[clang-tools-extra] [clang] [clang] Support parsing comments without ASTContext (PR #78491)

[Tom Praschan via cfe-commits]

https://github.com/tom-anders created https://github.com/llvm/llvm-project/pull/78491

This is in preparation for implementing doxygen parsing, see discussion in https://github.com/clangd/clangd/issues/529.

(Old Phabricator review: https://reviews.llvm.org/D143112)

>From b5b4ddc967df436d0879cb8bd22a41acdf68819c Mon Sep 17 00:00:00 2001
From: Tom Praschan <13141438+tom-anders at users.noreply.github.com>
Date: Sat, 18 Feb 2023 15:54:09 +0100
Subject: [PATCH] [clang] Support parsing comments without ASTContext

This is in preparation for implementing doxygen parsing, see discussion in https://github.com/clangd/clangd/issues/529.

Differential Revision: https://reviews.llvm.org/D143112
---
 .../clangd/CodeCompletionStrings.cpp          | 24 +++++++++++++++++++
 .../clangd/CodeCompletionStrings.h            | 11 +++++++++
 clang/include/clang/Basic/SourceManager.h     |  2 +-
 3 files changed, 36 insertions(+), 1 deletion(-)

diff --git a/clang-tools-extra/clangd/CodeCompletionStrings.cpp b/clang-tools-extra/clangd/CodeCompletionStrings.cpp
index 2075e5965f181e..540eaa9a3eb6d7 100644
--- a/clang-tools-extra/clangd/CodeCompletionStrings.cpp
+++ b/clang-tools-extra/clangd/CodeCompletionStrings.cpp
@@ -9,6 +9,9 @@
 #include "CodeCompletionStrings.h"
 #include "clang-c/Index.h"
 #include "clang/AST/ASTContext.h"
+#include "clang/AST/CommentLexer.h"
+#include "clang/AST/CommentParser.h"
+#include "clang/AST/CommentSema.h"
 #include "clang/AST/RawCommentList.h"
 #include "clang/Basic/SourceManager.h"
 #include "clang/Sema/CodeCompleteConsumer.h"
@@ -316,5 +319,26 @@ std::string getReturnType(const CodeCompletionString &CCS) {
   return "";
 }
 
+comments::FullComment *parseComment(llvm::StringRef Comment,
+                                    llvm::BumpPtrAllocator &Allocator,
+                                    comments::CommandTraits &Traits) {
+  // The comment lexer expects markers, so add them back
+  auto CommentWithMarkers = "/*" + Comment.str() + "*/";
+
+  SourceManagerForFile SourceMgrForFile("mock_file.cpp", CommentWithMarkers);
+  SourceManager &SourceMgr = SourceMgrForFile.get();
+
+  comments::Lexer L(Allocator, SourceMgr.getDiagnostics(), Traits,
+                    SourceMgr.getLocForStartOfFile(SourceMgr.getMainFileID()),
+                    CommentWithMarkers.data(),
+                    CommentWithMarkers.data() + CommentWithMarkers.size());
+  comments::Sema S(Allocator, SourceMgr, SourceMgr.getDiagnostics(), Traits,
+                   nullptr);
+  comments::Parser P(L, S, Allocator, SourceMgr, SourceMgr.getDiagnostics(),
+                     Traits);
+
+  return P.parseFullComment();
+}
+
 } // namespace clangd
 } // namespace clang
diff --git a/clang-tools-extra/clangd/CodeCompletionStrings.h b/clang-tools-extra/clangd/CodeCompletionStrings.h
index fa81ad64d406c3..b93420c68f32db 100644
--- a/clang-tools-extra/clangd/CodeCompletionStrings.h
+++ b/clang-tools-extra/clangd/CodeCompletionStrings.h
@@ -19,6 +19,11 @@
 namespace clang {
 class ASTContext;
 
+namespace comments {
+class CommandTraits;
+class FullComment;
+} // namespace comments
+
 namespace clangd {
 
 /// Gets a minimally formatted documentation comment of \p Result, with comment
@@ -67,6 +72,12 @@ std::string formatDocumentation(const CodeCompletionString &CCS,
 /// is usually the return type of a function.
 std::string getReturnType(const CodeCompletionString &CCS);
 
+/// Parse the \p Comment, storing the result in \p Allocator, assuming
+/// that comment markers have already been stripped (e.g. via getDocComment())
+comments::FullComment *parseComment(llvm::StringRef Comment,
+                                    llvm::BumpPtrAllocator &Allocator,
+                                    comments::CommandTraits &Traits);
+
 } // namespace clangd
 } // namespace clang
 
diff --git a/clang/include/clang/Basic/SourceManager.h b/clang/include/clang/Basic/SourceManager.h
index d2ece14da0b11a..07e3fca1641c73 100644
--- a/clang/include/clang/Basic/SourceManager.h
+++ b/clang/include/clang/Basic/SourceManager.h
@@ -1971,7 +1971,7 @@ class BeforeThanCompare<SourceRange> {
 };
 
 /// SourceManager and necessary dependencies (e.g. VFS, FileManager) for a
-/// single in-memorty file.
+/// single in-memory file.
 class SourceManagerForFile {
 public:
   /// Creates SourceManager and necessary dependencies (e.g. VFS, FileManager).