visual studio - How to enable Nullable Reference Types feature of C# 8.0 for the whole project

Question

According to the C# 8 announcement video the "nullable reference types" feature can be enabled for the whole project.

But how to enable it for the project? I did not find any new appropriate option in the Project Properties window in Visual Studio 2019 Preview 1.

Can it be enabled for 'legacy' .csproj projects if the C# language version is changed to 8.0?

Answer 1

In Visual Studio 16.2 (from preview 1) the property name is changed to Nullable, which is simpler and aligns with the command line argument.

Add the following properties to your .csproj file.

<PropertyGroup>
  <Nullable>enable</Nullable>
  <LangVersion>8.0</LangVersion>
</PropertyGroup>

If you're targeting netcoreapp3.0 or later, you don't need to specify a LangVersion to enable nullable reference types.

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For older Visual Studio versions:

• From 16.0 preview 2 to 16.1, set NullableContextOptions to enable.
• In 16.0 preview 1, set NullableReferenceTypes to true.