AST: Small cleanups

- Allow AbstractClosureExpr to be created with null body
- Split up ParameterList::CloneFlags::Inherited

Author: slavapestov

include/swift/AST/Expr.h

@@ -3748,7 +3748,8 @@ class AutoClosureExpr : public AbstractClosureExpr {
                   DeclContext *Parent)
       : AbstractClosureExpr(ExprKind::AutoClosure, ResultTy, /*Implicit=*/true,
                             Discriminator, Parent) {
-    setBody(Body);
+    if (Body != nullptr)
+      setBody(Body);
   }
 
   SourceRange getSourceRange() const;

include/swift/AST/ParameterList.h

@@ -103,15 +103,15 @@ class alignas(ParamDecl *) ParameterList final :
   /// Change the DeclContext of any contained parameters to the specified
   /// DeclContext.
   void setDeclContextOfParamDecls(DeclContext *DC);
-  
-  
+
   /// Flags used to indicate how ParameterList cloning should operate.
   enum CloneFlags {
     /// The cloned ParamDecls should be marked implicit.
     Implicit = 0x01,
-    /// The cloned pattern is for an inherited constructor; mark default
-    /// arguments as inherited, and mark unnamed arguments as named.
+    /// Mark default arguments as inherited.
     Inherited = 0x02,
+    /// Mark unnamed arguments as named.
+    NamedArguments = 0x04,
   };
 
   friend OptionSet<CloneFlags> operator|(CloneFlags flag1, CloneFlags flag2) {

lib/AST/Parameter.cpp

@@ -67,10 +67,9 @@ ParameterList *ParameterList::clone(const ASTContext &C,
     if (options & Implicit)
       decl->setImplicit();
 
-    // If the argument isn't named, and we're cloning for an inherited
-    // constructor, give the parameter a name so that silgen will produce a
-    // value for it.
-    if (decl->getName().empty() && (options & Inherited))
+    // If the argument isn't named, give the parameter a name so that
+    // silgen will produce a value for it.
+    if (decl->getName().empty() && (options & NamedArguments))
       decl->setName(C.getIdentifier("argument"));
 
     // If we're inheriting a default argument, mark it as such.

lib/Sema/CSApply.cpp

@@ -4338,7 +4338,8 @@ namespace {
       auto closureTy =
           FunctionType::get({ FunctionType::Param(baseTy) }, leafTy);
       auto closure = new (ctx)
-          AutoClosureExpr(E, leafTy, discriminator, cs.DC);
+          AutoClosureExpr(/*set body later*/nullptr, leafTy,
+                          discriminator, cs.DC);
       auto param = new (ctx) ParamDecl(
           SourceLoc(),
           /*argument label*/ SourceLoc(), Identifier(),
@@ -4352,7 +4353,8 @@ namespace {
       auto outerClosureTy =
           FunctionType::get({ FunctionType::Param(keyPathTy) }, closureTy);
       auto outerClosure = new (ctx)
-          AutoClosureExpr(closure, closureTy, discriminator, cs.DC);
+          AutoClosureExpr(/*set body later*/nullptr, closureTy,
+                          discriminator, cs.DC);
       auto outerParam =
           new (ctx) ParamDecl(SourceLoc(),
                               /*argument label*/ SourceLoc(), Identifier(),

lib/Sema/CodeSynthesis.cpp

@@ -642,7 +642,8 @@ createDesignatedInitOverride(ClassDecl *classDecl,
   // Create the initializer parameter patterns.
   OptionSet<ParameterList::CloneFlags> options
     = (ParameterList::Implicit |
-       ParameterList::Inherited);
+       ParameterList::Inherited |
+       ParameterList::NamedArguments);
   auto *superclassParams = superclassCtor->getParameters();
   auto *bodyParams = superclassParams->clone(ctx, options);