[libTooling] Add smart pointer support to the `access` Stencil

[scw]

Summary

This extends smart pointer support beyond the existing maybeDeref and
maybeAddressOf.

[ymandel]

Thanks!

clang/unittests/Tooling/StencilTest.cpp

410

Hmm. Looks like we could use smart pointer support in tooling::buildAddressOf as well. If you're interested, the code is at
clang/lib/Tooling/Transformer/SourceCodeBuilders.cpp line 94
but I understand if you want to stop here. :)

[scw]

clang/unittests/Tooling/StencilTest.cpp

410

I don't think this particular output "(*x).field" is from buildAddressOf. Instead, it's in buildDot where *x is x.operator*() instead of UO_Deref. Yes, there's potential improvement but at least it's correct output comparing to this change which fixes "x->->field" so I'm leaving it along just adding the test case to highlight the potential.

As for buildAddressOf, we shouldn't change &*x to x when x is a smart pointer -- the types don't match and may result in ill-typed expressions.

clang/lib/Tooling/Transformer/Stencil.cpp

 
 Error evalData(const AccessData &Data, const MatchFinder::MatchResult &Match,
                std::string *Result) {
   const auto *E = Match.Nodes.getNodeAs<Expr>(Data.BaseId);
   if (E == nullptr)
     return llvm::make_error<StringError>(errc::invalid_argument,
                                          "Id not bound: " + Data.BaseId);
   if (!E->isImplicitCXXThis()) {
-    if (llvm::Optional<std::string> S =
-            E->getType()->isAnyPointerType()
-                ? tooling::buildArrow(*E, *Match.Context)
-                : tooling::buildDot(*E, *Match.Context))
+    llvm::Optional<std::string> S;
+    if (E->getType()->isAnyPointerType() ||
+        isSmartPointerType(E->getType(), *Match.Context)) {
+      // Strip off any operator->. This can only occur inside an actual arrow
+      // member access, so we treat it as equivalent to an actual object
+      // expression.
+      if (const auto *OpCall = dyn_cast<clang::CXXOperatorCallExpr>(E)) {
+        if (OpCall->getOperator() == clang::OO_Arrow &&
+            OpCall->getNumArgs() == 1) {
+          E = OpCall->getArg(0);
+        }
+      }
+      S = tooling::buildArrow(*E, *Match.Context);
+    } else {
+      S = tooling::buildDot(*E, *Match.Context);
+    }
+    if (S.hasValue())
       *Result += *S;
     else
       return llvm::make_error<StringError>(
           errc::invalid_argument,
           "Could not construct object text from ID: " + Data.BaseId);
   }
   return Data.Member->eval(Match, Result);
 }

clang/unittests/Tooling/StencilTest.cpp

TEST_F(StencilTest, AccessOpPointerDereference) {
   StringRef Snippet = R"cc(
     S *x;
     *x;
   )cc";
   StringRef Id = "id";
   testExpr(Id, Snippet, access(Id, "field"), "x->field");
 }
 
+TEST_F(StencilTest, AccessOpSmartPointer) {
+  StringRef Snippet = R"cc(
+    Smart x;
+    x;
+  )cc";
+  StringRef Id = "id";
+  testExpr(Id, Snippet, access(Id, "field"), "x->field");
+}
+
+TEST_F(StencilTest, AccessOpSmartPointerDereference) {
+  StringRef Snippet = R"cc(
+    Smart x;
+    *x;
+  )cc";
+  StringRef Id = "id";
+  testExpr(Id, Snippet, access(Id, "field"), "(*x).field");
+}
+
+TEST_F(StencilTest, AccessOpSmartPointerMemberCall) {
+  StringRef Snippet = R"cc(
+    Smart x;
+    x->Field;
+  )cc";
+  StringRef Id = "id";
+  auto StmtMatch =
+      matchStmt(Snippet, memberExpr(hasObjectExpression(expr().bind(Id))));
+  ASSERT_TRUE(StmtMatch);
+  EXPECT_THAT_EXPECTED(access(Id, "field")->eval(StmtMatch->Result),
+                       HasValue("x->field"));
+}
+
 TEST_F(StencilTest, AccessOpExplicitThis) {
   using clang::ast_matchers::hasObjectExpression;
   using clang::ast_matchers::memberExpr;
 
   // Set up the code so we can bind to a use of this.
   StringRef Snippet = R"cc(
     class C {
      public: