[clang] [clang][ASTImporter] Improve structural equivalence of overloadable operators. (PR #72242)

[via cfe-commits]

================
@@ -437,12 +439,67 @@ class StmtComparer {
 };
 } // namespace
 
+static bool IsStructurallyEquivalent(StructuralEquivalenceContext &Context,
+                                     const UnaryOperator *E1,
+                                     const CXXOperatorCallExpr *E2) {
+  return UnaryOperator::getOverloadedOperator(E1->getOpcode()) ==
+             E2->getOperator() &&
+         IsStructurallyEquivalent(Context, E1->getSubExpr(), E2->getArg(0));
+}
+
+static bool IsStructurallyEquivalent(StructuralEquivalenceContext &Context,
+                                     const CXXOperatorCallExpr *E1,
+                                     const UnaryOperator *E2) {
+  return E1->getOperator() ==
+             UnaryOperator::getOverloadedOperator(E2->getOpcode()) &&
+         IsStructurallyEquivalent(Context, E1->getArg(0), E2->getSubExpr());
+}
+
+static bool IsStructurallyEquivalent(StructuralEquivalenceContext &Context,
+                                     const BinaryOperator *E1,
+                                     const CXXOperatorCallExpr *E2) {
+  return BinaryOperator::getOverloadedOperator(E1->getOpcode()) ==
+             E2->getOperator() &&
+         IsStructurallyEquivalent(Context, E1->getLHS(), E2->getArg(0)) &&
+         IsStructurallyEquivalent(Context, E1->getRHS(), E2->getArg(1));
+}
+
+static bool IsStructurallyEquivalent(StructuralEquivalenceContext &Context,
+                                     const CXXOperatorCallExpr *E1,
+                                     const BinaryOperator *E2) {
+  return E1->getOperator() ==
+             BinaryOperator::getOverloadedOperator(E2->getOpcode()) &&
+         IsStructurallyEquivalent(Context, E1->getArg(0), E2->getLHS()) &&
+         IsStructurallyEquivalent(Context, E1->getArg(1), E2->getRHS());
+}
+
 /// Determine structural equivalence of two statements.
 static bool IsStructurallyEquivalent(StructuralEquivalenceContext &Context,
                                      const Stmt *S1, const Stmt *S2) {
   if (!S1 || !S2)
     return S1 == S2;
 
+  // Check for statements with similar syntax but different AST.
+  // The unary and binary operators (like '+', '&') can be parsed as
+  // CXXOperatorCall too (and UnaryOperator or BinaryOperator).
+  // This depends on arguments with unresolved type and on the name lookup.
----------------
DonatNagyE wrote:

Could you perhaps elaborate this sentence a bit? Do I understand it correctly that e.g. in `CXXOperatorCallExprVsUnaryBinaryOperator` the presence of `struct Bar` in the second TU ensured that all the operators are parsed as `CXXOperatorCall`s, while in the first TU they are parsed as unary/binary operator expressions?

https://github.com/llvm/llvm-project/pull/72242