[ASTMatchers] adds isComparisonOperator to BinaryOperator and CXXOperatorCallExpr

Reviewers: aaron.ballman, gribozavr2

Reviewed By: aaron.ballman

Subscribers: cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D75800

Author: njames93

clang-tools-extra/clang-tidy/misc/RedundantExpressionCheck.cpp

@@ -567,7 +567,7 @@ matchRelationalIntegerConstantExpr(StringRef Id) {
   std::string OverloadId = (Id + "-overload").str();
 
   const auto RelationalExpr = ignoringParenImpCasts(binaryOperator(
-      isComparisonOperator(), expr().bind(Id),
+      matchers::isComparisonOperator(), expr().bind(Id),
       anyOf(allOf(hasLHS(matchSymbolicExpr(Id)),
                   hasRHS(matchIntegerConstantExpr(Id))),
             allOf(hasLHS(matchIntegerConstantExpr(Id)),
@@ -943,22 +943,22 @@ void RedundantExpressionCheck::registerMatchers(MatchFinder *Finder) {
   const auto SymRight = matchSymbolicExpr("rhs");
 
   // Match expressions like: x <op> 0xFF == 0xF00.
-  Finder->addMatcher(binaryOperator(isComparisonOperator(),
+  Finder->addMatcher(binaryOperator(matchers::isComparisonOperator(),
                                     hasEitherOperand(BinOpCstLeft),
                                     hasEitherOperand(CstRight))
                          .bind("binop-const-compare-to-const"),
                      this);
 
   // Match expressions like: x <op> 0xFF == x.
   Finder->addMatcher(
-      binaryOperator(isComparisonOperator(),
+      binaryOperator(matchers::isComparisonOperator(),
                      anyOf(allOf(hasLHS(BinOpCstLeft), hasRHS(SymRight)),
                            allOf(hasLHS(SymRight), hasRHS(BinOpCstLeft))))
           .bind("binop-const-compare-to-sym"),
       this);
 
   // Match expressions like: x <op> 10 == x <op> 12.
-  Finder->addMatcher(binaryOperator(isComparisonOperator(),
+  Finder->addMatcher(binaryOperator(matchers::isComparisonOperator(),
                                     hasLHS(BinOpCstLeft), hasRHS(BinOpCstRight),
                                     // Already reported as redundant.
                                     unless(operandsAreEquivalent()))

clang/docs/LibASTMatchersReference.html

@@ -2157,7 +2157,21 @@ <h2 id="narrowing-matchers">Narrowing Matchers</h2>
 Example 2: matches s1 = s2
            (matcher = cxxOperatorCallExpr(isAssignmentOperator()))
   struct S { S&amp; operator=(const S&amp;); };
-  void x() { S s1, s2; s1 = s2; })
+  void x() { S s1, s2; s1 = s2; }
+</pre></td></tr>
+
+
+<tr><td>Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1BinaryOperator.html">BinaryOperator</a>&gt;</td><td class="name" onclick="toggle('isComparisonOperator0')"><a name="isComparisonOperator0Anchor">isComparisonOperator</a></td><td></td></tr>
+<tr><td colspan="4" class="doc" id="isComparisonOperator0"><pre>Matches comparison operators.
+
+Example 1: matches a == b (matcher = binaryOperator(isComparisonOperator()))
+  if (a == b)
+    a += b;
+
+Example 2: matches s1 &lt; s2
+           (matcher = cxxOperatorCallExpr(isComparisonOperator()))
+  struct S { bool operator&lt;(const S&amp; other); };
+  void x(S s1, S s2) { bool b1 = s1 &lt; s2; }
 </pre></td></tr>
 
 
@@ -2616,7 +2630,21 @@ <h2 id="narrowing-matchers">Narrowing Matchers</h2>
 Example 2: matches s1 = s2
            (matcher = cxxOperatorCallExpr(isAssignmentOperator()))
   struct S { S&amp; operator=(const S&amp;); };
-  void x() { S s1, s2; s1 = s2; })
+  void x() { S s1, s2; s1 = s2; }
+</pre></td></tr>
+
+
+<tr><td>Matcher&lt;<a href="https://clang.llvm.org/doxygen/classclang_1_1CXXOperatorCallExpr.html">CXXOperatorCallExpr</a>&gt;</td><td class="name" onclick="toggle('isComparisonOperator1')"><a name="isComparisonOperator1Anchor">isComparisonOperator</a></td><td></td></tr>
+<tr><td colspan="4" class="doc" id="isComparisonOperator1"><pre>Matches comparison operators.
+
+Example 1: matches a == b (matcher = binaryOperator(isComparisonOperator()))
+  if (a == b)
+    a += b;
+
+Example 2: matches s1 &lt; s2
+           (matcher = cxxOperatorCallExpr(isComparisonOperator()))
+  struct S { bool operator&lt;(const S&amp; other); };
+  void x(S s1, S s2) { bool b1 = s1 &lt; s2; }
 </pre></td></tr>
 
 

clang/include/clang/AST/ExprCXX.h

@@ -118,6 +118,22 @@ class CXXOperatorCallExpr final : public CallExpr {
   }
   bool isAssignmentOp() const { return isAssignmentOp(getOperator()); }
 
+  static bool isComparisonOp(OverloadedOperatorKind Opc) {
+    switch (Opc) {
+    case OO_EqualEqual:
+    case OO_ExclaimEqual:
+    case OO_Greater:
+    case OO_GreaterEqual:
+    case OO_Less:
+    case OO_LessEqual:
+    case OO_Spaceship:
+      return true;
+    default:
+      return false;
+    }
+  }
+  bool isComparisonOp() const { return isComparisonOp(getOperator()); }
+
   /// Is this written as an infix binary operator?
   bool isInfixBinaryOp() const;
 

clang/include/clang/ASTMatchers/ASTMatchers.h

@@ -4783,14 +4783,34 @@ extern const internal::VariadicFunction<
 ///            (matcher = cxxOperatorCallExpr(isAssignmentOperator()))
 /// \code
 ///   struct S { S& operator=(const S&); };
-///   void x() { S s1, s2; s1 = s2; })
+///   void x() { S s1, s2; s1 = s2; }
 /// \endcode
 AST_POLYMORPHIC_MATCHER(isAssignmentOperator,
                         AST_POLYMORPHIC_SUPPORTED_TYPES(BinaryOperator,
                                                         CXXOperatorCallExpr)) {
   return Node.isAssignmentOp();
 }
 
+/// Matches comparison operators.
+///
+/// Example 1: matches a == b (matcher = binaryOperator(isComparisonOperator()))
+/// \code
+///   if (a == b)
+///     a += b;
+/// \endcode
+///
+/// Example 2: matches s1 < s2
+///            (matcher = cxxOperatorCallExpr(isComparisonOperator()))
+/// \code
+///   struct S { bool operator<(const S& other); };
+///   void x(S s1, S s2) { bool b1 = s1 < s2; }
+/// \endcode
+AST_POLYMORPHIC_MATCHER(isComparisonOperator,
+                        AST_POLYMORPHIC_SUPPORTED_TYPES(BinaryOperator,
+                                                        CXXOperatorCallExpr)) {
+  return Node.isComparisonOp();
+}
+
 /// Matches the left hand side of binary operator expressions.
 ///
 /// Example matches a (matcher = binaryOperator(hasLHS()))

clang/lib/ASTMatchers/Dynamic/Registry.cpp

@@ -358,6 +358,7 @@ RegistryMaps::RegistryMaps() {
   REGISTER_MATCHER(isClass);
   REGISTER_MATCHER(isClassMessage);
   REGISTER_MATCHER(isClassMethod);
+  REGISTER_MATCHER(isComparisonOperator);
   REGISTER_MATCHER(isConst);
   REGISTER_MATCHER(isConstQualified);
   REGISTER_MATCHER(isConstexpr);

clang/unittests/ASTMatchers/ASTMatchersNarrowingTest.cpp

@@ -2689,6 +2689,20 @@ TEST(IsAssignmentOperator, Basic) {
       notMatches("void x() { int a; if(a == 0) return; }", BinAsgmtOperator));
 }
 
+TEST(IsComparisonOperator, Basic) {
+  StatementMatcher BinCompOperator = binaryOperator(isComparisonOperator());
+  StatementMatcher CXXCompOperator =
+      cxxOperatorCallExpr(isComparisonOperator());
+
+  EXPECT_TRUE(matches("void x() { int a; a == 1; }", BinCompOperator));
+  EXPECT_TRUE(matches("void x() { int a; a > 2; }", BinCompOperator));
+  EXPECT_TRUE(matches("struct S { bool operator==(const S&); };"
+                      "void x() { S s1, s2; bool b1 = s1 == s2; }",
+                      CXXCompOperator));
+  EXPECT_TRUE(
+      notMatches("void x() { int a; if(a = 0) return; }", BinCompOperator));
+}
+
 TEST(HasInit, Basic) {
   EXPECT_TRUE(
     matches("int x{0};",