Xamarin.forms: 3.5.0 regression: two-way bindings with nullable types fail to propagate null values back

[mfeingol]

Description

Two-way bindings with nullable types no longer work correctly in Xamarin Forms 3.5.0. In particular, null values are not propagated back to the source binding object.

Steps to Reproduce

1. Run the attached project
2. Click the main page button
3. Note that the text label below never prints "null" with 3.5.0. It works fine with 3.4.0

Expected Behavior

Two-way bindings works as expected.

Actual Behavior

Null values are not propagated back to the source binding object.

Basic Information

• Version with issue: 3.5.0.129452
• Last known good version: 3.4.0.1029999
• IDE: VS 2017
• Platform Target Frameworks:
  
  
  
  • Android: 8.1
  
  
• Android Support Library Version: 28.0.0.1
• Nuget Packages:
• Affected Devices:

Screenshots

Reproduction Link

XamarinFormsSample.zip

[StephaneDelcroix]

might be related to #5255

[StephaneDelcroix]

this is indeed fixed by #5255, and will be part of the -sr of 3.5.0

[mfeingol]

@StephaneDelcroix: did this make it into 3.5.0.169047?

I just gave it a spin and I'm still seeing a problem:

[0:] Binding:  can not be converted to type 'System.Nullable`1[System.TimeSpan]'

[StephaneDelcroix]

@mfeingol not part of -sr1. will be part of the next -sr

[mfeingol]

This appears to be fixed in the first 3.6.0 release.