nc-explicitly-managed.diff

diff --git a/lib/NativeCall.pm6 b/lib/NativeCall.pm6
index e8ef82940..4d0bcf6fa 100644
--- a/lib/NativeCall.pm6
+++ b/lib/NativeCall.pm6
@@ -43,6 +43,9 @@ my role NativeCallMangled[$name] {
     method native_call_mangled() { $name }
 }
 
+my role NativeCallExplicitlyManaged {
+}
+
 
 # Throwaway type just to get us some way to get at the NativeCall
 # representation.
@@ -69,7 +72,7 @@ sub param_hash_for(Parameter $p) {
     if $type ~~ Str {
         my $enc := $p.?native_call_encoded() || 'utf8';
         nqp::bindkey($result, 'type', nqp::unbox_s(string_encoding_to_nci_type($enc)));
-        nqp::bindkey($result, 'free_str', nqp::unbox_i(1));
+        nqp::bindkey($result, 'free_str', nqp::unbox_i($p ~~ NativeCallExplicitlyManaged ?? 0 !! 1));
     }
     elsif $type ~~ Callable {
         nqp::bindkey($result, 'type', nqp::unbox_s(type_code_for($type)));
@@ -617,6 +620,9 @@ multi trait_mod:<is>(Routine $r, :$nativeconv!) is export(:DEFAULT, :traits) {
 multi trait_mod:<is>(Parameter $p, :$encoded!) is export(:DEFAULT, :traits) {
     $p does NativeCallEncoded[$encoded];
 }
+multi trait_mod:<is>(Parameter $p, :$explicitly-managed!) is export(:DEFAULT, :traits) {
+    $p does NativeCallExplicitlyManaged;
+}
 multi trait_mod:<is>(Routine $p, :$encoded!) is export(:DEFAULT, :traits) {
     $p does NativeCallEncoded[$encoded];
 }