As you can see from this diff, inline-attributes are viable and sometimes even useful (specifically: making diffs align properly, which has been an issue in Rand's lib.rs quite a few times).

-#[cfg(feature="alloc")] use core::slice;
+#[cfg(feature = "alloc")]
+use core::slice;

rustfmt is forcing multi-line attributes everywhere. I would like an option for inline attributes (when small).