[clangd] Get rid of AST matchers in CodeComplete, NFC

[hokein]

Summary

The isIndexedForCodeCompletion is called in the code patch of
SymbolCollector.

[kadircet]

LG

[kadircet]

clangd/CodeComplete.cpp

1654 ↗

(On Diff #176348)

nit: maybe just break in here

[hokein]

Using break.

clang-tools-extra/trunk/clangd/CodeComplete.cpp

 #include "Quality.h"
 #include "SourceCode.h"
 #include "TUScheduler.h"
 #include "Trace.h"
 #include "URI.h"
 #include "index/Index.h"
 #include "clang/AST/Decl.h"
 #include "clang/AST/DeclBase.h"
-#include "clang/ASTMatchers/ASTMatchFinder.h"
 #include "clang/Basic/LangOptions.h"
 #include "clang/Basic/SourceLocation.h"
 #include "clang/Format/Format.h"
 #include "clang/Frontend/CompilerInstance.h"
 #include "clang/Frontend/FrontendActions.h"
 #include "clang/Lex/PreprocessorOptions.h"
 #include "clang/Sema/CodeCompleteConsumer.h"
 #include "clang/Sema/Sema.h"
semaCodeComplete(
       llvm::make_unique<SignatureHelpCollector>(Options, Index, Result),
       Options,
       {FileName, Command, Preamble, Contents, Pos, std::move(VFS),
        std::move(PCHs)});
   return Result;
 }
 
 bool isIndexedForCodeCompletion(const NamedDecl &ND, ASTContext &ASTCtx) {
-  using namespace clang::ast_matchers;
-  auto InTopLevelScope = hasDeclContext(
-      anyOf(namespaceDecl(), translationUnitDecl(), linkageSpecDecl()));
-  return !match(decl(anyOf(InTopLevelScope,
-                           hasDeclContext(
-                               enumDecl(InTopLevelScope, unless(isScoped()))))),
-                ND, ASTCtx)
-              .empty();
+  auto InTopLevelScope = [](const NamedDecl &ND) {
+    switch (ND.getDeclContext()->getDeclKind()) {
+    case Decl::TranslationUnit:
+    case Decl::Namespace:
+    case Decl::LinkageSpec:
+      return true;
+    default:
+      break;
+    };
+    return false;
+  };
+  if (InTopLevelScope(ND))
+    return true;
+
+  if (const auto *EnumDecl = dyn_cast<clang::EnumDecl>(ND.getDeclContext()))
+    return InTopLevelScope(*EnumDecl) && !EnumDecl->isScoped();
+
+  return false;
 }
 
 CompletionItem CodeCompletion::render(const CodeCompleteOptions &Opts) const {
   CompletionItem LSP;
   const auto *InsertInclude = Includes.empty() ? nullptr : &Includes[0];
   LSP.label = ((InsertInclude && InsertInclude->Insertion)
                    ? Opts.IncludeIndicator.Insert
                    : Opts.IncludeIndicator.NoInsert) +