From e3ba2987b9d55fdc976362ddccdb8c5a73d19fc9 Mon Sep 17 00:00:00 2001
From: Richard Smith <richard-llvm@metafoo.co.uk>
Date: Tue, 1 May 2012 21:58:31 +0000
Subject: [PATCH] Fix RecursiveASTVisitor's data recursion to call the
 Traverse* functions if they have been overridden in the derived class. Also,
 remove a non-functional implementation of an incorrect optimization for
 ParenExprs.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@155951 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/clang/AST/RecursiveASTVisitor.h       | 25 ++++++++-----
 unittests/Tooling/RecursiveASTVisitorTest.cpp | 35 +++++++++++++++++++
 2 files changed, 51 insertions(+), 9 deletions(-)

diff --git a/include/clang/AST/RecursiveASTVisitor.h b/include/clang/AST/RecursiveASTVisitor.h
index 93363b1715..e326439334 100644
--- a/include/clang/AST/RecursiveASTVisitor.h
+++ b/include/clang/AST/RecursiveASTVisitor.h
@@ -405,18 +405,14 @@ private:
   bool TraverseFunctionHelper(FunctionDecl *D);
   bool TraverseVarHelper(VarDecl *D);
 
-  bool Walk(Stmt *S);
-
   struct EnqueueJob {
     Stmt *S;
     Stmt::child_iterator StmtIt;
 
-    EnqueueJob(Stmt *S) : S(S), StmtIt() {
-      if (Expr *E = dyn_cast_or_null<Expr>(S))
-        S = E->IgnoreParens();
-    }
+    EnqueueJob(Stmt *S) : S(S), StmtIt() {}
   };
   bool dataTraverse(Stmt *S);
+  bool dataTraverseNode(Stmt *S, bool &EnqueueChildren);
 };
 
 template<typename Derived>
@@ -435,7 +431,12 @@ bool RecursiveASTVisitor<Derived>::dataTraverse(Stmt *S) {
 
     if (getDerived().shouldUseDataRecursionFor(CurrS)) {
       if (job.StmtIt == Stmt::child_iterator()) {
-        if (!Walk(CurrS)) return false;
+        bool EnqueueChildren = true;
+        if (!dataTraverseNode(CurrS, EnqueueChildren)) return false;
+        if (!EnqueueChildren) {
+          Queue.pop_back();
+          continue;
+        }
         job.StmtIt = CurrS->child_begin();
       } else {
         ++job.StmtIt;
@@ -456,10 +457,16 @@ bool RecursiveASTVisitor<Derived>::dataTraverse(Stmt *S) {
 }
 
 template<typename Derived>
-bool RecursiveASTVisitor<Derived>::Walk(Stmt *S) {
+bool RecursiveASTVisitor<Derived>::dataTraverseNode(Stmt *S,
+                                                    bool &EnqueueChildren) {
 
+  // Dispatch to the corresponding WalkUpFrom* function only if the derived
+  // class didn't override Traverse* (and thus the traversal is trivial).
 #define DISPATCH_WALK(NAME, CLASS, VAR) \
-  return getDerived().WalkUpFrom##NAME(static_cast<CLASS*>(VAR));
+  if (&RecursiveASTVisitor::Traverse##NAME == &Derived::Traverse##NAME) \
+    return getDerived().WalkUpFrom##NAME(static_cast<CLASS*>(VAR)); \
+  EnqueueChildren = false; \
+  return getDerived().Traverse##NAME(static_cast<CLASS*>(VAR));
 
   if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(S)) {
     switch (BinOp->getOpcode()) {
diff --git a/unittests/Tooling/RecursiveASTVisitorTest.cpp b/unittests/Tooling/RecursiveASTVisitorTest.cpp
index d4fda73ccb..39803c35bc 100644
--- a/unittests/Tooling/RecursiveASTVisitorTest.cpp
+++ b/unittests/Tooling/RecursiveASTVisitorTest.cpp
@@ -165,6 +165,25 @@ public:
   }
 };
 
+class CXXOperatorCallExprTraverser
+  : public ExpectedLocationVisitor<CXXOperatorCallExprTraverser> {
+public:
+  // Use Traverse, not Visit, to check that data recursion optimization isn't
+  // bypassing the call of this function.
+  bool TraverseCXXOperatorCallExpr(CXXOperatorCallExpr *CE) {
+    Match(getOperatorSpelling(CE->getOperator()), CE->getExprLoc());
+    return ExpectedLocationVisitor::TraverseCXXOperatorCallExpr(CE);
+  }
+};
+
+class ParenExprVisitor : public ExpectedLocationVisitor<ParenExprVisitor> {
+public:
+  bool VisitParenExpr(ParenExpr *Parens) {
+    Match("", Parens->getExprLoc());
+    return true;
+  }
+};
+
 TEST(RecursiveASTVisitor, VisitsBaseClassDeclarations) {
   TypeLocVisitor Visitor;
   Visitor.ExpectMatch("class X", 1, 30);
@@ -345,4 +364,20 @@ TEST(RecursiveASTVisitor, NoRecursionInSelfFriend) {
     "vector_iterator<int> it_int;\n"));
 }
 
+TEST(RecursiveASTVisitor, TraversesOverloadedOperator) {
+  CXXOperatorCallExprTraverser Visitor;
+  Visitor.ExpectMatch("()", 4, 9);
+  EXPECT_TRUE(Visitor.runOver(
+    "struct A {\n"
+    "  int operator()();\n"
+    "} a;\n"
+    "int k = a();\n"));
+}
+
+TEST(RecursiveASTVisitor, VisitsParensDuringDataRecursion) {
+  ParenExprVisitor Visitor;
+  Visitor.ExpectMatch("", 1, 9);
+  EXPECT_TRUE(Visitor.runOver("int k = (4) + 9;\n"));
+}
+
 } // end namespace clang
-- 
2.40.0