String resource containing only whitespace characters are loaded as blank strings

.NET version

Replicated on .NET Core 3 and all later versions.

Did it work in .NET Framework?

Yes

Did it work in any of the earlier releases of .NET Core or .NET 5+?

I did not try this with versions prior to .NET Core 3.

Issue description

If a localized property’s value is set to a string that only contains whitespace characters, ComponentResourceManager methods such as ApplyResources or GetString retrieve it as a blank string. This is a breaking change for .NET Framework applications where this is not the case.

I could not find this change documented anywhere, or any issues related to it.

The XML generated for the property is the same in both .NET FX and .NET Core/5+:

<data name="label1.Text" xml:space="preserve">
  <value>  </value>
</data>

Steps to reproduce

I attached a solution containing two identical forms in .NET Framework 4.8 and .NET 6. T1080450.zip

To replicate:

• Create a new project using the Windows Forms App template.
• Set the main form’s Localizable property to true.
• Add a label and set its Text property to (a string with a single whitespace character).
• Debug the project and check the value of this property after it is set in the InitializeComponent method.

[kant2002]

I believe this is issue for https://github.com/dotnet/runtime

Tests which should be extended located here https://github.com/dotnet/runtime/blob/da5888aa4d7f8cac2519d5d35d7d8f59385fc6e8/src/libraries/System.ComponentModel.TypeConverter/tests/ComponentResourceManagerTests.cs

[TheLeftExit]

I guess that’s a wrap. Thanks @kant2002!