Server crash when duplicate labels given to ctx.expand_location

[illicitonion]

Description of the problem / feature request:

If a label appears twice in the targets list of a call to ctx.expand_location, the server crashes with java.lang.IllegalArgumentException: Multiple entries with same key.

Either the duplicate should be ignored, or the duplication should be forbidden by the API and a friendly error given.

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

This rule:

def _r_impl(ctx):
    out = ctx.actions.declare_file(ctx.label.name)

    ctx.actions.write(
        output = out,
        content = ctx.expand_location(ctx.attr.template_string, ctx.attr.deps + ctx.attr.deps),
    )   

    return [
        DefaultInfo(files = depset([out])),
    ]   

r = rule(
    implementation = _r_impl,
    attrs = { 
        "template_string": attr.string(),
        "deps": attr.label_list(),
    },  
)

Instantiated thus:

load("//:rule.bzl", "r")
    
r(  
    name = "write", 
    template_string = "Hello",
    deps = ["@bazel_tools//tools/cpp:empty"],
)

What operating system are you running Bazel on?

macOS

What's the output of bazel info release?

release 5.0.0

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

Stack trace from failure:

FATAL: bazel crashed due to an internal error. Printing stack trace:
java.lang.RuntimeException: Unrecoverable error while evaluating node 'ConfiguredTargetKey{label=//:write, config=BuildConfigurationValue.Key[63684d86ff47f33398646ba0e3860d9ff1fcad99873cee4f2aec407f500adbdd]}' (requested by nodes )
	at com.google.devtools.build.skyframe.AbstractParallelEvaluator$Evaluate.run(AbstractParallelEvaluator.java:674)
	at com.google.devtools.build.lib.concurrent.AbstractQueueVisitor$WrappedRunnable.run(AbstractQueueVisitor.java:382)
	at java.base/java.util.concurrent.ForkJoinTask$RunnableExecuteAction.exec(ForkJoinTask.java:1426)
	at java.base/java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:290)
	at java.base/java.util.concurrent.ForkJoinPool$WorkQueue.topLevelExec(ForkJoinPool.java:1020)
	at java.base/java.util.concurrent.ForkJoinPool.scan(ForkJoinPool.java:1656)
	at java.base/java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1594)
	at java.base/java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:183)
Caused by: net.starlark.java.eval.Starlark$UncheckedEvalException: IllegalArgumentException thrown during Starlark evaluation (//:write)
	at <starlark>.expand_location(<builtin>:0)
	at <starlark>._r_impl(/Users/dwagnerhall/tmp/bazelplay/rule.bzl:6)
Caused by: java.lang.IllegalArgumentException: Multiple entries with same key: @bazel_tools//tools/cpp:empty=[] and @bazel_tools//tools/cpp:empty=[]
	at com.google.common.collect.ImmutableMap.conflictException(ImmutableMap.java:210)
	at com.google.common.collect.ImmutableMap.checkNoConflict(ImmutableMap.java:204)
	at com.google.common.collect.RegularImmutableMap.checkNoConflictInKeyBucket(RegularImmutableMap.java:146)
	at com.google.common.collect.RegularImmutableMap.fromEntryArray(RegularImmutableMap.java:109)
	at com.google.common.collect.ImmutableMap$Builder.build(ImmutableMap.java:389)
	at com.google.devtools.build.lib.analysis.starlark.StarlarkRuleContext.makeLabelMap(StarlarkRuleContext.java:1102)
	at com.google.devtools.build.lib.analysis.starlark.StarlarkRuleContext.expandLocation(StarlarkRuleContext.java:902)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:566)
	at net.starlark.java.eval.MethodDescriptor.call(MethodDescriptor.java:162)
	at net.starlark.java.eval.BuiltinFunction.fastcall(BuiltinFunction.java:77)
	at net.starlark.java.eval.Starlark.fastcall(Starlark.java:619)
	at net.starlark.java.eval.Eval.evalCall(Eval.java:672)
	at net.starlark.java.eval.Eval.eval(Eval.java:489)
	at net.starlark.java.eval.Eval.evalCall(Eval.java:630)
	at net.starlark.java.eval.Eval.eval(Eval.java:489)
	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:191)
	at net.starlark.java.eval.Starlark.fastcall(Starlark.java:619)
	at com.google.devtools.build.lib.analysis.starlark.StarlarkRuleConfiguredTargetUtil.buildRule(StarlarkRuleConfiguredTargetUtil.java:98)
	at com.google.devtools.build.lib.analysis.ConfiguredTargetFactory.createRule(ConfiguredTargetFactory.java:353)
	at com.google.devtools.build.lib.analysis.ConfiguredTargetFactory.createConfiguredTarget(ConfiguredTargetFactory.java:188)
	at com.google.devtools.build.lib.skyframe.SkyframeBuildView.createConfiguredTarget(SkyframeBuildView.java:1108)
	at com.google.devtools.build.lib.skyframe.ConfiguredTargetFunction.createConfiguredTarget(ConfiguredTargetFunction.java:980)
	at com.google.devtools.build.lib.skyframe.ConfiguredTargetFunction.compute(ConfiguredTargetFunction.java:368)
	at com.google.devtools.build.skyframe.AbstractParallelEvaluator$Evaluate.run(AbstractParallelEvaluator.java:590)
	at com.google.devtools.build.lib.concurrent.AbstractQueueVisitor$WrappedRunnable.run(AbstractQueueVisitor.java:382)
	at java.base/java.util.concurrent.ForkJoinTask$RunnableExecuteAction.exec(ForkJoinTask.java:1426)
	at java.base/java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:290)
	at java.base/java.util.concurrent.ForkJoinPool$WorkQueue.topLevelExec(ForkJoinPool.java:1020)
	at java.base/java.util.concurrent.ForkJoinPool.scan(ForkJoinPool.java:1656)
	at java.base/java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1594)
	at java.base/java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:183)

[varungandhi-src]

I wonder if this is the same crash as the one I'm seeing in this branch: sourcegraph/scip-ruby@49be984 (includes full error + build step)

In my case, the keys are printed differently though:

Caused by: java.lang.IllegalArgumentException: Multiple entries with same key: TEST_NAME=//test/scip/repos:shopify-api-ruby and TEST_NAME=shopify-api-ruby

I haven't tried minimizing that one, because I wasn't even sure where to start minimizing. 😬

[illicitonion]

@varungandhi-src I suspect that's related to the env attribute rather than ctx.expand_location - could you post your full stack trace? It's currently truncated in library code before the code hits any bazel code.

[varungandhi-src]

@illicitonion I've filed #16094 with a minimal reproducer, I think it's a different issue.

[github-actions]

Thank you for contributing to the Bazel repository! This issue has been marked as stale since it has not had any activity in the last 1+ years. It will be closed in the next 90 days unless any other activity occurs. If you think this issue is still relevant and should stay open, please post any comment here and the issue will no longer be marked as stale.

[illicitonion]

This was fixed in 3db362c