[pjmlp]

Meanwhile .NET land requires writing reflection free specific code for AOT, while GraalVM can handle reflection just fine.

ART also does PGO for free, as does OpenJ9. Both of which also handle reflection.

The thing with Java ecosystem is choice of implementations, instead of Microsoft's single implementation, specially now since most of Xamarin's work has been consumed into modern .NET.

[neonsunset]

This is simply not true. AOT requires code that is free of uses of JIT-specific features like runtime reflection-emit or assembly loading, which is not possible without build instrumentation for AOT implementations on other platforms either[0], because it by definition needs a JIT compiler. Reflection itself not only works but is sometimes faster because closed world guarantee by AOT allows for a more streamlined implementation.

With that said, trimming, also known as tree-shaking, which is required to not have massive binary size, has to know at compile-time which types, members and metadata tokens are reachable. This means that certain patterns of unbound reflection are by definition not statically analyzable and require the user to annotate (with [RequiresUnreferencedCode(params)]) the corresponding types with details of what they need the trimmer/linker to preserve (the entire assembly can also be rooted but, well, that's bad for size).

Other features like compiled expressions have received proper interpreter fallback which makes them just work(tm) without developer intervention.

You can also see that GraalVM Native Image is subject to very similar restrictions[1].

[0] Like pre-generating generic types/method bodies for Unity with special tooling. NativeAOT currently has (planned to be deprecated) rd.xml to manually instantiate certain generic methods and root specific types, replace their bodies, etc., it will probably be fully superseded by further expansion of attributes-style annotations API or obsoleted by improving compile-time analysis in the future.

[1] https://www.graalvm.org/22.1/reference-manual/native-image/L...

p.s.: quick search shows that Java Swing is plagued by similar issues with Native Image (not mentioning having to generate metadata annotations) to making .NET's GUI frameworks work with NativeAOT save for certain blessed templates/workloads introduced in .NET 8. Java AWT appears to be faring somewhat better on hello world examples but I suspect it experience the same fate as the templates for WinForms that the community has come up with so far (let me know if that's not the case).

[pjmlp]

The difference is that GraalVM, OpenJ9 and ART, have the capability to feed PGO data into the AOT toolchain, as a means to automatically generate a rd.xml like archive, thus preserving the existing language ecosystem.

In ART's case that metadata is even shared across devices via PlayStore, which gathers and uploads it, packaging it for download along the APK for new installations. This metada is dynamic, as more devices take party into executing newer code paths.

This is the beauty of Java ecosystem versus .NET, the plethora of implementations, with different approaches solving the same set of problems, allowing us in many cases to pick and choose.

From Real Time GC with AOT compilation used by US and French military in embedded systems, factory automation robots, phones, infotainment systems, M2M gateways, runtime snapshots between executions, or crazy ideas like having PGO data from cloud based JITs sharing executable code.

[neonsunset]

I feel like I keep reading the same comment from your profile every time except the order of words changes slightly. So much for expecting a meaningful response.

(please, please read the documentation first before making confident assertions, like in this case, and at least google discussed topics to actualize the knowledge on the points in favour of which you're arguing)

[pjmlp]

The sentiment goes both ways, the big difference is that I am not invested in any specific ecosystem to let that influence my arguments.