--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/clang-tools-extra/clangd/DumpAST.h	Tue Jun 15 19:15:29 2021 +0900
@@ -0,0 +1,50 @@
+//===--- DumpAST.h - Serialize clang AST to LSP -----------------*- C++-*--===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// Exposing clang's AST can give insight into the precise meaning of code.
+// (C++ is a complicated language, and very few people know all its rules).
+// Despite the name, clang's AST describes *semantics* and so includes nodes
+// for implicit behavior like conversions.
+//
+// It's also useful to developers who work with the clang AST specifically,
+// and want to know how certain constructs are represented.
+//
+// The main representation is not based on the familiar -ast-dump output,
+// which is heavy on internal details.
+// It also does not use the -ast-dump=json output, which captures the same
+// detail in a machine-friendly way, but requires client-side logic to present.
+// Instead, the key information is bundled into a few fields (role/kind/detail)
+// with weakly-defined semantics, optimized for easy presentation.
+// The -ast-dump output is preserved in the 'arcana' field, and may be shown
+// e.g. as a tooltip.
+//
+// The textDocument/ast method implemented here is a clangd extension.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANGD_DUMPAST_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANGD_DUMPAST_H
+
+#include "Protocol.h"
+#include "clang/AST/ASTContext.h"
+
+namespace clang {
+namespace syntax {
+class TokenBuffer;
+} // namespace syntax
+namespace clangd {
+
+// Note: It's safe for the node to be a TranslationUnitDecl, as this function
+//       does not deserialize the preamble.
+ASTNode dumpAST(const DynTypedNode &, const syntax::TokenBuffer &Tokens,
+                const ASTContext &);
+
+} // namespace clangd
+} // namespace clang
+
+#endif