both) {
+    bool ResultWhenConstNeOther =
+        ConstIsLowerBound ^ (ValueType == LimitType::Max);
+    if (ResultWhenConstEqualsOther != ResultWhenConstNeOther)
+      return false; // The comparison is not tautological.
+  } else if (ResultWhenConstEqualsOther == ConstIsLowerBound)
+    return false; // The comparison is not tautological.
+
+  const bool Result = ResultWhenConstEqualsOther;
+
    // Should be enough for uint128 (39 decimal digits)
    SmallString<64> PrettySourceValue;
    llvm::raw_svector_ostream OS(PrettySourceValue);
@@ -8859,20 +8782,20 @@ static bool CheckTautologicalComparison(
      S.DiagRuntimeBehavior(
        E->getOperatorLoc(), E,
        S.PDiag(diag::warn_tautological_bool_compare)
-          << OS.str() << classifyConstantValue(Constant)
-          << OtherT << !OtherT->isBooleanType() << *Result
+          << OS.str() << classifyConstantValue(Constant->IgnoreParenImpCasts())
+          << OType << !OType->isBooleanType() << Result
            << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange());
      return true;
    }
- unsigned Diag = (isKnownToHaveUnsignedValue(OriginalOther) && Value == 0)
-                      ? (HasEnumType(OriginalOther)
+  unsigned Diag = (isKnownToHaveUnsignedValue(Other) && Value == 0)
+                      ? (HasEnumType(Other)
                               ? diag::warn_unsigned_enum_always_true_comparison
                               : diag::warn_unsigned_always_true_comparison)
                        : diag::warn_tautological_constant_compare;
S.Diag(E->getOperatorLoc(), Diag)
-      << RhsConstant << OtherT << E->getOpcodeStr() << OS.str() << *Result
+      << RhsConstant << OType << E->getOpcodeStr() << OS.str() << Result
        << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
return true;
@@ -8894,6 +8817,7 @@ static bool DiagnoseOutOfRangeComparison
    QualType OtherT = Other->getType();
    if (const auto *AT = OtherT->getAs<AtomicType>())
      OtherT = AT->getValueType();
+
    IntRange OtherRange = IntRange::forValueOfType(S.Context, OtherT);
// Whether we're treating Other as being a bool because of the form of
@@ -8903,25 +8827,91 @@ static bool DiagnoseOutOfRangeComparison
    if (OtherIsBooleanDespiteType)
      OtherRange = IntRange::forBoolType();
- if (FieldDecl *Bitfield = Other->getSourceBitField())
-    if (!Bitfield->getBitWidth()->isValueDependent())
-      OtherRange.Width =
-          std::min(Bitfield->getBitWidthValue(S.Context), OtherRange.Width);
+  unsigned OtherWidth = OtherRange.Width;
+
+  BinaryOperatorKind op = E->getOpcode();
+  bool IsTrue = true;
// Check whether the constant value can be represented in OtherRange. Bail
    // out if so; this isn't an out-of-range comparison.
-  PromotedRange OtherPromotedRange(OtherRange, Value.getBitWidth(),
-                                   Value.isUnsigned());
-  auto Cmp = OtherPromotedRange.compare(Value);
-
-  // If Value is in the range of possible Other values, this comparison is not
-  // tautological.
-  if (Cmp & PromotedRange::InRangeFlag)
-    return false;
+  {
+    QualType ConstantT = Constant->getType();
+    QualType CommonT = E->getLHS()->getType();
- auto IsTrue = PromotedRange::constantValue(E->getOpcode(), Cmp, RhsConstant);
-  if (!IsTrue)
-    return false;
+    if (S.Context.hasSameUnqualifiedType(OtherT, ConstantT) &&
+        !OtherIsBooleanDespiteType)
+      return false;
+    assert((OtherT->isIntegerType() && ConstantT->isIntegerType()) &&
+           "comparison with non-integer type");
+
+    bool ConstantSigned = ConstantT->isSignedIntegerType();
+    bool CommonSigned = CommonT->isSignedIntegerType();
+
+    bool EqualityOnly = false;
+
+    if (CommonSigned) {
+      // The common type is signed, therefore no signed to unsigned conversion.
+      if (!OtherRange.NonNegative) {
+        // Check that the constant is representable in type OtherT.
+        if (ConstantSigned) {
+          if (OtherWidth >= Value.getMinSignedBits())
+            return false;
+        } else { // !ConstantSigned
+          if (OtherWidth >= Value.getActiveBits() + 1)
+            return false;
+        }
+      } else { // !OtherSigned
+               // Check that the constant is representable in type OtherT.
+        // Negative values are out of range.
+        if (ConstantSigned) {
+          if (Value.isNonNegative() && OtherWidth >= Value.getActiveBits())
+            return false;
+        } else { // !ConstantSigned
+          if (OtherWidth >= Value.getActiveBits())
+            return false;
+        }
+      }
+    } else { // !CommonSigned
+      if (OtherRange.NonNegative) {
+        if (OtherWidth >= Value.getActiveBits())
+          return false;
+      } else { // OtherSigned
+        assert(!ConstantSigned &&
+               "Two signed types converted to unsigned types.");
+        // Check to see if the constant is representable in OtherT.
+        if (OtherWidth > Value.getActiveBits())
+          return false;
+        // Check to see if the constant is equivalent to a negative value
+        // cast to CommonT.
+        if (S.Context.getIntWidth(ConstantT) ==
+                S.Context.getIntWidth(CommonT) &&
+            Value.isNegative() && Value.getMinSignedBits() <= OtherWidth)
+          return false;
+        // The constant value rests between values that OtherT can represent
+        // after conversion.  Relational comparison still works, but equality
+        // comparisons will be tautological.
+        EqualityOnly = true;
+      }
+    }
+
+    bool PositiveConstant = !ConstantSigned || Value.isNonNegative();
+
+    if (op == BO_EQ || op == BO_NE) {
+      IsTrue = op == BO_NE;
+    } else if (EqualityOnly) {
+      return false;
+    } else if (RhsConstant) {
+      if (op == BO_GT || op == BO_GE)
+        IsTrue = !PositiveConstant;
+      else // op == BO_LT || op == BO_LE
+        IsTrue = PositiveConstant;
+    } else {
+      if (op == BO_LT || op == BO_LE)
+        IsTrue = !PositiveConstant;
+      else // op == BO_GT || op == BO_GE
+        IsTrue = PositiveConstant;
+    }
+  }
// If this is a comparison to an enum constant, include that
    // constant in the diagnostic.
@@ -8940,7 +8930,7 @@ static bool DiagnoseOutOfRangeComparison
      E->getOperatorLoc(), E,
      S.PDiag(diag::warn_out_of_range_compare)
          << OS.str() << classifyConstantValue(Constant)
-        << OtherT << OtherIsBooleanDespiteType << *IsTrue
+        << OtherT << OtherIsBooleanDespiteType << IsTrue
          << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange());
return true;

Modified: cfe/trunk/test/Sema/tautological-constant-compare.c
URL: 
http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/tautological-constant-compare.c?rev=320162&r1=320161&r2=320162&view=diff
==============================================================================
--- cfe/trunk/test/Sema/tautological-constant-compare.c (original)
+++ cfe/trunk/test/Sema/tautological-constant-compare.c Fri Dec  8 08:54:08 2017
@@ -94,17 +94,15 @@ int main()
    if (-32768 >= s)
        return 0;
- // Note: both sides are promoted to unsigned long prior to the comparison, so
-  // it is perfectly possible for a short to compare greater than 32767UL.
    if (s == 32767UL)
        return 0;
    if (s != 32767UL)
        return 0;
    if (s < 32767UL)
        return 0;
-  if (s <= 32767UL)
+  if (s <= 32767UL) // expected-warning {{comparison 'short' <= 32767 is 
always true}}
        return 0;
-  if (s > 32767UL)
+  if (s > 32767UL) // expected-warning {{comparison 'short' > 32767 is always 
false}}
        return 0;
    if (s >= 32767UL)
        return 0;
@@ -113,66 +111,13 @@ int main()
        return 0;
    if (32767UL != s)
        return 0;
-  if (32767UL < s)
+  if (32767UL < s) // expected-warning {{comparison 32767 < 'short' is always 
false}}
        return 0;
    if (32767UL <= s)
        return 0;
    if (32767UL > s)
        return 0;
-  if (32767UL >= s)
-      return 0;
-
-  if (s == 0UL)
-      return 0;
-  if (s != 0UL)
-      return 0;
-  if (s < 0UL) // expected-warning {{comparison of unsigned expression < 0 is 
always false}}
-      return 0;
-  if (s <= 0UL)
-      return 0;
-  if (s > 0UL)
-      return 0;
-  if (s >= 0UL) // expected-warning {{comparison of unsigned expression >= 0 
is always true}}
-      return 0;
-
-  if (0UL == s)
-      return 0;
-  if (0UL != s)
-      return 0;
-  if (0UL < s)
-      return 0;
-  if (0UL <= s) // expected-warning {{comparison of 0 <= unsigned expression 
is always true}}
-      return 0;
-  if (0UL > s) // expected-warning {{comparison of 0 > unsigned expression is 
always false}}
-      return 0;
-  if (0UL >= s)
-      return 0;
-
-  enum { ULONG_MAX = (2UL * (unsigned long)__LONG_MAX__ + 1UL) };
-  if (s == 2UL * (unsigned long)__LONG_MAX__ + 1UL)
-      return 0;
-  if (s != 2UL * (unsigned long)__LONG_MAX__ + 1UL)
-      return 0;
-  if (s < 2UL * (unsigned long)__LONG_MAX__ + 1UL)
-      return 0;
-  if (s <= 2UL * (unsigned long)__LONG_MAX__ + 1UL) // expected-warning-re 
{{comparison 'short' <= {{.*}} is always true}}
-      return 0;
-  if (s > 2UL * (unsigned long)__LONG_MAX__ + 1UL) // expected-warning-re 
{{comparison 'short' > {{.*}} is always false}}
-      return 0;
-  if (s >= 2UL * (unsigned long)__LONG_MAX__ + 1UL)
-      return 0;
-
-  if (2UL * (unsigned long)__LONG_MAX__ + 1UL == s)
-      return 0;
-  if (2UL * (unsigned long)__LONG_MAX__ + 1UL != s)
-      return 0;
-  if (2UL * (unsigned long)__LONG_MAX__ + 1UL < s) // expected-warning-re 
{{comparison {{.*}} < 'short' is always false}}
-      return 0;
-  if (2UL * (unsigned long)__LONG_MAX__ + 1UL <= s)
-      return 0;
-  if (2UL * (unsigned long)__LONG_MAX__ + 1UL > s)
-      return 0;
-  if (2UL * (unsigned long)__LONG_MAX__ + 1UL >= s) // expected-warning-re 
{{comparison {{.*}} >= 'short' is always true}}
+  if (32767UL >= s) // expected-warning {{comparison 32767 >= 'short' is 
always true}}
        return 0;
// FIXME: assumes two's complement
@@ -336,6 +281,8 @@ int main()
    if (0 >= s)
      return 0;
+ // However the comparison with 0U would warn
+
    unsigned short us = value();
#ifdef TEST

Modified: cfe/trunk/test/Sema/tautological-constant-enum-compare.c
URL: 
http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/tautological-constant-enum-compare.c?rev=320162&r1=320161&r2=320162&view=diff
==============================================================================
--- cfe/trunk/test/Sema/tautological-constant-enum-compare.c (original)
+++ cfe/trunk/test/Sema/tautological-constant-enum-compare.c Fri Dec  8 
08:54:08 2017
@@ -9,96 +9,78 @@ int main() {
#ifdef SILENCE
    // expected-no-diagnostics
-#else
-  // If we promote to unsigned, it doesn't matter whether the enum's underlying
-  // type was signed.
-  if (a < 0U) // expected-warning {{comparison of unsigned enum expression < 0 
is always false}}
-    return 0;
-  if (0U >= a)
-    return 0;
-  if (a > 0U)
-    return 0;
-  if (0U <= a) // expected-warning {{comparison of 0 <= unsigned enum 
expression is always true}}
-    return 0;
-  if (a <= 0U)
-    return 0;
-  if (0U > a) // expected-warning {{comparison of 0 > unsigned enum expression 
is always false}}
-    return 0;
-  if (a >= 0U) // expected-warning {{comparison of unsigned enum expression >= 
0 is always true}}
-    return 0;
-  if (0U < a)
-    return 0;
+#endif
- if (a < 4294967295U)
+#ifdef UNSIGNED
+#ifndef SILENCE
+  if (a < 0) // expected-warning {{comparison of unsigned enum expression < 0 
is always false}}
      return 0;
-  if (4294967295U >= a) // expected-warning {{comparison 4294967295 >= 'enum 
A' is always true}}
+  if (0 >= a)
      return 0;
-  if (a > 4294967295U) // expected-warning {{comparison 'enum A' > 4294967295 
is always false}}
+  if (a > 0)
      return 0;
-  if (4294967295U <= a)
+  if (0 <= a) // expected-warning {{comparison of 0 <= unsigned enum 
expression is always true}}
      return 0;
-  if (a <= 4294967295U) // expected-warning {{comparison 'enum A' <= 
4294967295 is always true}}
+  if (a <= 0)
      return 0;
-  if (4294967295U > a)
+  if (0 > a) // expected-warning {{comparison of 0 > unsigned enum expression 
is always false}}
      return 0;
-  if (a >= 4294967295U)
+  if (a >= 0) // expected-warning {{comparison of unsigned enum expression >= 
0 is always true}}
      return 0;
-  if (4294967295U < a) // expected-warning {{comparison 4294967295 < 'enum A' 
is always false}}
+  if (0 < a)
      return 0;
- if (a < 2147483647U)
+  if (a < 0U) // expected-warning {{comparison of unsigned enum expression < 0 
is always false}}
      return 0;
-  if (2147483647U >= a)
+  if (0U >= a)
      return 0;
-  if (a > 2147483647U)
+  if (a > 0U)
      return 0;
-  if (2147483647U <= a)
+  if (0U <= a) // expected-warning {{comparison of 0 <= unsigned enum 
expression is always true}}
      return 0;
-  if (a <= 2147483647U)
+  if (a <= 0U)
      return 0;
-  if (2147483647U > a)
+  if (0U > a) // expected-warning {{comparison of 0 > unsigned enum expression 
is always false}}
      return 0;
-  if (a >= 2147483647U)
+  if (a >= 0U) // expected-warning {{comparison of unsigned enum expression >= 
0 is always true}}
      return 0;
-  if (2147483647U < a)
+  if (0U < a)
      return 0;
-#endif
-#if defined(UNSIGNED) && !defined(SILENCE)
-  if (a < 0) // expected-warning {{comparison of unsigned enum expression < 0 
is always false}}
+  if (a < 4294967295)
      return 0;
-  if (0 >= a)
+  if (4294967295 >= a) // expected-warning {{comparison 4294967295 >= 'enum A' 
is always true}}
      return 0;
-  if (a > 0)
+  if (a > 4294967295) // expected-warning {{comparison 'enum A' > 4294967295 
is always false}}
      return 0;
-  if (0 <= a) // expected-warning {{comparison of 0 <= unsigned enum 
expression is always true}}
+  if (4294967295 <= a)
      return 0;
-  if (a <= 0)
+  if (a <= 4294967295) // expected-warning {{comparison 'enum A' <= 4294967295 
is always true}}
      return 0;
-  if (0 > a) // expected-warning {{comparison of 0 > unsigned enum expression 
is always false}}
+  if (4294967295 > a)
      return 0;
-  if (a >= 0) // expected-warning {{comparison of unsigned enum expression >= 
0 is always true}}
+  if (a >= 4294967295)
      return 0;
-  if (0 < a)
+  if (4294967295 < a) // expected-warning {{comparison 4294967295 < 'enum A' 
is always false}}
      return 0;
- if (a < 4294967295)
+  if (a < 4294967295U)
      return 0;
-  if (4294967295 >= a) // expected-warning {{comparison 4294967295 >= 'enum A' 
is always true}}
+  if (4294967295U >= a) // expected-warning {{comparison 4294967295 >= 'enum 
A' is always true}}
      return 0;
-  if (a > 4294967295) // expected-warning {{comparison 'enum A' > 4294967295 
is always false}}
+  if (a > 4294967295U) // expected-warning {{comparison 'enum A' > 4294967295 
is always false}}
      return 0;
-  if (4294967295 <= a)
+  if (4294967295U <= a)
      return 0;
-  if (a <= 4294967295) // expected-warning {{comparison 'enum A' <= 4294967295 
is always true}}
+  if (a <= 4294967295U) // expected-warning {{comparison 'enum A' <= 
4294967295 is always true}}
      return 0;
-  if (4294967295 > a)
+  if (4294967295U > a)
      return 0;
-  if (a >= 4294967295)
+  if (a >= 4294967295U)
      return 0;
-  if (4294967295 < a) // expected-warning {{comparison 4294967295 < 'enum A' 
is always false}}
+  if (4294967295U < a) // expected-warning {{comparison 4294967295 < 'enum A' 
is always false}}
      return 0;
-#else // SIGNED || SILENCE
+#else // SILENCE
    if (a < 0)
      return 0;
    if (0 >= a)
@@ -116,24 +98,23 @@ int main() {
    if (0 < a)
      return 0;
-#ifndef SILENCE
-  if (a < 4294967295) // expected-warning {{comparison of constant 4294967295 
with expression of type 'enum A' is always true}}
+  if (a < 0U)
      return 0;
-  if (4294967295 >= a) // expected-warning {{comparison of constant 4294967295 
with expression of type 'enum A' is always true}}
+  if (0U >= a)
      return 0;
-  if (a > 4294967295) // expected-warning {{comparison of constant 4294967295 
with expression of type 'enum A' is always false}}
+  if (a > 0U)
      return 0;
-  if (4294967295 <= a) // expected-warning {{comparison of constant 4294967295 
with expression of type 'enum A' is always false}}
+  if (0U <= a)
      return 0;
-  if (a <= 4294967295) // expected-warning {{comparison of constant 4294967295 
with expression of type 'enum A' is always true}}
+  if (a <= 0U)
      return 0;
-  if (4294967295 > a) // expected-warning {{comparison of constant 4294967295 
with expression of type 'enum A' is always true}}
+  if (0U > a)
      return 0;
-  if (a >= 4294967295) // expected-warning {{comparison of constant 4294967295 
with expression of type 'enum A' is always false}}
+  if (a >= 0U)
      return 0;
-  if (4294967295 < a) // expected-warning {{comparison of constant 4294967295 
with expression of type 'enum A' is always false}}
+  if (0U < a)
      return 0;
-#else
+
    if (a < 4294967295)
      return 0;
    if (4294967295 >= a)
@@ -150,10 +131,26 @@ int main() {
      return 0;
    if (4294967295 < a)
      return 0;
-#endif
-#endif
-#if defined(SIGNED) && !defined(SILENCE)
+  if (a < 4294967295U)
+    return 0;
+  if (4294967295U >= a)
+    return 0;
+  if (a > 4294967295U)
+    return 0;
+  if (4294967295U <= a)
+    return 0;
+  if (a <= 4294967295U)
+    return 0;
+  if (4294967295U > a)
+    return 0;
+  if (a >= 4294967295U)
+    return 0;
+  if (4294967295U < a)
+    return 0;
+#endif
+#elif defined(SIGNED)
+#ifndef SILENCE
    if (a < -2147483648) // expected-warning {{comparison 'enum A' < 
-2147483648 is always false}}
      return 0;
    if (-2147483648 >= a)
@@ -187,25 +184,24 @@ int main() {
      return 0;
    if (2147483647 < a) // expected-warning {{comparison 2147483647 < 'enum A' 
is always false}}
      return 0;
-#elif defined(UNSIGNED) && !defined(SILENCE)
-#ifndef SILENCE
-  if (a < -2147483648) // expected-warning {{comparison of constant 
-2147483648 with expression of type 'enum A' is always false}}
+
+  if (a < 2147483647U)
      return 0;
-  if (-2147483648 >= a) // expected-warning {{comparison of constant 
-2147483648 with expression of type 'enum A' is always false}}
+  if (2147483647U >= a) // expected-warning {{comparison 2147483647 >= 'enum 
A' is always true}}
      return 0;
-  if (a > -2147483648) // expected-warning {{comparison of constant 
-2147483648 with expression of type 'enum A' is always true}}
+  if (a > 2147483647U) // expected-warning {{comparison 'enum A' > 2147483647 
is always false}}
      return 0;
-  if (-2147483648 <= a) // expected-warning {{comparison of constant 
-2147483648 with expression of type 'enum A' is always true}}
+  if (2147483647U <= a)
      return 0;
-  if (a <= -2147483648) // expected-warning {{comparison of constant 
-2147483648 with expression of type 'enum A' is always false}}
+  if (a <= 2147483647U) // expected-warning {{comparison 'enum A' <= 
2147483647 is always true}}
      return 0;
-  if (-2147483648 > a) // expected-warning {{comparison of constant 
-2147483648 with expression of type 'enum A' is always false}}
+  if (2147483647U > a)
      return 0;
-  if (a >= -2147483648) // expected-warning {{comparison of constant 
-2147483648 with expression of type 'enum A' is always true}}
+  if (a >= 2147483647U)
      return 0;
-  if (-2147483648 < a) // expected-warning {{comparison of constant 
-2147483648 with expression of type 'enum A' is always true}}
+  if (2147483647U < a) // expected-warning {{comparison 2147483647 < 'enum A' 
is always false}}
      return 0;
-#else
+#else // SILENCE
    if (a < -2147483648)
      return 0;
    if (-2147483648 >= a)
@@ -222,7 +218,6 @@ int main() {
      return 0;
    if (-2147483648 < a)
      return 0;
-#endif
if (a < 2147483647)
      return 0;
@@ -240,6 +235,24 @@ int main() {
      return 0;
    if (2147483647 < a)
      return 0;
+
+  if (a < 2147483647U)
+    return 0;
+  if (2147483647U >= a)
+    return 0;
+  if (a > 2147483647U)
+    return 0;
+  if (2147483647U <= a)
+    return 0;
+  if (a <= 2147483647U)
+    return 0;
+  if (2147483647U > a)
+    return 0;
+  if (a >= 2147483647U)
+    return 0;
+  if (2147483647U < a)
+    return 0;
+#endif
  #endif
return 1;

Modified: cfe/trunk/test/SemaCXX/compare.cpp
URL: 
http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/compare.cpp?rev=320162&r1=320161&r2=320162&view=diff
==============================================================================
--- cfe/trunk/test/SemaCXX/compare.cpp (original)
+++ cfe/trunk/test/SemaCXX/compare.cpp Fri Dec  8 08:54:08 2017
@@ -245,8 +245,8 @@ void test4(short s) {
    // unsigned.
    const unsigned B = -1;
    void (s < B); // expected-warning{{comparison of integers of different 
signs: 'short' and 'const unsigned int'}}
-  void (s > B); // expected-warning{{comparison 'short' > 4294967295 is always 
false}}
-  void (s <= B); // expected-warning{{comparison 'short' <= 4294967295 is 
always true}}
+  void (s > B); // expected-warning{{comparison of integers of different 
signs: 'short' and 'const unsigned int'}}
+  void (s <= B); // expected-warning{{comparison of integers of different 
signs: 'short' and 'const unsigned int'}}
    void (s >= B); // expected-warning{{comparison of integers of different 
signs: 'short' and 'const unsigned int'}}
    void (s == B); // expected-warning{{comparison of integers of different 
signs: 'short' and 'const unsigned int'}}
    void (s != B); // expected-warning{{comparison of integers of different 
signs: 'short' and 'const unsigned int'}}


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--

-Bill Seurer

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