Below C# 10, WriteSourceFile silently drops the template's assembly:/module: attributes and file comments #77

What's wrong

The block-scoped namespace path added for consumers below C# 10 (#72, fixing #71) rebuilds the template as withoutNamespace but copies only FileName, Usings and Classes:

https://github.com/ktsu-dev/SourceGeneratorToolkit/blob/effd00a/SourceGeneratorToolkit/GeneratorBase.cs#L324-L344

SourceFileTemplate also carries Attributes and Comments (inherited from CodeBlocker's TemplateBase), and AddSourceFile writes both — global assembly:/module: attributes after the usings and before the namespace. On the C# 10+ path the template is passed through whole, so those are kept; on the block path they vanish with no diagnostic.

Repro

Template: Namespace = "Gen", Usings = { "System" }, Attributes = { "assembly: CLSCompliant(true)" }, one class A, rendered through GeneratorHarness:

• LanguageVersion = Latest: using System; / [assembly: CLSCompliant(true)] / namespace Gen; / class A {} — correct
• LanguageVersion = CSharp7_3: namespace Gen { using System; class A {} } — the attribute is gone, 0 diagnostics

Reproduced by running the harness at both language versions. File-level Comments are lost the same way.

Why it matters

A generator's output means something different depending on the consumer's LangVersion: an InternalsVisibleTo, CLSCompliant or other assembly attribute the generator emits simply isn't applied in C# 7.3–9 projects, and nothing tells either the generator author or the consumer.

Suggested fix

In the block path, write what has to live outside the namespace first — comments, then usings and attributes (attributes must follow usings and precede the namespace; an assembly: attribute inside a namespace block doesn't compile) — then open the namespace block around a classes-only copy. E.g. render a copy with only Usings/Attributes/Comments and no namespace or classes, then the block around a copy with only Classes. (Usings can stay outside the block too; that's equivalent.)

Acceptance criteria

• A C# 7.3 harness test with Attributes set emits the attribute before namespace Gen { and the output compiles
• A C# 7.3 test with Comments set keeps the comments
• Latest-version output unchanged