[clang][ASTMatcher] Fix execution order of hasOperands submatchers

The `hasOperands` matcher does not always execute matchers in the order they are
written. This can cause issues in code using bindings when one operand matcher
is relying on a binding set by the other. With this change, the first matcher
present in the code is always executed first and any binding it sets are
available to the second matcher.

Author: nicovank

clang/docs/ReleaseNotes.rst

@@ -350,6 +350,9 @@ AST Matchers
 - Fixed an issue with the `hasName` and `hasAnyName` matcher when matching
   inline namespaces with an enclosing namespace of the same name.
 
+- Fixed an ordering issue with the `hasOperands` matcher occuring when setting a
+  binding in the first matcher and using it in the second matcher.
+
 clang-format
 ------------
 

clang/include/clang/ASTMatchers/ASTMatchers.h

@@ -6027,7 +6027,7 @@ AST_POLYMORPHIC_MATCHER_P2(
     internal::Matcher<Expr>, Matcher1, internal::Matcher<Expr>, Matcher2) {
   return internal::VariadicDynCastAllOfMatcher<Stmt, NodeType>()(
              anyOf(allOf(hasLHS(Matcher1), hasRHS(Matcher2)),
-                   allOf(hasLHS(Matcher2), hasRHS(Matcher1))))
+                   allOf(hasRHS(Matcher1), hasLHS(Matcher2))))
       .matches(Node, Finder, Builder);
 }
 

clang/unittests/ASTMatchers/ASTMatchersTraversalTest.cpp

@@ -1745,6 +1745,18 @@ TEST(MatchBinaryOperator, HasOperands) {
   EXPECT_TRUE(notMatches("void x() { 0 + 1; }", HasOperands));
 }
 
+TEST(MatchBinaryOperator, HasOperandsEnsureOrdering) {
+  StatementMatcher HasOperandsWithBindings = binaryOperator(hasOperands(
+      cStyleCastExpr(has(declRefExpr(hasDeclaration(valueDecl().bind("d"))))),
+      declRefExpr(hasDeclaration(valueDecl(equalsBoundNode("d"))))));
+  EXPECT_TRUE(matches(
+      "int a; int b = ((int) a) + a;",
+      traverse(TK_IgnoreUnlessSpelledInSource, HasOperandsWithBindings)));
+  EXPECT_TRUE(matches(
+      "int a; int b = a + ((int) a);",
+      traverse(TK_IgnoreUnlessSpelledInSource, HasOperandsWithBindings)));
+}
+
 TEST(Matcher, BinaryOperatorTypes) {
   // Integration test that verifies the AST provides all binary operators in
   // a way we expect.