Support "-opt-in": Build results in "warning: '-Xuse-experimental' is deprecated..."

[brettwooldridge]

I am converting a project from Buck to Bazel, and it is mostly going smoothly, but build is emitting this warning:

INFO: From KotlinCompile //netld/org.ziptie.net:com-dancer-net { kt: 4, java: 30, srcjars: 0 } for darwin:
warning: '-Xuse-experimental' is deprecated and will be removed in a future release

My toolchain config looks like this:

load("@io_bazel_rules_kotlin//kotlin:core.bzl", "define_kt_toolchain")

define_kt_toolchain(
    name = "kotlin_toolchain",
    api_version = "1.5",
    jvm_target = "11",
    language_version = "1.5",
)

Running kotlin -version on the CLI returns:

Kotlin version 1.5.31-release-548 (JRE 17.0.2+8-LTS-86)

How can I get rid of the '-Xuse-experimental' warning?

[brettwooldridge]

Replying to myself. This seems to eliminate the warning:

kt_kotlinc_options(
    name = "kt_kotlinc_options",
    x_use_experimental = False,
)

define_kt_toolchain(
    name = "kotlin_toolchain",
    api_version = "1.4",
    jvm_target = "11",
    kotlinc_options = "//:kt_kotlinc_options",
    language_version = "1.4",
)

However, this may turn off needed features. Kotlin is apparently now using -opt-in from 1.6 and -Xopt-in in earlier versions.

https://kotlinlang.org/docs/opt-in-requirements.html

[Kernald]

See #676.