Generate kotlinc options from kotlin-compiler-arguments-description by agluszak · Pull Request #1406 · bazelbuild/rules_kotlin

agluszak · 2025-11-25T13:49:41Z

Implement automatic generation of kotlinc options using the official kotlin-compiler-arguments-description artifact from JetBrains.

Auto-generated options: WriteKotlincCapabilities generates both capabilities.bzl (flag existence/stability metadata) and generated_opts.bzl (full typed Starlark options) from the compiler metadata artifact.
Simplified maintenance: Manual _KOPTS dict replaced with GENERATED_KOPTS import, with _MANUAL_KOPTS for special cases only.

Changes:

Add kotlin-compiler-arguments-description dependency (version must match kotlin compiler version)
Rewrite WriteKotlincCapabilities to use the new artifact
Generate generated_opts_X.Y.bzl with attr.bool for booleans, attr.string for strings, attr.string_list for arrays
Simplify opts.kotlinc.bzl to merge generated + manual options

Closes #1444

restingbull

Aside from a few small backward compatibility issues, the approach looks ok.

Need to be solved:

Enumerated flags will need a set of valid values -- because you'd rather have the build fail in analysis that compiler invocation. Some invocations can live very deep in a build graph, which will cause maintenance headaches.
Flags must live on an allow list. The friends flag is the best example, as it pretty much cannot be used correctly, and overlaps with existing rule functionality.

Finally, please remove extra_kotlinc_args. That will inevitably be misused in large code repositories for all the reasons that the flags are treated as attributes.

src/main/starlark/core/options/opts.kotlinc.bzl

...ain/starlark/core/repositories/kotlin/capabilities_2.2.bzl.com_github_jetbrains_kotlin.bazel

...n/starlark/core/repositories/kotlin/generated_opts_2.2.bzl.com_github_jetbrains_kotlin.bazel

src/main/starlark/core/repositories/compiler.bzl

docs/kotlin.md

… kotlin-compiler-arguments-description artifact from JetBrains. - Auto-generated options: WriteKotlincCapabilities generates both capabilities.bzl (flag existence/stability metadata) and generated_opts.bzl (full typed Starlark options) from the compiler metadata artifact. - Simplified maintenance: Manual _KOPTS dict replaced with GENERATED_KOPTS import, with _MANUAL_KOPTS for special cases only. Changes: - Add kotlin-compiler-arguments-description dependency (version must match kotlin compiler version) - Rewrite WriteKotlincCapabilities to use the new artifact - Generate generated_opts_X.Y.bzl with attr.bool for booleans, attr.string for strings, attr.string_list for arrays - Simplify opts.kotlinc.bzl to merge generated + manual options

...n/starlark/core/repositories/kotlin/generated_opts_2.3.bzl.com_github_jetbrains_kotlin.bazel

restingbull · 2026-01-08T21:34:52Z

...n/starlark/core/repositories/kotlin/generated_opts_2.3.bzl.com_github_jetbrains_kotlin.bazel

+        map_value_to_flag = _map_string_flag("-jvm-default"),
+    ),
+    "jvm_target": struct(
+        flag = "-jvm-target",


This is set by the task, so it shouldn't be visible.

src/main/kotlin/io/bazel/kotlin/generate/WriteKotlincCapabilities.kt

src/main/starlark/core/options/opts.kotlinc.bzl

shalupov · 2026-01-09T13:48:55Z

@agluszak if we are making incompatible release anyway (Boolean -> String), it's worth comparing compiler arguments before and after, including default values, so it won't be a complete surprise (and document those changes in changelog).

agluszak · 2026-01-13T11:39:57Z

@agluszak if we are making incompatible release anyway (Boolean -> String)

that's reverted

agluszak · 2026-01-13T11:52:31Z

@restingbull okay, I think everything's been addressed

# Conflicts: # docs/kotlin.md # src/main/starlark/core/options/opts.kotlinc.bzl # src/main/starlark/core/repositories/kotlin/capabilities_2.3.bzl.com_github_jetbrains_kotlin.bazel

restingbull · 2026-01-24T23:54:30Z

...n/starlark/core/repositories/kotlin/generated_opts_2.3.bzl.com_github_jetbrains_kotlin.bazel

+        type = attr.bool,
+        value_to_flag = {True: ["-Xallow-unstable-dependencies"]},
+    ),
+    "x_annotation_default_target": struct(


This should be an enum

restingbull · 2026-01-24T23:56:03Z

...n/starlark/core/repositories/kotlin/generated_opts_2.3.bzl.com_github_jetbrains_kotlin.bazel

+        type = attr.bool,
+        value_to_flag = {True: ["-Xcheck-phase-conditions"]},
+    ),
+    "x_common_sources": struct(


This adds source files to the compilation -- it's not a reasonable option for the compiler.

restingbull · 2026-01-24T23:59:55Z

...n/starlark/core/repositories/kotlin/generated_opts_2.3.bzl.com_github_jetbrains_kotlin.bazel

+        value_to_flag = {True: ["-Xexplicit-backing-fields"]},
+    ),
+    "x_fragment_dependency": struct(
+        flag = "-Xfragment-dependency",


Another path flag.

restingbull · 2026-01-25T00:00:33Z

...n/starlark/core/repositories/kotlin/generated_opts_2.3.bzl.com_github_jetbrains_kotlin.bazel

+        value_to_flag = None,
+        map_value_to_flag = _map_string_list_flag("-Xfragment-dependency"),
+    ),
+    "x_fragment_friend_dependency": struct(


restingbull · 2026-01-25T00:01:31Z

...n/starlark/core/repositories/kotlin/generated_opts_2.3.bzl.com_github_jetbrains_kotlin.bazel

+        map_value_to_flag = _map_string_list_flag("-Xfragment-friend-dependency"),
+    ),
+    "x_fragment_refines": struct(
+        flag = "-Xfragment-refines",


This is a wierd one. I'm not sure this make sense to be exposed as an option -- it seems more like a feature that should be defined in the rules.

restingbull · 2026-01-25T00:01:40Z

...n/starlark/core/repositories/kotlin/generated_opts_2.3.bzl.com_github_jetbrains_kotlin.bazel

+        value_to_flag = None,
+        map_value_to_flag = _map_string_list_flag("-Xfragment-refines"),
+    ),
+    "x_fragment_sources": struct(


restingbull · 2026-01-25T00:02:58Z

...n/starlark/core/repositories/kotlin/generated_opts_2.3.bzl.com_github_jetbrains_kotlin.bazel

+        value_to_flag = None,
+        map_value_to_flag = _map_string_list_flag("-Xfragment-sources"),
+    ),
+    "x_fragments": struct(


See other -Xfragment flags. Pretty sure this are difficult, if not impossible to use correct when compiling via the rules.

restingbull

Given how often flags that do not make sense within the rules are sneaking into the generated options, it seems like having an allow list would make a lot more sense than a disallow list.

agluszak requested review from Bencodes, ahumesky, cgruber, nkoroste and restingbull as code owners November 25, 2025 13:49

agluszak force-pushed the flags branch from d20d49d to 8ee6f83 Compare November 25, 2025 13:53

restingbull requested changes Dec 1, 2025

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restingbull reviewed Dec 10, 2025

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docs/kotlin.md Outdated Show resolved Hide resolved

agluszak mentioned this pull request Jan 8, 2026

[maintenance] Add Kotlin 2.3 compiler options definitions #1445

Merged

agluszak force-pushed the flags branch 2 times, most recently from 20c7b23 to 7993c70 Compare January 8, 2026 19:20

agluszak force-pushed the flags branch from 7993c70 to d76e0ad Compare January 8, 2026 19:24

agluszak requested a review from restingbull January 8, 2026 19:24

restingbull reviewed Jan 8, 2026

View reviewed changes

agluszak force-pushed the flags branch from 992c5c1 to 9d03290 Compare January 13, 2026 11:35

Address code review issues

925cb59

agluszak force-pushed the flags branch from 9d03290 to 925cb59 Compare January 13, 2026 11:49

agluszak added 2 commits January 24, 2026 02:00

Merge branch 'master' into flags

0c52cb0

# Conflicts: # docs/kotlin.md # src/main/starlark/core/options/opts.kotlinc.bzl # src/main/starlark/core/repositories/kotlin/capabilities_2.3.bzl.com_github_jetbrains_kotlin.bazel

Simplify

bfac7ee

restingbull reviewed Jan 24, 2026

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restingbull reviewed Jan 25, 2026

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agluszak added 6 commits January 30, 2026 21:25

New approach

1ac97db

Formatting

e7ff8c2

Remove unused code

1535752

WIP

570f237

WIP

d4a94d1

Rework

4afcd91

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agluszak commented Nov 25, 2025 •

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