Reapply r359778: [clangd] Fix code completion of macros defined in the preamble region of the main file.

The bad assert has been removed, and updateOutOfDateIdentifier has been guarded.
This reverts commit r359796.

llvm-svn: 359799

1 files changed, 45 insertions, 4 deletions

diff --git a/clang-tools-extra/clangd/ClangdUnit.cpp b/clang-tools-extra/clangd/ClangdUnit.cpp
index 9d0efeca455..c8c41330054 100644
--- a/clang-tools-extra/clangd/ClangdUnit.cpp
+++ b/clang-tools-extra/clangd/ClangdUnit.cpp
@@ -20,6 +20,8 @@
 #include "index/Index.h"
 #include "clang/AST/ASTContext.h"
 #include "clang/Basic/LangOptions.h"
+#include "clang/Basic/SourceManager.h"
+#include "clang/Basic/TokenKinds.h"
 #include "clang/Frontend/CompilerInstance.h"
 #include "clang/Frontend/CompilerInvocation.h"
 #include "clang/Frontend/FrontendActions.h"
@@ -94,6 +96,35 @@ private:
   std::vector<Decl *> TopLevelDecls;
 };
 
+class CollectMainFileMacros : public PPCallbacks {
+public:
+  explicit CollectMainFileMacros(const SourceManager &SM,
+                                 std::vector<std::string> *Out)
+      : SM(SM), Out(Out) {}
+
+  void FileChanged(SourceLocation Loc, FileChangeReason,
+                   SrcMgr::CharacteristicKind, FileID Prev) {
+    InMainFile = SM.isWrittenInMainFile(Loc);
+  }
+
+  void MacroDefined(const Token &MacroName, const MacroDirective *MD) {
+    if (InMainFile)
+      MainFileMacros.insert(MacroName.getIdentifierInfo()->getName());
+  }
+
+  void EndOfMainFile() {
+    for (const auto& Entry : MainFileMacros)
+      Out->push_back(Entry.getKey());
+    llvm::sort(*Out);
+  }
+
+ private:
+  const SourceManager &SM;
+  bool InMainFile = true;
+  llvm::StringSet<> MainFileMacros;
+  std::vector<std::string> *Out;
+};
+
 class CppFilePreambleCallbacks : public PreambleCallbacks {
 public:
   CppFilePreambleCallbacks(PathRef File, PreambleParsedCallback ParsedCallback)
@@ -103,6 +134,10 @@ public:
 
   IncludeStructure takeIncludes() { return std::move(Includes); }
 
+  std::vector<std::string> takeMainFileMacros() {
+    return std::move(MainFileMacros);
+  }
+
   CanonicalIncludes takeCanonicalIncludes() { return std::move(CanonIncludes); }
 
   void AfterExecute(CompilerInstance &CI) override {
@@ -118,7 +153,9 @@ public:
 
   std::unique_ptr<PPCallbacks> createPPCallbacks() override {
     assert(SourceMgr && "SourceMgr must be set at this point");
-    return collectIncludeStructureCallback(*SourceMgr, &Includes);
+    return llvm::make_unique<PPChainedCallbacks>(
+        collectIncludeStructureCallback(*SourceMgr, &Includes),
+        llvm::make_unique<CollectMainFileMacros>(*SourceMgr, &MainFileMacros));
   }
 
   CommentHandler *getCommentHandler() override {
@@ -131,6 +168,7 @@ private:
   PreambleParsedCallback ParsedCallback;
   IncludeStructure Includes;
   CanonicalIncludes CanonIncludes;
+  std::vector<std::string> MainFileMacros;
   std::unique_ptr<CommentHandler> IWYUHandler = nullptr;
   SourceManager *SourceMgr = nullptr;
 };
@@ -459,11 +497,13 @@ const CanonicalIncludes &ParsedAST::getCanonicalIncludes() const {
 
 PreambleData::PreambleData(PrecompiledPreamble Preamble,
                            std::vector<Diag> Diags, IncludeStructure Includes,
+                           std::vector<std::string> MainFileMacros,
                            std::unique_ptr<PreambleFileStatusCache> StatCache,
                            CanonicalIncludes CanonIncludes)
     : Preamble(std::move(Preamble)), Diags(std::move(Diags)),
-      Includes(std::move(Includes)), StatCache(std::move(StatCache)),
-      CanonIncludes(std::move(CanonIncludes)) {}
+      Includes(std::move(Includes)), MainFileMacros(std::move(MainFileMacros)),
+      StatCache(std::move(StatCache)), CanonIncludes(std::move(CanonIncludes)) {
+}
 
 ParsedAST::ParsedAST(std::shared_ptr<const PreambleData> Preamble,
                      std::unique_ptr<CompilerInstance> Clang,
@@ -542,7 +582,8 @@ buildPreamble(PathRef FileName, CompilerInvocation &CI,
     std::vector<Diag> Diags = PreambleDiagnostics.take();
     return std::make_shared<PreambleData>(
         std::move(*BuiltPreamble), std::move(Diags),
-        SerializedDeclsCollector.takeIncludes(), std::move(StatCache),
+        SerializedDeclsCollector.takeIncludes(),
+        SerializedDeclsCollector.takeMainFileMacros(), std::move(StatCache),
         SerializedDeclsCollector.takeCanonicalIncludes());
   } else {
     elog("Could not build a preamble for file {0}", FileName);