Wrap only changes related to the closure frontend logic

Author: nickolas-pohilets

include/swift/AST/Stmt.h

@@ -715,7 +715,8 @@ class alignas(1 << PatternAlignInBits) StmtConditionElement {
   ///    RHS of the self condition references a var defined in a capture list.
   ///  - If `requireLoadExpr` is `true`, additionally requires that the RHS of
   ///    the self condition is a `LoadExpr`.
-  /// TODO: Remove `requireLoadExpr` after full-on of the WeakLet feature
+  /// TODO: Remove `requireLoadExpr` after full-on of the ImmutableWeakCaptures
+  /// feature
   bool rebindsSelf(ASTContext &Ctx, bool requiresCaptureListRef = false,
                    bool requireLoadExpr = false) const;
 

include/swift/Basic/Features.def

@@ -296,7 +296,7 @@ UPCOMING_FEATURE(InternalImportsByDefault, 409, 7)
 MIGRATABLE_UPCOMING_FEATURE(MemberImportVisibility, 444, 7)
 MIGRATABLE_UPCOMING_FEATURE(InferIsolatedConformances, 470, 7)
 MIGRATABLE_UPCOMING_FEATURE(NonisolatedNonsendingByDefault, 461, 7)
-UPCOMING_FEATURE(WeakLet, 481, 7)
+UPCOMING_FEATURE(ImmutableWeakCaptures, 481, 7)
 
 // Optional language features / modes
 

lib/AST/Expr.cpp

@@ -1373,7 +1373,8 @@ 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);
+  bool forceVar = ownershipKind == ReferenceOwnership::Weak &&
+                  !Ctx.LangOpts.hasFeature(Feature::ImmutableWeakCaptures);
   auto introducer = forceVar ? VarDecl::Introducer::Var : VarDecl::Introducer::Let;
   auto *VD =
       new (Ctx) VarDecl(/*isStatic==*/false, introducer, nameLoc, name, DC);

lib/AST/FeatureSet.cpp

@@ -441,15 +441,7 @@ UNINTERESTING_FEATURE(BuiltinSelect)
 UNINTERESTING_FEATURE(BuiltinInterleave)
 UNINTERESTING_FEATURE(BuiltinVectorsExternC)
 UNINTERESTING_FEATURE(AddressOfProperty2)
-
-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;
-}
+UNINTERESTING_FEATURE(ImmutableWeakCaptures)
 
 // ----------------------------------------------------------------------------
 // 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(getTypeProperties(

lib/Sema/MiscDiagnostics.cpp

@@ -1780,8 +1780,8 @@ class ImplicitSelfUsageChecker : public BaseDiagnosticWalker {
     if (!conditionalStmt) {
       return false;
     }
-    
-    if (Ctx.LangOpts.hasFeature(Feature::WeakLet)) {
+
+    if (Ctx.LangOpts.hasFeature(Feature::ImmutableWeakCaptures)) {
       // Require that the RHS of the `let self = self` condition
       // refers to a variable defined in a capture list.
       // This lets us reject invalid examples like:
@@ -1809,7 +1809,6 @@ class ImplicitSelfUsageChecker : public BaseDiagnosticWalker {
       //
       return conditionalStmt->rebindsSelf(Ctx, /*requiresCaptureListRef*/ false,
                                           /*requireLoadExpr*/ true);
-                                        
     }
   }
 
@@ -4108,9 +4107,12 @@ VarDeclUsageChecker::~VarDeclUsageChecker() {
 
     // 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))
+    if (var->getInterfaceType()->is<WeakStorageType>() &&
+        (access & RK_CaptureList) &&
+        !DC->getASTContext().LangOpts.hasFeature(
+            Feature::ImmutableWeakCaptures))
       access |= RK_Written;
-    
+
     // Diagnose variables that were never used (other than their
     // initialization).
     //

lib/Sema/TypeCheckAttr.cpp

@@ -5406,11 +5406,6 @@ 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

@@ -1,12 +1,12 @@
 // RUN: %target-swift-frontend -emit-sil -swift-version 6 -target %target-swift-5.1-abi-triple -verify -verify-additional-prefix old- %s -o /dev/null
-// RUN: %target-swift-frontend -emit-sil -swift-version 6 -target %target-swift-5.1-abi-triple -verify -verify-additional-prefix new- -enable-upcoming-feature WeakLet %s -o /dev/null
+// RUN: %target-swift-frontend -emit-sil -swift-version 6 -target %target-swift-5.1-abi-triple -verify -verify-additional-prefix new- -enable-upcoming-feature ImmutableWeakCaptures %s -o /dev/null
 
 // This test validates the behavior of transfer non sendable around ownership
 // constructs like non copyable types, consuming/borrowing parameters, and inout
 // parameters.
 
 // REQUIRES: concurrency
-// REQUIRES: swift_feature_WeakLet
+// REQUIRES: swift_feature_ImmutableWeakCaptures
 
 final class S: Sendable {
   func foo() {}
@@ -30,15 +30,12 @@ final class CheckOptionality1: Sendable {
 }
 
 final class CheckOptionality2: Sendable {
-  // expected-old-error@+3 {{'weak' must be a mutable variable, because it may change at runtime}}
-  // expected-old-error@+2 {{'weak' variable should have optional type 'S?'}}
-  // expected-new-error@+1 {{'weak' variable should have optional type 'S?'}}
+  // expected-error@+1 {{'weak' variable should have optional type 'S?'}}
   weak let x: S = getS()
 }
 
 final class CheckSendability1: Sendable {
-  // expected-old-error@+2 {{stored property 'x' of 'Sendable'-conforming class 'CheckSendability1' is mutable}}
-  // expected-new-error@+1 {{stored property 'x' of 'Sendable'-conforming class 'CheckSendability1' is mutable}}
+  // expected-error@+1 {{stored property 'x' of 'Sendable'-conforming class 'CheckSendability1' is mutable}}
   weak var x: S? = nil
 
   weak var y: S? {
@@ -48,32 +45,26 @@ final class CheckSendability1: Sendable {
 }
 
 final class CheckSendability2: Sendable {
-  // expected-old-error@+2 {{stored property 'x' of 'Sendable'-conforming class 'CheckSendability2' is mutable}}
-  // expected-new-error@+1 {{stored property 'x' of 'Sendable'-conforming class 'CheckSendability2' is mutable}}
+  // expected-error@+1 {{stored property 'x' of 'Sendable'-conforming class 'CheckSendability2' is mutable}}
   weak var x: NS? = nil
 }
 
 final class CheckSendability3: Sendable {
-  // expected-old-error@+1 {{'weak' must be a mutable variable, because it may change at runtime}}
   weak let x: S? = nil
 }
 
 final class CheckSendability4: Sendable {
-  // expected-old-error@+3 {{'weak' must be a mutable variable, because it may change at runtime}}
-  // expected-old-error@+2 {{stored property 'x' of 'Sendable'-conforming class 'CheckSendability4' contains non-Sendable type 'NS'}}
-  // expected-new-error@+1 {{stored property 'x' of 'Sendable'-conforming class 'CheckSendability4' contains non-Sendable type 'NS'}}
+  // expected-error@+1 {{stored property 'x' of 'Sendable'-conforming class 'CheckSendability4' contains non-Sendable type 'NS'}}
   weak let x: NS? = nil
 }
 
 final class CheckSendability5: Sendable {
-  // expected-old-error@+2 {{stored property 'x' of 'Sendable'-conforming class 'CheckSendability5' is mutable}}
-  // expected-new-error@+1 {{stored property 'x' of 'Sendable'-conforming class 'CheckSendability5' is mutable}}
+  // expected-error@+1 {{stored property 'x' of 'Sendable'-conforming class 'CheckSendability5' is mutable}}
   unowned var x: S = getS()
 }
 
 final class CheckSendability6: Sendable {
-  // expected-old-error@+2 {{stored property 'x' of 'Sendable'-conforming class 'CheckSendability6' is mutable}}
-  // expected-new-error@+1 {{stored property 'x' of 'Sendable'-conforming class 'CheckSendability6' is mutable}}
+  // expected-error@+1 {{stored property 'x' of 'Sendable'-conforming class 'CheckSendability6' is mutable}}
   unowned var x: NS = getNS()
 }
 
@@ -87,14 +78,12 @@ final class CheckSendability8: Sendable {
 }
 
 final class CheckSendability9: Sendable {
-  // expected-old-error@+2 {{stored property 'x' of 'Sendable'-conforming class 'CheckSendability9' is mutable}}
-  // expected-new-error@+1 {{stored property 'x' of 'Sendable'-conforming class 'CheckSendability9' is mutable}}
+  // expected-error@+1 {{stored property 'x' of 'Sendable'-conforming class 'CheckSendability9' is mutable}}
   unowned(unsafe) var x: S = getS()
 }
 
 final class CheckSendability10: Sendable {
-  // expected-old-error@+2 {{stored property 'x' of 'Sendable'-conforming class 'CheckSendability10' is mutable}}
-  // expected-new-error@+1 {{stored property 'x' of 'Sendable'-conforming class 'CheckSendability10' is mutable}}
+  // expected-error@+1 {{stored property 'x' of 'Sendable'-conforming class 'CheckSendability10' is mutable}}
   unowned(unsafe) var x: NS = getNS()
 }
 
@@ -109,17 +98,15 @@ final class CheckSendability12: Sendable {
 
 
 func checkWeakCapture1(_ strongRef: S) -> @Sendable () -> Void {
-  // expected-new-warning@+1 {{variable 'weakRef' was never mutated; consider changing to 'let' constant}}
+  // expected-warning@+1 {{variable 'weakRef' was never mutated; consider changing to 'let' constant}}
   weak var weakRef: S? = strongRef
   return {
-    // expected-old-error@+2 {{reference to captured var 'weakRef' in concurrently-executing code}}
-    // expected-new-error@+1 {{reference to captured var 'weakRef' in concurrently-executing code}}
+    // expected-error@+1 {{reference to captured var 'weakRef' in concurrently-executing code}}
     weakRef?.foo()
   }
 }
 
 func checkWeakCapture2(_ strongRef: S) -> @Sendable () -> Void {
-  // expected-old-error@+1 {{'weak' must be a mutable variable, because it may change at runtime}}
   weak let weakRef: S? = strongRef
   return {
     weakRef?.foo()
@@ -137,7 +124,7 @@ func checkWeakCapture3(_ strongRef: S) -> @Sendable () -> Void {
 }
 
 func checkWeakCapture4(_ strongRef: NS) -> @Sendable () -> Void {
-  // expected-new-warning@+1 {{variable 'weakRef' was never mutated; consider changing to 'let' constant}}
+  // expected-warning@+1 {{variable 'weakRef' was never mutated; consider changing to 'let' constant}}
   weak var weakRef: NS? = strongRef
   return {
     // expected-error@+2 {{capture of 'weakRef' with non-Sendable type 'NS?' in a '@Sendable' closure}}
@@ -147,7 +134,6 @@ func checkWeakCapture4(_ strongRef: NS) -> @Sendable () -> Void {
 }
 
 func checkWeakCapture5(_ strongRef: NS) -> @Sendable () -> Void {
-  // expected-old-error@+1 {{'weak' must be a mutable variable, because it may change at runtime}}
   weak let weakRef: NS? = strongRef
   return {
     // expected-error@+1 {{capture of 'weakRef' with non-Sendable type 'NS?' in a '@Sendable' closure}}

test/DebugInfo/WeakCapture.swift

@@ -1,7 +1,7 @@
 // RUN: %target-swift-frontend %s -emit-ir -g -o - | %FileCheck %s
-// RUN: %target-swift-frontend %s -enable-upcoming-feature WeakLet -emit-ir -g -o - | %FileCheck %s
+// RUN: %target-swift-frontend %s -enable-upcoming-feature ImmutableWeakCaptures -emit-ir -g -o - | %FileCheck %s
 
-// REQUIRES: swift_feature_WeakLet
+// REQUIRES: swift_feature_ImmutableWeakCaptures
 
 class A {
     init(handler: (() -> ())) { }

test/DebugInfo/guard-let-scope4.swift

@@ -1,6 +1,6 @@
 // RUN: %target-swift-frontend -g -Xllvm -sil-print-types -emit-sil %s -parse-as-library -module-name a | %FileCheck %s
-// RUN: %target-swift-frontend -g -Xllvm -sil-print-types -emit-sil %s -parse-as-library -module-name a -enable-upcoming-feature WeakLet | %FileCheck %s --check-prefixes=CHECK,CHECK-HAS-WEAK-LET
-// REQUIRES: swift_feature_WeakLet
+// RUN: %target-swift-frontend -g -Xllvm -sil-print-types -emit-sil %s -parse-as-library -module-name a -enable-upcoming-feature ImmutableWeakCaptures | %FileCheck %s --check-prefixes=CHECK,CHECK-HAS-WEAK-LET
+// REQUIRES: swift_feature_ImmutableWeakCaptures
 open class C {
   public func run() {
     { [weak self] in