fix(gnovm): recover panics when having unhashable type as map key

gnovm/pkg/gnolang/values.go

@@ -1583,6 +1583,15 @@ func (tv *TypedValue) ComputeMapKey(m *Machine, store Store, omitType bool) (key
 		}
 		return nilStr, false
 	}
+	// Statically uncomparable key types are rejected at preprocess, so any
+	// uncomparable tv.T here arrived via interface boxing. Match Go by
+	// naming the outer dynamic type — isComparable recurses, so a struct
+	// or array with an uncomparable field reports the enclosing type, not
+	// the leaf.
+	if !isComparable(tv.T) {
+		panic(&Exception{Value: typedString(
+			"runtime error: hash of unhashable type " + tv.T.String())})
+	}
 	// General case.
 	bz := make([]byte, 0, 64)
 	// Charge per-byte for all bytes appended to bz in this call (TypeID
@@ -1658,8 +1667,6 @@ func (tv *TypedValue) ComputeMapKey(m *Machine, store Store, omitType bool) (key
 			bz = append(bz, av.Data...)
 		}
 		bz = append(bz, ']')
-	case *SliceType:
-		panic(&Exception{Value: typedString("runtime error: slice type cannot be used as map key")})
 	case *StructType:
 		sv := tv.V.(*StructValue)
 		sl := len(sv.Fields)
@@ -1681,9 +1688,11 @@ func (tv *TypedValue) ComputeMapKey(m *Machine, store Store, omitType bool) (key
 	case *ChanType:
 		panic("channel type is not yet supported")
 	default:
-		panic(fmt.Sprintf(
-			"unexpected map key type %s",
-			tv.T.String()))
+		// Defensive fallback. The isComparable check above already
+		// catches *SliceType, *MapType, *FuncType, and any composite that
+		// reaches here via interface boxing.
+		panic(&Exception{Value: typedString(
+			"runtime error: hash of unhashable type " + tv.T.String())})
 	}
 	return MapKey(bz), false
 }

gnovm/tests/files/maplit6.gno

@@ -10,4 +10,4 @@ func main() {
 }
 
 // Error:
-// runtime error: slice type cannot be used as map key
+// runtime error: hash of unhashable type []int

gnovm/tests/files/maplit7.gno

@@ -8,4 +8,4 @@ func main() {
 }
 
 // Error:
-// runtime error: slice type cannot be used as map key
+// runtime error: hash of unhashable type []int

gnovm/tests/files/range13.gno

@@ -7,9 +7,9 @@ func main() {
 }
 
 // Stacktrace:
-// panic: runtime error: slice type cannot be used as map key
+// panic: runtime error: hash of unhashable type []int
 // main<VPBlock(1,0)>()
 //     main/range13.gno:5
 
 // Error:
-// runtime error: slice type cannot be used as map key
+// runtime error: hash of unhashable type []int

gnovm/tests/files/types/hash_uncomp_iface_array_map.gno

@@ -0,0 +1,15 @@
+package main
+
+// Array of maps via interface{}: panic must name the outer array
+// type, not the inner map element type.
+func main() {
+	defer func() {
+		r := recover()
+		println("recover:", r)
+	}()
+	m := map[interface{}]int{}
+	m[[1]map[int]int{}] = 1
+}
+
+// Output:
+// recover: runtime error: hash of unhashable type [1]map[int]int

gnovm/tests/files/types/hash_uncomp_iface_func.gno

@@ -0,0 +1,15 @@
+package main
+
+// Func dynamic key via interface{}: previously triggered an uncatchable
+// host panic. Must be a Gno-catchable Exception now.
+func main() {
+	defer func() {
+		r := recover()
+		println("recover:", r)
+	}()
+	m := map[interface{}]int{}
+	m[func() {}] = 1
+}
+
+// Output:
+// recover: runtime error: hash of unhashable type func()

gnovm/tests/files/types/hash_uncomp_iface_map.gno

@@ -0,0 +1,15 @@
+package main
+
+// Map dynamic key via interface{}: previously triggered an uncatchable
+// host panic. Must be a Gno-catchable Exception now.
+func main() {
+	defer func() {
+		r := recover()
+		println("recover:", r)
+	}()
+	m := map[interface{}]int{}
+	m[map[int]int{}] = 1
+}
+
+// Output:
+// recover: runtime error: hash of unhashable type map[int]int

gnovm/tests/files/types/hash_uncomp_iface_slice.gno

@@ -0,0 +1,15 @@
+package main
+
+// Slice as map[interface{}] key: must be a Gno-catchable panic naming
+// the dynamic type, matching Go's runtime "hash of unhashable type".
+func main() {
+	defer func() {
+		r := recover()
+		println("recover:", r)
+	}()
+	m := map[interface{}]int{}
+	m[[]int{}] = 1
+}
+
+// Output:
+// recover: runtime error: hash of unhashable type []int

gnovm/tests/files/types/hash_uncomp_iface_struct_slice.gno

@@ -0,0 +1,17 @@
+package main
+
+// Struct containing a slice, used as map[interface{}] key: the panic
+// must name the outer struct dynamic type, not the inner slice leaf.
+type S struct{ s []int }
+
+func main() {
+	defer func() {
+		r := recover()
+		println("recover:", r)
+	}()
+	m := map[interface{}]int{}
+	m[S{}] = 1
+}
+
+// Output:
+// recover: runtime error: hash of unhashable type main.S