[Parse] Check the SourceFile to see if bodies can be delayed

Remove the `DelayBodyParsing` flag from the parser
and instead query the source file.

include/swift/AST/SourceFile.h

@@ -569,6 +569,10 @@ public:
 
   bool isSuitableForASTScopes() const { return canBeParsedInFull(); }
 
+  /// Whether the bodies of types and functions within this file can be lazily
+  /// parsed.
+  bool hasDelayedBodyParsing() const;
+
   syntax::SourceFileSyntax getSyntaxRoot() const;
   void setSyntaxRoot(syntax::SourceFileSyntax &&Root);
   bool hasSyntaxRoot() const;

include/swift/Parse/Parser.h

@@ -173,9 +173,9 @@ public:
 
   LocalContext *CurLocalContext = nullptr;
 
-  bool isDelayedParsingEnabled() const {
-    return DelayBodyParsing || isCodeCompletionFirstPass();
-  }
+  /// Whether we should delay parsing nominal type, extension, and function
+  /// bodies.
+  bool isDelayedParsingEnabled() const;
 
   void setCodeCompletionCallbacks(CodeCompletionCallbacks *Callbacks) {
     CodeCompletion = Callbacks;
@@ -213,16 +213,6 @@ public:
   /// Always empty if !SF.shouldBuildSyntaxTree().
   ParsedTrivia TrailingTrivia;
 
-  /// Whether we should delay parsing nominal type and extension bodies,
-  /// and skip function bodies.
-  ///
-  /// This is false in primary files, since we want to type check all
-  /// declarations and function bodies.
-  ///
-  /// This is true for non-primary files, where declarations only need to be
-  /// lazily parsed and type checked.
-  bool DelayBodyParsing;
-
   /// Whether to evaluate the conditions of #if decls, meaning that the bodies
   /// of any active clauses are hoisted such that they become sibling nodes with
   /// the #if decl.
@@ -408,16 +398,16 @@ public:
          SILParserTUStateBase *SIL,
          PersistentParserState *PersistentState,
          std::shared_ptr<SyntaxParseActions> SPActions = nullptr,
-         bool DelayBodyParsing = true, bool EvaluateConditionals = true);
+         bool EvaluateConditionals = true);
   Parser(unsigned BufferID, SourceFile &SF, SILParserTUStateBase *SIL,
          PersistentParserState *PersistentState = nullptr,
          std::shared_ptr<SyntaxParseActions> SPActions = nullptr,
-         bool DelayBodyParsing = true, bool EvaluateConditionals = true);
+         bool EvaluateConditionals = true);
   Parser(std::unique_ptr<Lexer> Lex, SourceFile &SF,
          SILParserTUStateBase *SIL = nullptr,
          PersistentParserState *PersistentState = nullptr,
          std::shared_ptr<SyntaxParseActions> SPActions = nullptr,
-         bool DelayBodyParsing = true, bool EvaluateConditionals = true);
+         bool EvaluateConditionals = true);
   ~Parser();
 
   /// Returns true if the buffer being parsed is allowed to contain SIL.

include/swift/Subsystems.h

@@ -108,11 +108,7 @@ namespace swift {
   /// \param SF The file within the module being parsed.
   ///
   /// \param BufferID The buffer to parse from.
-  ///
-  /// \param DelayBodyParsing Whether parsing of type and function bodies can be
-  /// delayed.
   void parseIntoSourceFile(SourceFile &SF, unsigned BufferID,
-                           bool DelayBodyParsing = true,
                            bool EvaluateConditionals = true);
 
   /// Parse a source file's SIL declarations into a given SIL module.