Skip to content

Changelog

Unreleased

0.4.0

2025-06-23

  • New: Injected constructors may now be private. This can be useful for scenarios where you want @Inject-annotated constructors to only be invokable by Metro’s generated code.
  • New: If reporting is enabled, write unused bindings diagnostics to keys-unused-*.txt.
  • New: Support for generic assisted injection.
  • New: Support for generic member injection.
  • New: Add diagnostic to prohibit type parameters on injected member functions.
  • Enhancement: Enable child graphs to depend on parent-scoped dependencies that are unused and not referenced in the parent scope. This involves generating hints for scoped @Inject classes and is gated on a new Metro option enableScopedInjectClassHints, which is enabled by default.
  • Enhancement: Check for context parameters in top-level function injection checker.
  • Enhancement: Store member injection info in metro metadata to slightly optimize member injection code gen.
  • Enhancement: Avoid writing providers fields in graphs for unused bindings.
  • Enhancement: Improve missing binding trace originating from root member injectors.
  • Fix: Fix support for generic injected constructor parameters.
  • Fix: Fix support for repeated contributes annotations by moving contribution binding function generation to IR.
  • Fix: Ensure scope/qualifier annotation changes on constructor-injected classes dirty consuming graphs in incremental compilation.
  • Fix: Report member injection dependencies when looking up constructor-injected classes during graph population.
  • Fix: Disable IR hint generation on JS targets too, as these now have the same limitation as native/WASM targets in Kotlin 2.2. Pending upstream support for generating top-level FIR declarations in KT-75865.
  • Fix: Ensure private provider function annotations are propagated across compilation boundaries.
  • Fix: Substitute copied FIR type parameter symbols with symbols from their target functions.
  • Fix: Improved support for generic member injection.
  • Fix: Propagate qualifiers on graph member injector functions.
  • Fix: Fix support for requesting MembersInjector types.
  • [internal] Report IR errors through IrDiagnosticReporter.
  • [internal] Significantly refactor + simplify IR parameter handling.
  • Fix publishing Apple native targets in snapshots.
  • Update to Kotlin 2.2.0.
  • Update Gradle plugin to target Kotlin language version to 1.9 (requires Gradle 8.3+).

Special thanks to @kevinguitar, @gabrielittner, and @JoelWilcox for contributing to this release!

0.3.8

2025-06-16

  • Enhancement: Disambiguate MetroContribution class names based on scope to better support IC when changing scopes.
  • Enhancement: Minimize deferred types when breaking cycles.
  • Fix: Disallow injection of Lazy<T> where T is an @AssistedFactory-annotated class.
  • Fix: Don’t short-circuit assisted injection validation if only an accessor exists.
  • Fix: Allow cycles of assisted factories to their target classes.
  • Update shaded okio to 3.13.0.
  • Update atomicfu to 0.28.0.

Special thanks to @kevinguitar, @bnorm, and @JoelWilcox for contributing to this release!

0.3.7

2025-06-08

  • Fix: Record lookups of generated static member inject functions for IC.
  • Fix: Dedupe merged overrides of @Includes accessors.

Special thanks to @kevinguitar for contributing to this release!

0.3.6

2025-06-06

  • New: Add new Provider.map, Provider.flatMap, Provider.zip, and Provider.memoize utility APIs.
  • Enhancement: Improve graph validation performance by avoiding unnecessary intermediate sorts (again).
  • Enhancement: Fail eagerly with a clear error message if languageVersion is too old.
  • Enhancement: Validate improperly depending on assisted-injected classes directly at compile-time.
  • Fix: Support constructing nested function return types for provider functions.
  • Fix: Propagate @Include bindings from parent graphs to extension graphs.
  • Fix: Reparent copied lambda default values in IR.
  • [internal] Make internal renderings of IrType more deterministic.

Special thanks to @kevinguitar for contributing to this release!

0.3.5

2025-05-31

  • New: Implement top-level function injection checkers.
  • Change: Disallow top-level function injections to be scoped.
  • Fix: Support type parameters with where bounds.
  • Fix: Support injected class type parameters with any bounds.
  • Fix: Support generic graph factory interfaces.
  • Fix: In the presence of multiple contributing annotations to the same scope, ensure only hint function/file is generated.
  • Fix: Improve shading to avoid packaging in stdlib and other dependency classes.
  • Fix: Revert #483 as it broke some cases we haven’t been able to debug yet.

Special thanks to @gabrielittner and @kevinguitar for contributing to this release!

0.3.4

2025-05-27

  • Enhancement: Use a simple numbered (but deterministic) naming for contributed graph classes to avoid long class names.
  • Enhancement: Improve graph validation performance by avoiding unnecessary intermediate sorts.
  • Enhancement: Move binding validation into graph validation step.
  • Enhancement: Avoid unnecessary BFS graph walk in provider field collection.
  • Fix: Fix provider field populating missing types that previously seen types dependent on.

Special thanks to @ChristianKatzmann and @madisp for contributing to this release!

0.3.3

2025-05-26

  • Enhancement: Don’t unnecessarily wrap Provider graph accessors.
  • Enhancement: Allow multiple contributed graphs to the same parent graph.
  • Fix: Don’t unnecessarily recompute bindings for roots when populating graphs.
  • Fix: Better handle generic assisted factory interfaces.
  • Fix: Use fully qualified names when generating hint files to avoid collisions.
  • Fix: Support provides functions with capitalized names.
  • Fix: Prohibit consuming Provider<Lazy<...>> graph accessors.
  • [internal] Migrate to new IR parameters/arguments/typeArguments compiler APIs.

Special thanks to @gabrielittner for contributing to this release!

0.3.2

2025-05-15

  • Enhancement: Optimize supertype lookups in IR.
  • Fix: Fix generic members inherited from generic supertypes of contributed graphs.
  • Fix: Fix @ContributedGraphExtension that extends the same interface as the parent causes a duplicate binding error.
  • Fix: Fix contributed binding replacements not being respected in contributed graphs.
  • Fix: Fix contributed providers not being visible to N+2+ descendant graphs.
  • Fix: Collect bindings from member injectors as well as exposed accessors when determining scoped provider fields.
  • Fix: Fix a few -Xverify-ir and -Xverify-ir-visibility issues + run all tests with these enabled now.

Special thanks to @bnorm, @gabrielittner, @kevinguitar, and @JoelWilcox for contributing to this release!

0.3.1

2025-05-13

  • Enhancement: Rewrite graph resolution using topological sorting to vastly improve performance and simplify generation.
  • Enhancement: Return early once an externally-compiled dependency graph is found.
  • Enhancement: Simplify multibinding contributor handling in graph resolution by generating synthetic qualifiers for each of them. This allows them to participate in standard graph resolution.
  • Enhancement: When there are multiple empty @Multibinds errors, report them all at once.
  • Enhancement: Avoid unnecessary StringBuilder allocations.
  • Fix: Don’t transform @Provides function’s to be private if its visibility is already explicitly defined.
  • Fix: Fix a comparator infinite loop vector.
  • Fix: Fix @ElementsIntoSet multibinding contributions triggering a dependency cycle in some situations.
  • Fix: Fix assertion error for generated multibinding name hint when using both @Multibinds and @ElementsIntoSet for the same multibinding.
  • Fix: Fix contributed graph extensions not inheriting empty declared multibindings.
  • Fix: Ensure we report the @Multibinds declaration location in errors if one is available.
  • Fix: Dedupe overrides by all parameters not just value parameters.
  • Fix: Dedupe overrides by signature rather than name when generating contributed graphs.
  • Fix: Fix accidentally adding contributed graphs as child elements of parent graphs twice.
  • Fix: Fix not deep copying extensionReceiverParameter when implementing fake overrides in contributed graphs.
  • Fix: Report fully qualified qualifier renderings in diagnostics.
  • Fix: Don’t generate provider fields for multibinding elements unnecessarily.
  • When debug logging + reports dir is enabled, output a logTrace.txt to the reports dir for tracing data.
  • Update to Kotlin 2.1.21.

Special thanks to @asapha, @gabrielittner, @jzbrooks, and @JoelWilcox for contributing to this release!

0.3.0

2025-05-05

  • New: Add support for @ContributesGraphExtension! See the docs for more info.
  • New: Add a asContribution() compiler intrinsic to upcast graphs to expected contribution types. For example: val contributedInterface = appGraph.asContribution<ContributedInterface>(). This is validated at compile-time.
  • New: Automatically transform @Provides functions to be private. This is enabled by defaults and supersedes the publicProviderSeverity when enabled, and can be disabled via the Gradle extension or transform-providers-to-private compiler option. Note that properties and providers with any annotations with KClass arguments are not supported yet pending upstream kotlinc changes.
  • Enhancement: Rewrite the internal BindingGraph implementation to be more performant, accurate, and testable.
  • Enhancement: Add diagnostic to check that graph factories don’t provide their target graphs as parameters.
  • Enhancement: Add diagnostic to check that a primary scope is defined if any additionalScopes are also defined on a graph annotation.
  • Enhancement: Add diagnostic to validate that contributed types do not have narrower visibility that aggregating graphs. i.e. detect if you accidentally try to contribute an internal type to a public graph.
  • Enhancement: Optimize supertype lookups when building binding classes by avoiding previously visited classes.
  • Enhancement: Don’t generate hints for contributed types with non-public API visibility.
  • Enhancement: When reporting duplicate binding errors where one of the bindings is contributed, report the contributing class in the error message.
  • Enhancement: When reporting scope incompatibility, check any extended parents match the scope and suggest a workaround in the error diagnostic.
  • Enhancement: Allow AssistedFactory methods to be protected.
  • Fix: Fix incremental compilation when a parent graph or supertype modifies/removes a provider.
  • Fix: Fix rank processing error when the outranked binding is contributed using Metro’s ContributesBinding annotation.
  • Fix: Fix @Provides graph parameters not getting passed on to extended child graphs.
  • Fix: Fix qualifiers on bindings not getting seen by extended child graphs.
  • Fix: Fix qualifiers getting ignored on accessors from @Includes dependencies.
  • Fix: Fix transitive scoped dependencies not always getting initialized first in graph provider fields.
  • Fix: Fix injected lateinit var properties being treated as if they have default values.
  • Fix: Alias bindings not always having their backing type visited during graph validation.
  • Fix: Fix race condition in generating parent graphs first even if child graph is encountered first in processing.
  • Fix: Fallback AssistedInjectChecker error report to the declaration source.
  • Fix: Fix missing parent supertype bindings in graph extensions.
  • Change: InstanceFactory is no longer a value class. This wasn’t going to offer much value in practice.
  • Change: Change debug reports dir to be per-compilation rather than per-platform.

Special thanks to @gabrielittner, @kevinguitar, @JoelWilcox, and @japplin for contributing to this release!

0.2.0

2025-04-21

  • New: Nullable bindings are now allowed! See the nullability docs for more info.
  • Enhancement: Add diagnostics for multibindings with star projections.
  • Enhancement: Add diagnostic for map multibindings with nullable keys.
  • Fix: Ensure assisted factories’ target bindings’ parameters are processed in MetroGraph creation. Previously, these weren’t processed and could result in scoped bindings not being cached.
  • Fix: Fix duplicate field accessors generated for graph supertypes.
  • Add compose navigation sample.

Special thanks to @bnorm and @yschimke for contributing to this release!

0.1.3

2025-04-18

  • Change: Multibindings may not be empty by default. To allow an empty multibinding, @Multibinds(allowEmpty = true) must be explicitly declared now.
  • New: Write graph metadata to reports (if enabled).
  • New: Support configuring debug and reports globally via metro.debug and metro.reportsDestination Gradle properties (respectively).
  • Enhancement: Change how aggregation hints are generated to improve incremental compilation. Externally contributed hints are now looked up lazily per-scope instead of all at once.
  • Enhancement: Optimize empty map multibindings to reuse a singleton instance.
  • Enhancement: Report error diagnostic if Dagger’s @Reusable is used on a provider or injected class.
  • Enhancement: Tweak diagnostic error strings for members so that IDE terminals auto-link them better. i.e., instead of printing example.AppGraph.provideString, Metro will print example.AppGraph#provideString instead.
  • Enhancement: Support repeatable @ContributesBinding annotations with different scopes.
  • Fix: Fix incremental compilation when @Includes-annotated graph parameters change accessor signatures.
  • Fix: Don’t allow graph extensions to use the same scope as any extended ancestor graphs.
  • Fix: Don’t allow multiple ancestor graphs of graph extensions to use the same scope.
  • Fix: Handle scenarios where the compose-compiler plugin runs before Metro’s when generating wrapper classes for top-level @Composable functions.
  • Fix: Fix an edge case in graph extensions where child graphs would miss a provided scoped binding in a parent graph that was also exposed as an accessor.
  • Fix: Fix Dagger interop issue when calling Javax/Jakarta/Dagger providers from Metro factories.
  • Fix: Fix Dagger interop issue when calling dagger.Lazy from Metro factories.
  • Fix: Preserve the original Provider or Lazy type used in injected types when generating factory creators.
  • Temporarily disable hint generation in WASM targets to avoid file count mismatches until KT-75865.
  • Add an Android sample: https://github.com/ZacSweers/metro/tree/main/samples/android-app
  • Add a multiplatform Circuit sample: https://github.com/ZacSweers/metro/tree/main/samples/circuit-app
  • Add samples docs: https://zacsweers.github.io/metro/samples
  • Add FAQ docs: https://zacsweers.github.io/metro/faq

Special thanks to @JoelWilcox, @bnorm, and @japplin for contributing to this release!

0.1.2

2025-04-08

  • Enhancement: Implement createGraph and createGraphFactory FIR checkers for better error diagnostics on erroneous type arguments.
  • Enhancement: Add ContributesBinding.rank interop support with Anvil.
  • Enhancement: Check Kotlin version compatibility. Use the metro.version.check=false Gradle property to disable these warnings if you’re feeling adventurous.
  • Fix: Fix class-private qualifiers on multibinding contributions in other modules not being recognized in downstream graphs.
  • Fix: Fix member injectors not getting properly visited in graph validation.
  • Fix: Fix a bug where Map<Key, Provider<Value>> multibindings weren’t always unwrapped correctly.
  • Fix: Fix Map<Key, Provider<Value>> type keys not correctly interpreting the underlying type key as Map<Key, Value>.
  • Change: Change InstanceFactory to a value class.
  • Change: Make providerOf use InstanceFactory under the hood.

Special thanks to @JoelWilcox, @bnorm, @japplin, @kevinguitar, and @erawhctim for contributing to this release!

0.1.1

2025-04-03

Initial release!

See the announcement blog post: https://www.zacsweers.dev/introducing-metro/