[ASTDump] Add utility for dumping a label with child nodes

Summary:
Use it to add optional label nodes to Stmt dumps.  This preserves
behavior of InitExprList dump:

// CHECK-NEXT: `-InitListExpr {{.+}} <col:13, col:15> 'U [3]'
// CHECK-NEXT:   |-array_filler: InitListExpr {{.+}} <col:15> 'U' field Field {{.+}} 'i' 'int'
// CHECK-NEXT:   `-InitListExpr {{.+}} <col:14> 'U' field Field {{.+}} 'i' 'int'
// CHECK-NEXT:     `-IntegerLiteral {{.+}} <col:14> 'int' 1

Reviewers: aaron.ballman

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D55488

llvm-svn: 350957

1 files changed, 13 insertions, 1 deletions

diff --git a/clang/include/clang/AST/TextNodeDumper.h b/clang/include/clang/AST/TextNodeDumper.h
index 8b6fde938d2e..7948fdc696ea 100644
--- a/clang/include/clang/AST/TextNodeDumper.h
+++ b/clang/include/clang/AST/TextNodeDumper.h
@@ -41,6 +41,12 @@ class TextTreeStructure {
 public:
   /// Add a child of the current node.  Calls DoAddChild without arguments
   template <typename Fn> void AddChild(Fn DoAddChild) {
+    return AddChild("", DoAddChild);
+  }
+
+  /// Add a child of the current node with an optional label.
+  /// Calls DoAddChild without arguments.
+  template <typename Fn> void AddChild(StringRef Label, Fn DoAddChild) {
     // If we're at the top level, there's nothing interesting to do; just
     // run the dumper.
     if (TopLevel) {
@@ -56,7 +62,10 @@ public:
       return;
     }
 
-    auto DumpWithIndent = [this, DoAddChild](bool IsLastChild) {
+    // We need to capture an owning-string in the lambda because the lambda
+    // is invoked in a deferred manner.
+    std::string LabelStr = Label;
+    auto DumpWithIndent = [this, DoAddChild, LabelStr](bool IsLastChild) {
       // Print out the appropriate tree structure and work out the prefix for
       // children of this node. For instance:
       //
@@ -73,6 +82,9 @@ public:
         OS << '\n';
         ColorScope Color(OS, ShowColors, IndentColor);
         OS << Prefix << (IsLastChild ? '`' : '|') << '-';
+        if (!LabelStr.empty())
+          OS << LabelStr << ": ";
+
         this->Prefix.push_back(IsLastChild ? ' ' : '|');
         this->Prefix.push_back(' ');
       }