Fix for Broken (Value)Task.Cast<>

#1135
louthy · Nov 16, 2022 · b86d98e · tomachristian · Nov 16, 2022 · tomachristian
1 parent c124a20
commit b86d98e
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Showing 2 changed files with 14 additions and 23 deletions.
diff --git a/LanguageExt.Core/Concurrency/Task/Task.Extensions.cs b/LanguageExt.Core/Concurrency/Task/Task.Extensions.cs
@@ -279,19 +279,18 @@ public static async Task<Unit> Iter<T>(this Task<T> self, Action<T> f)
         public static Task<A> PlusFirst<A>(this Task<A> ma, Task<A> mb) =>
             default(MTaskFirst<A>).Plus(ma, mb);
 
-        class PropCache<T>
-        {
-            public static PropertyInfo Info = typeof(T).GetTypeInfo().DeclaredProperties.Where(p => p.Name == "Result").FirstOrDefault();
-        }
-
         public static async Task<A> Cast<A>(this Task source)
         {
             if (source == null) throw new ArgumentNullException(nameof(source));
             await source.ConfigureAwait(false);
-            var prop = PropCache<A>.Info;
-            return prop != null
-                ? (A) prop.GetValue(source)
-                : default(A);
+
+            return source.GetType() switch
+            {
+                var taskTy when taskTy.IsGenericType && 
+                                taskTy.GenericTypeArguments.Length == 1 &&
+                                taskTy.GenericTypeArguments[0] == typeof(A) => (A)((dynamic)source).Result,
+                _ => default!
+            };            
         }
 
         public static async Task<Unit> ToUnit(this Task source)

diff --git a/LanguageExt.Core/Concurrency/ValueTask/ValueTask.Extensions.cs b/LanguageExt.Core/Concurrency/ValueTask/ValueTask.Extensions.cs
@@ -278,20 +278,12 @@ public static async ValueTask<Unit> Iter<T>(this ValueTask<T> self, Action<T> f)
         [Pure]
         public static ValueTask<A> Plus<A>(this ValueTask<A> ma, ValueTask<A> mb) =>
             default(MValueTask<A>).Plus(ma, mb);
-
-        class PropCache<T>
-        {
-            public static PropertyInfo Info = typeof(T).GetTypeInfo().DeclaredProperties.Where(p => p.Name == "Result").FirstOrDefault();
-        }
-
-        public static async ValueTask<A> Cast<A>(this ValueTask source)
-        {
-            await source.ConfigureAwait(false);
-            var prop = PropCache<A>.Info;
-            return prop != null
-                ? (A) prop.GetValue(source)
-                : default(A);
-        }
+
+        /// <summary>
+        /// Cast a ValueTask to a ValueTask<A> (may throw if underlying value doesn't exist)
+        /// </summary>
+        public static ValueTask<A> Cast<A>(this ValueTask source) => 
+            new(source.AsTask().Cast<A>());
 
         public static async ValueTask<Unit> ToUnit(this ValueTask source)
         {