working (without type-checking)

src/lowering/desugar.ml

@@ -591,7 +591,8 @@ and build_actor at ts exp_opt self_id es obj_typ =
                   let vi = fresh_var ("v_"^i) (T.as_immut t) in
                   (i, switch_optE (dotE (varE v) i (T.Opt (T.as_immut t)))
                        (primE (Ir.OtherPrim "trap")
-                         [textE ("stable variable " ^ i ^ " expected but not found")])
+                          [textE (Printf.sprintf
+                             "stable variable `%s` of type `%s` expected but not found" i (T.string_of_typ t))])
                        (varP vi) (varE vi)
                        (T.as_immut t))) dom_fields) dom_fields)
               (letE v_rng (callE e [] (varE v_dom))

test/run-drun/ok/upgrade-migration.drun.ok

@@ -0,0 +1,20 @@
+ingress Completed: Reply: 0x4449444c016c01b3c4b1f204680100010a00000000000000000101
+debug.print: Version 0
+ingress Completed: Reply: 0x4449444c0000
+ingress Completed: Reply: 0x4449444c0000
+debug.print: {migration = {new = {three = [var (1, "1"), (2, "2"), (3, "3"), (4, "4")]}; old = {one = [var 1, 2, 3, 4]; two = [var "1", "2", "3", "4"]}}}
+debug.print: Version 1
+ingress Completed: Reply: 0x4449444c0000
+ingress Completed: Reply: 0x4449444c0000
+debug.print: {three = [var (1, "1"), (2, "2"), (3, "3"), (4, "4")]}
+ingress Completed: Reply: 0x4449444c0000
+debug.print: {migration = {new = {four = [var (1, "1"), (2, "2"), (3, "3"), (4, "4")]}; old = {three = [var (1, "1"), (2, "2"), (3, "3"), (4, "4")]}}}
+debug.print: Version 2
+ingress Completed: Reply: 0x4449444c0000
+ingress Completed: Reply: 0x4449444c0000
+debug.print: {four = [var (1, "1"), (2, "2"), (3, "3"), (4, "4")]}
+ingress Completed: Reply: 0x4449444c0000
+ingress Err: IC0503: Error from Canister rwlgt-iiaaa-aaaaa-aaaaa-cai: Canister called `ic0.trap` with message: stable variable `three` of type `var [var (Nat, Text)]` expected but not found.
+Consider gracefully handling failures from this canister or altering the canister to handle exceptions. See documentation: http://internetcomputer.org/docs/current/references/execution-errors#trapped-explicitly
+debug.print: {four = [var (1, "1"), (2, "2"), (3, "3"), (4, "4")]}
+ingress Completed: Reply: 0x4449444c0000

test/run-drun/upgrade-migration/Migration1.mo

@@ -1,12 +1,27 @@
+import Prim "mo:prim";
 module {
 
-  public func run( o: { var one : [var Nat];
-                        var two : [var Nat];
-                      } ) :
-    { var three : [var (Nat,Nat)] } {
+  func zip<T,U>(ts : [var T], us: [var U]) : [var (T, U)] {
+      let size = if (ts.size() <= us.size()) ts.size()  else us.size();
+      if (size == 0) return [var];
+      let res = Prim.Array_init<(T,U)>(size, (ts[0], us[0]));
+      for (i in res.keys()) {
+        res[i] := (ts[i], us[i]);
+      };
+      res
+  };
+
+  public func run( old : {
+      var one : [var Nat];
+      var two : [var Text];
+    } ) :
+    { var three : [var (Nat, Text)] } {
+    let new =
     {
-      var three = [var (o.one[0], o.two[0])]
-    }
+      var three = zip(old.one, old.two);
+    };
+    Prim.debugPrint(debug_show{migration={old;new}});
+    new
   }
 
 }

test/run-drun/upgrade-migration/Migration2.mo

@@ -1,14 +1,15 @@
 import Prim "mo:prim";
+
 module {
 
-  public func run( pre : { var three : [var (Nat,Nat)] } ) :
-     { var four : [var (Nat,Nat)] } {
-    let post =
+  public func run( old : { var three : [var (Nat, Text)] } ) :
+      { var four : [var (Nat, Text)] } {
+    let new =
     {
-      var four = pre.three;
+      var four = old.three;
     };
-    Prim.debugPrint(debug_show{pre;post});
-    post
+    Prim.debugPrint(debug_show {migration = {old; new}});
+    new
   }
 
 }

test/run-drun/upgrade-migration/version0.mo

@@ -3,8 +3,8 @@ import Prim "mo:prim";
 actor {
    Prim.debugPrint("Version 0");
 
-   stable var one : [var Nat] = [var 1,2];
-   stable var two : [var Nat] = [var 1,2];
+   stable var one : [var Nat] = [var 1, 2, 3, 4];
+   stable var two : [var Text] = [var "1", "2", "3", "4"];
 
    public func check(): async() {
    };

test/run-drun/upgrade-migration/version1.mo

@@ -7,8 +7,9 @@ actor [Migration.run] {
 
    stable var version = 0;
 
-   stable var three : [var (Nat,Nat)] = [var ];
+   stable var three : [var (Nat, Text)] = [var];
 
    public func check(): async() {
+     Prim.debugPrint (debug_show {three});
    }
 };

test/run-drun/upgrade-migration/version2.mo

@@ -6,8 +6,9 @@ actor [Migration.run] {
    Prim.debugPrint("Version 2");
 
    stable var version = 2;
-   stable var four : [var (Nat,Nat)] = [var];
+   stable var four : [var (Nat, Text)] = [var];
 
    public func check(): async() {
+     Prim.debugPrint(debug_show{four});
    }
 };