Kotlin recipe DSL: trailing-lambda parens + Java-static chain inner + bare-param after body#7709
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…ng lambda is present
`preserveTrailingLambdaShape` was unconditionally adding `OmitParentheses`
to the args container whenever the last arg was a `TrailingLambdaArgument`-
marked lambda. For multi-arg calls (`obj.method(arg, lambda)`),
`OmitParentheses` tells the Kotlin printer to drop ALL the call's parens
— so the call rendered as `obj.methodarg { lambda }` with no `(` after
the method name and no `)` before the lambda.
Gate `OmitParentheses` on `padded.size() == 1` (single-lambda-only form).
For multi-arg trailing-lambda calls, the `TrailingLambdaArgument` marker
on the lambda is the only signal needed: `KotlinPrinter.visitArgumentsContainer`
already emits `(` ... `)` around the non-lambda args and the lambda
outside.
Unblocks `xs.map(f).toMutableList()` -> `xs.mapTo(mutableListOf(), f)`
and the rest of the `mapTo`/`filterTo`/`flatMapTo` family.
…fter bodies
Two fixes in `RecipeIrGenerationExtension` that landed together because
the second only surfaces once the first is in place — verified by a new
end-to-end test `chain with Java-static inner segment — Optional_of_x_get
to x`.
1. Chain validator rejected Java-static inner segments. K2 wraps Java-
platform-typed call results (`Optional<T>!` -> `Optional<T>`) in an
`IrTypeOperatorCall(IMPLICIT_CAST)`. The chain detector's
`rawReceiver is IrCall` check was false because `rawReceiver` was the
type-op wrapper, not the wrapped `IrCall`. Added
`unwrapImplicitCasts(expr)` that peels `IMPLICIT_CAST` / `IMPLICIT_NOTNULL`
wrappers and call it at every `IrCall`-shape-check site in
`validateBeforeLambda` (root receiver, inner receiver, inner args,
outer args, root args).
2. `buildAfterTemplate` missed bare-param-reference after bodies.
With (1) in place, `Optional.of("hi").get()` matched but the rewrite
emitted the literal `x` instead of `"hi"`. The substitution-spot
visitor was driven by `expr.acceptChildrenVoid(visitor)`, which only
walks expr's CHILDREN. For an after body that's a single
`{ x -> x }`, expr IS the `IrGetValue` — it has no children, so the
visitor never registered it as a substitution spot and the template
rendered the source slice unchanged. Switched to
`expr.accept(visitor, null)` so the visitor sees expr itself first.
Unblocks `Optional.of(x).get() -> x` style chain rewrites where the
inner segment is a Java static call (the same shape covers
`Stream.of(x).findFirst()`, `List.of(x).getFirst()`, etc.).
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Summary
preserveTrailingLambdaShapewas dropping parens around non-lambda args. Multi-arg calls with a trailing lambda (obj.method(arg) { lambda }) were rendering asobj.methodarg { lambda }. Caused by unconditionally addingOmitParenthesesto the args container whenever the last arg carriedTrailingLambdaArgument. Fix: gateOmitParenthesesonpadded.size() == 1. For multi-arg trailing-lambda calls, the marker on the lambda is sufficient —KotlinPrinter.visitArgumentsContaineralready handles the rendering.Chain validator rejected Java-static inner segments. Patterns like
Optional.of(x).get()were silently falling through to the imperative path (thepluginRequiredruntime stub). Root cause: K2 wraps Java-platform-typed call results (Optional<T>!→Optional<T>) inIrTypeOperatorCall(IMPLICIT_CAST), so the chain detector'srawReceiver is IrCallcheck was false. Fix: addedunwrapImplicitCasts(expr)and called it at everyIrCall-shape-check site invalidateBeforeLambda.buildAfterTemplatemissed bare-param after bodies. With (2) in place,Optional.of("hi").get()matched but rewrote to the literalxinstead of"hi". The substitution-spot visitor usedexpr.acceptChildrenVoid(visitor), which only walksexpr's CHILDREN. For an after body like{ x -> x },exprIS theIrGetValue— it has no children, so the visitor never registered it and the template rendered the source slice unchanged. Fix:expr.accept(visitor, null)instead.New end-to-end test
RecipePluginRewriteTest."chain with Java-static inner segment — Optional_of_x_get to x"exercises all three fixes.Test plan
:rewrite-kotlin:test— all 1205+ tests green locally.moderneinc/recipes-kotlinPerformance and Interop recipe families against the rebuilt8.82.0-SNAPSHOT. Unblocksxs.map(f).toMutableList() → xs.mapTo(mutableListOf(), f)(and thefilterTo/filterNotTo/flatMapTosiblings) andOptional.of(x).get() → x.