accurate type signature for make-tuple

library/generic/tuple.factor

@@ -15,7 +15,8 @@ hashtables errors sequences vectors ;
 : make-tuple ( class size -- tuple )
     #! Internal allocation function. Do not call it directly,
     #! since you can fool the runtime and corrupt memory by
-    #! specifying an incorrect size.
+    #! specifying an incorrect size. Note that this word is also
+    #! handled specially by the compiler's type inferencer.
     <tuple> [ 2 set-slot ] keep ;
 
 IN: generic

library/inference/class-infer.factor

@@ -1,8 +1,8 @@
 ! Copyright (C) 2004, 2005 Slava Pestov.
 ! See http://factor.sf.net/license.txt for BSD license.
 IN: inference
-USING: generic hashtables kernel namespaces sequences vectors
-words ;
+USING: generic hashtables kernel kernel-internals namespaces
+sequences vectors words ;
 
 ! Infer possible classes of values in a dataflow IR.
 
@@ -85,11 +85,21 @@ M: node child-ties ( node -- seq )
         2drop
     ] ifte ;
 
+\ make-tuple [
+    dup node-in-d first literal-value 1vector
+] "output-classes" set-word-prop
+
+: output-classes ( node -- seq )
+    dup node-param "output-classes" word-prop [
+        call
+    ] [
+        node-param "infer-effect" word-prop second
+    ] ?ifte ;
+
 M: #call infer-classes* ( node -- )
     dup node-param [
         dup create-ties
-        dup node-param "infer-effect" word-prop second
-        swap node-out-d intersect-classes
+        dup output-classes swap node-out-d intersect-classes
     ] [
         drop
     ] ifte ;