Remove friend references to TypeChecker

TypeChecker has no friends

Author: CodaFi

include/swift/AST/Decl.h

@@ -3597,7 +3597,6 @@ class EnumDecl final : public NominalTypeDecl {
 
   friend class EnumRawValuesRequest;
   friend class EnumRawTypeRequest;
-  friend class TypeChecker;
 
 public:
   EnumDecl(SourceLoc EnumLoc, Identifier Name, SourceLoc NameLoc,
@@ -3883,7 +3882,6 @@ class ClassDecl final : public NominalTypeDecl {
   friend class EmittedMembersRequest;
   friend class HasMissingDesignatedInitializersRequest;
   friend class InheritsSuperclassInitializersRequest;
-  friend class TypeChecker;
 
 public:
   ClassDecl(SourceLoc ClassLoc, Identifier Name, SourceLoc NameLoc,
@@ -4258,7 +4256,6 @@ class ProtocolDecl final : public NominalTypeDecl {
   friend class ProtocolRequiresClassRequest;
   friend class ExistentialConformsToSelfRequest;
   friend class ExistentialTypeSupportedRequest;
-  friend class TypeChecker;
 
 public:
   ProtocolDecl(DeclContext *DC, SourceLoc ProtocolLoc, SourceLoc NameLoc,

lib/Sema/ConstraintSystem.h

@@ -2229,8 +2229,15 @@ class ConstraintSystem {
   /// constraint system for further exploration.
   void applySolution(const Solution &solution);
 
-  // FIXME: Allows the type checker to apply solutions.
-  friend class swift::TypeChecker;
+  // FIXME: Perhaps these belong on ConstraintSystem itself.
+  friend Optional<BraceStmt *>
+  swift::TypeChecker::applyFunctionBuilderBodyTransform(FuncDecl *func,
+                                                        Type builderType);
+  friend Optional<SolutionApplicationTarget>
+  swift::TypeChecker::typeCheckExpression(SolutionApplicationTarget &target,
+                                          bool &unresolvedTypeExprs,
+                                          TypeCheckExprOptions options,
+                                          ExprTypeCheckListener *listener);
 
   /// Emit the fixes computed as part of the solution, returning true if we were
   /// able to emit an error message, or false if none of the fixits worked out.