ConfigurationBinder source generator generates code with the wrong nullable annotations

eerhardt commented 10 months ago

Description

When attempting to use the ConfigurationBinder source generator in dotnet/extensions (see https://github.com/dotnet/extensions/pull/4625), I'm getting a nullable warning that is causing the generated code to not compile (I would need to disable nullable validation for the whole project if I wanted to ignore the nullable warning, which isn't acceptable).

I'm not sure what the general pattern is here that causes this issue, so I logged the issue for the scenario specifically. I think it might need to include nested generics where one of the nested generic types is nullable.

Reproduction Steps

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net8.0</TargetFramework>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
    <EnableConfigurationBindingGenerator>true</EnableConfigurationBindingGenerator>
    <NoWarn>$(NoWarn);SYSLIB1100;SYSLIB1101</NoWarn>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.Extensions.Configuration.Binder" Version="8.0.0-rtm.23511.16" />
    <PackageReference Include="Microsoft.Extensions.Http.Resilience" Version="8.0.0-rc.2.23510.2" />
  </ItemGroup>

</Project>

// needed to work around https://github.com/dotnet/runtime/issues/94065
global using Polly;
global using Polly.Hedging;
global using Polly.RateLimiting;
global using Polly.Timeout;

using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Http.Resilience;

var c = new ConfigurationBuilder().Build();
c.Get<HttpStandardHedgingResilienceOptions>();

Expected behavior

Should be without warnings

Actual behavior

Get a nullable warning from generated code:

CS8619  Nullability of reference types in value of type 'Func<HedgingActionGeneratorArguments<HttpResponseMessage>, Func<ValueTask<Outcome<HttpResponseMessage>>>?>' doesn't match target type 'Func<HedgingActionGeneratorArguments<HttpResponseMessage>, Func<ValueTask<Outcome<HttpResponseMessage>>>>'. ConsoleApp101   C:\Users\eerhardt\source\repos\ConsoleApp101\ConsoleApp101\Microsoft.Extensions.Configuration.Binder.SourceGeneration\Microsoft.Extensions.Configuration.Binder.SourceGeneration.ConfigurationBindingGenerator\BindingExtensions.g.cs   1418

The generated code looks like:

            if (AsConfigWithChildren(configuration.GetSection("ActionGenerator")) is IConfigurationSection section256)
            {
                Func<HedgingActionGeneratorArguments<HttpResponseMessage>, Func<ValueTask<Outcome<HttpResponseMessage>>>>? temp258 = instance.ActionGenerator;
                if (temp258 is not null)
                {

That middle line is the issue, it is of type:

Func<HedgingActionGeneratorArguments<HttpResponseMessage>, Func<ValueTask<Outcome<HttpResponseMessage>>>> but the type of instance.ActionGenerator is: Func<HedgingActionGeneratorArguments<TResult>, Func<ValueTask<Outcome<TResult>>>?>

Note the ? inside the last > brace.

Regression?

No response

Known Workarounds

No response

Configuration

No response

Other information

cc @tarekgh @ericstj

ghost commented 10 months ago

Tagging subscribers to this area: @dotnet/area-extensions-configuration See info in area-owners.md if you want to be subscribed.

Issue Details

### Description When attempting to use the ConfigurationBinder source generator in dotnet/extensions (see https://github.com/dotnet/extensions/pull/4625), I'm getting a nullable warning that is causing the generated code to not compile (I would need to disable nullable validation for the whole project if I wanted to ignore the nullable warning, which isn't acceptable). I'm not sure what the general pattern is here that causes this issue, so I logged the issue for the scenario specifically. I think it might need to include nested generics where one of the nested generic types is nullable. ### Reproduction Steps ```xml Exe net8.0 enable enable true $(NoWarn);SYSLIB1100;SYSLIB1101 ``` ```csharp // needed to work around https://github.com/dotnet/runtime/issues/94065 global using Polly; global using Polly.Hedging; global using Polly.RateLimiting; global using Polly.Timeout; using Microsoft.Extensions.Configuration; using Microsoft.Extensions.Http.Resilience; var c = new ConfigurationBuilder().Build(); c.Get(); ``` ### Expected behavior Should be without warnings ### Actual behavior Get a nullable warning from generated code: ``` CS8619 Nullability of reference types in value of type 'Func, Func>>?>' doesn't match target type 'Func, Func>>>'. ConsoleApp101 C:\Users\eerhardt\source\repos\ConsoleApp101\ConsoleApp101\Microsoft.Extensions.Configuration.Binder.SourceGeneration\Microsoft.Extensions.Configuration.Binder.SourceGeneration.ConfigurationBindingGenerator\BindingExtensions.g.cs 1418 ``` The generated code looks like: ```csharp if (AsConfigWithChildren(configuration.GetSection("ActionGenerator")) is IConfigurationSection section256) { Func, Func>>>? temp258 = instance.ActionGenerator; if (temp258 is not null) { ``` That middle line is the issue, it is of type: `Func, Func>>>` but the type of `instance.ActionGenerator` is: `Func, Func>>?>` Note the `?` inside the last `>` brace. ### Regression? _No response_ ### Known Workarounds _No response_ ### Configuration _No response_ ### Other information cc @tarekgh @ericstj

Author:	eerhardt
Assignees:	-
Labels:	`area-Extensions-Configuration`
Milestone:	-