fix(gnovm): load map from state

gnovm/docs/go-gno-compatibility.md

@@ -45,12 +45,12 @@ Legend: full, partial, missing, TBD.
 | `rune`                                        | full                   | full                                                       |
 | `interface{}`                                 | full                   | full                                                       |
 | `[]T` (slices)                                | full                   | full*                                                      |
-| `map[T1]T2`                                   | full                   | missing (in progress, will be for launch)                  |
+| `map[T1]T2`                                   | full                   | full*                                                      |
 | `func (T1...) T2...`                          | full                   | full (needs more tests)                                    |
 | `*T` (pointers)                               | full                   | full*                                                      |
 | `chan T` (channels)                           | missing (after launch) | missing (after launch)                                     |
 
-**\*:** depends on `T`
+**\*:** depends on `T`/`T1`/`T2`
 
 Additional native types:
 

gnovm/pkg/gnolang/realm.go

@@ -1341,7 +1341,7 @@ func fillTypesOfValue(store Store, val Value) Value {
 		fillTypesTV(store, &cv.Receiver)
 		return cv
 	case *MapValue:
-		cv.MakeMap(cv.List.Size) // TODO move out.
+		cv.vmap = make(map[MapKey]*MapListItem, cv.List.Size)
 		for cur := cv.List.Head; cur != nil; cur = cur.Next {
 			fillTypesTV(store, &cur.Key)
 			fillTypesTV(store, &cur.Value)

gnovm/pkg/gnolang/values.go

@@ -11,6 +11,7 @@ import (
 	"unsafe"
 
 	"github.com/cockroachdb/apd"
+
 	"github.com/gnolang/gno/tm2/pkg/crypto"
 )
 
@@ -661,7 +662,9 @@ func (ml *MapList) UnmarshalAmino(mlimg MapListImage) error {
 			ml.Head = item
 		}
 		item.Prev = ml.Tail
-		ml.Tail.Next = item
+		if ml.Tail != nil {
+			ml.Tail.Next = item
+		}
 		ml.Tail = item
 		ml.Size++
 	}

gnovm/tests/files/persist_map.gno

@@ -0,0 +1,22 @@
+// PKGPATH: gno.land/r/demo/tests_test
+package tests_test
+
+var amap map[string]string = map[string]string{"a": "1"}
+
+func init() {
+	println("preinit", amap)
+	amap["b"] = "2"
+	println("postinit", amap)
+}
+
+func main() {
+	println("premain", amap)
+	amap["c"] = "3"
+	println("postmain", amap)
+}
+
+// Output:
+// preinit map{("a" string):("1" string)}
+// postinit map{("a" string):("1" string),("b" string):("2" string)}
+// premain map{("a" string):("1" string),("b" string):("2" string)}
+// postmain map{("a" string):("1" string),("b" string):("2" string),("c" string):("3" string)}