[Parser] Expose a flag to allow users explicitly disable delayed parsing. NFC

Discussed with @dcci, this patch is necessary to fix an lldb test failure. rdar://38396444

Author: nkcsgexi

include/swift/Parse/Parser.h

@@ -206,6 +206,9 @@ class Parser {
   /// Always empty if !SF.shouldBuildSyntaxTree().
   syntax::Trivia TrailingTrivia;
 
+  /// Whether we should disable delayed parsing.
+  bool DisableDelayedParsing;
+
   /// \brief The receiver to collect all consumed tokens.
   ConsumeTokenReceiver *TokReceiver;
 
@@ -351,12 +354,15 @@ class Parser {
 public:
   Parser(unsigned BufferID, SourceFile &SF, DiagnosticEngine* LexerDiags,
          SILParserTUStateBase *SIL,
-         PersistentParserState *PersistentState);
+         PersistentParserState *PersistentState,
+         bool DisableDelayedParsing = false);
   Parser(unsigned BufferID, SourceFile &SF, SILParserTUStateBase *SIL,
-         PersistentParserState *PersistentState = nullptr);
+         PersistentParserState *PersistentState = nullptr,
+         bool DisableDelayedParsing = false);
   Parser(std::unique_ptr<Lexer> Lex, SourceFile &SF,
          SILParserTUStateBase *SIL = nullptr,
-         PersistentParserState *PersistentState = nullptr);
+         PersistentParserState *PersistentState = nullptr,
+         bool DisableDelayedParsing = false);
   ~Parser();
 
   bool isInSILMode() const { return SIL != nullptr; }

include/swift/Subsystems.h

@@ -119,7 +119,8 @@ namespace swift {
   bool parseIntoSourceFile(SourceFile &SF, unsigned BufferID, bool *Done,
                            SILParserState *SIL = nullptr,
                            PersistentParserState *PersistentState = nullptr,
-                           DelayedParsingCallbacks *DelayedParseCB = nullptr);
+                           DelayedParsingCallbacks *DelayedParseCB = nullptr,
+                           bool DisableDelayedParsing = false);
 
   /// \brief Finish the parsing by going over the nodes that were delayed
   /// during the first parsing pass.

lib/Parse/ParseDecl.cpp

@@ -3469,6 +3469,9 @@ bool Parser::parseDeclList(SourceLoc LBLoc, SourceLoc &RBLoc,
 }
 
 bool Parser::canDelayMemberDeclParsing() {
+  // If explicitly disabled, respect the flag.
+  if (DisableDelayedParsing)
+    return false;
   // There's no fundamental reasons that SIL cannnot be lasily parsed. We need
   // to keep SILParserTUStateBase persistent to make it happen.
   if (isInSILMode())

lib/Parse/Parser.cpp

@@ -333,12 +333,15 @@ swift::tokenizeWithTrivia(const LangOptions &LangOpts, const SourceManager &SM,
 
 
 Parser::Parser(unsigned BufferID, SourceFile &SF, SILParserTUStateBase *SIL,
-               PersistentParserState *PersistentState)
-    : Parser(BufferID, SF, &SF.getASTContext().Diags, SIL, PersistentState) {}
+               PersistentParserState *PersistentState,
+               bool DisableDelayedParsing)
+    : Parser(BufferID, SF, &SF.getASTContext().Diags, SIL, PersistentState,
+             DisableDelayedParsing) {}
 
 Parser::Parser(unsigned BufferID, SourceFile &SF, DiagnosticEngine* LexerDiags,
                SILParserTUStateBase *SIL,
-               PersistentParserState *PersistentState)
+               PersistentParserState *PersistentState,
+               bool DisableDelayedParsing)
     : Parser(
           std::unique_ptr<Lexer>(new Lexer(
               SF.getASTContext().LangOpts, SF.getASTContext().SourceMgr,
@@ -353,7 +356,7 @@ Parser::Parser(unsigned BufferID, SourceFile &SF, DiagnosticEngine* LexerDiags,
               SF.shouldBuildSyntaxTree()
                   ? TriviaRetentionMode::WithTrivia
                   : TriviaRetentionMode::WithoutTrivia)),
-          SF, SIL, PersistentState) {}
+          SF, SIL, PersistentState, DisableDelayedParsing) {}
 
 namespace {
 
@@ -472,14 +475,16 @@ class TokenRecorder: public ConsumeTokenReceiver {
 
 Parser::Parser(std::unique_ptr<Lexer> Lex, SourceFile &SF,
                SILParserTUStateBase *SIL,
-               PersistentParserState *PersistentState)
+               PersistentParserState *PersistentState,
+               bool DisableDelayedParsing)
   : SourceMgr(SF.getASTContext().SourceMgr),
     Diags(SF.getASTContext().Diags),
     SF(SF),
     L(Lex.release()),
     SIL(SIL),
     CurDeclContext(&SF),
     Context(SF.getASTContext()),
+    DisableDelayedParsing(DisableDelayedParsing),
     TokReceiver(SF.shouldCollectToken() ?
                 new TokenRecorder(SF) :
                 new ConsumeTokenReceiver()),

lib/ParseSIL/ParseSIL.cpp

@@ -112,9 +112,11 @@ bool swift::parseIntoSourceFile(SourceFile &SF,
                                 bool *Done,
                                 SILParserState *SIL,
                                 PersistentParserState *PersistentState,
-                                DelayedParsingCallbacks *DelayedParseCB) {
+                                DelayedParsingCallbacks *DelayedParseCB,
+                                bool DisableDelayedParsing) {
   SharedTimer timer("Parsing");
-  Parser P(BufferID, SF, SIL ? SIL->Impl.get() : nullptr, PersistentState);
+  Parser P(BufferID, SF, SIL ? SIL->Impl.get() : nullptr, PersistentState,
+    DisableDelayedParsing);
   PrettyStackTraceParser StackTrace(P);
 
   llvm::SaveAndRestore<bool> S(P.IsParsingInterfaceTokens,