[clangd] Early return for #include goto definition.

[hokein]

Summary

This would save cost of walking over the AST, NFC.

[ilya-biryukov]

LGTM.
I think this was part of initial changed and I asked to make it this way, but I don't remember why.

[ilya-biryukov]

Sorry, being pedantic here... We're not saving time on parsing, but on walking over the AST :-)

[malaperle]

In D44251#1031370, @ilya-biryukov wrote:

LGTM.
I think this was part of initial changed and I asked to make it this way, but I don't remember why.

I think it was just to have a single place that returns. I think it's OK to early return in this case, it's a good optimization.

[hokein]

In D44251#1031373, @ilya-biryukov wrote:

Sorry, being pedantic here... We're not saving time on parsing, but on walking over the AST :-)

Yeah, rephased it.

clangd/XRefs.cpp

 std::vector<Location> findDefinitions(ParsedAST &AST, Position Pos) {
   const SourceManager &SourceMgr = AST.getASTContext().getSourceManager();
   const FileEntry *FE = SourceMgr.getFileEntryForID(SourceMgr.getMainFileID());
   if (!FE)
     return {};
 
   SourceLocation SourceLocationBeg = getBeginningOfIdentifier(AST, Pos, FE);
 
+  std::vector<Location> Result;
+  // Handle goto definition for #include.
+  for (auto &IncludeLoc : AST.getInclusionLocations()) {
+    Range R = IncludeLoc.first;
+    Position Pos = sourceLocToPosition(SourceMgr, SourceLocationBeg);
+
+    if (R.contains(Pos))
+      Result.push_back(Location{URIForFile{IncludeLoc.second}, {}});
+  }
+  if (!Result.empty())
+    return Result;
+
   auto DeclMacrosFinder = std::make_shared<DeclarationAndMacrosFinder>(
       llvm::errs(), SourceLocationBeg, AST.getASTContext(),
       AST.getPreprocessor());
   index::IndexingOptions IndexOpts;
   IndexOpts.SystemSymbolFilter =
       index::IndexingOptions::SystemSymbolFilterKind::All;
   IndexOpts.IndexFunctionLocals = true;
 
   indexTopLevelDecls(AST.getASTContext(), AST.getTopLevelDecls(),
                      DeclMacrosFinder, IndexOpts);
 
   std::vector<const Decl *> Decls = DeclMacrosFinder->takeDecls();
   std::vector<MacroDecl> MacroInfos = DeclMacrosFinder->takeMacroInfos();
-  std::vector<Location> Result;
 
   for (auto Item : Decls) {
     auto L = getDeclarationLocation(AST, Item->getSourceRange());
     if (L)
       Result.push_back(*L);
   }
 
   for (auto Item : MacroInfos) {
     SourceRange SR(Item.Info->getDefinitionLoc(),
                    Item.Info->getDefinitionEndLoc());
     auto L = getDeclarationLocation(AST, SR);
     if (L)
       Result.push_back(*L);
   }
 
-  /// Process targets for paths inside #include directive.
-  for (auto &IncludeLoc : AST.getInclusionLocations()) {
-    Range R = IncludeLoc.first;
-    Position Pos = sourceLocToPosition(SourceMgr, SourceLocationBeg);
-
-    if (R.contains(Pos))
-      Result.push_back(Location{URIForFile{IncludeLoc.second}, {}});
-  }
-
   return Result;
 }
 
 namespace {
 
 /// Finds document highlights that a given list of declarations refers to.
 class DocumentHighlightsFinder : public index::IndexDataConsumer {
   std::vector<const Decl *> &Decls;