Fix/687 - NativeAoT Support by upgrading to Dotnet 8 (lts) and implementing System.Text.Json source generation

[ThaDaVos]

These changes should allow one to use the project with NativeAoT as it now uses the latest LTS (Dotnet 8) and includes source generation for System.Text.Json.

Only thing I noticed after getting all System.Text.Json stuff working while setting <JsonSerializerIsReflectionEnabledByDefault>false</JsonSerializerIsReflectionEnabledByDefault> in my project - is that I get an error from the grpc package used:

Exception has occurred: CLR/Grpc.Core.RpcException
An exception of type 'Grpc.Core.RpcException' occurred in Pulumi.dll but was not handled in user code: 'Status(StatusCode="Unimplemented", Detail="")'
   at Pulumirpc.LanguageRuntime.LanguageRuntimeBase.GetRequiredPackages(GetRequiredPackagesRequest request, ServerCallContext context) in {PROJECT_PATH}\pulumi-dotnet\sdk\Pulumi\obj\Debug\net8.0\pulumi\LanguageGrpc.cs:line 311
   at Grpc.Shared.Server.UnaryServerMethodInvoker`3.Invoke(HttpContext httpContext, ServerCallContext serverCallContext, TRequest request)

Which I cannot figure out the actual cause of

[Copilot]

Pull Request Overview

This PR upgrades the Pulumi .NET SDK from .NET 6.0 to .NET 8.0 and updates numerous dependencies to their latest versions. The changes modernize the codebase with C# 12 features including collection expressions, primary constructors, and improved null checks.

Key changes:

• Upgrade target framework from net6.0 to net8.0 across all projects
• Update semver package from v2.1.0 to v3.0.0 (requires API changes due to removed IComparable interface)
• Update multiple Grpc, Microsoft, and other NuGet packages to latest versions
• Modernize C# code with collection expressions ([] syntax), ArgumentNullException.ThrowIfNull(), and other C# 12 features
• Add source generation context for JSON serialization performance improvements

Reviewed Changes

Copilot reviewed 35 out of 37 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
sdk/Pulumi/Pulumi.csproj	Updates target framework to net8.0 and dependencies to latest versions
sdk/Pulumi/Serialization/ResourcePackages.cs	Adapts SemVer usage to v3.0 API (CompareSortOrderTo instead of comparison operators)
sdk/Pulumi/Stack.cs	Replaces .Any() with .Count != 0 for performance
sdk/Pulumi/Core/Output.cs	Modernizes null checks and adds cached JsonSerializerOptions
sdk/Pulumi/Deployment/*.cs	Modernizes argument validation and string operations
sdk/Pulumi.Automation/*.cs	Updates to collection expressions and SemVer v3.0 API
sdk/Pulumi.Automation/Serialization/*.cs	Adds source generation for JSON serialization
Test projects	Updates test dependencies to latest versions
PublicAPI files	Adds nullable reference type annotations

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[Frassle]

Upgrade target framework from net6.0 to net8.0 across all projects

We'll have to think about this. We don't officially support net6 anymore (neither does Microsoft) but it is still a breaking change. I'll see if we can collect some data to see if we're likely to break anyone doing this.

[ThaDaVos]

@Frassle - why not release it as a new major version? Also, as far as I know, if the Dotnet version is bumped, older dotnet based projects shouldn't pull it anyway (as far as I know).

That aside, how can I fix the protobuf "not implemented" issue? That way I could build it locally and use it for myself at least.

[ThaDaVos]

Just got my GRPC issue fixed, I missed the -p:PulumiSdkVersion=3.205.0 - this is needed it seems.
Also noticed I missed a JsonSerializer.Serialize call and added this one too

[ThaDaVos]

It's been months since I made this PR and I haven't heard anything since, has there been any progress?

[Frassle]

We still think bumping to net8 is going to cause significant downstream breakage because of how net builds work, so we're still stuck to targeting net6 for now.

We started making a plan to fix this but it hasn't been an internal priority to actually get it finished, and is made more complicated by the fact that we need to coordinate the fix across multiple internal teams and external provider developers.

[ThaDaVos]

Can't you do a bump to DotNet 8 in a major version of the (Automation) SDK? This would partially resolve the issue as most of the time major versions are allowed to break backwards compatibility and instead of targeting DotNet 8, go straight for DotNet 10 LTS to also get some other improvements - also DotNet 8 will be end of support in November this year (https://dotnet.microsoft.com/en-us/platform/support/policy/dotnet-core)

[Frassle]

Can't you do a bump to DotNet 8 in a major version of the (Automation) SDK?

We have historically avoided major version changes because of a want to keep the engine version and sdk versions tied. That might be less important now so we could consider it.

go straight for DotNet 10 LTS to also get some other improvements - also DotNet 8 will be end of support in November this year

Yes, we're aware of the dotnet 8 LTS coming to an end soon. A major bump direct to 10 as we drop 8 LTS is definitely worth considering.

[ThaDaVos]

If there is help wanted with a PR for DotNet 10 (Including a redo of the source generation here for NativeAoT) let me know, I may be able to lend a hand if I have the time

[ThaDaVos]

@Frassle can you check the new PR?
#1109