crash defining a late-bound attribute

[benjaminp]

$ bazel version
Build label: f4523e7dac4e96c924257acc63cbe237c3fc5e24 
Build target: bazel-out/k8-opt/bin/src/main/java/com/google/devtools/build/lib/bazel/BazelServer_deploy.jar
Build time: Thu Jun 6 00:00:49 2019 (1559779249)
Build timestamp: 1559779249
Build timestamp as int: 1559779249
$ touch WORKSPACE
$ cat > x.bzl
def _impl(): pass

blah = rule(
    implementation = _impl,
    attrs = {
        ":myattr": attr.label(),
    }
)
$ cat > BUILD 
load(":x.bzl", "blah")
$ bazel build *
Internal error thrown during build. Printing stack trace: java.lang.RuntimeException: Unrecoverable error while evaluating node '//:x.bzl' (requested by nodes 'PACKAGE:')
	at com.google.devtools.build.skyframe.AbstractParallelEvaluator$Evaluate.run(AbstractParallelEvaluator.java:528)
	at com.google.devtools.build.lib.concurrent.AbstractQueueVisitor$WrappedRunnable.run(AbstractQueueVisitor.java:399)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
	at java.base/java.lang.Thread.run(Unknown Source)
Caused by: java.lang.IllegalArgumentException: late bound attributes require a default value that is late bound (and vice versa): :myattr
	at com.google.common.base.Preconditions.checkArgument(Preconditions.java:216)
	at com.google.devtools.build.lib.packages.Attribute.<init>(Attribute.java:1938)
	at com.google.devtools.build.lib.packages.Attribute$ImmutableAttributeFactory.build(Attribute.java:415)
	at com.google.devtools.build.lib.analysis.skylark.SkylarkAttr$Descriptor.build(SkylarkAttr.java:886)
	at com.google.devtools.build.lib.analysis.skylark.SkylarkRuleClassFunctions$SkylarkRuleFunction.export(SkylarkRuleClassFunctions.java:683)
	at com.google.devtools.build.lib.skyframe.SkylarkImportLookupFunction.possiblyExport(SkylarkImportLookupFunction.java:566)
	at com.google.devtools.build.lib.skyframe.SkylarkImportLookupFunction.execAndExport(SkylarkImportLookupFunction.java:548)
	at com.google.devtools.build.lib.skyframe.SkylarkImportLookupFunction.createExtension(SkylarkImportLookupFunction.java:528)
	at com.google.devtools.build.lib.skyframe.SkylarkImportLookupFunction.computeInternal(SkylarkImportLookupFunction.java:384)
	at com.google.devtools.build.lib.skyframe.SkylarkImportLookupFunction.compute(SkylarkImportLookupFunction.java:102)
	at com.google.devtools.build.skyframe.AbstractParallelEvaluator$Evaluate.run(AbstractParallelEvaluator.java:451)
	... 4 more

INFO: Elapsed time: 0.548s
INFO: 0 processes.
FAILED: Build did NOT complete successfully (0 packages loaded)
    currently loading: 
Internal error thrown during build. Printing stack trace: java.lang.RuntimeException: Unrecoverable error while evaluating node '//:x.bzl' (requested by nodes 'PACKAGE:')
	at com.google.devtools.build.skyframe.AbstractParallelEvaluator$Evaluate.run(AbstractParallelEvaluator.java:528)
	at com.google.devtools.build.lib.concurrent.AbstractQueueVisitor$WrappedRunnable.run(AbstractQueueVisitor.java:399)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
	at java.base/java.lang.Thread.run(Unknown Source)
Caused by: java.lang.IllegalArgumentException: late bound attributes require a default value that is late bound (and vice versa): :myattr
	at com.google.common.base.Preconditions.checkArgument(Preconditions.java:216)
	at com.google.devtools.build.lib.packages.Attribute.<init>(Attribute.java:1938)
	at com.google.devtools.build.lib.packages.Attribute$ImmutableAttributeFactory.build(Attribute.java:415)
	at com.google.devtools.build.lib.analysis.skylark.SkylarkAttr$Descriptor.build(SkylarkAttr.java:886)
	at com.google.devtools.build.lib.analysis.skylark.SkylarkRuleClassFunctions$SkylarkRuleFunction.export(SkylarkRuleClassFunctions.java:683)
	at com.google.devtools.build.lib.skyframe.SkylarkImportLookupFunction.possiblyExport(SkylarkImportLookupFunction.java:566)
	at com.google.devtools.build.lib.skyframe.SkylarkImportLookupFunction.execAndExport(SkylarkImportLookupFunction.java:548)
	at com.google.devtools.build.lib.skyframe.SkylarkImportLookupFunction.createExtension(SkylarkImportLookupFunction.java:528)
	at com.google.devtools.build.lib.skyframe.SkylarkImportLookupFunction.computeInternal(SkylarkImportLookupFunction.java:384)
	at com.google.devtools.build.lib.skyframe.SkylarkImportLookupFunction.compute(SkylarkImportLookupFunction.java:102)
	at com.google.devtools.build.skyframe.AbstractParallelEvaluator$Evaluate.run(AbstractParallelEvaluator.java:451)
	... 4 more
java.lang.RuntimeException: Unrecoverable error while evaluating node '//:x.bzl' (requested by nodes 'PACKAGE:')
	at com.google.devtools.build.skyframe.AbstractParallelEvaluator$Evaluate.run(AbstractParallelEvaluator.java:528)
	at com.google.devtools.build.lib.concurrent.AbstractQueueVisitor$WrappedRunnable.run(AbstractQueueVisitor.java:399)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
	at java.base/java.lang.Thread.run(Unknown Source)
Caused by: java.lang.IllegalArgumentException: late bound attributes require a default value that is late bound (and vice versa): :myattr
	at com.google.common.base.Preconditions.checkArgument(Preconditions.java:216)
	at com.google.devtools.build.lib.packages.Attribute.<init>(Attribute.java:1938)
	at com.google.devtools.build.lib.packages.Attribute$ImmutableAttributeFactory.build(Attribute.java:415)
	at com.google.devtools.build.lib.analysis.skylark.SkylarkAttr$Descriptor.build(SkylarkAttr.java:886)
	at com.google.devtools.build.lib.analysis.skylark.SkylarkRuleClassFunctions$SkylarkRuleFunction.export(SkylarkRuleClassFunctions.java:683)
	at com.google.devtools.build.lib.skyframe.SkylarkImportLookupFunction.possiblyExport(SkylarkImportLookupFunction.java:566)
	at com.google.devtools.build.lib.skyframe.SkylarkImportLookupFunction.execAndExport(SkylarkImportLookupFunction.java:548)
	at com.google.devtools.build.lib.skyframe.SkylarkImportLookupFunction.createExtension(SkylarkImportLookupFunction.java:528)
	at com.google.devtools.build.lib.skyframe.SkylarkImportLookupFunction.computeInternal(SkylarkImportLookupFunction.java:384)
	at com.google.devtools.build.lib.skyframe.SkylarkImportLookupFunction.compute(SkylarkImportLookupFunction.java:102)
	at com.google.devtools.build.skyframe.AbstractParallelEvaluator$Evaluate.run(AbstractParallelEvaluator.java:451)
	... 4 more
java.lang.RuntimeException: Unrecoverable error while evaluating node '//:x.bzl' (requested by nodes 'PACKAGE:')
	at com.google.devtools.build.skyframe.AbstractParallelEvaluator$Evaluate.run(AbstractParallelEvaluator.java:528)
	at com.google.devtools.build.lib.concurrent.AbstractQueueVisitor$WrappedRunnable.run(AbstractQueueVisitor.java:399)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
	at java.base/java.lang.Thread.run(Unknown Source)
Caused by: java.lang.IllegalArgumentException: late bound attributes require a default value that is late bound (and vice versa): :myattr
	at com.google.common.base.Preconditions.checkArgument(Preconditions.java:216)
	at com.google.devtools.build.lib.packages.Attribute.<init>(Attribute.java:1938)
	at com.google.devtools.build.lib.packages.Attribute$ImmutableAttributeFactory.build(Attribute.java:415)
	at com.google.devtools.build.lib.analysis.skylark.SkylarkAttr$Descriptor.build(SkylarkAttr.java:886)
	at com.google.devtools.build.lib.analysis.skylark.SkylarkRuleClassFunctions$SkylarkRuleFunction.export(SkylarkRuleClassFunctions.java:683)
	at com.google.devtools.build.lib.skyframe.SkylarkImportLookupFunction.possiblyExport(SkylarkImportLookupFunction.java:566)
	at com.google.devtools.build.lib.skyframe.SkylarkImportLookupFunction.execAndExport(SkylarkImportLookupFunction.java:548)
	at com.google.devtools.build.lib.skyframe.SkylarkImportLookupFunction.createExtension(SkylarkImportLookupFunction.java:528)
	at com.google.devtools.build.lib.skyframe.SkylarkImportLookupFunction.computeInternal(SkylarkImportLookupFunction.java:384)
	at com.google.devtools.build.lib.skyframe.SkylarkImportLookupFunction.compute(SkylarkImportLookupFunction.java:102)
FAILED: Build did NOT complete successfully (0 packages loaded)

[laurentlb]

We should provide a proper error message, but attribute names may not start or contain special characters like :.

[benjaminp]

Okay, but writing '$'-prefixed attributes has at least historically been essential for working on around bugs like #6293.

[laurentlb]

The only convention that's supported is "_myattr": attr.label().
In 6293, I see the commit is using "_lcov_merger" (jayconrod/rules_go@593d269), so that's fine for me.

[benjaminp]

I used the name $lcov_merger successfully in my project. My point here is that enforcing such a restriction is an incompatible change.

[laurentlb]

Yes, I agree. We should add an incompatible flag for that.

[laurentlb]

This breaking change is tracked here: #6437