Why can't Kotlin infer types here?

[tieskedh]

New Type Inference in Kotlin 1.3.0-rc-190

This has been answered in Slack Slack but I’ll repeat the answer for others here: This flag hasn’t landed in the compiler yet. You have to use the old -X flags for now. Groovy DSL: compileKotlin { kotlinOptions { freeCompilerArgs = ["-XXLanguage:+NewInference"] } } Kotlin DSL: tasks.withType(KotlinCompile::class) .forEach { it.kotlinOptions { freeCompilerArgs = listOf("-Xnew-inference") } }

use this and it works.
(I assume you need a version newer than 1-3-0-rc-190, but didn’t try)