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Migrate to BCR rules_scala and Bazel BSP #453

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c6c2667
Migrate to BCR rules_scala
MrAMS Dec 17, 2025
3a96177
refactor: replace Bloop with Bazel BSP for IDE support
MrAMS Dec 17, 2025
02c1976
doc: toolchains/scala/README.md, chisel/README.md
MrAMS Dec 18, 2025
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12 changes: 12 additions & 0 deletions .bazelproject
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Original file line number Diff line number Diff line change
@@ -0,0 +1,12 @@
targets:
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@oharboe oharboe Dec 17, 2025

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should this be manually edited or created from bazel?

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@MrAMS MrAMS Dec 18, 2025 •
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Metals need this file to tell which index targets should be indexed. It can be edited. You can check more here

//chisel:codegenlib
//chisel:applicationlib

allow_manual_targets_sync: false

derive_targets_from_directories: false

enabled_rules:
rules_scala
rules_java
rules_jvm
20 changes: 0 additions & 20 deletions .github/workflows/ci.yml
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Expand Up @@ -29,26 +29,6 @@ jobs:
run: |
buildifier -lint warn -r .

bloop:
name: Check Bloop
runs-on: ubuntu-22.04
env:
DEBIAN_FRONTEND: "noninteractive"
steps:
- name: Checkout bazel-orfs
uses: actions/checkout@v4

- name: Setup Bazel
uses: bazel-contrib/setup-bazel@0.15.0
with:
bazelisk-cache: true
disk-cache: ${{ github.workflow }}-${{ github.job }}
repository-cache: true

- name: Run Bloop
run: |
bazel run :bloop

test-make-target:
name: ${{ matrix.STAGE_TARGET }}
runs-on: ubuntu-22.04
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36 changes: 15 additions & 21 deletions BUILD
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Expand Up @@ -3,11 +3,10 @@ load("@aspect_rules_js//js:defs.bzl", "js_binary")
# Unused in CI
#
# load("@bazel-orfs//tools/pin:pin.bzl", "pin_data")
load("@bazel-orfs//toolchains/scala:chisel.bzl", "chisel_library")
load("@bazel-orfs//toolchains/scala:scala_bloop.bzl", "scala_bloop")
load("@npm//:defs.bzl", "npm_link_all_packages")
load("@rules_python//python:defs.bzl", "py_binary")
load("@rules_python//python:pip.bzl", "compile_pip_requirements")
load("@rules_scala//scala:scala_toolchain.bzl", "scala_toolchain")
load("@rules_shell//shell:sh_binary.bzl", "sh_binary")

# Reenable when we add test back in
Expand Down Expand Up @@ -524,6 +523,20 @@ sh_binary(
visibility = ["//visibility:public"],
)

# Custom Scala toolchain with SemanticDB enabled
scala_toolchain(
name = "semanticdb_toolchain_impl",
enable_semanticdb = True,
semanticdb_bundle_in_jar = False,
visibility = ["//visibility:public"],
)

toolchain(
name = "semanticdb_toolchain",
toolchain = ":semanticdb_toolchain_impl",
toolchain_type = "@rules_scala//scala:toolchain_type",
)

# Not in use in CI
#
# pin_data(
Expand All @@ -542,22 +555,3 @@ sh_binary(
# ],
# tags = ["manual"],
# )

# This library lists all the scala files we will be editing in vscode via bloop
chisel_library(
name = "blooplib",
srcs = [
"//chisel:chiselfiles",
"//sby:chiselfiles",
"//toolchains/scala:chiselfiles",
],
deps = [
"@maven//:org_scalatest_scalatest_2_13",
],
)

# Set up bloop
scala_bloop(
name = "bloop",
src = "blooplib",
)
20 changes: 16 additions & 4 deletions MODULE.bazel
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Expand Up @@ -10,6 +10,7 @@ module(
bazel_dep(name = "googletest", version = "1.15.2")
bazel_dep(name = "rules_jvm_external", version = "6.7")
bazel_dep(name = "rules_java", version = "8.14.0")
bazel_dep(name = "rules_scala", version = "7.1.5")
bazel_dep(name = "aspect_rules_js", version = "2.1.3")
bazel_dep(name = "rules_verilator", version = "0.1.0")
bazel_dep(name = "verilator", version = "5.036.bcr.3")
Expand Down Expand Up @@ -117,9 +118,7 @@ CIRCE_VERSION = "0.14.4"

MAVEN_DEPS = {
"org.apache.commons:commons-text": "1.12.0",
"org.scala-lang:scala-compiler": SCALA_VERSION,
"org.scala-lang:scala-library": SCALA_VERSION,
"org.scala-lang:scala-reflect": SCALA_VERSION,
# BCR rules_scala automatically provides scala-compiler, scala-library, scala-reflect
}

MAVEN_SHORT_DEPS = {
Expand All @@ -142,6 +141,19 @@ MAVEN_LONG_DEPS = {
"org.scalameta:semanticdb-scalac": "4.14.1",
}

# Configure BCR rules_scala
scala_config = use_extension("@rules_scala//scala/extensions:config.bzl", "scala_config")
scala_config.settings(scala_version = "2.13.17")
use_repo(scala_config, "rules_scala_config")

scala_deps = use_extension("@rules_scala//scala/extensions:deps.bzl", "scala_deps")
scala_deps.scala() # Provides scala-compiler, scala-library, scala-reflect
scala_deps.scalatest() # Provides scalatest framework
use_repo(scala_deps, "rules_scala_toolchains")

# Register custom Scala toolchain with SemanticDB enabled
register_toolchains("//:semanticdb_toolchain")

maven = use_extension("@rules_jvm_external//:extensions.bzl", "maven")
maven.install(
artifacts = [
Expand Down Expand Up @@ -176,7 +188,7 @@ use_repo(maven, "maven")

register_toolchains(
"@rules_verilator//verilator:verilator_toolchain",
"//toolchains/scala:all",
"@rules_scala_toolchains//...:all",
# "@llvm_toolchain//:all",
)

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232 changes: 232 additions & 0 deletions MODULE.bazel.lock
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8 changes: 2 additions & 6 deletions chisel/README.md
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Expand Up @@ -16,13 +16,9 @@ Create a Chisel test bench module that has one `done` top level output signal to

See BUILD file in this folder and read the test.bzl on how to set up chisel_bench_test().

Unfortunately, there isn't enough disk space in CI to have LLVM + verilator toolchains enabled, so it has been temporarily disabled. To enable, revert the disabling:
Run the test:

git revert 60f0a5e5335feca1b0c9a4b8ae087d23a5fb99b2

Now run the test:

bazelisk test :life_test
bazel test :life_test

Output:

Expand Down
2 changes: 0 additions & 2 deletions generate.bzl
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Expand Up @@ -8,7 +8,6 @@ def _fir_library_impl(ctx):
fir = ctx.actions.declare_file(ctx.attr.name + ".fir")

args = ctx.actions.args()
args.add("-jar", ctx.file.generator)
args.add_all([ctx.expand_location(opt, ctx.attr.data) for opt in ctx.attr.opts])
args.add("-o", fir)
ctx.actions.run(
Expand Down Expand Up @@ -39,7 +38,6 @@ fir_library = rule(
allow_files = True,
),
"generator": attr.label(
allow_single_file = True,
cfg = "exec",
executable = True,
mandatory = True,
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2 changes: 1 addition & 1 deletion maven_install.json
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@@ -1,6 +1,6 @@
{
"__AUTOGENERATED_FILE_DO_NOT_MODIFY_THIS_FILE_MANUALLY": "THERE_IS_NO_DATA_ONLY_ZUUL",
"__INPUT_ARTIFACTS_HASH": 1558645857,
"__INPUT_ARTIFACTS_HASH": -214173014,
"__RESOLVED_ARTIFACTS_HASH": -206215189,
"conflict_resolution": {
"com.google.errorprone:error_prone_annotations:2.5.1": "com.google.errorprone:error_prone_annotations:2.18.0",
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155 changes: 18 additions & 137 deletions toolchains/scala/BUILD.bazel
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@@ -1,140 +1,21 @@
load(":defs.bzl", "scala_toolchain")
load(":scala_binary.bzl", "scala_binary", "scala_test")
load(":scala_library.bzl", "scala_library")

toolchain_type(
name = "toolchain_type",
visibility = ["//visibility:public"],
)

scala_toolchain(
name = "toolchain_impl",
args = [
"//toolchains/scala/args:use_java_classpath",
"//toolchains/scala/args:classpath",
"//toolchains/scala/args:sources",
"//toolchains/scala/args:plugins",
"//toolchains/scala/args:scalacopts",
],
tool_map = "//toolchains/scala/tools:tools",
)

toolchain(
name = "toolchain",
toolchain = "toolchain_impl",
toolchain_type = "//toolchains/scala:toolchain_type",
visibility = ["//visibility:public"],
)

scala_binary(
name = "hello",
srcs = [
"Main.scala",
],
main_class = "Goodbye",
)

scala_test(
name = "stack",
srcs = [
"Stack.scala",
],
)

scala_binary(
name = "example",
srcs = [
"Example.scala",
],
main_class = "Main",
plugins = [
"@maven//:org_chipsalliance_chisel_plugin_2_13_17",
],
scalacopts = [
"-language:reflectiveCalls",
"-deprecation", # Warning and location for usages of deprecated APIs.
"-encoding",
"utf-8", # Specify character encoding used by source files.
"-explaintypes", # Explain type errors in more detail.
"-feature", # For features that should be imported explicitly.
"-unchecked", # Generated code depends on assumptions.
"-Xcheckinit", # Wrap field accessors to throw an exception on uninitialized access.
"-Xlint:adapted-args", # An argument list is modified to match the receiver.
"-Xlint:constant", # Constant arithmetic expression results in an error.
"-Xlint:delayedinit-select", # Selecting member of DelayedInit.
"-Xlint:doc-detached", # A detached Scaladoc comment.
"-Xlint:inaccessible", # Inaccessible types in method signatures.
"-Xlint:infer-any", # A type argument is inferred to be `Any`.
"-Xlint:missing-interpolator", # A string literal appears to be missing an interpolator id.
"-Xlint:nullary-unit", # Warn when nullary methods return Unit.
"-Xlint:option-implicit", # Option.apply used implicit view.
"-Xlint:package-object-classes", # Class or object defined in package object.
"-Xlint:poly-implicit-overload", # Parameterized overloaded implicit methods are not visible as view bounds.
"-Xlint:private-shadow", # A private field (or class parameter) shadows a superclass field.
"-Xlint:stars-align", # Pattern sequence wildcard must align with sequence component.
"-Xlint:type-parameter-shadow", # A local type parameter shadows a type already in scope.
"-Ywarn-dead-code", # Warn when dead code is identified.
"-Ywarn-extra-implicit", # More than one implicit parameter section is defined.
"-Ywarn-numeric-widen", # Numerics are implicitly widened.
"-Ywarn-unused:implicits", # An implicit parameter is unused.
"-Ywarn-unused:imports", # An import selector is not referenced.
"-Ywarn-unused:locals", # A local definition is unused.
"-Ywarn-unused:params", # A value parameter is unused.
"-Ywarn-unused:patvars", # A variable bound in a pattern is unused.
"-Ywarn-value-discard", # Non-Unit expression results are unused.
"-Ywarn-unused:privates", # A private member is unused.
],
deps = [
"@maven//:org_chipsalliance_chisel_2_13",
],
)

scala_library(
name = "examplelib",
srcs = [
"Example.scala",
],
plugins = [
"@maven//:org_chipsalliance_chisel_plugin_2_13_17",
],
scalacopts = [
"-language:reflectiveCalls",
"-deprecation", # Warning and location for usages of deprecated APIs.
"-encoding",
"utf-8", # Specify character encoding used by source files.
"-explaintypes", # Explain type errors in more detail.
"-feature", # For features that should be imported explicitly.
"-unchecked", # Generated code depends on assumptions.
"-Xcheckinit", # Wrap field accessors to throw an exception on uninitialized access.
"-Xlint:adapted-args", # An argument list is modified to match the receiver.
"-Xlint:constant", # Constant arithmetic expression results in an error.
"-Xlint:delayedinit-select", # Selecting member of DelayedInit.
"-Xlint:doc-detached", # A detached Scaladoc comment.
"-Xlint:inaccessible", # Inaccessible types in method signatures.
"-Xlint:infer-any", # A type argument is inferred to be `Any`.
"-Xlint:missing-interpolator", # A string literal appears to be missing an interpolator id.
"-Xlint:nullary-unit", # Warn when nullary methods return Unit.
"-Xlint:option-implicit", # Option.apply used implicit view.
"-Xlint:package-object-classes", # Class or object defined in package object.
"-Xlint:poly-implicit-overload", # Parameterized overloaded implicit methods are not visible as view bounds.
"-Xlint:private-shadow", # A private field (or class parameter) shadows a superclass field.
"-Xlint:stars-align", # Pattern sequence wildcard must align with sequence component.
"-Xlint:type-parameter-shadow", # A local type parameter shadows a type already in scope.
"-Ywarn-dead-code", # Warn when dead code is identified.
"-Ywarn-extra-implicit", # More than one implicit parameter section is defined.
"-Ywarn-numeric-widen", # Numerics are implicitly widened.
"-Ywarn-unused:implicits", # An implicit parameter is unused.
"-Ywarn-unused:imports", # An import selector is not referenced.
"-Ywarn-unused:locals", # A local definition is unused.
"-Ywarn-unused:params", # A value parameter is unused.
"-Ywarn-unused:patvars", # A variable bound in a pattern is unused.
"-Ywarn-value-discard", # Non-Unit expression results are unused.
"-Ywarn-unused:privates", # A private member is unused.
],
deps = [
"@maven//:org_chipsalliance_chisel_2_13",
],
)
# Scala toolchain has been migrated to BCR rules_scala
# See //toolchains/scala:chisel.bzl for Chisel wrapper rules

# Optional: Example usage for documentation
# Uncomment to test chisel rules with BCR rules_scala
#
# load("//toolchains/scala:chisel.bzl", "chisel_binary", "chisel_library")
#
# chisel_library(
# name = "examplelib",
# srcs = ["Example.scala"],
# )
#
# chisel_binary(
# name = "example",
# srcs = ["Example.scala"],
# main_class = "Main",
# )

filegroup(
name = "chiselfiles",
Expand Down
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