instruction_set attribute can be applied to anything

[oli-obk]

I tried this code:

#[instruction_set(asdfasdf)]
type Foo = ();

I expected to see this happen: compilation failure because of attribute on an item where it makes no sense

Instead, this happened: compiled successfully

Meta

rustc --version --verbose:

1.80 stable

cc #74727

see #128444 for where to fix this issue, though it will be a breaking change if we hard error. That seems fine though, as the attribute is completely useless on these places.

[chansuke]

@rustbot claim