[clangd] Refine recoveryAST flags in clangd

so that we could start experiment for C.

Previously, these flags in clangd were only meaningful for C++. We need
to flip them for C, this patch repurpose these flags.

- if true, just set it.
- if false, just respect the value in clang.

this would allow us to keep flags on for C++, and optionally flip them on for C.

Differential Revision: https://reviews.llvm.org/D89233

Author: hokein

clang-tools-extra/clangd/ClangdServer.h

@@ -128,11 +128,13 @@ class ClangdServer {
     /// enabled.
     ClangTidyOptionsBuilder GetClangTidyOptions;
 
-    /// If true, turn on the `-frecovery-ast` clang flag.
-    bool BuildRecoveryAST = true;
+    /// If true, force -frecovery-ast flag.
+    /// If false, respect the value in clang.
+    bool BuildRecoveryAST = false;
 
-    /// If true, turn on the `-frecovery-ast-type` clang flag.
-    bool PreserveRecoveryASTType = true;
+    /// If true, force -frecovery-ast-type flag.
+    /// If false, respect the value in clang.
+    bool PreserveRecoveryASTType = false;
 
     /// Clangd's workspace root. Relevant for "workspace" operations not bound
     /// to a particular file.

clang-tools-extra/clangd/Compiler.cpp

@@ -81,11 +81,11 @@ buildCompilerInvocation(const ParseInputs &Inputs, clang::DiagnosticConsumer &D,
   // Don't crash on `#pragma clang __debug parser_crash`
   CI->getPreprocessorOpts().DisablePragmaDebugCrash = true;
 
-  // Recovery expression currently only works for C++.
-  if (CI->getLangOpts()->CPlusPlus) {
-    CI->getLangOpts()->RecoveryAST = Inputs.Opts.BuildRecoveryAST;
-    CI->getLangOpts()->RecoveryASTType = Inputs.Opts.PreserveRecoveryASTType;
-  }
+  if (Inputs.Opts.BuildRecoveryAST)
+    CI->getLangOpts()->RecoveryAST = true;
+  if (Inputs.Opts.PreserveRecoveryASTType)
+    CI->getLangOpts()->RecoveryASTType = true;
+
   return CI;
 }
 

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

@@ -310,7 +310,7 @@ opt<bool> CrossFileRename{
 opt<bool> RecoveryAST{
     "recovery-ast",
     cat(Features),
-    desc("Preserve expressions in AST for broken code (C++ only)."),
+    desc("Preserve expressions in AST for broken code."),
     init(ClangdServer::Options().BuildRecoveryAST),
 };
 

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

@@ -111,8 +111,6 @@ CodeCompleteResult completions(const TestTU &TU, Position Point,
 
   MockFS FS;
   auto Inputs = TU.inputs(FS);
-  Inputs.Opts.BuildRecoveryAST = true;
-  Inputs.Opts.PreserveRecoveryASTType = true;
   IgnoreDiagnostics Diags;
   auto CI = buildCompilerInvocation(Inputs, Diags);
   if (!CI) {
@@ -1100,8 +1098,6 @@ SignatureHelp signatures(llvm::StringRef Text, Position Point,
   MockFS FS;
   auto Inputs = TU.inputs(FS);
   Inputs.Index = Index.get();
-  Inputs.Opts.BuildRecoveryAST = true;
-  Inputs.Opts.PreserveRecoveryASTType = true;
   IgnoreDiagnostics Diags;
   auto CI = buildCompilerInvocation(Inputs, Diags);
   if (!CI) {

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

@@ -148,6 +148,17 @@ TEST_F(TargetDeclTest, Exprs) {
   EXPECT_DECLS("LabelStmt", "label:");
 }
 
+TEST_F(TargetDeclTest, RecoveryForC) {
+  Flags = {"-xc", "-Xclang", "-frecovery-ast"};
+  Code = R"cpp(
+    // error-ok: testing behavior on broken code
+    // int f();
+    int f(int);
+    int x = [[f]]();
+  )cpp";
+  EXPECT_DECLS("DeclRefExpr", "int f(int)");
+}
+
 TEST_F(TargetDeclTest, Recovery) {
   Code = R"cpp(
     // error-ok: testing behavior on broken code

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

@@ -59,8 +59,6 @@ ParseInputs TestTU::inputs(MockFS &FS) const {
     FS.OverlayRealFileSystemForModules = true;
   Inputs.TFS = &FS;
   Inputs.Opts = ParseOptions();
-  Inputs.Opts.BuildRecoveryAST = true;
-  Inputs.Opts.PreserveRecoveryASTType = true;
   Inputs.Opts.ClangTidyOpts.Checks = ClangTidyChecks;
   Inputs.Opts.ClangTidyOpts.WarningsAsErrors = ClangTidyWarningsAsErrors;
   Inputs.Index = ExternalIndex;