Change the feature name for BuiltinTaskGroup.

The `createTaskGroup` builtin has changed its signature and now requires
a type metadata argument. Change the feature accordingly so that
compilers with the new and old versions have disjoint feature sets.

Fixes rdar://79561865.

Author: DougGregor

include/swift/Basic/Features.def

@@ -47,7 +47,7 @@ LANGUAGE_FEATURE(BuiltinJob, 0, "Builtin.Job type", true)
 LANGUAGE_FEATURE(Sendable, 0, "Sendable and @Sendable", true)
 LANGUAGE_FEATURE(BuiltinExecutor, 0, "Builtin.Executor type", true)
 LANGUAGE_FEATURE(BuiltinContinuation, 0, "Continuation builtins", true)
-LANGUAGE_FEATURE(BuiltinTaskGroup, 0, "TaskGroup builtins", true)
+LANGUAGE_FEATURE(BuiltinTaskGroupWithArgument, 0, "TaskGroup builtins", true)
 LANGUAGE_FEATURE(InheritActorContext, 0, "@_inheritActorContext attribute", true)
 LANGUAGE_FEATURE(ImplicitSelfCapture, 0, "@_implicitSelfCapture attribute", true)
 LANGUAGE_FEATURE(BuiltinBuildExecutor, 0, "Executor-building builtins", true)

lib/AST/ASTPrinter.cpp

@@ -2775,7 +2775,7 @@ static bool usesFeatureBuiltinContinuation(Decl *decl) {
   return false;
 }
 
-static bool usesFeatureBuiltinTaskGroup(Decl *decl) {
+static bool usesFeatureBuiltinTaskGroupWithArgument(Decl *decl) {
   return false;
 }
 

stdlib/public/Concurrency/TaskGroup.swift

@@ -68,7 +68,7 @@ public func withTaskGroup<ChildTaskResult, GroupResult>(
   returning returnType: GroupResult.Type = GroupResult.self,
   body: (inout TaskGroup<ChildTaskResult>) async -> GroupResult
 ) async -> GroupResult {
-  #if compiler(>=5.5) && $BuiltinTaskGroup
+  #if compiler(>=5.5) && $BuiltinTaskGroupWithArgument
 
   let _group = Builtin.createTaskGroup(ChildTaskResult.self)
   var group = TaskGroup<ChildTaskResult>(group: _group)
@@ -147,7 +147,7 @@ public func withThrowingTaskGroup<ChildTaskResult, GroupResult>(
   returning returnType: GroupResult.Type = GroupResult.self,
   body: (inout ThrowingTaskGroup<ChildTaskResult, Error>) async throws -> GroupResult
 ) async rethrows -> GroupResult {
-  #if compiler(>=5.5) && $BuiltinTaskGroup
+  #if compiler(>=5.5) && $BuiltinTaskGroupWithArgument
 
   let _group = Builtin.createTaskGroup(ChildTaskResult.self)
   var group = ThrowingTaskGroup<ChildTaskResult, Error>(group: _group)