Remove redundant state from PersistentParserState

Now that we parse Swift decls in one pass, we no
longer need to track the parser's position across
multiple parser calls.

Author: hamishknight

include/swift/Parse/Parser.h

@@ -431,9 +431,8 @@ class Parser {
                           PreviousLoc);
   }
 
-  ParserPosition getParserPosition(const PersistentParserState::ParserPos &Pos){
-    return ParserPosition(L->getStateForBeginningOfTokenLoc(Pos.Loc),
-                          Pos.PrevLoc);
+  ParserPosition getParserPosition(SourceLoc loc, SourceLoc previousLoc) {
+    return ParserPosition(L->getStateForBeginningOfTokenLoc(loc), previousLoc);
   }
 
   void restoreParserPosition(ParserPosition PP, bool enableDiagnostics = false) {

include/swift/Parse/PersistentParserState.h

@@ -59,23 +59,12 @@ class CodeCompletionDelayedDeclState {
 /// Parser state persistent across multiple parses.
 class PersistentParserState {
 public:
-  struct ParserPos {
-    SourceLoc Loc;
-    SourceLoc PrevLoc;
-
-    bool isValid() const { return Loc.isValid(); }
-  };
-
-  bool InPoundLineEnvironment = false;
   // FIXME: When condition evaluation moves to a later phase, remove this bit
   // and adjust the client call 'performParseOnly'.
   bool PerformConditionEvaluation = true;
 private:
   swift::ScopeInfo ScopeInfo;
 
-  /// Parser sets this if it stopped parsing before the buffer ended.
-  ParserPosition MarkedPos;
-
   std::unique_ptr<CodeCompletionDelayedDeclState> CodeCompletionDelayedDeclStat;
 
   /// The local context for all top-level code.
@@ -113,19 +102,6 @@ class PersistentParserState {
   TopLevelContext &getTopLevelContext() {
     return TopLevelCode;
   }
-
-  void markParserPosition(ParserPosition Pos,
-                          bool InPoundLineEnvironment) {
-    MarkedPos = Pos;
-    this->InPoundLineEnvironment = InPoundLineEnvironment;
-  }
-
-  /// Returns the marked parser position and resets it.
-  ParserPosition takeParserPosition() {
-    ParserPosition Pos = MarkedPos;
-    MarkedPos = ParserPosition();
-    return Pos;
-  }
 };
 
 } // end namespace swift

lib/Parse/ParseDecl.cpp

@@ -239,11 +239,6 @@ void Parser::parseTopLevel() {
   SF.ASTStage = SourceFile::Parsed;
   verify(SF);
 
-  // Next time start relexing from the beginning of the comment so that we can
-  // attach it to the token.
-  State->markParserPosition(getParserPosition(),
-                            InPoundLineEnvironment);
-
   // Finalize the token receiver.
   SyntaxContext->addToken(Tok, LeadingTrivia, TrailingTrivia);
   TokReceiver->finalize();
@@ -4012,7 +4007,8 @@ Parser::parseDeclListDelayed(IterableDeclContext *IDC) {
     return {std::vector<Decl *>(), None};
   }
 
-  auto BeginParserPosition = getParserPosition({BodyRange.Start, SourceLoc()});
+  auto BeginParserPosition = getParserPosition(BodyRange.Start,
+                                               /*previousLoc*/ SourceLoc());
   auto EndLexerState = L->getStateForEndOfTokenLoc(BodyRange.End);
 
   // ParserPositionRAII needs a primed parser to restore to.
@@ -6426,7 +6422,8 @@ BraceStmt *Parser::parseAbstractFunctionBodyDelayed(AbstractFunctionDecl *AFD) {
          "function body should be delayed");
 
   auto bodyRange = AFD->getBodySourceRange();
-  auto BeginParserPosition = getParserPosition({bodyRange.Start, SourceLoc()});
+  auto BeginParserPosition = getParserPosition(bodyRange.Start,
+                                               /*previousLoc*/ SourceLoc());
   auto EndLexerState = L->getStateForEndOfTokenLoc(AFD->getEndLoc());
 
   // ParserPositionRAII needs a primed parser to restore to.

lib/Parse/Parser.cpp

@@ -148,7 +148,7 @@ void Parser::performCodeCompletionSecondPassImpl(
   if (info.PrevOffset != ~0U)
     prevLoc = SourceMgr.getLocForOffset(BufferID, info.PrevOffset);
   // Set the parser position to the start of the delayed decl or the body.
-  restoreParserPosition(getParserPosition({startLoc, prevLoc}));
+  restoreParserPosition(getParserPosition(startLoc, prevLoc));
 
   // Do not delay parsing in the second pass.
   llvm::SaveAndRestore<bool> DisableDelayedBody(DelayBodyParsing, false);
@@ -543,13 +543,6 @@ Parser::Parser(std::unique_ptr<Lexer> Lex, SourceFile &SF,
   // Set the token to a sentinel so that we know the lexer isn't primed yet.
   // This cannot be tok::unknown, since that is a token the lexer could produce.
   Tok.setKind(tok::NUM_TOKENS);
-
-  auto ParserPos = State->takeParserPosition();
-  if (ParserPos.isValid() &&
-      L->isStateForCurrentBuffer(ParserPos.LS)) {
-    restoreParserPosition(ParserPos);
-    InPoundLineEnvironment = State->InPoundLineEnvironment;
-  }
 }
 
 Parser::~Parser() {