x/params/types: make KeyTable.RegisterType fully dereference pointers (#6915)

Use a for loop to correctly and fully dereference and
extract the type for the type of ParamSetPair.Value.

Fixes #6785

Co-authored-by: Alexander Bezobchuk <alexanderbez@users.noreply.github.com>

x/params/types/deref_test.go

@@ -0,0 +1,27 @@
+package types
+
+import (
+	"reflect"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestKeyTableUnfurlsPointers(t *testing.T) {
+	tbl := NewKeyTable()
+	validator := func(_ interface{}) error {
+		return nil
+	}
+	tbl = tbl.RegisterType(ParamSetPair{
+		Key:         []byte("key"),
+		Value:       (*****string)(nil),
+		ValidatorFn: validator,
+	})
+
+	got := tbl.m["key"]
+	want := attribute{
+		vfn: validator,
+		ty:  reflect.ValueOf("").Type(),
+	}
+	require.Equal(t, got.ty, want.ty)
+}

x/params/types/table.go

@@ -48,7 +48,7 @@ func (t KeyTable) RegisterType(psp ParamSetPair) KeyTable {
 	rty := reflect.TypeOf(psp.Value)
 
 	// indirect rty if it is a pointer
-	if rty.Kind() == reflect.Ptr {
+	for rty.Kind() == reflect.Ptr {
 		rty = rty.Elem()
 	}