[Distributed] Runtime: Implement a way to access generic env of distributed target

Author: xedin

stdlib/public/Concurrency/Actor.cpp

@@ -1709,6 +1709,14 @@ findDistributedAccessor(const char *targetNameStart, size_t targetNameLength) {
   return nullptr;
 }
 
+SWIFT_CC(swift)
+SWIFT_RUNTIME_STDLIB_SPI
+void *swift_distributed_get_generic_environment(const char *targetNameStart,
+                                                size_t targetNameLength) {
+  auto *accessor = findDistributedAccessor(targetNameStart, targetNameLength);
+  return accessor ? accessor->GenericEnvironment.get() : nullptr;
+}
+
 /// func _executeDistributedTarget(
 ///    on: AnyObject,
 ///    _ targetName: UnsafePointer<UInt8>,
@@ -1766,7 +1774,7 @@ void ::swift_distributed_execute_target(
     AsyncContext *callContext) {
   auto *accessor = findDistributedAccessor(targetNameStart, targetNameLength);
   if (!accessor) {
-    assert(false && "no distributed accessor accessor");
+    assert(false && "no distributed accessor");
     return; // FIXME(distributed): return -1 here so the lib can fail the call
   }
 

stdlib/public/Distributed/DistributedMetadata.swift

@@ -78,3 +78,14 @@ func __getReturnTypeInfo(
     _ typeNameStart: UnsafePointer<UInt8>,
     _ typeNameLength: UInt
 ) -> Any.Type?
+
+
+/// Retrieve a generic environment descriptor associated with
+/// the given distributed target
+@available(SwiftStdlib 5.6, *)
+@_silgen_name("swift_distributed_get_generic_environment")
+public // SPI _Distributed
+func _getGenericEnvironmentOfDistributedTarget(
+    _ targetNameStart: UnsafePointer<UInt8>,
+    _ targetNameLength: UInt
+) -> UnsafeRawPointer?