Replace var with interface type in UseLambdaForFunctionalInterface#896
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A lambda is a poly expression and needs an explicit target type from
the declaration (JLS 14.4.1, 15.27.1), but `var` borrows its type from
the right-hand side. Converting `var x = new Foo() {...}` to a lambda
while keeping `var` produced code that no longer compiles.
When the initializer of a `var` local is converted to a lambda, replace
the `var` token with the anonymous class's interface type. Diamonds on
the right-hand side are expanded from the resolved lambda type so the
emitted declaration compiles without unchecked warnings.
Fixes #895
Detect `var` via the `JavaVarKeyword` marker the parser attaches, rather than string-comparing the identifier name — avoids tripping on a user identifier literally named `var`. Extract the diamond-to-resolved-type rebuild that `maybeAddCast` and the new `visitVariableDeclarations` share into a `resolveDiamond` helper, and inline the single-use `isVarType` predicate.
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… 2.34.0 to 2.36.0 [skip ci] Bumps [org.openrewrite.recipe:rewrite-static-analysis](https://github.com/openrewrite/rewrite-static-analysis) from 2.34.0 to 2.36.0. Release notes *Sourced from [org.openrewrite.recipe:rewrite-static-analysis's releases](https://github.com/openrewrite/rewrite-static-analysis/releases).* > 2.36.0 > ------ > > What's Changed > -------------- > > * Guard `instanceof` to `Class::isInstance` conversion on lambda arity by [`@timtebeek`](https://github.com/timtebeek) in [openrewrite/rewrite-static-analysis#903](https://redirect.github.com/openrewrite/rewrite-static-analysis/pull/903) > * Preserve cast on argument to overloaded method in `RemoveRedundantTypeCast` by [`@timtebeek`](https://github.com/timtebeek) in [openrewrite/rewrite-static-analysis#904](https://redirect.github.com/openrewrite/rewrite-static-analysis/pull/904) > * Preserve raw cast on parameterized expression in `RemoveRedundantTypeCast` by [`@timtebeek`](https://github.com/timtebeek) in [openrewrite/rewrite-static-analysis#905](https://redirect.github.com/openrewrite/rewrite-static-analysis/pull/905) > * Skip Python sources in `CombineSemanticallyEqualCatchBlocks` by [`@timtebeek`](https://github.com/timtebeek) in [openrewrite/rewrite-static-analysis#908](https://redirect.github.com/openrewrite/rewrite-static-analysis/pull/908) > * Use receiver type for unbound instance method reference in `ReplaceLambdaWithMethodReference` by [`@timtebeek`](https://github.com/timtebeek) in [openrewrite/rewrite-static-analysis#909](https://redirect.github.com/openrewrite/rewrite-static-analysis/pull/909) > * Regenerate recipes.csv by [`@timtebeek`](https://github.com/timtebeek) in [openrewrite/rewrite-static-analysis#910](https://redirect.github.com/openrewrite/rewrite-static-analysis/pull/910) > * Retain load-bearing type witness in select position in `UnnecessaryExplicitTypeArguments` by [`@knutwannheden`](https://github.com/knutwannheden) in [openrewrite/rewrite-static-analysis#911](https://redirect.github.com/openrewrite/rewrite-static-analysis/pull/911) > > **Full Changelog**: <openrewrite/rewrite-static-analysis@v2.35.0...v2.36.0> > > 2.35.0 > ------ > > What's Changed > -------------- > > * Document identity-semantics caveat on PrimitiveWrapperClassConstructorToValueOf by [`@timtebeek`](https://github.com/timtebeek) in [openrewrite/rewrite-static-analysis#883](https://redirect.github.com/openrewrite/rewrite-static-analysis/pull/883) > * Skip `FinalClass` when class has anonymous inner subclasses by [`@timtebeek`](https://github.com/timtebeek) in [openrewrite/rewrite-static-analysis#886](https://redirect.github.com/openrewrite/rewrite-static-analysis/pull/886) > * Skip `ReplaceLambdaWithMethodReference` for parameterized types with multiple constructors by [`@timtebeek`](https://github.com/timtebeek) in [openrewrite/rewrite-static-analysis#887](https://redirect.github.com/openrewrite/rewrite-static-analysis/pull/887) > * Preserve `null` cast at varargs position in `RemoveRedundantTypeCast` by [`@timtebeek`](https://github.com/timtebeek) in [openrewrite/rewrite-static-analysis#888](https://redirect.github.com/openrewrite/rewrite-static-analysis/pull/888) > * Retain explicit type arguments on no-arg static methods in `UnnecessaryExplicitTypeArguments` by [`@timtebeek`](https://github.com/timtebeek) in [openrewrite/rewrite-static-analysis#889](https://redirect.github.com/openrewrite/rewrite-static-analysis/pull/889) > * Detect overloads on parameterized receiver in `hasMethodOverloading` by [`@timtebeek`](https://github.com/timtebeek) in [openrewrite/rewrite-static-analysis#890](https://redirect.github.com/openrewrite/rewrite-static-analysis/pull/890) > * Preserve cast on generic method invocation in overloaded outer call by [`@timtebeek`](https://github.com/timtebeek) in [openrewrite/rewrite-static-analysis#891](https://redirect.github.com/openrewrite/rewrite-static-analysis/pull/891) > * Guard cast to `JavaType.Annotation` in `ReorderAnnotations` by [`@timtebeek`](https://github.com/timtebeek) in [openrewrite/rewrite-static-analysis#894](https://redirect.github.com/openrewrite/rewrite-static-analysis/pull/894) > * Strip diamond operator from cast in `UseLambdaForFunctionalInterface` by [`@timtebeek`](https://github.com/timtebeek) in [openrewrite/rewrite-static-analysis#893](https://redirect.github.com/openrewrite/rewrite-static-analysis/pull/893) > * Replace `var` with interface type in `UseLambdaForFunctionalInterface` by [`@timtebeek`](https://github.com/timtebeek) in [openrewrite/rewrite-static-analysis#896](https://redirect.github.com/openrewrite/rewrite-static-analysis/pull/896) > > **Full Changelog**: <openrewrite/rewrite-static-analysis@v2.34.1...v2.35.0> > > v2.34.1 > ------- > > What's Changed > -------------- > > * OpenRewrite [v8.81.6](https://github.com/openrewrite/rewrite/releases/tag/v8.81.6) > * Preserve statement order in `UseTryWithResources` by [`@timtebeek`](https://github.com/timtebeek) in [openrewrite/rewrite-static-analysis#866](https://redirect.github.com/openrewrite/rewrite-static-analysis/pull/866) > * Skip meta-annotated `@Configuration` in `FinalClass` and `HideUtilityClassConstructor` by [`@timtebeek`](https://github.com/timtebeek) in [openrewrite/rewrite-static-analysis#867](https://redirect.github.com/openrewrite/rewrite-static-analysis/pull/867) > * OpenRewrite recipe best practices by [`@timtebeek`](https://github.com/timtebeek) in [openrewrite/rewrite-static-analysis#869](https://redirect.github.com/openrewrite/rewrite-static-analysis/pull/869) > * Revert to using rewrite-java-21 for test runtime by [`@timtebeek`](https://github.com/timtebeek) in [openrewrite/rewrite-static-analysis#870](https://redirect.github.com/openrewrite/rewrite-static-analysis/pull/870) > * Preserve casts pinning generic-method return type in lambdas by [`@timtebeek`](https://github.com/timtebeek) in [openrewrite/rewrite-static-analysis#872](https://redirect.github.com/openrewrite/rewrite-static-analysis/pull/872) > * Preserve `(Object)` bridge cast for unchecked generic casts by [`@timtebeek`](https://github.com/timtebeek) in [openrewrite/rewrite-static-analysis#876](https://redirect.github.com/openrewrite/rewrite-static-analysis/pull/876) > * Skip `Objects::nonNull`/`isNull` when lambda parameter does not match by [`@timtebeek`](https://github.com/timtebeek) in [openrewrite/rewrite-static-analysis#875](https://redirect.github.com/openrewrite/rewrite-static-analysis/pull/875) > * Regression tests for ReplaceStackWithDeque ControlFlow crashes by [`@knutwannheden`](https://github.com/knutwannheden) in [openrewrite/rewrite-static-analysis#879](https://redirect.github.com/openrewrite/rewrite-static-analysis/pull/879) > * Skip `SimplifyConsecutiveAssignments` when initializer would self-reference by [`@timtebeek`](https://github.com/timtebeek) in [openrewrite/rewrite-static-analysis#882](https://redirect.github.com/openrewrite/rewrite-static-analysis/pull/882) > > **Full Changelog**: <openrewrite/rewrite-static-analysis@v2.34.0...v2.34.1> Commits * [`01d4a78`](openrewrite/rewrite-static-analysis@01d4a78) Update Gradle wrapper 9.5.1 * [`421318a`](openrewrite/rewrite-static-analysis@421318a) Retain load-bearing type witness in select position in `UnnecessaryExplicitTy... * [`c488082`](openrewrite/rewrite-static-analysis@c488082) Regenerate recipes.csv ([#910](https://redirect.github.com/openrewrite/rewrite-static-analysis/issues/910)) * [`829a5a5`](openrewrite/rewrite-static-analysis@829a5a5) Use receiver type for unbound instance method reference in `ReplaceLambdaWith... * [`5ab23a2`](openrewrite/rewrite-static-analysis@5ab23a2) Skip Python sources in `CombineSemanticallyEqualCatchBlocks` ([#908](https://redirect.github.com/openrewrite/rewrite-static-analysis/issues/908)) * [`e4bcb09`](openrewrite/rewrite-static-analysis@e4bcb09) Preserve raw cast on parameterized expression in `RemoveRedundantTypeCast` (#... * [`62e6a08`](openrewrite/rewrite-static-analysis@62e6a08) Preserve cast on argument to overloaded method in `RemoveRedundantTypeCast` (... * [`3ef523d`](openrewrite/rewrite-static-analysis@3ef523d) Guard `instanceof` to `Class::isInstance` conversion on lambda arity ([#903](https://redirect.github.com/openrewrite/rewrite-static-analysis/issues/903)) * [`03d153e`](openrewrite/rewrite-static-analysis@03d153e) Replace `var` with interface type in `UseLambdaForFunctionalInterface` ([#896](https://redirect.github.com/openrewrite/rewrite-static-analysis/issues/896)) * [`8e930b0`](openrewrite/rewrite-static-analysis@8e930b0) Strip diamond operator from cast in `UseLambdaForFunctionalInterface` ([#893](https://redirect.github.com/openrewrite/rewrite-static-analysis/issues/893)) * Additional commits viewable in [compare view](openrewrite/rewrite-static-analysis@v2.34.0...v2.36.0) [](https://docs.github.com/en/github/managing-security-vulnerabilities/about-dependabot-security-updates#about-compatibility-scores) Dependabot will resolve any conflicts with this PR as long as you don't alter it yourself. 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Summary
A lambda is a poly expression that needs an explicit target type from the declaration (JLS 14.4.1, 15.27.1), but
varborrows its type from the right-hand side. Convertingvar x = new Foo() {...}to a lambda while keepingvarproduced code that no longer compiles:This change replaces
varwith the anonymous class's interface type whenever the initializer is converted to a lambda. Diamonds on the right-hand side (new Foo<>() {...}) are expanded from the resolved lambda type so the emitted declaration compiles without unchecked warnings.Test plan
./gradlew test --tests "UseLambdaForFunctionalInterfaceTest"— full class passesvarLocalVariableReplacedWithInterfaceTypecovers the issue's exact reproducervarLocalVariableWithDiamondReplacedWithResolvedTypecovers a parameterized interface on the RHS