fix(#5192): bundle the JasperFx.Events.SourceGenerator 2.42.1 published-types fix

[jeremydmiller]

Fixes #5192. Consumes jasperfx#637, shipped in JasperFx 2.42.1.

The bug

The bundled JasperFx.Events.SourceGenerator registers an EventProjection's discovered published document types (#4166) by writing into the user's partial class. It used to do that by emitting a parameterless constructor — which fails for exactly the projections that need dependencies injected, i.e. the ones that have to be registered through AddProjectionWithServices.

A primary constructor made it a build break. C# requires every other constructor to chain through the primary one, so this failed to compile with CS8862 inside the generated <T>.TypeRegistration.g.cs:

public partial class MyProjection(ILogger<MyProjection> logger) : EventProjection
{
    public override ValueTask ApplyAsync(IDocumentOperations operations, IEvent e, CancellationToken cancellation)
    {
        operations.Store(new Thing());
        return new ValueTask();
    }
}

That is what #5192 reported.

An ordinary injected constructor made it a silent no-op. The container calls the dependency-taking constructor, so the generated parameterless one never ran and the published types went unregistered — which also left #626's teardown registration nothing to register. Confirmed on 9.22.4:

new MyProjection(logger).PublishedTypes()  ->  []

#637 moves registration onto an override of ProjectionBase.PublishedTypes(), which does not care how the instance was constructed.

Regression window

Marten 9.22.2 builds, 9.22.3 does not. 9.22.3 bundles a generator built from JasperFx.Events 2.38.0, which included #611 — published-type discovery became semantic. Before that only an explicit Store<Doc>(x) produced a registration and the far more common Store(doc) produced none, so the constructor was rarely emitted at all. The constructor defect itself is older: Store<Doc>(x) plus a primary constructor breaks on 9.22.0 too.

Why only the source generator pin moves

JasperFx.Events.SourceGenerator goes 2.41.0 → 2.42.1 while the rest of the JasperFx line stays at 2.41.0. That package is analyzer-only, declares no dependencies, and Marten bundles its dll into Marten.nupkg (_BundleEventsSourceGeneratorAnalyzer, #4557), so its version is independent of the runtime family's — which should stay at 2.41.0 until Marten adopts the strong-typed identity compliance suite that landed in 2.42.0. The generator is byte-identical from 2.38.0 through 2.42.0, so this is an isolated swap of that one fix rather than a version of drift. The reasoning is recorded in a comment on the pin itself.

Behavior change worth knowing

The generator used to skip registration entirely when the class already had an explicit parameterless constructor — a guard that existed only because you cannot add a second one. An override has no such conflict, so those projections now get their published types registered too. That is the intended #4166 behavior, but it means this upgrade can newly provision document storage, and newly register teardown targets under #626, for a projection that was quietly getting neither.

Verification

Bug_5192_event_projection_with_injected_dependencies covers both shapes plus a store-level assertion that the discovered types reach AllPublishedTypes().

The primary-constructor half is enforced by compilation itself — pinned back to the older generator, the test file does not build, with exactly the error the issue reported:

Bug_5192_..._PrimaryConstructorProjection.TypeRegistration.g.cs(12,12):
error CS8862: A constructor declared in a type with parameter list must have 'this' constructor initializer.

Locally against the published 2.42.1: the three new tests pass, full Marten.slnx builds, and EventSourcingTests (net9.0) runs 1627 passed / 0 failed / 7 skipped.

(One incidental note: the test class is partial because the generator wraps a nested projection's emitted members in their containing types. Pre-existing generator behavior, not introduced here.)

🤖 Generated with Claude Code

https://claude.ai/code/session_01VpDCvJcBDZerieJB4JEHde