[FileCheck] Implement equality operators for ExpressionValue.

[paulwalker-arm]

I've extracted this change from my other patch to break a dependency chain.

[thopre]

llvm/unittests/Support/FileCheckTest.cpp

487–488

Maybe also test numbers which would have the same representation when cast to unsigned, e.g.

UINT64_MAX and -1

[paulwalker-arm]

Added tests to protect against unintentional casts and mismatched binary encodings.

[thopre]

LGTM, thanks!

[jhenderson]

LGTM too.

llvm/lib/Support/FileCheckImpl.h

public:
   explicit operator bool() const { return Value != Kind::NoFormat; }
 
   /// Define format equality: formats are equal if neither is NoFormat and
   /// their kinds are the same.
   bool operator==(const ExpressionFormat &Other) const {
     return Value != Kind::NoFormat && Value == Other.Value;
   }
 
-  bool operator!=(const ExpressionFormat &other) const {
-    return !(*this == other);
+  bool operator!=(const ExpressionFormat &Other) const {
+    return !(*this == Other);
   }
 
   bool operator==(Kind OtherValue) const { return Value == OtherValue; }
 
   bool operator!=(Kind OtherValue) const { return !(*this == OtherValue); }
 
   /// \returns the format specifier corresponding to this format as a string.
   StringRef toString() const;

 private:
   uint64_t Value;
   bool Negative;
 
 public:
   template <class T>
   explicit ExpressionValue(T Val) : Value(Val), Negative(Val < 0) {}
 
+  bool operator==(const ExpressionValue &Other) const {
+    return Value == Other.Value && isNegative() == Other.isNegative();
+  }
+
+  bool operator!=(const ExpressionValue &Other) const {
+    return !(*this == Other);
+  }
+
   /// Returns true if value is signed and negative, false otherwise.
-  bool isNegative() const { return Negative; }
+  bool isNegative() const {
+    assert((Value != 0 || !Negative) && "Unexpected negative zero!");
+    return Negative;
+  }
 
   /// \returns the value as a signed integer or an error if the value is out of
   /// range.
   Expected<int64_t> getSignedValue() const;
 
   /// \returns the value as an unsigned integer or an error if the value is out
   /// of range.
   Expected<uint64_t> getUnsignedValue() const;

llvm/unittests/Support/FileCheckTest.cpp

TEST_F(FileCheckTest, ExpressionValueSubtraction) {
   expectOperationValueResult(operator-, 10,
                              static_cast<uint64_t>(MaxInt64) + 11,
                              -MaxInt64 - 1);
 
   // Test both positive values with 0 > result > -(max int64_t)
   expectOperationValueResult(operator-, 10, 11, -1);
 }
 
+TEST_F(FileCheckTest, ExpressionValueEquality) {
+  // Test negative and positive value.
+  EXPECT_FALSE(ExpressionValue(5) == ExpressionValue(-3));
+  EXPECT_TRUE(ExpressionValue(5) != ExpressionValue(-3));
+  EXPECT_FALSE(ExpressionValue(-2) == ExpressionValue(6));
+  EXPECT_TRUE(ExpressionValue(-2) != ExpressionValue(6));
+  EXPECT_FALSE(ExpressionValue(-7) == ExpressionValue(7));
+  EXPECT_TRUE(ExpressionValue(-7) != ExpressionValue(7));
+  EXPECT_FALSE(ExpressionValue(4) == ExpressionValue(-4));
+  EXPECT_TRUE(ExpressionValue(4) != ExpressionValue(-4));
+  EXPECT_FALSE(ExpressionValue(MaxUint64) == ExpressionValue(-1));
+  EXPECT_TRUE(ExpressionValue(MaxUint64) != ExpressionValue(-1));
+
+  // Test both negative values.
+  EXPECT_FALSE(ExpressionValue(-2) == ExpressionValue(-7));
+  EXPECT_TRUE(ExpressionValue(-2) != ExpressionValue(-7));
+  EXPECT_TRUE(ExpressionValue(-3) == ExpressionValue(-3));
+  EXPECT_FALSE(ExpressionValue(-3) != ExpressionValue(-3));
+  EXPECT_FALSE(ExpressionValue(MinInt64) == ExpressionValue(-1));
+  EXPECT_TRUE(ExpressionValue(MinInt64) != ExpressionValue(-1));
+  EXPECT_FALSE(ExpressionValue(MinInt64) == ExpressionValue(-0));
+  EXPECT_TRUE(ExpressionValue(MinInt64) != ExpressionValue(-0));
+
+  // Test both positive values.
+  EXPECT_FALSE(ExpressionValue(8) == ExpressionValue(9));
+  EXPECT_TRUE(ExpressionValue(8) != ExpressionValue(9));
+  EXPECT_TRUE(ExpressionValue(1) == ExpressionValue(1));
+  EXPECT_FALSE(ExpressionValue(1) != ExpressionValue(1));
+
+  // Check the signedness of zero doesn't affect equality.
+  EXPECT_TRUE(ExpressionValue(0) == ExpressionValue(0));
+  EXPECT_FALSE(ExpressionValue(0) != ExpressionValue(0));
+  EXPECT_TRUE(ExpressionValue(0) == ExpressionValue(-0));
+  EXPECT_FALSE(ExpressionValue(0) != ExpressionValue(-0));
+  EXPECT_TRUE(ExpressionValue(-0) == ExpressionValue(0));
+  EXPECT_FALSE(ExpressionValue(-0) != ExpressionValue(0));
+  EXPECT_TRUE(ExpressionValue(-0) == ExpressionValue(-0));
+  EXPECT_FALSE(ExpressionValue(-0) != ExpressionValue(-0));
+}
+
 TEST_F(FileCheckTest, Literal) {
   SourceMgr SM;
 
   // Eval returns the literal's value.
   ExpressionLiteral Ten(bufferize(SM, "10"), 10u);
   Expected<ExpressionValue> Value = Ten.eval();
   ASSERT_THAT_EXPECTED(Value, Succeeded());
   EXPECT_EQ(10, cantFail(Value->getSignedValue()));