Removed the feature and made changes unconditional

Author: nickolas-pohilets

include/swift/Basic/Features.def

@@ -511,9 +511,6 @@ SUPPRESSIBLE_EXPERIMENTAL_FEATURE(ExtensibleAttribute, false)
 /// Allow use of `Module::name` syntax
 EXPERIMENTAL_FEATURE(ModuleSelector, false)
 
-/// Allow `weak let` and make weak captures immutable
-EXPERIMENTAL_FEATURE(WeakLet, true)
-
 #undef EXPERIMENTAL_FEATURE_EXCLUDED_FROM_MODULE_INTERFACE
 #undef EXPERIMENTAL_FEATURE
 #undef UPCOMING_FEATURE

lib/AST/Expr.cpp

@@ -1366,10 +1366,8 @@ CaptureListEntry CaptureListEntry::createParsed(
     SourceRange ownershipRange, Identifier name, SourceLoc nameLoc,
     SourceLoc equalLoc, Expr *initializer, DeclContext *DC) {
 
-  bool forceVar = ownershipKind == ReferenceOwnership::Weak && !Ctx.LangOpts.hasFeature(Feature::WeakLet);
-  auto introducer = forceVar ? VarDecl::Introducer::Var : VarDecl::Introducer::Let;
   auto *VD =
-      new (Ctx) VarDecl(/*isStatic==*/false, introducer, nameLoc, name, DC);
+      new (Ctx) VarDecl(/*isStatic==*/false, VarDecl::Introducer::Let, nameLoc, name, DC);
 
   if (ownershipKind != ReferenceOwnership::Strong)
     VD->getAttrs().add(

lib/AST/FeatureSet.cpp

@@ -624,15 +624,6 @@ static bool usesFeatureExtensibleAttribute(Decl *decl) {
   return decl->getAttrs().hasAttribute<ExtensibleAttr>();
 }
 
-static bool usesFeatureWeakLet(Decl *decl) {
-  if (auto *VD = dyn_cast<VarDecl>(decl)) {
-    if (auto *refAttr = VD->getAttrs().getAttribute<ReferenceOwnershipAttr>()) {
-      return VD->isLet() && refAttr->get() == ReferenceOwnership::Weak;
-    }
-  }
-  return false;
-}
-
 // ----------------------------------------------------------------------------
 // MARK: - FeatureSet
 // ----------------------------------------------------------------------------

lib/SIL/IR/TypeLowering.cpp

@@ -170,15 +170,6 @@ CaptureKind TypeConverter::getDeclCaptureKind(CapturedValue capture,
       return CaptureKind::StorageAddress;
   }
 
-  // Reference storage types can appear in a capture list, which means
-  // we might allocate boxes to store the captures. However, those boxes
-  // have the same lifetime as the closure itself, so we must capture
-  // the box itself and not the payload, even if the closure is noescape,
-  // otherwise they will be destroyed when the closure is formed.
-  if (var->getInterfaceType()->is<ReferenceStorageType>() && !Context.LangOpts.hasFeature(Feature::WeakLet)) {
-    return CaptureKind::Box;
-  }
-
   // For 'let' constants
   if (!var->supportsMutation()) {
     assert(getTypeLowering(

lib/Sema/MiscDiagnostics.cpp

@@ -4003,11 +4003,6 @@ VarDeclUsageChecker::~VarDeclUsageChecker() {
       access &= ~RK_Written;
     }
 
-    // If this variable has WeakStorageType, then it can be mutated in ways we
-    // don't know.
-    if (var->getInterfaceType()->is<WeakStorageType>() && !DC->getASTContext().LangOpts.hasFeature(Feature::WeakLet))
-      access |= RK_Written;
-    
     // Diagnose variables that were never used (other than their
     // initialization).
     //

lib/Sema/TypeCheckAttr.cpp

@@ -5285,11 +5285,6 @@ Type TypeChecker::checkReferenceOwnershipAttr(VarDecl *var, Type type,
   case ReferenceOwnershipOptionality::Allowed:
     break;
   case ReferenceOwnershipOptionality::Required:
-    if (var->isLet() && !ctx.LangOpts.hasFeature(Feature::WeakLet)) {
-      var->diagnose(diag::invalid_ownership_is_let, ownershipKind);
-      attr->setInvalid();
-    }
-
     if (!isOptional) {
       attr->setInvalid();
 

test/Concurrency/weak_ref_sendability.swift

@@ -1,8 +1,4 @@
 // RUN: %target-swift-frontend %s -emit-ir -g -o - | %FileCheck %s
-// RUN: %target-swift-frontend %s -enable-experimental-feature WeakLet -emit-ir -g -o - | %FileCheck %s
-
-// REQUIRES: swift_feature_WeakLet
-
 class A {
     init(handler: (() -> ())) { }
 }

test/DebugInfo/WeakCapture.swift

@@ -1,8 +1,4 @@
 // RUN: %target-swift-frontend %s -emit-ir -g -o - | %FileCheck %s
-// RUN: %target-swift-frontend %s -enable-experimental-feature WeakLet -emit-ir -g -o - | %FileCheck %s
-
-// REQUIRES: swift_feature_WeakLet
-
 public class ClosureMaker {
     var a : Int
 

test/DebugInfo/weak-self-capture.swift

@@ -1,8 +1,5 @@
 // RUN: %target-run-simple-swift | %FileCheck %s
-// RUN: %target-run-simple-swift(-Xfrontend -enable-experimental-feature -Xfrontend WeakLet) | %FileCheck %s --check-prefixes=CHECK,CHECK-WEAK-LET
-
 // REQUIRES: executable_test
-// REQUIRES: swift_feature_WeakLet
 
 protocol Protocol : class {
   func noop()
@@ -79,19 +76,17 @@ func testWeakInLet() {
 
 testWeakInLet()
 
-#if hasFeature(WeakLet)
 func testWeakLet() {
-  print("testWeakLet") // CHECK-WEAK-LET-LABEL: testWeakLet
+  print("testWeakLet") // CHECK-LABEL: testWeakLet
 
-  var obj: SwiftClassBase? = SwiftClass() // CHECK-WEAK-LET: SwiftClass Created
+  var obj: SwiftClassBase? = SwiftClass() // CHECK: SwiftClass Created
   weak let weakRef = obj
-  printState(weakRef) // CHECK-WEAK-LET-NEXT: is present
-  obj = nil // CHECK-WEAK-LET-NEXT: SwiftClass Destroyed
-  printState(weakRef) // CHECK-WEAK-LET-NEXT: is nil
+  printState(weakRef) // CHECK-NEXT: is present
+  obj = nil // CHECK-NEXT: SwiftClass Destroyed
+  printState(weakRef) // CHECK-NEXT: is nil
 }
 
 testWeakLet()
-#endif
 
 
 //======================== Test Classbound Protocols ========================