Rollup merge of #124926 - Alexendoo:feature-maybe-incorrect, r=est31

Make `#![feature]` suggestion MaybeIncorrect

Fixes rust-lang/rust-clippy#12784

The `unstable_name_collisions` lint uses `disabled_nightly_features` to mention the feature name, but accepting the suggestion would result in an ambiguity error

There are other calls where accepting the feature gate would fix code when ran with `cargo fix --broken-code`, though it's not always desirable to add a feature gate even if the user is currently on nightly so MaybeIncorrect seems appropriate

Author: matthiaskrgr

compiler/rustc_middle/src/ty/context.rs

@@ -2449,7 +2449,7 @@ impl<'tcx> TyCtxt<'tcx> {
                     span,
                     msg,
                     format!("#![feature({feature})]\n"),
-                    Applicability::MachineApplicable,
+                    Applicability::MaybeIncorrect,
                 );
             } else {
                 diag.help(msg);