Crash when using module extension

[mtribiere]

Description of the bug:

While trying to use the Bazel Module extension feature, I found a crash and I have not idea what's causing it.
I'm configuring the module build_tools_reloaded (a custom toolchain) from the TEST_PARTITION project.

The crash :

Loading: 0 packages loaded
FATAL: bazel crashed due to an internal error. Printing stack trace:
java.lang.RuntimeException: Unrecoverable error while evaluating node 'SINGLE_EXTENSION_EVAL:ModuleExtensionId{bzlFileLabel=@build_tools_reloaded~override//extensions:extensions.bzl, extensionName=build_tools_reloaded}' (requested by nodes 'BZLMOD_REPO_RULE:@build_tools_reloaded~override~build_tools_reloaded~build_tools_reloaded')
        at com.google.devtools.build.skyframe.AbstractParallelEvaluator$Evaluate.run(AbstractParallelEvaluator.java:642)
        at com.google.devtools.build.lib.concurrent.AbstractQueueVisitor$WrappedRunnable.run(AbstractQueueVisitor.java:382)
        at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
        at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
        at java.base/java.lang.Thread.run(Unknown Source)
Caused by: net.starlark.java.eval.Starlark$UncheckedEvalException: IllegalStateException thrown during Starlark evaluation
        at <starlark>.init_helionix_toolchain(<builtin>:0)
        at <starlark>._build_tools_reloaded_impl(C:/tools/dev/bazel_install/6fao65yg/external/build_tools_reloaded~override/extensions/extensions.bzl:7)
Caused by: java.lang.IllegalStateException: Expected BazelStarlarkContext to be available in this Starlark thread
        at com.google.common.base.Preconditions.checkState(Preconditions.java:502)
        at com.google.devtools.build.lib.packages.BazelStarlarkContext.from(BazelStarlarkContext.java:77)
        at com.google.devtools.build.lib.analysis.starlark.StarlarkRuleClassFunctions$StarlarkRuleFunction.call(StarlarkRuleClassFunctions.java:776)
        at net.starlark.java.eval.StarlarkCallable.fastcall(StarlarkCallable.java:86)
        at net.starlark.java.eval.Starlark.fastcall(Starlark.java:638)
        at net.starlark.java.eval.Eval.evalCall(Eval.java:682)
        at net.starlark.java.eval.Eval.eval(Eval.java:497)
        at net.starlark.java.eval.Eval.exec(Eval.java:271)
        at net.starlark.java.eval.Eval.execStatements(Eval.java:82)
        at net.starlark.java.eval.Eval.execFunctionBody(Eval.java:66)
        at net.starlark.java.eval.StarlarkFunction.fastcall(StarlarkFunction.java:173)
        at net.starlark.java.eval.Starlark.fastcall(Starlark.java:638)
        at com.google.devtools.build.lib.bazel.bzlmod.SingleExtensionEvalFunction.compute(SingleExtensionEvalFunction.java:187)
        at com.google.devtools.build.skyframe.AbstractParallelEvaluator$Evaluate.run(AbstractParallelEvaluator.java:571)
        at com.google.devtools.build.lib.concurrent.AbstractQueueVisitor$WrappedRunnable.run(AbstractQueueVisitor.java:382)
        at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
        at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
        at java.base/java.lang.Thread.run(Unknown Source)

The command:

bazel build //:TEST_BIN --enable_bzlmod --override_module=build_tools_reloaded=..\BUILD_TOOLS_RELOADED  --platforms=@build_tools_reloaded//platforms:myPlatform 

What's the simplest, easiest way to reproduce this bug? Please provide a minimal example if possible.

TEST_PARTITION/MODULE.bazel:

[...]
bazel_dep(name = "build_tools_reloaded", version = "0.0.1", repo_name="build_tools_reloaded_unconfigured")
build_tools_reloaded = use_extension("@build_tools_reloaded_unconfigured//extensions:extensions.bzl", "build_tools_reloaded")
build_tools_reloaded.configure(includes=["TEST1","TEST2","TEST3"])
use_repo(build_tools_reloaded, "build_tools_reloaded")
[...]

---

build_tools_reloaded/extensions/extensions.bzl:

load("//toolchain/:rules.bzl", "init_my_toolchain")

def _build_tools_reloaded_impl(module_ctx):
    init_my_toolchain(arg1=["TEST4","TEST5","TEST6"])


_configure = tag_class(attrs = 
        {
            "includes": attr.string_list(),          
        })

build_tools_reloaded = module_extension(
    implementation = _build_tools_reloaded_impl,
    tag_classes = {
            "configure": _configure
    }
)

---

build_tools_reloaded/toolchain/rules.bzl:

def _init_my_toolchain_impl(ctx):
    print("RULE CALLED")


init_my_toolchain = rule(
    _init_my_toolchain_impl,
    attrs = {
        "arg1": attr.string_list()
    }
)

Which operating system are you running Bazel on?

Windows

What is the output of bazel info release?

release 6.2.0

If bazel info release returns development version or (@non-git), tell us how you built Bazel.

No response

What's the output of git remote get-url origin; git rev-parse master; git rev-parse HEAD ?

No response

Is this a regression? If yes, please try to identify the Bazel commit where the bug was introduced.

No response

Have you found anything relevant by searching the web?

Maybe similar to : #14974

Any other information, logs, or outputs that you want to share?

No response

[Wyverald]

The cause of the crash is that you're calling a build rule (instead of a repo rule) from a module extension. init_my_toolchain should be a repository_rule.

Nevertheless, we shouldn't crash Bazel, but provide a helpful error message instead.

[garymm]

This code seems to cause a similar crash. Is the cause the same?

https://github.com/garymm/bazel-bugs/tree/master/llvm-toolchain-starlark

If not I can file another issue.

[Wyverald]

That one looks different. Please file another issue.

[mtribiere]

Oh alright, I see. How would you go about initializing a custom toolchain in a Module then? (Set includes, flags,...)