Multiple lints incorrectly not included with unused lint group

[sanmai-NL]

In rustc 1.19.0-nightly (01951a61a 2017-05-20), and reproducible.

[sanmai-NL]

In #30849 @alexcrichton wrote this lint has been allow by default. Based on a short survey of this issue tracker and that issue in particular, I think there's no reason left to leave it at allow instead of warn.

[sanmai-NL]

Same issue for the unused-features lint.

I don't know if rustc -W help is reliable, but it does not list the two ‘sub-lints’ there (same rustc version):

Lint groups provided by rustc:

                   name  sub-lints
                   ----  ---------
               warnings  all built-in lints
              bad-style  non-camel-case-types, non-snake-case, non-upper-case-globals
    future-incompatible  private-in-public, inaccessible-extern-crate, invalid-type-param-default, super-or-self-in-global-path, illegal-floating-point-constant-pattern, illegal-floating-point-literal-pattern, illegal-struct-or-enum-constant-pattern, hr-lifetime-in-assoc-type, lifetime-underscore, resolve-trait-on-defaulted-unit, safe-extern-statics, patterns-in-fns-without-body, extra-requirement-in-impl, legacy-directory-ownership, legacy-imports, legacy-constructor-visibility, missing-fragment-specifier, anonymous-parameters
                 unused  unused-imports, unused-variables, unused-assignments, dead-code, unused-mut, unreachable-code, unreachable-patterns, unused-must-use, unused-unsafe, path-statements, unused-attributes, unused-macros

[JohnTitor]

Triage: The unused lint group now contains unused_extern_crates and unused_features.

Lint groups provided by rustc:

name  sub-lints
----  ---------
unused  unused-imports, unused-variables, unused-assignments, dead-code, unused-mut, unreachable-code, unreachable-patterns, overlapping-patterns, unused-must-use, unused-unsafe, path-statements, unused-attributes, unused-macros, unused-allocation, unused-doc-comments, unused-extern-crates, unused-features, unused-labels, unused-parens, unused-braces, redundant-semicolons