Bring back capture by box

Author: nickolas-pohilets

lib/SIL/IR/TypeLowering.cpp

@@ -170,6 +170,15 @@ 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>()) {
+    return CaptureKind::Box;
+  }
+
   // For 'let' constants
   if (!var->supportsMutation()) {
     assert(getTypeProperties(

test/SILGen/capture-transitive.swift

@@ -34,8 +34,7 @@ class C {
 
     func returnsSelf1() -> Self {
         return { [weak self] in self?.f(); return .init() }()
-      // CHECK-NO-WEAK-LET-LABEL: sil private [ossa] @{{.*}}returnsSelf{{.*}} : $@convention(thin) (@inout_aliasable @sil_weak Optional<C>, @thick @dynamic_self C.Type) -> @owned C {
-        // CHECK-HAS-WEAK-LET-LABEL: sil private [ossa] @{{.*}}returnsSelf{{.*}} : $@convention(thin) (@in_guaranteed @sil_weak Optional<C>, @thick @dynamic_self C.Type) -> @owned C {
+        // CHECK-LABEL: sil private [ossa] @{{.*}}returnsSelf{{.*}}  : $@convention(thin) (@guaranteed { var @sil_weak Optional<C> }, @thick @dynamic_self C.Type) -> @owned C
     }
 
     func returnsSelf2() -> Self {

test/SILGen/dynamic_self.swift

@@ -241,12 +241,10 @@ class Z {
 
     // CHECK:      [[WEAK_SELF:%.*]] = alloc_box ${ var @sil_weak Optional<Z> }
     // CHECK:      [[WEAK_SELF_LIFETIME:%.*]] = begin_borrow [lexical] [var_decl] [[WEAK_SELF]]
-    // CHECK:      [[WEAK_SELF_ADDR:%.*]] = project_box [[WEAK_SELF_LIFETIME]] : ${ var @sil_weak Optional<Z> }, 0
-    // CHECK:      [[FN:%.*]] = function_ref @$s12dynamic_self1ZC23testDynamicSelfCaptures1xACXDSi_tFyycfU1_ : $@convention(thin) (@in_guaranteed @sil_weak Optional<Z>, @thick @dynamic_self Z.Type) -> ()
-    // CHECK:      [[WEAK_SELF_COPY:%.*]] = alloc_stack $@sil_weak Optional<Z>
-    // CHECK:      copy_addr [[WEAK_SELF_ADDR]] to [init] [[WEAK_SELF_COPY]] : $*@sil_weak Optional<Z>
+    // CHECK:      [[FN:%.*]] = function_ref @$s12dynamic_self1ZC23testDynamicSelfCaptures1xACXDSi_tFyycfU1_ : $@convention(thin) (@guaranteed { var @sil_weak Optional<Z> }, @thick @dynamic_self Z.Type) -> ()
+    // CHECK:      [[WEAK_SELF_COPY:%.*]] = copy_value [[WEAK_SELF_LIFETIME]] : ${ var @sil_weak Optional<Z> }
     // CHECK-NEXT: [[DYNAMIC_SELF:%.*]] = metatype $@thick @dynamic_self Z.Type
-    // CHECK:      partial_apply [callee_guaranteed] [[FN]]([[WEAK_SELF_COPY]], [[DYNAMIC_SELF]]) : $@convention(thin) (@in_guaranteed @sil_weak Optional<Z>, @thick @dynamic_self Z.Type) -> ()
+    // CHECK:      partial_apply [callee_guaranteed] [[FN]]([[WEAK_SELF_COPY]], [[DYNAMIC_SELF]]) : $@convention(thin) (@guaranteed { var @sil_weak Optional<Z> }, @thick @dynamic_self Z.Type) -> ()
     let fn3 = {
       [weak self] in
       _ = self
@@ -429,7 +427,7 @@ class Derived : Base {
 class Generic<T> {
   // Examples where we have to add a special argument to capture Self's metadata
   func t1() -> Self {
-    // CHECK-LABEL: sil private [ossa] @$s12dynamic_self7GenericC2t1ACyxGXDyFAEXDSgycfU_ : $@convention(thin) <T> (@in_guaranteed @sil_weak Optional<Generic<T>>, @thick @dynamic_self Generic<T>.Type) -> @owned Optional<Generic<T>>
+    // CHECK-LABEL: sil private [ossa] @$s12dynamic_self7GenericC2t1ACyxGXDyFAEXDSgycfU_ : $@convention(thin) <T> (@guaranteed <τ_0_0> { var @sil_weak Optional<Generic<τ_0_0>> } <T>, @thick @dynamic_self Generic<T>.Type) -> @owned Optional<Generic<T>>
     _ = {[weak self] in self }
     return self
   }

test/SILGen/unowned-class-bound-generic-parameter.swift

@@ -8,7 +8,7 @@ func makeGenericClosureWithUnknownClass<T>(t: T) where T : ClassProtocol {
   _ = { [unowned t] in _ = t }
 }
 
-// CHECK-LABEL: sil private [ossa] @$s4main34makeGenericClosureWithUnknownClass1tyx_tAA0G8ProtocolRzlFyycfU_ : $@convention(thin) <T where T : ClassProtocol> (@in_guaranteed @sil_unowned T) -> () {
+// CHECK-LABEL: sil private [ossa] @$s4main34makeGenericClosureWithUnknownClass1tyx_tAA0G8ProtocolRzlFyycfU_ : $@convention(thin) <T where T : ClassProtocol> (@guaranteed <τ_0_0 where τ_0_0 : ClassProtocol> { var @sil_unowned τ_0_0 } <T>) -> () {
 
 func makeGenericClosureWithNativeClass1<T>(t: T) where T : BaseClass {
   _ = { [unowned t] in _ = t }