safe print_r/var_dump when resolving property values

ref #1162

Author: jakubmisek

src/Peachpie.Library/Variables.cs

@@ -1027,7 +1027,11 @@ public override void AcceptObject(object obj)
                     _indent++;
 
                     // object members
-                    var flds = (obj is IPhpPrintable printable ? printable.Properties : TypeMembersUtils.EnumerateInstanceFieldsForPrint(obj)).ToList();
+                    var flds = obj is IPhpPrintable printable
+                        ? printable.Properties
+                        : TypeMembersUtils.EnumerateInstanceFieldsForPrint(obj)
+                        ;
+
                     foreach (var fld in flds)
                     {
                         // [name] => value

src/Peachpie.Runtime/Reflection/TypeMembersUtils.cs

@@ -81,7 +81,8 @@ public static IEnumerable<KeyValuePair<IntStringKey, PhpValue>> EnumerateVisible
             return EnumerateInstanceFields(instance,
                 (p) => new IntStringKey(p.PropertyName),
                 FuncExtensions.Identity<IntStringKey>(),
-                (m) => m.IsVisible(caller));
+                (m) => m.IsVisible(caller)
+            );
         }
 
         /// <summary>
@@ -93,9 +94,23 @@ public static IEnumerable<KeyValuePair<string, PhpValue>> EnumerateInstanceField
         {
             return EnumerateInstanceFields(instance,
                 s_formatPropertyNameForPrint,
-                s_keyToString);
+                s_keyToString,
+                getValue: s_getValueWithTryCatch
+            );
         }
 
+        static readonly Func<PhpPropertyInfo, object, PhpValue> s_getValueWithTryCatch = (p, instance) =>
+        {
+            try
+            {
+                return p.GetValue(null, instance);
+            }
+            catch (Exception e)
+            {
+                return $"Property '{p.PropertyName}' threw an exception of type {e.GetType().Name}: {e.Message}";
+            }
+        };
+
         public static readonly Func<IntStringKey, string> s_keyToString = k => k.ToString();
 
         public static readonly Func<PhpPropertyInfo, string> s_propertyName = p => p.PropertyName;
@@ -127,7 +142,9 @@ public static IEnumerable<KeyValuePair<string, PhpValue>> EnumerateInstanceField
         {
             return EnumerateInstanceFields(instance,
                 s_formatPropertyNameForDump,
-                s_keyToString);
+                s_keyToString,
+                getValue: s_getValueWithTryCatch
+            );
         }
 
         /// <summary>
@@ -170,9 +187,10 @@ public static IEnumerable<KeyValuePair<string, PhpValue>> EnumerateInstanceField
         /// <param name="keyFormatter2">Function converting </param>
         /// <param name="predicate">Optional. Predicate filtering fields.</param>
         /// <param name="ignoreRuntimeFields">Whether to ignore listing runtime fields.</param>
+        /// <param name="getValue">Function getting property value on given <paramref name="instance"/>.</param>
         /// <returns>Enumeration of fields and their values, including runtime fields.</returns>
         /// <typeparam name="TKey">Enumerated pairs key. Usually <see cref="IntStringKey"/>.</typeparam>
-        public static IEnumerable<KeyValuePair<TKey, PhpValue>> EnumerateInstanceFields<TKey>(object instance, Func<PhpPropertyInfo, TKey> keyFormatter, Func<IntStringKey, TKey> keyFormatter2, Func<PhpPropertyInfo, bool> predicate = null, bool ignoreRuntimeFields = false)
+        public static IEnumerable<KeyValuePair<TKey, PhpValue>> EnumerateInstanceFields<TKey>(object instance, Func<PhpPropertyInfo, TKey> keyFormatter, Func<IntStringKey, TKey> keyFormatter2, Func<PhpPropertyInfo, bool> predicate = null, bool ignoreRuntimeFields = false, Func<PhpPropertyInfo, object, PhpValue> getValue = null)
         {
             Debug.Assert(instance != null);
 
@@ -189,7 +207,8 @@ public static IEnumerable<KeyValuePair<TKey, PhpValue>> EnumerateInstanceFields<
                     {
                         yield return new KeyValuePair<TKey, PhpValue>(
                             keyFormatter(p),
-                            p.GetValue(null, instance));
+                            getValue != null ? getValue(p, instance) : p.GetValue(null, instance)
+                        );
                     }
                 }
             }