#[test] attributes in modules defined in functions are ignored

[Kimundi]

pub fn foo() {
    mod bar {
        #[test]
        fn test2() {}
    }
}

#[test]
fn test1() {}

nested_test_bug.rs:4:9: 4:22 warning: function is never used: `test2`, #[warn(dead_code)] on by default
nested_test_bug.rs:4         fn test2() {}
                             ^~~~~~~~~~~~~
nested_test_bug.rs:3:9: 3:16 warning: unused attribute, #[warn(unused_attributes)] on by default
nested_test_bug.rs:3         #[test]
                             ^~~~~~~

I'm not sure if this is a bug or intended behavior, but if its the latter, the compiler messages should probably explain it somehow.

[lambda-fairy]

The relevant code is in libsyntax/test.rs:

// We don't want to recurse into anything other than mods, since
// mods or tests inside of functions will break things
let res = match i.node {
    ast::ItemMod(..) => fold::noop_fold_item(i, self),
    _ => SmallVector::one(i),
};

I'm not sure what things it'll break, though. @sfackler do you know anything about this?

[sfackler]

There's no way for anything outside of the function to access test2, which includes the thing running the tests.

[lambda-fairy]

That makes sense.

Should test2 cause a compile error then? Annotating non-functions with #[test] yields an error already (error: only functions may be used as tests) so there's some precedent here.

[sfackler]

That seems reasonable.

On Thu, Dec 11, 2014, 1:18 AM Chris Wong [email protected] wrote:

That makes sense.

Should test2 cause a compile error then? Annotating non-functions with
#[test] yields an error already (error: only functions may be used as
tests) so there's some precedent here.

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#19694 (comment).

[steveklabnik]

Closing in favor of rust-lang/rfcs#612