fix #1647

Author: jonsequitur

src/System.CommandLine.Tests/Binding/TypeConversionTests.cs

@@ -1,4 +1,4 @@
-// Copyright (c) .NET Foundation and contributors. All rights reserved.
+// Copyright (c) .NET Foundation and contributors. All rights reserved.
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
 
 using System.Collections;
@@ -221,6 +221,21 @@ public void Nullable_bool_parses_as_null_when_the_option_has_not_been_applied()
                 .Be(null);
         }
 
+        [Fact] // https://github.com/dotnet/command-line-api/issues/1647
+        public void Generic_option_bool_parses_when_passed_to_non_generic_GetValueForOption()
+        {
+            var option = new Option<bool>("-b");
+
+            var cmd = new RootCommand
+            {
+                option
+            };
+
+            var parseResult = cmd.Parse("-b");
+
+            parseResult.GetValueForOption((Option)option).Should().Be(true);
+        }
+
         [Fact]
         public void By_default_an_option_with_zero_or_one_argument_parses_as_the_argument_string_value()
         {

src/System.CommandLine/Binding/ArgumentConverter.cs

@@ -1,4 +1,4 @@
-// Copyright (c) .NET Foundation and contributors. All rights reserved.
+// Copyright (c) .NET Foundation and contributors. All rights reserved.
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
 
 using System.Collections;
@@ -204,8 +204,8 @@ internal static ArgumentConversionResult ConvertIfNeeded(
                                   toType,
                                   successful.Value,
                                   symbolResult.LocalizationResources),
-             
-                NoArgumentConversionResult _ when toType == typeof(bool) || toType == typeof(bool?) =>
+                    
+                NoArgumentConversionResult _ when conversionResult.Argument.ValueType == typeof(bool) || conversionResult.Argument.ValueType == typeof(bool?) => 
                     Success(conversionResult.Argument, true),
 
                 NoArgumentConversionResult _ when conversionResult.Argument.Arity.MinimumNumberOfValues > 0 =>