Move Vending Top-Level Autoclosure discriminators into ASTContext

This bit has historically survived typechecking and parsing across source files.  Stick it where we stick the other global state.

This also means we don't have to thread TopLevelContext around anymore when invoking high-level typechecking entrypoints.

Author: CodaFi

include/swift/AST/ASTContext.h

@@ -277,6 +277,10 @@ class ASTContext final {
   /// The # of times we have performed typo correction.
   unsigned NumTypoCorrections = 0;
 
+  /// The next auto-closure discriminator.  This needs to be preserved
+  /// across invocations of both the parser and the type-checker.
+  unsigned NextAutoClosureDiscriminator = 0;
+
 private:
   /// The current generation number, which reflects the number of
   /// times that external modules have been loaded.

include/swift/Parse/LocalContext.h

@@ -61,12 +61,7 @@ class LocalContext {
 };
 
 /// Information associated with parsing the top-level context.
-class TopLevelContext : public LocalContext {
-public:
-  /// The next auto-closure discriminator.  This needs to be preserved
-  /// across invocations of both the parser and the type-checker.
-  unsigned NextAutoClosureDiscriminator = 0;
-};
+class TopLevelContext : public LocalContext {};
 
 } // end namespace swift
 

lib/Sema/PCMacro.cpp

@@ -692,7 +692,7 @@ void swift::performPCMacro(SourceFile &SF, TopLevelContext &TLC) {
             if (NewBody != Body) {
               TLCD->setBody(NewBody);
               TypeChecker::checkTopLevelErrorHandling(TLCD);
-              TypeChecker::contextualizeTopLevelCode(TLC, TLCD);
+              TypeChecker::contextualizeTopLevelCode(TLCD);
             }
             return false;
           }

lib/Sema/TypeCheckStmt.cpp

@@ -231,14 +231,14 @@ bool TypeChecker::contextualizeInitializer(Initializer *DC, Expr *E) {
   return CC.hasAutoClosures();
 }
 
-void TypeChecker::contextualizeTopLevelCode(TopLevelContext &TLC,
-                                            TopLevelCodeDecl *TLCD) {
-  unsigned nextDiscriminator = TLC.NextAutoClosureDiscriminator;
+void TypeChecker::contextualizeTopLevelCode(TopLevelCodeDecl *TLCD) {
+  auto &Context = TLCD->DeclContext::getASTContext();
+  unsigned nextDiscriminator = Context.NextAutoClosureDiscriminator;
   ContextualizeClosures CC(TLCD, nextDiscriminator);
   TLCD->getBody()->walk(CC);
-  assert(nextDiscriminator == TLC.NextAutoClosureDiscriminator &&
+  assert(nextDiscriminator == Context.NextAutoClosureDiscriminator &&
          "reentrant/concurrent invocation of contextualizeTopLevelCode?");
-  TLC.NextAutoClosureDiscriminator = CC.NextDiscriminator;
+  Context.NextAutoClosureDiscriminator = CC.NextDiscriminator;
 }
 
 /// Emits an error with a fixit for the case of unnecessary cast over a

lib/Sema/TypeChecker.cpp

@@ -366,7 +366,7 @@ void swift::performTypeChecking(SourceFile &SF, TopLevelContext &TLC,
       if (auto *TLCD = dyn_cast<TopLevelCodeDecl>(D)) {
         // Immediately perform global name-binding etc.
         TypeChecker::typeCheckTopLevelCodeDecl(TLCD);
-        TypeChecker::contextualizeTopLevelCode(TLC, TLCD);
+        TypeChecker::contextualizeTopLevelCode(TLCD);
       } else {
         TypeChecker::typeCheckDecl(D);
       }

lib/Sema/TypeChecker.h

@@ -1159,8 +1159,7 @@ class TypeChecker final {
   ///
   /// \returns true if any closures were found
   static bool contextualizeInitializer(Initializer *DC, Expr *init);
-  static void contextualizeTopLevelCode(TopLevelContext &TLC,
-                                        TopLevelCodeDecl *TLCD);
+  static void contextualizeTopLevelCode(TopLevelCodeDecl *TLCD);
 
   /// Return the type-of-reference of the given value.
   ///