audit: ensure every gated feature has a compile-fail test

[pnkfelix]

I was sloppy when I implemented #22173 and did not include a test. So, surprise, a follow-on commit a few days later broke it.

As self-punishment for neglecting to include a regression test, I am assigning myself the task of reviewing our test suite to make sure that every feature-gate has a test.

---

Here is a transcribed list of feature gates, based on feature_gate.rs, that I have annotated according to whether the feature is Accepted/Removed (and thus needs no tests), Active/Deprecated but has tests already (marked with an x, or Active/Deprecated but has no tests that I saw via a cursory grep/skim.

• - ("globs", "1.0.0", Accepted),
• - ("macro_rules", "1.0.0", Accepted),
• - ("struct_variant", "1.0.0", Accepted),
• - ("asm", "1.0.0", Active),
  • asm-gated.rs
  • asm-gated2.rs
• - ("managed_boxes", "1.0.0", Removed),
• - ("non_ascii_idents", "1.0.0", Active),
  • gated-non-ascii-idents.rs
• - ("thread_local", "1.0.0", Active),
  • Add tests checking that a number of feature gates are gating their features #23226
• - ("link_args", "1.0.0", Active),
  • Add tests checking that a number of feature gates are gating their features #23226
• - ("phase", "1.0.0", Removed),
• - ("plugin_registrar", "1.0.0", Active),
  • gated-plugin_registrar.rs but it is not clear whether this is testing the plugin gate or the plugin_registrar gate. From the error message it seems like the plugin_registrar gate is firing.
• - ("log_syntax", "1.0.0", Active),
  • log-syntax-gate.rs
  • log-syntax-gate2.rs
• - ("trace_macros", "1.0.0", Active),
  • gated-trace_macros.rs
• - ("concat_idents", "1.0.0", Active),
  • concat_idents-gate.rs
  • concat_idents-gate2.rs
• - ("unsafe_destructor", "1.0.0", Active),
  • Add tests checking that a number of feature gates are gating their features #23226
• - ("intrinsics", "1.0.0", Active),
  • feature-gate-intrinsics.rs
• - ("lang_items", "1.0.0", Active),
  • feature-gate-lang-items.rs
• - ("simd", "1.0.0", Active),
  • gated-simd.rs
• - ("default_type_params", "1.0.0", Accepted),
• - ("quote", "1.0.0", Active),
  • Add tests checking that a number of feature gates are gating their features #23226
• - ("link_llvm_intrinsics", "1.0.0", Active),
  • Add tests checking that a number of feature gates are gating their features #23226
• - ("linkage", "1.0.0", Active),
  • linkage1.rs
• - ("struct_inherit", "1.0.0", Removed),
• - ("quad_precision_float", "1.0.0", Removed),
• - ("rustc_diagnostic_macros", "1.0.0", Active),
• - ("unboxed_closures", "1.0.0", Active),
• - ("import_shadowing", "1.0.0", Removed),
• - ("advanced_slice_patterns", "1.0.0", Active),
• - ("tuple_indexing", "1.0.0", Accepted),
• - ("associated_types", "1.0.0", Accepted),
• - ("visible_private_types", "1.0.0", Active),
• - ("slicing_syntax", "1.0.0", Accepted),
• - ("box_syntax", "1.0.0", Active), gated-box-syntax.rs
• - ("on_unimplemented", "1.0.0", Active),
• - ("simd_ffi", "1.0.0", Active), gated-simd-ffi.rs
• - ("if_let", "1.0.0", Accepted),
• - ("while_let", "1.0.0", Accepted),
• - ("plugin", "1.0.0", Active),
  • gated-plugin_registrar.rs but it is not clear whether this is testing the plugin gate or the plugin_registrar gate
• - ("start", "1.0.0", Active),
  • feature-gate-start.rs
• - ("main", "1.0.0", Active),
  • feature-gate-main.rs
• - ("issue_5723_bootstrap", "1.0.0", Accepted),
• - ("opt_out_copy", "1.0.0", Removed),
• - ("old_orphan_check", "1.0.0", Deprecated),
• - ("old_impl_check", "1.0.0", Deprecated),
• - ("optin_builtin_traits", "1.0.0", Active),
• - ("int_uint", "1.0.0", Active),
  • feature-gate-int-uint.rs
• - ("macro_reexport", "1.0.0", Active), gated-macro-reexports.rs
• - ("test_accepted_feature", "1.0.0", Accepted),
• - ("test_removed_feature", "1.0.0", Removed),
• - ("staged_api", "1.0.0", Active), staged_api.rs
• - ("unmarked_api", "1.0.0", Active),
• - ("no_std", "1.0.0", Active),
  • gated-no-std.rs
• - ("box_patterns", "1.0.0", Active), gated-box-patterns.rs
• - ("unsafe_no_drop_flag", "1.0.0", Active),
  • unsafe_no_drop_flag-gate.rs
• - ("custom_attribute", "1.0.0", Active),
• - ("custom_derive", "1.0.0", Active), single-derive-attr.rs
• - ("rustc_attrs", "1.0.0", Active),
• - ("static_assert", "1.0.0", Active),
  • feature-gate-static-assert.rs
• - ("allow_internal_unstable", "1.0.0", Active),
  • feature-gate-allow-internal-unstable.rs
  • feature-gate-allow-internal-unstable-nested-macro.rs

[pnkfelix]

(but hey, if other people want to add such missing tests in the meantime, while I am asleep, I will not mind. :)

[pnkfelix]

In case its not clear: If you want to help, just find a case above that does not have a check-mark and also does not have a pull request number attached beneath it. (And I guess write your name so that other people do not waste time adding a test for the same feature gate).