Migrate prebindgen-jni to kotlin-codegen's class model and ident module

[milyin]

Merge order: needs milyin/kotlin-codegen#21 first. KOTLIN_CODEGEN_REV currently points at that PR's branch head so CI can run; re-point it to the squash-merge commit on kotlin-codegen main before merging (there is a TODO on the line).

Why

#379 renamed kotlin-codegen's types (Code → KtCode, …). It did not migrate the model restructure sitting behind those names, so prebindgen-jni did not actually compile against kotlin-codegen main:

error: could not compile `prebindgen-jni` (lib) due to 24 previous errors

24 errors across render.rs, kotlin_emit.rs and iface.rs.

Class model

KtClassKind now carries what each kind can hold, so the constructors replace the unit variants:

before	after
KtClassKind::Plain	KtClass::class_(name)
KtClassKind::Abstract	KtClass::class_with(KtClassModifier::Abstract, name)
KtClassKind::Data	KtClass::data(name, first)
KtClassKind::DataObject	KtClass::data_object(name)
KtClassKind::Enum(entries)	KtClass::enum_(name) + .entry(e)
KtClassKind::Interface / SealedInterface	KtClass::interface_ / sealed_interface
KtClass::companion_object()	KtCompanion::new()
.supertype(ty, args)	.extends(ty, args) / .implements(ty)
class.supertypes.push((ty, None))	class.supertypes.interfaces.push(ty)
KtFunInterface::new(name, KtFun)	… (name, KtFunSig)

Three of these needed more than a substitution:

• data class takes its first constructor property at construction, because Kotlin requires at least one. The two emitters that built the whole parameter list first now hand over its head and append the rest. A data_class-declared struct with no fields now panics with a message naming the struct, rather than rendering data class Foo() — which never compiled as Kotlin anyway.
• Supertypes split into the one superclass a class may construct and any number of interfaces, so each site had to say which it meant: NativeHandle is extended, AutoCloseable and the generated <Name>Api are implemented.
• KtFunInterface takes a signature, which is the honest type — a SAM interface's one method is abstract by definition. to_decl / to_raw_decl build KtFunSig now.

apply_class_interface marks ctor properties override, which needs mutable access to storage that moved onto the kind; a small ctor_params_mut helper covers it.

Four latent runtime panics

.modifier("external") → .external(). external is a body kind rather than a modifier in the new model, and .modifier asserts against the string — so these four sites were not merely compile errors, they would have panicked at generation time.

asRaw — needs kotlin-codegen#21

The extension-function proxy was built by packing the receiver into the function name ("PayloadCallback<G>.asRaw"). The new InvalidIdentifier check reported all twelve, correctly. With KtFun::receiver from milyin/kotlin-codegen#21 the name is a plain identifier again, and the rendered output is unchanged.

Identifier de-duplication

symbols.rs carried its own HARD_KEYWORDS, is_valid_kotlin_ident, mangle_kotlin_ident and mangle_package. All four are byte-identical in behaviour to kotlin_codegen::ident — same 28-keyword list in the same order, same predicate, same mangling rules — which did not exist when they were written. Two copies means the crate that mangles a name and the crate that validates the file it lands in can drift apart.

Deleted, together with the four tests that duplicate kotlin-codegen's own, and re-exported upstream. mangle_package takes the upstream spelling (mangle_kotlin_package) so there is one name rather than an alias. −179 lines in that file.

Two deliberate non-changes:

• check_ident keeps is_valid_kotlin_ident, not kotlin-codegen's is_writable_kotlin_ident. A back-ticked name is legal Kotlin but cannot be a native-symbol component, so the generator must not emit one — the stricter predicate is the correct one here, and there is now a comment saying so.
• validate_symbols stays. It is not duplicated work: it runs before emission, its messages name the Rust origin and the build.rs knob that produced a bad name, and its JVM-erasure overload table catches platform declaration clashes that Check::DuplicateFunction — a structural parameter-list comparison — does not.

Banner

Generated files had started announcing kotlin-codegen as their generator, since kotlin-codegen changed its default constant and this crate never set one. Restored to Auto-generated by JniGen via KtFile::banner, applied after the merge so it does not depend on fragment order.

Verification

The result worth checking: after a forced regeneration — cargo clean -p covertest-kotlin -p perftest-kotlin, then rebuild, since a cached build would pass without regenerating anything — the emitted Kotlin differs from main in exactly the 8 banner lines and nothing else. The class-model migration and the asRaw change are output-preserving.

• cargo build --workspace --all-features
• cargo test --workspace, and again with --all-features — CI runs both
• cargo fmt --check with the CI config flags
• cargo clippy --all-targets --all-features -- -D warnings on stable and 1.85.0

[Copilot]

Pull request overview

Updates prebindgen-jni to compile and generate Kotlin correctly against kotlin-codegen’s restructured class model and centralized identifier utilities, while restoring the intended “JniGen” generator banner in emitted .kt files.

Changes:

• Migrates Kotlin emission to the new kotlin-codegen class model APIs (KtClass::{class_,data,enum_,…}, KtCompanion, extends/implements, .external()).
• De-duplicates Kotlin identifier mangling/validation by re-exporting kotlin_codegen::ident helpers from prebindgen-jni and updating call sites.
• Restores a stable generated-file banner by applying KtFile::banner after fragment merging.

Reviewed changes

Copilot reviewed 7 out of 15 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
prebindgen-jni/src/jni/symbols.rs	Re-exports identifier helpers from kotlin-codegen and removes duplicated implementations/tests.
prebindgen-jni/src/jni/render.rs	Adapts enum/data-class/handle rendering to the new class model (KtCompanion, enum_().entry, data(...first), extends/implements, .external()).
prebindgen-jni/src/jni/kotlin_emit.rs	Applies a consistent generated-file banner after merge_files; updates class construction/supertypes and companion handling.
prebindgen-jni/src/jni/iface.rs	Switches SAM method construction to KtFunSig and uses KtFun::receiver for asRaw.
prebindgen-jni/src/jni/decl.rs	Switches package sanitization to mangle_kotlin_package spelling.
prebindgen-jni/src/jni/config.rs	Switches base-package sanitization to mangle_kotlin_package spelling.
examples/perftest-kotlin/kotlin/generated/io/prebindgen/perftest/storage.kt	Regenerated banner line.
examples/perftest-kotlin/kotlin/generated/io/prebindgen/perftest.kt	Regenerated banner line.
examples/covertest-kotlin/kotlin/generated/io/prebindgen/covertest/storage.kt	Regenerated banner line.
examples/covertest-kotlin/kotlin/generated/io/prebindgen/covertest/model.kt	Regenerated banner line.
examples/covertest-kotlin/kotlin/generated/io/prebindgen/covertest/esc_pkg.kt	Regenerated banner line.
examples/covertest-kotlin/kotlin/generated/io/prebindgen/covertest/errors.kt	Regenerated banner line.
examples/covertest-kotlin/kotlin/generated/io/prebindgen/covertest/analytics.kt	Regenerated banner line.
examples/covertest-kotlin/kotlin/generated/io/prebindgen/covertest.kt	Regenerated banner line.
.github/workflows/rust.yml	Updates pinned KOTLIN_CODEGEN_REV used by CI.

Suppressed comments (1)

prebindgen-jni/src/jni/iface.rs:556

• The generic arguments are still embedded into the return type’s class-name string (KtType::cls(format!("{}{gen_args}", ...))), which drops structured type arguments from KtType (it leaves args empty and bakes <...> into fqn). That can break any logic that inspects KtType::Named { fqn, args, .. } (e.g. erasure/descriptor validation). Build the generic return type via KtType::generic instead.

        let mut f = KtFun::new("asRaw").vis(KtVis::Public).receiver(recv);

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[Copilot]

Pull request overview

Copilot reviewed 7 out of 15 changed files in this pull request and generated 1 comment.

Suppressed comments (2)

prebindgen-jni/src/jni/kotlin_emit.rs:1988

• ctor_params_mut must not fabricate an empty mutable slice (&mut []). For kinds that cannot have primary-ctor params, return None instead; otherwise return the underlying storage slice.

fn ctor_params_mut(class: &mut KtClass) -> &mut [KtCtorParam] {
    match &mut class.kind {
        KtClassKind::Class { ctor, .. }
        | KtClassKind::Data { ctor }
        | KtClassKind::Enum { ctor, .. } => ctor,
        KtClassKind::Value { field } => std::slice::from_mut(field),
        KtClassKind::Object
        | KtClassKind::Interface
        | KtClassKind::SealedInterface
        | KtClassKind::DataObject => &mut [],
    }

.github/workflows/rust.yml:37

• PR description says KOTLIN_CODEGEN_REV is temporarily pointing at a PR branch head and there is a TODO on this line to re-point it before merging. That TODO isn't present in the workflow, increasing the chance it gets merged still pointing at a non-main commit.

  # Local development still tracks kotlin-codegen `main` (see
  # download_repositories.sh), matching how the other sibling repos work.
  KOTLIN_CODEGEN_REV: 796c25c19d2dbeecbdc58637194d3d3ee9da2993