Implements equalsNode for Decl and Stmt.

This is a powerful tool when doing iterative refined matches,
where another match is started inside the match callback of the first
one; this allows for example to find out whether the node was in
the condition or body of its parent if-statement.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@174605 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 66 insertions, 0 deletions

diff --git a/docs/LibASTMatchersReference.html b/docs/LibASTMatchersReference.html
index 30270835ad..930b922cdd 100644
--- a/docs/LibASTMatchersReference.html
+++ b/docs/LibASTMatchersReference.html
@@ -1398,6 +1398,13 @@ declCountIs(2)
 </pre></td></tr>
 
 
+<tr><td>Matcher&lt<a href="http://clang.llvm.org/doxygen/classclang_1_1Decl.html">Decl</a>&gt;</td><td class="name" onclick="toggle('equalsNode0')"><a name="equalsNode0Anchor">equalsNode</a></td><td>Decl* Other</td></tr>
+<tr><td colspan="4" class="doc" id="equalsNode0"><pre>Matches if a node equals another node.
+
+Decl has pointer identity in the AST.
+</pre></td></tr>
+
+
 <tr><td>Matcher&lt<a href="http://clang.llvm.org/doxygen/classclang_1_1FloatingLiteral.html">FloatingLiteral</a>&gt;</td><td class="name" onclick="toggle('equals1')"><a name="equals1Anchor">equals</a></td><td>ValueT  Value</td></tr>
 <tr><td colspan="4" class="doc" id="equals1"><pre>Matches literals that are equal to the given value.
 
@@ -1581,6 +1588,14 @@ matches "a(int)", "b(long)", but not "c(double)".
 </pre></td></tr>
 
 
+<tr><td>Matcher&lt<a href="http://clang.llvm.org/doxygen/classclang_1_1Stmt.html">Stmt</a>&gt;</td><td class="name" onclick="toggle('equalsNode1')"><a name="equalsNode1Anchor">equalsNode</a></td><td>Stmt* Other</td></tr>
+<tr><td colspan="4" class="doc" id="equalsNode1"><pre>Matches if a node equals another node.
+
+Stmt has pointer identity in the AST.
+
+</pre></td></tr>
+
+
 <tr><td>Matcher&lt<a href="http://clang.llvm.org/doxygen/classclang_1_1TagDecl.html">TagDecl</a>&gt;</td><td class="name" onclick="toggle('isDefinition0')"><a name="isDefinition0Anchor">isDefinition</a></td><td></td></tr>
 <tr><td colspan="4" class="doc" id="isDefinition0"><pre>Matches if a declaration has a body attached.
 
diff --git a/include/clang/ASTMatchers/ASTMatchers.h b/include/clang/ASTMatchers/ASTMatchers.h
index 15c9565d39..d41aa1b6e8 100644
--- a/include/clang/ASTMatchers/ASTMatchers.h
+++ b/include/clang/ASTMatchers/ASTMatchers.h
@@ -2945,6 +2945,26 @@ AST_MATCHER_P(NestedNameSpecifier, specifiesNamespace,
   return InnerMatcher.matches(*Node.getAsNamespace(), Finder, Builder);
 }
 
+/// \brief Overloads for the \c equalsNode matcher.
+/// FIXME: Implement for other node types.
+/// @{
+
+/// \brief Matches if a node equals another node.
+///
+/// \c Decl has pointer identity in the AST.
+AST_MATCHER_P_OVERLOAD(Decl, equalsNode, Decl*, Other, 0) {
+  return &Node == Other;
+}
+/// \brief Matches if a node equals another node.
+///
+/// \c Stmt has pointer identity in the AST.
+///
+AST_MATCHER_P_OVERLOAD(Stmt, equalsNode, Stmt*, Other, 1) {
+  return &Node == Other;
+}
+
+/// @}
+
 } // end namespace ast_matchers
 } // end namespace clang
 
diff --git a/unittests/ASTMatchers/ASTMatchersTest.cpp b/unittests/ASTMatchers/ASTMatchersTest.cpp
index 60a79e86de..618ac6ec51 100644
--- a/unittests/ASTMatchers/ASTMatchersTest.cpp
+++ b/unittests/ASTMatchers/ASTMatchersTest.cpp
@@ -3546,6 +3546,37 @@ TEST(MatchFinder, CanMatchSingleNodesRecursively) {
           "X", recordDecl(has(recordDecl(hasName("X::Z")).bind("Z"))), "Z")));
 }
 
+template <typename T>
+class VerifyAncestorHasChildIsEqual : public BoundNodesCallback {
+public:
+  virtual bool run(const BoundNodes *Nodes) { return false; }
+
+  virtual bool run(const BoundNodes *Nodes, ASTContext *Context) {
+    const T *Node = Nodes->getNodeAs<T>("");
+    return verify(*Nodes, *Context, Node);
+  }
+
+  bool verify(const BoundNodes &Nodes, ASTContext &Context, const Stmt *Node) {
+    return selectFirst<const T>(
+        "", match(stmt(hasParent(stmt(has(stmt(equalsNode(Node)))).bind(""))),
+                  *Node, Context)) != NULL;
+  }
+  bool verify(const BoundNodes &Nodes, ASTContext &Context, const Decl *Node) {
+    return selectFirst<const T>(
+        "", match(decl(hasParent(decl(has(decl(equalsNode(Node)))).bind(""))),
+                  *Node, Context)) != NULL;
+  }
+};
+
+TEST(IsEqualTo, MatchesNodesByIdentity) {
+  EXPECT_TRUE(matchAndVerifyResultTrue(
+      "class X { class Y {}; };", recordDecl(hasName("::X::Y")).bind(""),
+      new VerifyAncestorHasChildIsEqual<Decl>()));
+  EXPECT_TRUE(
+      matchAndVerifyResultTrue("void f() { if(true) {} }", ifStmt().bind(""),
+                               new VerifyAncestorHasChildIsEqual<Stmt>()));
+}
+
 class VerifyStartOfTranslationUnit : public MatchFinder::MatchCallback {
 public:
   VerifyStartOfTranslationUnit() : Called(false) {}