[ParseableInterfaces] Handle lazy vars

For lazy vars, we need to make public the top-level entry point, and the fact
that the lazy storage contributes to the layout of a type (if it’s fixed
layout, or if the type is not resilient.) We also shouldn’t ever print `lazy`
in a parseable interface.

Since we need to parse these identifiers, give them a new name,
`$__lazy_storage_$_{propname}`, which is parseable only in parseable interfaces
so it doesn’t conflict with other properties.

Author: Harlan Haskins

lib/AST/ASTPrinter.cpp

@@ -178,7 +178,7 @@ PrintOptions PrintOptions::printParseableInterfaceFile() {
   result.PrintAccess = true;
 
   result.ExcludeAttrList = {DAK_ImplicitlyUnwrappedOptional, DAK_AccessControl,
-                            DAK_SetterAccess};
+                            DAK_SetterAccess, DAK_Lazy};
 
   return result;
 }

lib/Sema/CodeSynthesis.cpp

@@ -1346,8 +1346,9 @@ void swift::completeLazyVarImplementation(VarDecl *VD) {
   assert(!VD->isStatic() && "Static vars are already lazy on their own");
 
   // Create the storage property as an optional of VD's type.
-  SmallString<64> NameBuf = VD->getName().str();
-  NameBuf += ".storage";
+  SmallString<64> NameBuf;
+  NameBuf += "$__lazy_storage_$_";
+  NameBuf += VD->getName().str();
   auto StorageName = Context.getIdentifier(NameBuf);
   auto StorageTy = OptionalType::get(VD->getType());
   auto StorageInterfaceTy = OptionalType::get(VD->getInterfaceType());

test/ParseableInterface/lazy-vars.swift

@@ -0,0 +1,41 @@
+// RUN: %empty-directory(%t)
+
+// RUN: %target-swift-frontend -typecheck -module-name Test -emit-parseable-module-interface-path %t/Test.swiftinterface %s
+// RUN: %FileCheck %s < %t/Test.swiftinterface --check-prefix CHECK --check-prefix NONRESILIENT
+// RUN: %target-swift-frontend -build-module-from-parseable-interface %t/Test.swiftinterface -o %t/Test.swiftmodule
+// RUN: %target-swift-frontend -emit-module -o /dev/null -merge-modules -emit-parseable-module-interface-path - %t/Test.swiftmodule -module-name Test | %FileCheck %s --check-prefix CHECK --check-prefix NONRESILIENT
+
+// RUN: %target-swift-frontend -typecheck -module-name TestResilient -emit-parseable-module-interface-path %t/TestResilient.swiftinterface -enable-resilience %s
+// RUN: %FileCheck %s < %t/TestResilient.swiftinterface --check-prefix CHECK --check-prefix RESILIENT
+
+// RUN: %target-swift-frontend -build-module-from-parseable-interface %t/TestResilient.swiftinterface -o %t/TestResilient.swiftmodule
+// RUN: %target-swift-frontend -emit-module -o /dev/null -merge-modules -emit-parseable-module-interface-path - %t/TestResilient.swiftmodule -module-name TestResilient | %FileCheck %s --check-prefix CHECK --check-prefix RESILIENT
+
+// CHECK: @_fixed_layout public struct HasLazyVarsFixedLayout {
+// CHECK-NEXT: public var foo: [[INT:(Swift\.)?Int]] {
+// CHECK-NEXT:   mutating get
+// CHECK-NEXT:   set
+// CHECK-NEXT: }
+// CHECK: private var $__lazy_storage_$_foo: [[INT]]?
+// CHECK-NOT: private var bar
+// CHECK: private var $__lazy_storage_$_bar: [[INT]]?
+// CHECK-NEXT: }
+@_fixed_layout
+public struct HasLazyVarsFixedLayout {
+  public lazy var foo: Int = 0
+  private lazy var bar: Int = 0
+}
+
+// CHECK: public struct HasLazyVars {
+// CHECK-NEXT: public var foo: [[INT:(Swift\.)?Int]] {
+// CHECK-NEXT:   mutating get
+// CHECK-NEXT:   set
+// CHECK-NEXT: }
+// NONRESILIENT: private var $__lazy_storage_$_foo: [[INT]]?
+// CHECK-NOT: private var bar
+// NONRESILIENT: private var $__lazy_storage_$_bar: [[INT]]?
+// CHECK-NEXT: }
+public struct HasLazyVars {
+  public lazy var foo: Int = 0
+  private lazy var bar: Int = 0
+}

test/api-digester/Outputs/Cake-abi.txt

@@ -62,8 +62,8 @@ cake1: Var fixedLayoutStruct.b in a non-resilient type changes position from 0 t
 cake1: Var fixedLayoutStruct2.BecomeFixedBinaryOrder is now a stored property
 cake1: Var fixedLayoutStruct2.NoLongerWithFixedBinaryOrder is no longer a stored property
 cake2: EnumElement FrozenKind.AddedCase is added to a non-resilient type
+cake2: Var fixedLayoutStruct.$__lazy_storage_$_lazy_d is added to a non-resilient type
 cake2: Var fixedLayoutStruct.c is added to a non-resilient type
-cake2: Var fixedLayoutStruct.lazy_d.storage is added to a non-resilient type
 
 /* Conformance changes */
 cake1: Func ObjCProtocol.addOptional() is now an optional requirement