[asl] Introduce asl-carpenter

This is a test-generator for ASL, working in two modes:
 - Enumerating all possible ASTs by increasing size
 - Randomly generating ASTs that respect some type-checking constraints

It can also work as a fuzzing tool, and as an execution tool for ASLRef.

Building and installing it is completely optional.

asllib/Interpreter.ml

@@ -1269,8 +1269,10 @@ module Make (B : Backend.S) (C : Config) = struct
           | Some i -> i
         in
         L_BitVector (Bitvector.zeros length) |> lit
-    | T_Enum li ->
+    | T_Enum li ->  (
+      try
         IMap.find (List.hd li) env.global.static.constants_values |> lit
+      with Not_found -> fatal_from t Error.TypeInferenceNeeded)
     | T_Int UnConstrained -> L_Int Z.zero |> lit
     | T_Int (UnderConstrained _) ->
         failwith "Cannot request the base value of a under-constrained integer."

asllib/Typing.ml

@@ -1782,8 +1782,7 @@ module Annotate (C : ANNOTATE_CONFIG) = struct
             let env', ldi' = annotate_local_decl_item_uninit s env ldi in
             (S_Decl (LDK_Var, ldi', None) |> here, env') |: TypingRule.SDeclNone
         | (LDK_Constant | LDK_Let), None ->
-            (* by construction in Parser. *)
-            assert false)
+            fatal_from s UnrespectedParserInvariant)
     (* End *)
     (* Begin SThrowSome *)
     | S_Throw (Some (e, _)) ->