[clangd] Add a flag to turn on recovery-expr.

Reviewers: sammccall

Subscribers: ilya-biryukov, MaskRay, jkorous, arphaman, kadircet, usaxena95, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D77142

Author: hokein

clang-tools-extra/clangd/ClangdServer.cpp

@@ -134,7 +134,8 @@ ClangdServer::ClangdServer(const GlobalCompilationDatabase &CDB,
                      : nullptr),
       GetClangTidyOptions(Opts.GetClangTidyOptions),
       SuggestMissingIncludes(Opts.SuggestMissingIncludes),
-      TweakFilter(Opts.TweakFilter), WorkspaceRoot(Opts.WorkspaceRoot),
+      BuildRecoveryAST(Opts.BuildRecoveryAST), TweakFilter(Opts.TweakFilter),
+      WorkspaceRoot(Opts.WorkspaceRoot),
       // Pass a callback into `WorkScheduler` to extract symbols from a newly
       // parsed file and rebuild the file index synchronously each time an AST
       // is parsed.
@@ -191,6 +192,7 @@ void ClangdServer::addDocument(PathRef File, llvm::StringRef Contents,
   Inputs.ForceRebuild = ForceRebuild;
   Inputs.Opts = std::move(Opts);
   Inputs.Index = Index;
+  Inputs.Opts.BuildRecoveryAST = BuildRecoveryAST;
   bool NewFile = WorkScheduler.update(File, Inputs, WantDiags);
   // If we loaded Foo.h, we want to make sure Foo.cpp is indexed.
   if (NewFile && BackgroundIdx)

clang-tools-extra/clangd/ClangdServer.h

@@ -118,6 +118,9 @@ class ClangdServer {
     /// enabled.
     ClangTidyOptionsBuilder GetClangTidyOptions;
 
+    /// If true, turn on the `-frecovery-ast` clang flag.
+    bool BuildRecoveryAST = false;
+
     /// Clangd's workspace root. Relevant for "workspace" operations not bound
     /// to a particular file.
     /// FIXME: If not set, should use the current working directory.
@@ -345,6 +348,9 @@ class ClangdServer {
   // can be caused by missing includes (e.g. member access in incomplete type).
   bool SuggestMissingIncludes = false;
 
+  // If true, preserve expressions in AST for broken code.
+  bool BuildRecoveryAST = false;
+
   std::function<bool(const Tweak &)> TweakFilter;
 
   // GUARDED_BY(CachedCompletionFuzzyFindRequestMutex)

clang-tools-extra/clangd/Compiler.h

@@ -38,6 +38,7 @@ class IgnoreDiagnostics : public DiagnosticConsumer {
 struct ParseOptions {
   tidy::ClangTidyOptions ClangTidyOpts;
   bool SuggestMissingIncludes = false;
+  bool BuildRecoveryAST = false;
 };
 
 /// Information required to run clang, e.g. to parse AST or do code completion.

clang-tools-extra/clangd/ParsedAST.cpp

@@ -253,6 +253,10 @@ ParsedAST::build(llvm::StringRef Version,
   const PrecompiledPreamble *PreamblePCH =
       Preamble ? &Preamble->Preamble : nullptr;
 
+  // Recovery expression currently only works for C++.
+  if (CI->getLangOpts()->CPlusPlus)
+    CI->getLangOpts()->RecoveryAST = Opts.BuildRecoveryAST;
+
   StoreDiags ASTDiags;
   std::string Content = std::string(Buffer->getBuffer());
   std::string Filename =

clang-tools-extra/clangd/Preamble.cpp

@@ -132,6 +132,10 @@ buildPreamble(PathRef FileName, CompilerInvocation &CI,
   // to read back. We rely on dynamic index for the comments instead.
   CI.getPreprocessorOpts().WriteCommentListToPCH = false;
 
+  // Recovery expression currently only works for C++.
+  if (CI.getLangOpts()->CPlusPlus)
+    CI.getLangOpts()->RecoveryAST = Inputs.Opts.BuildRecoveryAST;
+
   CppFilePreambleCallbacks SerializedDeclsCollector(FileName, PreambleCallback);
   if (Inputs.FS->setCurrentWorkingDirectory(Inputs.CompileCommand.Directory)) {
     log("Couldn't set working directory when building the preamble.");

clang-tools-extra/clangd/tool/ClangdMain.cpp

@@ -281,6 +281,15 @@ opt<bool> CrossFileRename{
     Hidden,
 };
 
+opt<bool> RecoveryAST{
+    "recovery-ast",
+    cat(Features),
+    desc("Preserve expressions in AST for broken code (C++ only). Note that "
+         "this feature is experimental and may lead to crashes"),
+    init(false),
+    Hidden,
+};
+
 opt<unsigned> WorkerThreadsCount{
     "j",
     cat(Misc),
@@ -629,6 +638,7 @@ clangd accepts flags on the commandline, and in the CLANGD_FLAGS environment var
   }
   Opts.StaticIndex = StaticIdx.get();
   Opts.AsyncThreadsCount = WorkerThreadsCount;
+  Opts.BuildRecoveryAST = RecoveryAST;
 
   clangd::CodeCompleteOptions CCOpts;
   CCOpts.IncludeIneligibleResults = IncludeIneligibleResults;

clang-tools-extra/clangd/unittests/FindTargetTests.cpp

@@ -132,6 +132,16 @@ TEST_F(TargetDeclTest, Exprs) {
   EXPECT_DECLS("CXXOperatorCallExpr", "void operator()(int n)");
 }
 
+TEST_F(TargetDeclTest, Recovery) {
+  Code = R"cpp(
+    // error-ok: testing behavior on broken code
+    int f();
+    int f(int, int);
+    int x = [[f]](42);
+  )cpp";
+  EXPECT_DECLS("UnresolvedLookupExpr", "int f()", "int f(int, int)");
+}
+
 TEST_F(TargetDeclTest, UsingDecl) {
   Code = R"cpp(
     namespace foo {
@@ -685,6 +695,15 @@ TEST_F(FindExplicitReferencesTest, All) {
         )cpp",
         "0: targets = {x}\n"
         "1: targets = {X::a}\n"},
+       {R"cpp(
+        // error-ok: testing with broken code
+        int bar();
+        int foo() {
+          return $0^bar() + $1^bar(42);
+        }
+        )cpp",
+        "0: targets = {bar}\n"
+        "1: targets = {bar}\n"},
        // Namespaces and aliases.
        {R"cpp(
           namespace ns {}

clang-tools-extra/clangd/unittests/TestTU.cpp

@@ -56,6 +56,7 @@ ParseInputs TestTU::inputs() const {
   Inputs.Contents = Code;
   Inputs.FS = buildTestFS(Files);
   Inputs.Opts = ParseOptions();
+  Inputs.Opts.BuildRecoveryAST = true;
   Inputs.Opts.ClangTidyOpts.Checks = ClangTidyChecks;
   Inputs.Opts.ClangTidyOpts.WarningsAsErrors = ClangTidyWarningsAsErrors;
   Inputs.Index = ExternalIndex;