Aspect attr does not support default values for bool or int

[luispadron]

Description of the bug:

Given the following aspect:

def _example_aspect_impl(target, aspect_ctx):
    print("Example aspect implementation")

example_aspect = aspect(
    implementation = _example_aspect_impl,
    attr_aspects = ["input"],
    attrs = {
        "example_string_attr": attr.string(
            default = "example value",
            values = ["example value"],
        ),
        # "example_bool_attr": attr.bool(
        #     default = False,
        # ),
        # "example_int_attr": attr.int(
        #     default = 0,
        #     values = [0, 1],
        # ),
    },
)

Applied to the following rule:

load("//:example_aspect.bzl", "example_aspect")

def _example_rule_impl(ctx):
    file = ctx.actions.declare_file("reversed.txt")

    ctx.actions.run_shell(
        outputs = [file],
        inputs = [ctx.file.input],
        command = "rev < \"%s\" > \"%s\"" % (ctx.file.input.path, file.path),
    )

    return DefaultInfo(
        runfiles = ctx.runfiles(files = [ctx.file.input]),
        files = depset([file]),
    )

example_rule = rule(
    implementation = _example_rule_impl,
    attrs = {
        "input": attr.label(
            mandatory = True,
            allow_single_file = True,
            aspects = [example_aspect],
        ),
    },
)

When the example_bool_attr or the example_int_attr are uncommented the build fails with an error that reads like:

Error in example_rule: Aspect //:example_aspect.bzl%example_aspect requires rule example_rule to specify attribute 'example_bool_attr'

This is unexpected because both of these attrs have default values, even more confusing is that the string attr with a default value works without requiring example_rule to have an attr of the name example_string_attr.

Am I missing something here and this behavior is expected or is this a bug?

Which category does this issue belong to?

Core, Documentation, Rules API

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

Use the provided example rule and aspect to verify the failure.

Which operating system are you running Bazel on?

macOS

What is the output of bazel info release?

release 7.2.0

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 HEAD ?

No response

If this is a regression, please try to identify the Bazel commit where the bug was introduced with bazelisk --bisect.

No response

Have you found anything relevant by searching the web?

No response

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

No response

[comius]

cc @mai93

[mai93]

I think it is because of the way we set hasDefault here. For int and boolean types, defaults of 0 and false are considered unset because it is the default values of them without the aspect author setting them (attr.bool, attr.int). This needs to be adjusted to distinguish between the 2 cases.