Concurrency: Promote BuiltinBuildTaskExecutorRef feature to baseline.

Author: tshortli

include/swift/Basic/Features.def

@@ -146,7 +146,7 @@ BASELINE_LANGUAGE_FEATURE(BuiltinHopToActor, 0, "Builtin.HopToActor")
 BASELINE_LANGUAGE_FEATURE(BuiltinTaskGroupWithArgument, 0, "TaskGroup builtins")
 BASELINE_LANGUAGE_FEATURE(InheritActorContext, 0, "@_inheritActorContext attribute")
 BASELINE_LANGUAGE_FEATURE(ImplicitSelfCapture, 0, "@_implicitSelfCapture attribute")
-LANGUAGE_FEATURE(BuiltinBuildTaskExecutorRef, 0, "TaskExecutor-building builtins")
+BASELINE_LANGUAGE_FEATURE(BuiltinBuildTaskExecutorRef, 0, "TaskExecutor-building builtins")
 BASELINE_LANGUAGE_FEATURE(BuiltinBuildExecutor, 0, "Executor-building builtins")
 LANGUAGE_FEATURE(BuiltinBuildComplexEqualityExecutor, 0, "Executor-building for 'complexEquality executor' builtins")
 BASELINE_LANGUAGE_FEATURE(BuiltinBuildMainExecutor, 0, "MainActor executor building builtin")

lib/AST/FeatureSet.cpp

@@ -124,7 +124,6 @@ static bool usesFeatureRethrowsProtocol(Decl *decl) {
   return usesFeatureRethrowsProtocol(decl, checked);
 }
 
-UNINTERESTING_FEATURE(BuiltinBuildTaskExecutorRef)
 UNINTERESTING_FEATURE(BuiltinBuildComplexEqualityExecutor)
 UNINTERESTING_FEATURE(BuiltinCreateAsyncTaskInGroupWithExecutor)
 UNINTERESTING_FEATURE(BuiltinCreateAsyncDiscardingTaskInGroup)

stdlib/public/Concurrency/Executor.swift

@@ -401,11 +401,7 @@ public struct UnownedTaskExecutor: Sendable {
 
   @inlinable
   public init<E: TaskExecutor>(ordinary executor: __shared E) {
-    #if $BuiltinBuildTaskExecutorRef
     self.executor = Builtin.buildOrdinaryTaskExecutorRef(executor)
-    #else
-    fatalError("Swift compiler is incompatible with this SDK version")
-    #endif
   }
 }