[silgen] Place the correct isolation on protocol witness thunks.

We were using the isolation from the witness not from the requirement which we
are supposed to do. The witness thunk thunks the isolation from the requirement
to the witness so from an ABI perspective it should have the interface implied
by the requirement's isolation since that is what callers of the witness method
will expect.

rdar://151394209

Author: gottesmm

lib/SIL/IR/SILFunctionType.cpp

@@ -2390,6 +2390,25 @@ std::optional<ActorIsolation>
 swift::getSILFunctionTypeActorIsolation(CanAnyFunctionType substFnInterfaceType,
                                         std::optional<SILDeclRef> origConstant,
                                         std::optional<SILDeclRef> constant) {
+  // If we have origConstant then we are creating a protocol method thunk. In
+  // such a case, we want to use the origConstant's actor isolation.
+  if (origConstant && constant &&
+      *origConstant != *constant) {
+    if (auto *decl = origConstant->getAbstractFunctionDecl()) {
+      if (auto *nonisolatedAttr =
+              decl->getAttrs().getAttribute<NonisolatedAttr>()) {
+        if (nonisolatedAttr->isNonSending())
+          return ActorIsolation::forCallerIsolationInheriting();
+      }
+
+      if (decl->getAttrs().hasAttribute<ConcurrentAttr>()) {
+        return ActorIsolation::forNonisolated(false /*unsafe*/);
+      }
+    }
+
+    return getActorIsolationOfContext(origConstant->getInnermostDeclContext());
+  }
+
   if (constant) {
     // TODO: It should to be possible to `getActorIsolation` if
     // reference is to a decl instead of trying to get isolation

test/Concurrency/attr_execution/protocols_silgen.swift

@@ -48,17 +48,17 @@ struct AllCaller : P {
   // CHECK: } // end sil function '$s21attr_execution_silgen9AllCallerVAA1PA2aDP10callerTestyyYaFTW'
   nonisolated(nonsending) func callerTest() async {}
 
-  // CHECK-LABEL: sil private [transparent] [thunk] [ossa] @$s21attr_execution_silgen9AllCallerVAA1PA2aDP14concurrentTestyyYaFTW : $@convention(witness_method: P) @async (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>, @in_guaranteed AllCaller) -> () {
-  // CHECK: bb0([[ACTOR:%.*]] : @guaranteed $Optional<any Actor>, [[SELF:%.*]] : $*AllCaller):
+  // CHECK-LABEL: sil private [transparent] [thunk] [ossa] @$s21attr_execution_silgen9AllCallerVAA1PA2aDP14concurrentTestyyYaFTW : $@convention(witness_method: P) @async (@in_guaranteed AllCaller) -> () {
+  // CHECK: bb0([[SELF:%.*]] : $*AllCaller):
   // CHECK:   [[LOAD:%.*]] = load [trivial] [[SELF]]
   // CHECK:   [[FUNC:%.*]] = function_ref @$s21attr_execution_silgen9AllCallerV14concurrentTestyyYaF : $@convention(method) @async (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>, AllCaller) -> ()
   // CHECK:   [[NIL:%.*]] = enum $Optional<any Actor>, #Optional.none!enumelt
   // CHECK:   apply [[FUNC]]([[NIL]], [[LOAD]])
   // CHECK: } // end sil function '$s21attr_execution_silgen9AllCallerVAA1PA2aDP14concurrentTestyyYaFTW'
   nonisolated(nonsending) func concurrentTest() async {}
 
-  // CHECK-LABEL: sil private [transparent] [thunk] [ossa] @$s21attr_execution_silgen9AllCallerVAA1PA2aDP13mainActorTestyyYaFTW : $@convention(witness_method: P) @async (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>, @in_guaranteed AllCaller) -> () {
-  // CHECK: bb0({{%.*}} : @guaranteed $Optional<any Actor>, [[SELF:%.*]] : $*AllCaller):
+  // CHECK-LABEL: sil private [transparent] [thunk] [ossa] @$s21attr_execution_silgen9AllCallerVAA1PA2aDP13mainActorTestyyYaFTW : $@convention(witness_method: P) @async (@in_guaranteed AllCaller) -> () {
+  // CHECK: bb0([[SELF:%.*]] : $*AllCaller):
   // CHECK:   [[LOAD:%.*]] = load [trivial] [[SELF]]
   // CHECK:   [[FUNC:%.*]] = function_ref @$s21attr_execution_silgen9AllCallerV13mainActorTestyyYaF : $@convention(method) @async (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>, AllCaller) -> ()
   // CHECK:   [[MAIN_ACTOR:%.*]] = apply {{%.*}}({{%.*}}) : $@convention(method) (@thick MainActor.Type) -> @owned MainActor
@@ -70,11 +70,8 @@ struct AllCaller : P {
 }
 
 struct AllConcurrent : P {
-  // TODO: This seems wrong. We need to have our thunk have the implicit
-  // isolated parameter from an ABI perspective.
-  //
-  // CHECK-LABEL: sil private [transparent] [thunk] [ossa] @$s21attr_execution_silgen13AllConcurrentVAA1PA2aDP10callerTestyyYaFTW : $@convention(witness_method: P) @async (@in_guaranteed AllConcurrent) -> () {
-  // CHECK: bb0([[SELF:%.*]] :
+  // CHECK-LABEL: sil private [transparent] [thunk] [ossa] @$s21attr_execution_silgen13AllConcurrentVAA1PA2aDP10callerTestyyYaFTW : $@convention(witness_method: P) @async (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>, @in_guaranteed AllConcurrent) -> () {
+  // CHECK: bb0([[ACTOR]] : @guaranteed $Optional<any Actor>, [[SELF:%.*]] :
   // CHECK:   [[LOAD:%.*]] = load [trivial] [[SELF]]
   // CHECK:   [[FUNC:%.*]] = function_ref @$s21attr_execution_silgen13AllConcurrentV10callerTestyyYaF : $@convention(method) @async (AllConcurrent) -> ()
   // CHECK:   apply [[FUNC]]([[LOAD]])
@@ -99,11 +96,8 @@ struct AllConcurrent : P {
 }
 
 struct AllMainActor : P {
-  // TODO: This is incorrect from an ABI perspective. The witness needs to have
-  // the implicit isolated parameter.
-  //
-  // CHECK-LABEL: sil private [transparent] [thunk] [ossa] @$s21attr_execution_silgen12AllMainActorVAA1PA2aDP10callerTestyyYaFTW : $@convention(witness_method: P) @async (@in_guaranteed AllMainActor) -> () {
-  // CHECK: bb0([[SELF:%.*]] :
+  // CHECK-LABEL: sil private [transparent] [thunk] [ossa] @$s21attr_execution_silgen12AllMainActorVAA1PA2aDP10callerTestyyYaFTW : $@convention(witness_method: P) @async (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>, @in_guaranteed AllMainActor) -> () {
+  // CHECK: bb0([[ACTOR:%.*]] : @guaranteed $Optional<any Actor>, [[SELF:%.*]] :
   // CHECK:   [[LOAD:%.*]] = load [trivial] [[SELF]]
   // CHECK:   [[FUNC:%.*]] = function_ref @$s21attr_execution_silgen12AllMainActorV10callerTestyyYaF : $@convention(method) @async (AllMainActor) -> ()
   // CHECK:   apply [[FUNC]]([[LOAD]])