Cake v6 - Packages imported inside sub scripts aren't being used in another script

[jaimewukb]

Prerequisites

• I have written a descriptive issue title
• I have searched issues to ensure it has not already been reported

Cake runner

Cake .NET Tool

Cake version

6.0.0

Operating system

Linux

Operating system architecture

x64

CI Server

No response

What are you seeing?

Let say we have a script setup.cs that references another script context.cs

Inside context.cs we have imported some packages to use

#:package YamlDotNet@16.3.0
#:package Cake.Yaml@6.0.0
...

If this isn't also defined inside setup.cs then we get this error
The type or namespace name 'YamlDotNet' could not be found (are you missing a using directive or an assembly reference?)

What is expected?

We shouldn't need to also import

#:package YamlDotNet@16.3.0
#:package Cake.Yaml@6.0.0
...

In setup.cs

Steps to Reproduce

Create two files and make one reference the other one with the imported packages

Output log

No response

[devlead]

Assume you're running Cake.Sdk and not Cake.Tool.

With Cake.Tool custom pre-processor directives are handled by Cake scripting engine essentially they're parsed and processed first and not part of the final merged C# file that's compiled by Roslyn (C#) compiler.

With Cake.Sdk and file-based apps the #: directives are pre-processed not by Cake but by the .NET CLI and ignored by Roslyn compiler, essentially the entry C# file behind the scenes is used by the .NET CLI to generate a temporary csproj (C# project) file then passed to MSBuild which passes cs to Roslyn, but at that point all references, properties, SDKs, etc. are already handled.
So additional C# files are just treated as any C# file would normally be in a .NET top level statement console application.

A good starting point to read about file-based apps is this Microsoft Learn page
https://learn.microsoft.com/en-us/dotnet/core/sdk/file-based-apps

Additional files aren't supported out of the box, it's added by the Cake SDK simplified as additional additional Compile items to the generated csproj.

So the limitation here is that only entry cs file can have packages, or MSBuild files like Directory.Build.props for whole directory

https://learn.microsoft.com/en-us/visualstudio/msbuild/customize-by-directory?view=visualstudio