[Concurrency] Don't infer nonisolated(nonsending) on synchronous witnesses

If the requirement is `nonisolated(nonsending)` but witness is
synchronous, prevent actor isolation inference from requirements
because this isolation only applies to asynchronous declarations
at the moment.

Resolves: rdar://153680826
(cherry picked from commit a964282)

Author: xedin

lib/Sema/TypeCheckConcurrency.cpp

@@ -5271,9 +5271,18 @@ getIsolationFromWitnessedRequirements(ValueDecl *value) {
       case ActorIsolation::Erased:
         llvm_unreachable("requirement cannot have erased isolation");
 
+      case ActorIsolation::CallerIsolationInheriting: {
+        if (value->isAsync())
+          break;
+
+        // It's possible to witness requirement with an non-async
+        // declaration, in such cases `nonisolated(nonsending)` does
+        // not apply.
+        continue;
+      }
+
       case ActorIsolation::GlobalActor:
       case ActorIsolation::Nonisolated:
-      case ActorIsolation::CallerIsolationInheriting:
       case ActorIsolation::NonisolatedUnsafe:
         break;
       }

test/Concurrency/attr_execution/protocols_silgen.swift

@@ -13,6 +13,11 @@ protocol P {
   @MainActor func mainActorTest() async
 }
 
+protocol Q {
+  nonisolated(nonsending) var test: String { get async throws }
+  nonisolated(nonsending) func fnTest() async
+}
+
 struct AllDefault : P {
   // CHECK-LABEL: sil private [transparent] [thunk] [ossa] @$s21attr_execution_silgen10AllDefaultVAA1PA2aDP10callerTestyyYaFTW : $@convention(witness_method: P) @async (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>, @in_guaranteed AllDefault) -> () {
   // CHECK: bb0([[ACTOR:%.*]] : @guaranteed $Optional<any Actor>, [[SELF:%.*]] : $*AllDefault):
@@ -120,3 +125,49 @@ struct AllMainActor : P {
   // CHECK: } // end sil function '$s21attr_execution_silgen12AllMainActorVAA1PA2aDP04mainF4TestyyYaFTW'
   @MainActor func mainActorTest() async {}
 }
+
+// Make sure that stored/non-async witness doesn't inherit `nonisolated(nonsending)` but thunk dismatches correctly
+
+struct TestWitnessWithStorage: Q {
+  // CHECK-LABEL: sil hidden [transparent] [ossa] @$s21attr_execution_silgen22TestWitnessWithStorageV4testSSvg : $@convention(method) (@guaranteed TestWitnessWithStorage) -> @owned String
+  // CHECK-LABEL: sil hidden [transparent] [ossa] @$s21attr_execution_silgen22TestWitnessWithStorageV4testSSvs : $@convention(method) (@owned String, @inout TestWitnessWithStorage) -> ()
+  var test: String
+
+  // CHECK-LABEL: sil hidden [ossa] @$s21attr_execution_silgen22TestWitnessWithStorageV02fnD0yyF : $@convention(method) (@guaranteed TestWitnessWithStorage) -> ()
+  func fnTest() {}
+
+  // CHECK-LABEL: sil private [transparent] [thunk] [ossa] @$s21attr_execution_silgen22TestWitnessWithStorageVAA1QA2aDP4testSSvgTW : $@convention(witness_method: Q) @async (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>, @in_guaranteed TestWitnessWithStorage) -> (@owned String, @error any Error)
+  // CHECK: bb0([[ISOLATION:%.*]] : @guaranteed $Optional<any Actor>, [[SELF:%.*]] : $*TestWitnessWithStorage):
+  // CHECK-NEXT: [[BORROWED_SELF:%.*]] = load_borrow [[SELF]]
+  // CHECK: [[WITNESS:%.*]] = function_ref @$s21attr_execution_silgen22TestWitnessWithStorageV4testSSvg : $@convention(method) (@guaranteed TestWitnessWithStorage) -> @owned String
+  // CHECK-NEXT: [[RESULT:%.*]] = apply [[WITNESS]]([[BORROWED_SELF]]) : $@convention(method) (@guaranteed TestWitnessWithStorage) -> @owned String
+  // CHECK-NEXT: end_borrow [[BORROWED_SELF]]
+  // CHECK-NEXT: return [[RESULT]]
+  // CHECK-NEXT: } // end sil function '$s21attr_execution_silgen22TestWitnessWithStorageVAA1QA2aDP4testSSvgTW'
+
+  // CHECK: sil private [transparent] [thunk] [ossa] @$s21attr_execution_silgen22TestWitnessWithStorageVAA1QA2aDP02fnD0yyYaFTW : $@convention(witness_method: Q) @async (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>, @in_guaranteed TestWitnessWithStorage) -> ()
+  // CHECK: bb0([[ISOLATION:%.*]] : @guaranteed $Optional<any Actor>, [[SELF:%.*]] : $*TestWitnessWithStorage):
+  // CHECK-NEXT: [[BORROWED_SELF]] = load_borrow [[SELF]]
+  // CHECK: [[WITNESS:%.*]] = function_ref @$s21attr_execution_silgen22TestWitnessWithStorageV02fnD0yyF : $@convention(method) (@guaranteed TestWitnessWithStorage) -> ()
+  // CHECK-NEXT: {{.*}} = apply [[WITNESS]]([[BORROWED_SELF]]) : $@convention(method) (@guaranteed TestWitnessWithStorage) -> ()
+  // CHECK-NEXT: [[RESULT:%.*]] = tuple ()
+  // CHECK-NEXT: end_borrow [[BORROWED_SELF]]
+  // CHECK-NEXT: return [[RESULT]]
+  // CHECK-NEXT: } // end sil function '$s21attr_execution_silgen22TestWitnessWithStorageVAA1QA2aDP02fnD0yyYaFTW'
+}
+
+struct TestSyncWitness: Q {
+  // CHECK-LABEL: sil hidden [ossa] @$s21attr_execution_silgen15TestSyncWitnessV4testSSvg : $@convention(method) (TestSyncWitness) -> @owned String
+  var test: String { "" }
+
+  // CHECK-LABEL: sil private [transparent] [thunk] [ossa] @$s21attr_execution_silgen15TestSyncWitnessVAA1QA2aDP4testSSvgTW : $@convention(witness_method: Q) @async (@sil_isolated @sil_implicit_leading_param @guaranteed Optional<any Actor>, @in_guaranteed TestSyncWitness) -> (@owned String, @error any Error)
+  // CHECK: bb0([[ISOLATION:%.*]] : @guaranteed $Optional<any Actor>, [[SELF:%.*]] : $*TestSyncWitness):
+  // CHECK-NEXT: [[BORROWED_SELF:%.*]] = load [trivial] [[SELF]]
+  // CHECK: [[WITNESS:%.*]] = function_ref @$s21attr_execution_silgen15TestSyncWitnessV4testSSvg : $@convention(method) (TestSyncWitness) -> @owned String
+  // CHECK-NEXT: [[RESULT:%.*]] = apply [[WITNESS]]([[BORROWED_SELF]]) : $@convention(method) (TestSyncWitness) -> @owned String
+  // CHECK-NEXT: return [[RESULT]]
+  // CHECK-NEXT: } // end sil function '$s21attr_execution_silgen15TestSyncWitnessVAA1QA2aDP4testSSvgTW'
+
+  // Tested in the `TestWitnessWithStorage`
+  func fnTest() {}
+}