Rollup merge of #41295 - frewsxcv:frewsxcxv-unstability, r=steveklabnik

Add top level sections to the Unstable Book.

Prior to this commit, the contents of the Unstable Book were assumed to
be unstable features. This commit moves features into 'language features'
or 'library features' subsections. It also moves the 'linker_flavor'
compiler flag into a new 'Compiler Flags' subsection.

Even though it was helpful, I removed the tidy check that
cross-references the SUMMARY.md links with the Unstable Book directory
contents just because it would be difficult to maintain.

Relevant PR: https://github.com/rust-lang/rust/issues/41142.

238 files changed, 308 insertions, 301 deletions

diff --git a/src/Cargo.lock b/src/Cargo.lock
index 62b85348039..26c7dc3ce97 100644
--- a/src/Cargo.lock
+++ b/src/Cargo.lock
@@ -922,9 +922,6 @@ dependencies = [
 [[package]]
 name = "tidy"
 version = "0.1.0"
-dependencies = [
- "regex 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
-]
 
 [[package]]
 name = "toml"
diff --git a/src/doc/book b/src/doc/book
-Subproject beea82b9230cd641dd1ca263cf31025ace4aebb
+Subproject ad7de198561b3a12217ea2da76d796d9c7fc0ed
diff --git a/src/doc/guide-plugins.md b/src/doc/guide-plugins.md
index 1ba28c0117d..6c511548789 100644
--- a/src/doc/guide-plugins.md
+++ b/src/doc/guide-plugins.md
@@ -1,4 +1,4 @@
 % The (old) Rust Compiler Plugins Guide
 
 This content has moved into
-[the Unstable Book](unstable-book/plugin.html).
+[the Unstable Book](unstable-book/language-features/plugin.html).
diff --git a/src/doc/reference b/src/doc/reference
-Subproject b060f732145f2fa16df84c74e511df08a3a47c5
+Subproject 6b0de90d87dda15e323ef24cdf7ed873ac5cf4d
diff --git a/src/doc/unstable-book/src/SUMMARY.md b/src/doc/unstable-book/src/SUMMARY.md
index 36999eb143f..3e041543977 100644
--- a/src/doc/unstable-book/src/SUMMARY.md
+++ b/src/doc/unstable-book/src/SUMMARY.md
@@ -1,226 +1,228 @@
 [The Unstable Book](the-unstable-book.md)
 
-- [abi_msp430_interrupt](abi-msp430-interrupt.md)
-- [abi_ptx](abi-ptx.md)
-- [abi_sysv64](abi-sysv64.md)
-- [abi_unadjusted](abi-unadjusted.md)
-- [abi_vectorcall](abi-vectorcall.md)
-- [abi_x86_interrupt](abi-x86-interrupt.md)
-- [advanced_slice_patterns](advanced-slice-patterns.md)
-- [alloc](alloc.md)
-- [alloc_jemalloc](alloc-jemalloc.md)
-- [alloc_system](alloc-system.md)
-- [allocator](allocator.md)
-- [allow_internal_unstable](allow-internal-unstable.md)
-- [as_c_str](as-c-str.md)
-- [as_unsafe_cell](as-unsafe-cell.md)
-- [ascii_ctype](ascii-ctype.md)
-- [asm](asm.md)
-- [associated_consts](associated-consts.md)
-- [associated_type_defaults](associated-type-defaults.md)
-- [attr_literals](attr-literals.md)
-- [binary_heap_extras](binary-heap-extras.md)
-- [binary_heap_peek_mut_pop](binary-heap-peek-mut-pop.md)
-- [borrow_state](borrow-state.md)
-- [box_heap](box-heap.md)
-- [box_patterns](box-patterns.md)
-- [box_syntax](box-syntax.md)
-- [c_void_variant](c-void-variant.md)
-- [catch_expr](catch-expr.md)
-- [cfg_target_feature](cfg-target-feature.md)
-- [cfg_target_has_atomic](cfg-target-has-atomic.md)
-- [cfg_target_thread_local](cfg-target-thread-local.md)
-- [cfg_target_vendor](cfg-target-vendor.md)
-- [char_escape_debug](char-escape-debug.md)
-- [closure_to_fn_coercion](closure-to-fn-coercion.md)
-- [coerce_unsized](coerce-unsized.md)
-- [collection_placement](collection-placement.md)
-- [collections](collections.md)
-- [collections_range](collections-range.md)
-- [command_envs](command-envs.md)
-- [compiler_fences](compiler-fences.md)
-- [compiler_builtins](compiler-builtins.md)
-- [compiler_builtins_lib](compiler-builtins-lib.md)
-- [concat_idents](concat-idents.md)
-- [concat_idents_macro](concat-idents-macro.md)
-- [conservative_impl_trait](conservative-impl-trait.md)
-- [const_fn](const-fn.md)
-- [const_indexing](const-indexing.md)
-- [core_char_ext](core-char-ext.md)
-- [core_float](core-float.md)
-- [core_intrinsics](core-intrinsics.md)
-- [core_panic](core-panic.md)
-- [core_private_bignum](core-private-bignum.md)
-- [core_private_diy_float](core-private-diy-float.md)
-- [core_slice_ext](core-slice-ext.md)
-- [core_str_ext](core-str-ext.md)
-- [custom_attribute](custom-attribute.md)
-- [custom_derive](custom-derive.md)
-- [dec2flt](dec2flt.md)
-- [decode_utf8](decode-utf8.md)
-- [default_type_parameter_fallback](default-type-parameter-fallback.md)
-- [derive_clone_copy](derive-clone-copy.md)
-- [derive_eq](derive-eq.md)
-- [discriminant_value](discriminant-value.md)
-- [drop_types_in_const](drop-types-in-const.md)
-- [dropck_eyepatch](dropck-eyepatch.md)
-- [dropck_parametricity](dropck-parametricity.md)
-- [enumset](enumset.md)
-- [error_type_id](error-type-id.md)
-- [exact_size_is_empty](exact-size-is-empty.md)
-- [exclusive_range_pattern](exclusive-range-pattern.md)
-- [fd](fd.md)
-- [fd_read](fd-read.md)
-- [fixed_size_array](fixed-size-array.md)
-- [float_bits_conv](float-bits-conv.md)
-- [float_extras](float-extras.md)
-- [flt2dec](flt2dec.md)
-- [fmt_flags_align](fmt-flags-align.md)
-- [fmt_internals](fmt-internals.md)
-- [fn_traits](fn-traits.md)
-- [fnbox](fnbox.md)
-- [from_utf8_error_as_bytes](from_utf8_error_as_bytes.md)
-- [fundamental](fundamental.md)
-- [fused](fused.md)
-- [future_atomic_orderings](future-atomic-orderings.md)
-- [generic_param_attrs](generic-param-attrs.md)
-- [get_type_id](get-type-id.md)
-- [global_asm](global_asm.md)
-- [heap_api](heap-api.md)
-- [i128](i128.md)
-- [i128_type](i128-type.md)
-- [inclusive_range](inclusive-range.md)
-- [inclusive_range_syntax](inclusive-range-syntax.md)
-- [int_error_internals](int-error-internals.md)
-- [integer_atomics](integer-atomics.md)
-- [into_boxed_c_str](into-boxed-c-str.md)
-- [into_boxed_os_str](into-boxed-os-str.md)
-- [into_boxed_path](into-boxed-path.md)
-- [intrinsics](intrinsics.md)
-- [io](io.md)
-- [io_error_internals](io-error-internals.md)
-- [ip](ip.md)
-- [is_unique](is-unique.md)
-- [iter_rfind](iter-rfind.md)
-- [lang_items](lang-items.md)
-- [libstd_io_internals](libstd-io-internals.md)
-- [libstd_sys_internals](libstd-sys-internals.md)
-- [libstd_thread_internals](libstd-thread-internals.md)
-- [link_args](link-args.md)
-- [link_cfg](link-cfg.md)
-- [link_llvm_intrinsics](link-llvm-intrinsics.md)
-- [linkage](linkage.md)
-- [linked_list_extras](linked-list-extras.md)
-- [linker_flavor](linker-flavor.md)
-- [log_syntax](log-syntax.md)
-- [lookup_host](lookup-host.md)
-- [loop_break_value](loop-break-value.md)
-- [macro_reexport](macro-reexport.md)
-- [macro_vis_matcher](macro-vis-matcher.md)
-- [main](main.md)
-- [manually_drop](manually-drop.md)
-- [map_entry_recover_keys](map-entry-recover-keys.md)
-- [mpsc_select](mpsc-select.md)
-- [n16](n16.md)
-- [naked_functions](naked-functions.md)
-- [needs_allocator](needs-allocator.md)
-- [needs_panic_runtime](needs-panic-runtime.md)
-- [never_type](never-type.md)
-- [never_type_impls](never-type-impls.md)
-- [no_core](no-core.md)
-- [no_debug](no-debug.md)
-- [non_ascii_idents](non-ascii-idents.md)
-- [nonzero](nonzero.md)
-- [offset_to](offset-to.md)
-- [omit_gdb_pretty_printer_section](omit-gdb-pretty-printer-section.md)
-- [on_unimplemented](on-unimplemented.md)
-- [once_poison](once-poison.md)
-- [oom](oom.md)
-- [optin_builtin_traits](optin-builtin-traits.md)
-- [option_entry](option-entry.md)
-- [osstring_shrink_to_fit](osstring-shrink-to-fit.md)
-- [overlapping_marker_traits](overlapping-marker-traits.md)
-- [panic_abort](panic-abort.md)
-- [panic_runtime](panic-runtime.md)
-- [panic_unwind](panic-unwind.md)
-- [pattern](pattern.md)
-- [peek](peek.md)
-- [placement_in](placement-in.md)
-- [placement_in_syntax](placement-in-syntax.md)
-- [placement_new_protocol](placement-new-protocol.md)
-- [platform_intrinsics](platform-intrinsics.md)
-- [plugin](plugin.md)
-- [plugin_registrar](plugin-registrar.md)
-- [prelude_import](prelude-import.md)
-- [print](print.md)
-- [proc_macro](proc-macro.md)
-- [proc_macro_internals](proc-macro-internals.md)
-- [process_try_wait](process-try-wait.md)
-- [question_mark_carrier](question-mark-carrier.md)
-- [quote](quote.md)
-- [rand](rand.md)
-- [range_contains](range-contains.md)
-- [raw](raw.md)
-- [rc_would_unwrap](rc-would-unwrap.md)
-- [relaxed_adts](relaxed-adts.md)
-- [repr_simd](repr-simd.md)
-- [retain_hash_collection](retain-hash-collection.md)
-- [reverse_cmp_key](reverse-cmp-key.md)
-- [rt](rt.md)
-- [rustc_attrs](rustc-attrs.md)
-- [rustc_diagnostic_macros](rustc-diagnostic-macros.md)
-- [rustc_private](rustc-private.md)
-- [rvalue_static_promotion](rvalue-static-promotion.md)
-- [sanitizer_runtime](sanitizer-runtime.md)
-- [sanitizer_runtime_lib](sanitizer-runtime-lib.md)
-- [set_stdio](set-stdio.md)
-- [shared](shared.md)
-- [simd](simd.md)
-- [simd_ffi](simd-ffi.md)
-- [sip_hash_13](sip-hash-13.md)
-- [slice_concat_ext](slice-concat-ext.md)
-- [slice_get_slice](slice-get-slice.md)
-- [slice_patterns](slice-patterns.md)
-- [slice_rsplit](slice-rsplit.md)
-- [sort_internals](sort-internals.md)
-- [sort_unstable](sort-unstable.md)
-- [specialization](specialization.md)
-- [staged_api](staged-api.md)
-- [start](start.md)
-- [static_nobundle](static-nobundle.md)
-- [step_by](step-by.md)
-- [step_trait](step-trait.md)
-- [stmt_expr_attributes](stmt-expr-attributes.md)
-- [str_checked_slicing](str-checked-slicing.md)
-- [str_escape](str-escape.md)
-- [str_internals](str-internals.md)
-- [str_mut_extras](str-mut-extras.md)
-- [struct_field_attributes](struct-field-attributes.md)
-- [structural_match](structural-match.md)
-- [target_feature](target-feature.md)
-- [test](test.md)
-- [thread_id](thread-id.md)
-- [thread_local](thread-local.md)
-- [thread_local_internals](thread-local-internals.md)
-- [thread_local_state](thread-local-state.md)
-- [toowned_clone_into](toowned-clone-into.md)
-- [trace_macros](trace-macros.md)
-- [trusted_len](trusted-len.md)
-- [try_from](try-from.md)
-- [type_ascription](type-ascription.md)
-- [unboxed_closures](unboxed-closures.md)
-- [unicode](unicode.md)
-- [unique](unique.md)
-- [unsize](unsize.md)
-- [untagged_unions](untagged-unions.md)
-- [unwind_attributes](unwind-attributes.md)
-- [update_panic_count](update-panic-count.md)
-- [use_extern_macros](use-extern-macros.md)
-- [used](used.md)
-- [utf8_error_error_len](utf8-error-error-len.md)
-- [vec_remove_item](vec-remove-item.md)
-- [windows_c](windows-c.md)
-- [windows_handle](windows-handle.md)
-- [windows_net](windows-net.md)
-- [windows_stdio](windows-stdio.md)
-- [zero_one](zero-one.md)
+- [Compiler flags](compiler-flags.md)
+    - [linker_flavor](compiler-flags/linker-flavor.md)
+- [Language features](language-features.md)
+    - [abi_msp430_interrupt](language-features/abi-msp430-interrupt.md)
+    - [abi_ptx](language-features/abi-ptx.md)
+    - [abi_sysv64](language-features/abi-sysv64.md)
+    - [abi_unadjusted](language-features/abi-unadjusted.md)
+    - [abi_vectorcall](language-features/abi-vectorcall.md)
+    - [abi_x86_interrupt](language-features/abi-x86-interrupt.md)
+    - [advanced_slice_patterns](language-features/advanced-slice-patterns.md)
+    - [allocator](language-features/allocator.md)
+    - [allow_internal_unstable](language-features/allow-internal-unstable.md)
+    - [asm](language-features/asm.md)
+    - [associated_consts](language-features/associated-consts.md)
+    - [associated_type_defaults](language-features/associated-type-defaults.md)
+    - [attr_literals](language-features/attr-literals.md)
+    - [box_patterns](language-features/box-patterns.md)
+    - [box_syntax](language-features/box-syntax.md)
+    - [catch_expr](language-features/catch-expr.md)
+    - [cfg_target_feature](language-features/cfg-target-feature.md)
+    - [cfg_target_has_atomic](language-features/cfg-target-has-atomic.md)
+    - [cfg_target_thread_local](language-features/cfg-target-thread-local.md)
+    - [cfg_target_vendor](language-features/cfg-target-vendor.md)
+    - [closure_to_fn_coercion](language-features/closure-to-fn-coercion.md)
+    - [compiler_builtins](language-features/compiler-builtins.md)
+    - [concat_idents](language-features/concat-idents.md)
+    - [conservative_impl_trait](language-features/conservative-impl-trait.md)
+    - [const_fn](language-features/const-fn.md)
+    - [const_indexing](language-features/const-indexing.md)
+    - [custom_attribute](language-features/custom-attribute.md)
+    - [custom_derive](language-features/custom-derive.md)
+    - [default_type_parameter_fallback](language-features/default-type-parameter-fallback.md)
+    - [drop_types_in_const](language-features/drop-types-in-const.md)
+    - [dropck_eyepatch](language-features/dropck-eyepatch.md)
+    - [dropck_parametricity](language-features/dropck-parametricity.md)
+    - [exclusive_range_pattern](language-features/exclusive-range-pattern.md)
+    - [fundamental](language-features/fundamental.md)
+    - [generic_param_attrs](language-features/generic-param-attrs.md)
+    - [global_asm](language-features/global_asm.md)
+    - [i128_type](language-features/i128-type.md)
+    - [inclusive_range_syntax](language-features/inclusive-range-syntax.md)
+    - [intrinsics](language-features/intrinsics.md)
+    - [lang_items](language-features/lang-items.md)
+    - [link_args](language-features/link-args.md)
+    - [link_cfg](language-features/link-cfg.md)
+    - [link_llvm_intrinsics](language-features/link-llvm-intrinsics.md)
+    - [linkage](language-features/linkage.md)
+    - [log_syntax](language-features/log-syntax.md)
+    - [loop_break_value](language-features/loop-break-value.md)
+    - [macro_reexport](language-features/macro-reexport.md)
+    - [macro_vis_matcher](language-features/macro-vis-matcher.md)
+    - [main](language-features/main.md)
+    - [naked_functions](language-features/naked-functions.md)
+    - [needs_allocator](language-features/needs-allocator.md)
+    - [needs_panic_runtime](language-features/needs-panic-runtime.md)
+    - [never_type](language-features/never-type.md)
+    - [no_core](language-features/no-core.md)
+    - [no_debug](language-features/no-debug.md)
+    - [non_ascii_idents](language-features/non-ascii-idents.md)
+    - [omit_gdb_pretty_printer_section](language-features/omit-gdb-pretty-printer-section.md)
+    - [on_unimplemented](language-features/on-unimplemented.md)
+    - [optin_builtin_traits](language-features/optin-builtin-traits.md)
+    - [overlapping_marker_traits](language-features/overlapping-marker-traits.md)
+    - [panic_runtime](language-features/panic-runtime.md)
+    - [placement_in_syntax](language-features/placement-in-syntax.md)
+    - [platform_intrinsics](language-features/platform-intrinsics.md)
+    - [plugin](language-features/plugin.md)
+    - [plugin_registrar](language-features/plugin-registrar.md)
+    - [prelude_import](language-features/prelude-import.md)
+    - [proc_macro](language-features/proc-macro.md)
+    - [quote](language-features/quote.md)
+    - [relaxed_adts](language-features/relaxed-adts.md)
+    - [repr_simd](language-features/repr-simd.md)
+    - [rustc_attrs](language-features/rustc-attrs.md)
+    - [rustc_diagnostic_macros](language-features/rustc-diagnostic-macros.md)
+    - [rvalue_static_promotion](language-features/rvalue-static-promotion.md)
+    - [sanitizer_runtime](language-features/sanitizer-runtime.md)
+    - [simd](language-features/simd.md)
+    - [simd_ffi](language-features/simd-ffi.md)
+    - [slice_patterns](language-features/slice-patterns.md)
+    - [specialization](language-features/specialization.md)
+    - [staged_api](language-features/staged-api.md)
+    - [start](language-features/start.md)
+    - [static_nobundle](language-features/static-nobundle.md)
+    - [stmt_expr_attributes](language-features/stmt-expr-attributes.md)
+    - [struct_field_attributes](language-features/struct-field-attributes.md)
+    - [structural_match](language-features/structural-match.md)
+    - [target_feature](language-features/target-feature.md)
+    - [thread_local](language-features/thread-local.md)
+    - [trace_macros](language-features/trace-macros.md)
+    - [type_ascription](language-features/type-ascription.md)
+    - [unboxed_closures](language-features/unboxed-closures.md)
+    - [untagged_unions](language-features/untagged-unions.md)
+    - [unwind_attributes](language-features/unwind-attributes.md)
+    - [use_extern_macros](language-features/use-extern-macros.md)
+    - [used](language-features/used.md)
+- [Library Features](library-features.md)
+    - [alloc_jemalloc](library-features/alloc-jemalloc.md)
+    - [alloc_system](library-features/alloc-system.md)
+    - [alloc](library-features/alloc.md)
+    - [as_c_str](library-features/as-c-str.md)
+    - [as_unsafe_cell](library-features/as-unsafe-cell.md)
+    - [ascii_ctype](library-features/ascii-ctype.md)
+    - [binary_heap_extras](library-features/binary-heap-extras.md)
+    - [binary_heap_peek_mut_pop](library-features/binary-heap-peek-mut-pop.md)
+    - [borrow_state](library-features/borrow-state.md)
+    - [box_heap](library-features/box-heap.md)
+    - [c_void_variant](library-features/c-void-variant.md)
+    - [char_escape_debug](library-features/char-escape-debug.md)
+    - [coerce_unsized](library-features/coerce-unsized.md)
+    - [collection_placement](library-features/collection-placement.md)
+    - [collections_range](library-features/collections-range.md)
+    - [collections](library-features/collections.md)
+    - [command_envs](library-features/command-envs.md)
+    - [compiler_builtins_lib](library-features/compiler-builtins-lib.md)
+    - [compiler_fences](library-features/compiler-fences.md)
+    - [concat_idents_macro](library-features/concat-idents-macro.md)
+    - [core_char_ext](library-features/core-char-ext.md)
+    - [core_float](library-features/core-float.md)
+    - [core_intrinsics](library-features/core-intrinsics.md)
+    - [core_panic](library-features/core-panic.md)
+    - [core_private_bignum](library-features/core-private-bignum.md)
+    - [core_private_diy_float](library-features/core-private-diy-float.md)
+    - [core_slice_ext](library-features/core-slice-ext.md)
+    - [core_str_ext](library-features/core-str-ext.md)
+    - [dec2flt](library-features/dec2flt.md)
+    - [decode_utf8](library-features/decode-utf8.md)
+    - [derive_clone_copy](library-features/derive-clone-copy.md)
+    - [derive_eq](library-features/derive-eq.md)
+    - [discriminant_value](library-features/discriminant-value.md)
+    - [enumset](library-features/enumset.md)
+    - [error_type_id](library-features/error-type-id.md)
+    - [exact_size_is_empty](library-features/exact-size-is-empty.md)
+    - [fd](library-features/fd.md)
+    - [fd_read](library-features/fd-read.md)
+    - [fixed_size_array](library-features/fixed-size-array.md)
+    - [float_bits_conv](library-features/float-bits-conv.md)
+    - [float_extras](library-features/float-extras.md)
+    - [flt2dec](library-features/flt2dec.md)
+    - [fmt_flags_align](library-features/fmt-flags-align.md)
+    - [fmt_internals](library-features/fmt-internals.md)
+    - [fn_traits](library-features/fn-traits.md)
+    - [fnbox](library-features/fnbox.md)
+    - [from_utf8_error_as_bytes](library-features/from_utf8_error_as_bytes.md)
+    - [fused](library-features/fused.md)
+    - [future_atomic_orderings](library-features/future-atomic-orderings.md)
+    - [get_type_id](library-features/get-type-id.md)
+    - [heap_api](library-features/heap-api.md)
+    - [i128](library-features/i128.md)
+    - [inclusive_range](library-features/inclusive-range.md)
+    - [integer_atomics](library-features/integer-atomics.md)
+    - [into_boxed_c_str](library-features/into-boxed-c-str.md)
+    - [into_boxed_os_str](library-features/into-boxed-os-str.md)
+    - [into_boxed_path](library-features/into-boxed-path.md)
+    - [io_error_internals](library-features/io-error-internals.md)
+    - [io](library-features/io.md)
+    - [ip](library-features/ip.md)
+    - [is_unique](library-features/is-unique.md)
+    - [iter_rfind](library-features/iter-rfind.md)
+    - [libstd_io_internals](library-features/libstd-io-internals.md)
+    - [libstd_sys_internals](library-features/libstd-sys-internals.md)
+    - [libstd_thread_internals](library-features/libstd-thread-internals.md)
+    - [linked_list_extras](library-features/linked-list-extras.md)
+    - [lookup_host](library-features/lookup-host.md)
+    - [manually_drop](library-features/manually-drop.md)
+    - [map_entry_recover_keys](library-features/map-entry-recover-keys.md)
+    - [mpsc_select](library-features/mpsc-select.md)
+    - [n16](library-features/n16.md)
+    - [never_type_impls](library-features/never-type-impls.md)
+    - [nonzero](library-features/nonzero.md)
+    - [offset_to](library-features/offset-to.md)
+    - [once_poison](library-features/once-poison.md)
+    - [oom](library-features/oom.md)
+    - [option_entry](library-features/option-entry.md)
+    - [osstring_shrink_to_fit](library-features/osstring-shrink-to-fit.md)
+    - [panic_abort](library-features/panic-abort.md)
+    - [panic_unwind](library-features/panic-unwind.md)
+    - [pattern](library-features/pattern.md)
+    - [peek](library-features/peek.md)
+    - [placement_in](library-features/placement-in.md)
+    - [placement_new_protocol](library-features/placement-new-protocol.md)
+    - [print](library-features/print.md)
+    - [proc_macro_internals](library-features/proc-macro-internals.md)
+    - [process_try_wait](library-features/process-try-wait.md)
+    - [question_mark_carrier](library-features/question-mark-carrier.md)
+    - [rand](library-features/rand.md)
+    - [range_contains](library-features/range-contains.md)
+    - [raw](library-features/raw.md)
+    - [rc_would_unwrap](library-features/rc-would-unwrap.md)
+    - [retain_hash_collection](library-features/retain-hash-collection.md)
+    - [reverse_cmp_key](library-features/reverse-cmp-key.md)
+    - [rt](library-features/rt.md)
+    - [rustc_private](library-features/rustc-private.md)
+    - [sanitizer_runtime_lib](library-features/sanitizer-runtime-lib.md)
+    - [set_stdio](library-features/set-stdio.md)
+    - [shared](library-features/shared.md)
+    - [sip_hash_13](library-features/sip-hash-13.md)
+    - [slice_concat_ext](library-features/slice-concat-ext.md)
+    - [slice_get_slice](library-features/slice-get-slice.md)
+    - [slice_rsplit](library-features/slice-rsplit.md)
+    - [sort_internals](library-features/sort-internals.md)
+    - [sort_unstable](library-features/sort-unstable.md)
+    - [step_by](library-features/step-by.md)
+    - [step_trait](library-features/step-trait.md)
+    - [str_checked_slicing](library-features/str-checked-slicing.md)
+    - [str_escape](library-features/str-escape.md)
+    - [str_internals](library-features/str-internals.md)
+    - [str_mut_extras](library-features/str-mut-extras.md)
+    - [test](library-features/test.md)
+    - [thread_id](library-features/thread-id.md)
+    - [thread_local_internals](library-features/thread-local-internals.md)
+    - [thread_local_state](library-features/thread-local-state.md)
+    - [toowned_clone_into](library-features/toowned-clone-into.md)
+    - [trusted_len](library-features/trusted-len.md)
+    - [try_from](library-features/try-from.md)
+    - [unicode](library-features/unicode.md)
+    - [unique](library-features/unique.md)
+    - [unsize](library-features/unsize.md)
+    - [utf8_error_error_len](library-features/utf8-error-error-len.md)
+    - [vec_remove_item](library-features/vec-remove-item.md)
+    - [windows_c](library-features/windows-c.md)
+    - [windows_handle](library-features/windows-handle.md)
+    - [windows_net](library-features/windows-net.md)
+    - [windows_stdio](library-features/windows-stdio.md)
+    - [zero_one](library-features/zero-one.md)
+>>>>>> Add top level sections to the Unstable Book.
diff --git a/src/doc/unstable-book/src/compiler-flags.md b/src/doc/unstable-book/src/compiler-flags.md
new file mode 100644
index 00000000000..43eadb35101
--- /dev/null
+++ b/src/doc/unstable-book/src/compiler-flags.md
@@ -0,0 +1 @@
+# Compiler flags
diff --git a/src/doc/unstable-book/src/linker-flavor.md b/src/doc/unstable-book/src/compiler-flags/linker-flavor.md
index 39659602e01..39659602e01 100644
--- a/src/doc/unstable-book/src/linker-flavor.md
+++ b/src/doc/unstable-book/src/compiler-flags/linker-flavor.md
diff --git a/src/doc/unstable-book/src/language-features.md b/src/doc/unstable-book/src/language-features.md
new file mode 100644
index 00000000000..a27514df97d
--- /dev/null
+++ b/src/doc/unstable-book/src/language-features.md
@@ -0,0 +1 @@
+# Language features
diff --git a/src/doc/unstable-book/src/abi-msp430-interrupt.md b/src/doc/unstable-book/src/language-features/abi-msp430-interrupt.md
index b10bc41cb14..b10bc41cb14 100644
--- a/src/doc/unstable-book/src/abi-msp430-interrupt.md
+++ b/src/doc/unstable-book/src/language-features/abi-msp430-interrupt.md
diff --git a/src/doc/unstable-book/src/abi-ptx.md b/src/doc/unstable-book/src/language-features/abi-ptx.md
index 0ded3ceeaef..0ded3ceeaef 100644
--- a/src/doc/unstable-book/src/abi-ptx.md
+++ b/src/doc/unstable-book/src/language-features/abi-ptx.md
diff --git a/src/doc/unstable-book/src/abi-sysv64.md b/src/doc/unstable-book/src/language-features/abi-sysv64.md
index 27f61d56342..27f61d56342 100644
--- a/src/doc/unstable-book/src/abi-sysv64.md
+++ b/src/doc/unstable-book/src/language-features/abi-sysv64.md
diff --git a/src/doc/unstable-book/src/abi-unadjusted.md b/src/doc/unstable-book/src/language-features/abi-unadjusted.md
index 2e3113abdbf..2e3113abdbf 100644
--- a/src/doc/unstable-book/src/abi-unadjusted.md
+++ b/src/doc/unstable-book/src/language-features/abi-unadjusted.md
diff --git a/src/doc/unstable-book/src/abi-vectorcall.md b/src/doc/unstable-book/src/language-features/abi-vectorcall.md
index 3e36b1569fd..3e36b1569fd 100644
--- a/src/doc/unstable-book/src/abi-vectorcall.md
+++ b/src/doc/unstable-book/src/language-features/abi-vectorcall.md
diff --git a/src/doc/unstable-book/src/abi-x86-interrupt.md b/src/doc/unstable-book/src/language-features/abi-x86-interrupt.md
index c89d2ee2106..c89d2ee2106 100644
--- a/src/doc/unstable-book/src/abi-x86-interrupt.md
+++ b/src/doc/unstable-book/src/language-features/abi-x86-interrupt.md
diff --git a/src/doc/unstable-book/src/advanced-slice-patterns.md b/src/doc/unstable-book/src/language-features/advanced-slice-patterns.md
index 30d22ca8208..30d22ca8208 100644
--- a/src/doc/unstable-book/src/advanced-slice-patterns.md
+++ b/src/doc/unstable-book/src/language-features/advanced-slice-patterns.md
diff --git a/src/doc/unstable-book/src/allocator.md b/src/doc/unstable-book/src/language-features/allocator.md
index cfcf8e22d70..cfcf8e22d70 100644
--- a/src/doc/unstable-book/src/allocator.md
+++ b/src/doc/unstable-book/src/language-features/allocator.md
diff --git a/src/doc/unstable-book/src/allow-internal-unstable.md b/src/doc/unstable-book/src/language-features/allow-internal-unstable.md
index 74709ad5aeb..74709ad5aeb 100644
--- a/src/doc/unstable-book/src/allow-internal-unstable.md
+++ b/src/doc/unstable-book/src/language-features/allow-internal-unstable.md
diff --git a/src/doc/unstable-book/src/asm.md b/src/doc/unstable-book/src/language-features/asm.md
index 5e68be633e7..5e68be633e7 100644
--- a/src/doc/unstable-book/src/asm.md
+++ b/src/doc/unstable-book/src/language-features/asm.md
diff --git a/src/doc/unstable-book/src/associated-consts.md b/src/doc/unstable-book/src/language-features/associated-consts.md
index d661108e7d9..d661108e7d9 100644
--- a/src/doc/unstable-book/src/associated-consts.md
+++ b/src/doc/unstable-book/src/language-features/associated-consts.md
diff --git a/src/doc/unstable-book/src/associated-type-defaults.md b/src/doc/unstable-book/src/language-features/associated-type-defaults.md
index 56cc8a5b306..56cc8a5b306 100644
--- a/src/doc/unstable-book/src/associated-type-defaults.md
+++ b/src/doc/unstable-book/src/language-features/associated-type-defaults.md
diff --git a/src/doc/unstable-book/src/attr-literals.md b/src/doc/unstable-book/src/language-features/attr-literals.md
index 67eee214a4f..67eee214a4f 100644
--- a/src/doc/unstable-book/src/attr-literals.md
+++ b/src/doc/unstable-book/src/language-features/attr-literals.md
diff --git a/src/doc/unstable-book/src/box-patterns.md b/src/doc/unstable-book/src/language-features/box-patterns.md
index 86346364a71..86346364a71 100644
--- a/src/doc/unstable-book/src/box-patterns.md
+++ b/src/doc/unstable-book/src/language-features/box-patterns.md
diff --git a/src/doc/unstable-book/src/box-syntax.md b/src/doc/unstable-book/src/language-features/box-syntax.md
index 47aade0d045..47aade0d045 100644
--- a/src/doc/unstable-book/src/box-syntax.md
+++ b/src/doc/unstable-book/src/language-features/box-syntax.md
diff --git a/src/doc/unstable-book/src/catch-expr.md b/src/doc/unstable-book/src/language-features/catch-expr.md
index 44eb2a6dd4f..44eb2a6dd4f 100644
--- a/src/doc/unstable-book/src/catch-expr.md
+++ b/src/doc/unstable-book/src/language-features/catch-expr.md
diff --git a/src/doc/unstable-book/src/cfg-target-feature.md b/src/doc/unstable-book/src/language-features/cfg-target-feature.md
index ddd88bdc2cb..ddd88bdc2cb 100644
--- a/src/doc/unstable-book/src/cfg-target-feature.md
+++ b/src/doc/unstable-book/src/language-features/cfg-target-feature.md
diff --git a/src/doc/unstable-book/src/cfg-target-has-atomic.md b/src/doc/unstable-book/src/language-features/cfg-target-has-atomic.md
index 7496e42e1cd..7496e42e1cd 100644
--- a/src/doc/unstable-book/src/cfg-target-has-atomic.md
+++ b/src/doc/unstable-book/src/language-features/cfg-target-has-atomic.md
diff --git a/src/doc/unstable-book/src/cfg-target-thread-local.md b/src/doc/unstable-book/src/language-features/cfg-target-thread-local.md
index a5adb38db3d..a5adb38db3d 100644
--- a/src/doc/unstable-book/src/cfg-target-thread-local.md
+++ b/src/doc/unstable-book/src/language-features/cfg-target-thread-local.md
diff --git a/src/doc/unstable-book/src/cfg-target-vendor.md b/src/doc/unstable-book/src/language-features/cfg-target-vendor.md
index ddd88bdc2cb..ddd88bdc2cb 100644
--- a/src/doc/unstable-book/src/cfg-target-vendor.md
+++ b/src/doc/unstable-book/src/language-features/cfg-target-vendor.md
diff --git a/src/doc/unstable-book/src/closure-to-fn-coercion.md b/src/doc/unstable-book/src/language-features/closure-to-fn-coercion.md
index 4e3b735e24f..4e3b735e24f 100644
--- a/src/doc/unstable-book/src/closure-to-fn-coercion.md
+++ b/src/doc/unstable-book/src/language-features/closure-to-fn-coercion.md
diff --git a/src/doc/unstable-book/src/compiler-builtins.md b/src/doc/unstable-book/src/language-features/compiler-builtins.md
index 52fac575b6e..52fac575b6e 100644
--- a/src/doc/unstable-book/src/compiler-builtins.md
+++ b/src/doc/unstable-book/src/language-features/compiler-builtins.md
diff --git a/src/doc/unstable-book/src/concat-idents.md b/src/doc/unstable-book/src/language-features/concat-idents.md
index ecfd34a22e5..ecfd34a22e5 100644
--- a/src/doc/unstable-book/src/concat-idents.md
+++ b/src/doc/unstable-book/src/language-features/concat-idents.md
diff --git a/src/doc/unstable-book/src/conservative-impl-trait.md b/src/doc/unstable-book/src/language-features/conservative-impl-trait.md
index 0be6a321103..0be6a321103 100644
--- a/src/doc/unstable-book/src/conservative-impl-trait.md
+++ b/src/doc/unstable-book/src/language-features/conservative-impl-trait.md
diff --git a/src/doc/unstable-book/src/const-fn.md b/src/doc/unstable-book/src/language-features/const-fn.md
index d5a22436838..d5a22436838 100644
--- a/src/doc/unstable-book/src/const-fn.md
+++ b/src/doc/unstable-book/src/language-features/const-fn.md
diff --git a/src/doc/unstable-book/src/const-indexing.md b/src/doc/unstable-book/src/language-features/const-indexing.md
index 42d46ce15f6..42d46ce15f6 100644
--- a/src/doc/unstable-book/src/const-indexing.md
+++ b/src/doc/unstable-book/src/language-features/const-indexing.md
diff --git a/src/doc/unstable-book/src/custom-attribute.md b/src/doc/unstable-book/src/language-features/custom-attribute.md
index 838f09670d2..838f09670d2 100644
--- a/src/doc/unstable-book/src/custom-attribute.md
+++ b/src/doc/unstable-book/src/language-features/custom-attribute.md
diff --git a/src/doc/unstable-book/src/custom-derive.md b/src/doc/unstable-book/src/language-features/custom-derive.md
index d5fdd2b708b..d5fdd2b708b 100644
--- a/src/doc/unstable-book/src/custom-derive.md
+++ b/src/doc/unstable-book/src/language-features/custom-derive.md
diff --git a/src/doc/unstable-book/src/default-type-parameter-fallback.md b/src/doc/unstable-book/src/language-features/default-type-parameter-fallback.md
index fd16dbf8985..fd16dbf8985 100644
--- a/src/doc/unstable-book/src/default-type-parameter-fallback.md
+++ b/src/doc/unstable-book/src/language-features/default-type-parameter-fallback.md
diff --git a/src/doc/unstable-book/src/drop-types-in-const.md b/src/doc/unstable-book/src/language-features/drop-types-in-const.md
index b3367d0df44..b3367d0df44 100644
--- a/src/doc/unstable-book/src/drop-types-in-const.md
+++ b/src/doc/unstable-book/src/language-features/drop-types-in-const.md
diff --git a/src/doc/unstable-book/src/dropck-eyepatch.md b/src/doc/unstable-book/src/language-features/dropck-eyepatch.md
index 2f189e9b645..2f189e9b645 100644
--- a/src/doc/unstable-book/src/dropck-eyepatch.md
+++ b/src/doc/unstable-book/src/language-features/dropck-eyepatch.md
diff --git a/src/doc/unstable-book/src/dropck-parametricity.md b/src/doc/unstable-book/src/language-features/dropck-parametricity.md
index c5ae721954b..c5ae721954b 100644
--- a/src/doc/unstable-book/src/dropck-parametricity.md
+++ b/src/doc/unstable-book/src/language-features/dropck-parametricity.md
diff --git a/src/doc/unstable-book/src/exclusive-range-pattern.md b/src/doc/unstable-book/src/language-features/exclusive-range-pattern.md
index b669ce83132..b669ce83132 100644
--- a/src/doc/unstable-book/src/exclusive-range-pattern.md
+++ b/src/doc/unstable-book/src/language-features/exclusive-range-pattern.md
diff --git a/src/doc/unstable-book/src/fundamental.md b/src/doc/unstable-book/src/language-features/fundamental.md
index a068dadf95d..a068dadf95d 100644
--- a/src/doc/unstable-book/src/fundamental.md
+++ b/src/doc/unstable-book/src/language-features/fundamental.md
diff --git a/src/doc/unstable-book/src/generic-param-attrs.md b/src/doc/unstable-book/src/language-features/generic-param-attrs.md
index ba49c850e4d..ba49c850e4d 100644
--- a/src/doc/unstable-book/src/generic-param-attrs.md
+++ b/src/doc/unstable-book/src/language-features/generic-param-attrs.md
diff --git a/src/doc/unstable-book/src/global_asm.md b/src/doc/unstable-book/src/language-features/global_asm.md
index 44921aa309f..44921aa309f 100644
--- a/src/doc/unstable-book/src/global_asm.md
+++ b/src/doc/unstable-book/src/language-features/global_asm.md
diff --git a/src/doc/unstable-book/src/i128-type.md b/src/doc/unstable-book/src/language-features/i128-type.md
index a850b7644c3..a850b7644c3 100644
--- a/src/doc/unstable-book/src/i128-type.md
+++ b/src/doc/unstable-book/src/language-features/i128-type.md
diff --git a/src/doc/unstable-book/src/inclusive-range-syntax.md b/src/doc/unstable-book/src/language-features/inclusive-range-syntax.md
index 255445c318d..255445c318d 100644
--- a/src/doc/unstable-book/src/inclusive-range-syntax.md
+++ b/src/doc/unstable-book/src/language-features/inclusive-range-syntax.md
diff --git a/src/doc/unstable-book/src/intrinsics.md b/src/doc/unstable-book/src/language-features/intrinsics.md
index bc35c2a0305..bc35c2a0305 100644
--- a/src/doc/unstable-book/src/intrinsics.md
+++ b/src/doc/unstable-book/src/language-features/intrinsics.md
diff --git a/src/doc/unstable-book/src/lang-items.md b/src/doc/unstable-book/src/language-features/lang-items.md
index 375b8bd6b82..375b8bd6b82 100644
--- a/src/doc/unstable-book/src/lang-items.md
+++ b/src/doc/unstable-book/src/language-features/lang-items.md
diff --git a/src/doc/unstable-book/src/link-args.md b/src/doc/unstable-book/src/language-features/link-args.md
index 2507197661a..2507197661a 100644
--- a/src/doc/unstable-book/src/link-args.md
+++ b/src/doc/unstable-book/src/language-features/link-args.md
diff --git a/src/doc/unstable-book/src/link-cfg.md b/src/doc/unstable-book/src/language-features/link-cfg.md
index 7393d0628e4..7393d0628e4 100644
--- a/src/doc/unstable-book/src/link-cfg.md
+++ b/src/doc/unstable-book/src/language-features/link-cfg.md
diff --git a/src/doc/unstable-book/src/link-llvm-intrinsics.md b/src/doc/unstable-book/src/language-features/link-llvm-intrinsics.md
index ba639cb57fc..ba639cb57fc 100644
--- a/src/doc/unstable-book/src/link-llvm-intrinsics.md
+++ b/src/doc/unstable-book/src/language-features/link-llvm-intrinsics.md
diff --git a/src/doc/unstable-book/src/linkage.md b/src/doc/unstable-book/src/language-features/linkage.md
index 5773d28a00e..5773d28a00e 100644
--- a/src/doc/unstable-book/src/linkage.md
+++ b/src/doc/unstable-book/src/language-features/linkage.md
diff --git a/src/doc/unstable-book/src/log-syntax.md b/src/doc/unstable-book/src/language-features/log-syntax.md
index b13f5ccfd91..b13f5ccfd91 100644
--- a/src/doc/unstable-book/src/log-syntax.md
+++ b/src/doc/unstable-book/src/language-features/log-syntax.md
diff --git a/src/doc/unstable-book/src/loop-break-value.md b/src/doc/unstable-book/src/language-features/loop-break-value.md
index 54d6e62ce4c..54d6e62ce4c 100644
--- a/src/doc/unstable-book/src/loop-break-value.md
+++ b/src/doc/unstable-book/src/language-features/loop-break-value.md
diff --git a/src/doc/unstable-book/src/macro-reexport.md b/src/doc/unstable-book/src/language-features/macro-reexport.md
index 32ffa3b4c31..32ffa3b4c31 100644
--- a/src/doc/unstable-book/src/macro-reexport.md
+++ b/src/doc/unstable-book/src/language-features/macro-reexport.md
diff --git a/src/doc/unstable-book/src/macro-vis-matcher.md b/src/doc/unstable-book/src/language-features/macro-vis-matcher.md
index 7918a356843..7918a356843 100644
--- a/src/doc/unstable-book/src/macro-vis-matcher.md
+++ b/src/doc/unstable-book/src/language-features/macro-vis-matcher.md
diff --git a/src/doc/unstable-book/src/main.md b/src/doc/unstable-book/src/language-features/main.md
index 579aabfff88..579aabfff88 100644
--- a/src/doc/unstable-book/src/main.md
+++ b/src/doc/unstable-book/src/language-features/main.md
diff --git a/src/doc/unstable-book/src/naked-functions.md b/src/doc/unstable-book/src/language-features/naked-functions.md
index e56ce4770aa..e56ce4770aa 100644
--- a/src/doc/unstable-book/src/naked-functions.md
+++ b/src/doc/unstable-book/src/language-features/naked-functions.md
diff --git a/src/doc/unstable-book/src/needs-allocator.md b/src/doc/unstable-book/src/language-features/needs-allocator.md
index 22aa10b2183..22aa10b2183 100644
--- a/src/doc/unstable-book/src/needs-allocator.md
+++ b/src/doc/unstable-book/src/language-features/needs-allocator.md
diff --git a/src/doc/unstable-book/src/needs-panic-runtime.md b/src/doc/unstable-book/src/language-features/needs-panic-runtime.md
index 627c946c1bb..627c946c1bb 100644
--- a/src/doc/unstable-book/src/needs-panic-runtime.md
+++ b/src/doc/unstable-book/src/language-features/needs-panic-runtime.md
diff --git a/src/doc/unstable-book/src/never-type.md b/src/doc/unstable-book/src/language-features/never-type.md
index 3b3729a4b21..3b3729a4b21 100644
--- a/src/doc/unstable-book/src/never-type.md
+++ b/src/doc/unstable-book/src/language-features/never-type.md
diff --git a/src/doc/unstable-book/src/no-core.md b/src/doc/unstable-book/src/language-features/no-core.md
index 6238753447c..6238753447c 100644
--- a/src/doc/unstable-book/src/no-core.md
+++ b/src/doc/unstable-book/src/language-features/no-core.md
diff --git a/src/doc/unstable-book/src/no-debug.md b/src/doc/unstable-book/src/language-features/no-debug.md
index 7536ed9d4e1..7536ed9d4e1 100644
--- a/src/doc/unstable-book/src/no-debug.md
+++ b/src/doc/unstable-book/src/language-features/no-debug.md
diff --git a/src/doc/unstable-book/src/non-ascii-idents.md b/src/doc/unstable-book/src/language-features/non-ascii-idents.md
index d5600c58fd9..d5600c58fd9 100644
--- a/src/doc/unstable-book/src/non-ascii-idents.md
+++ b/src/doc/unstable-book/src/language-features/non-ascii-idents.md
diff --git a/src/doc/unstable-book/src/omit-gdb-pretty-printer-section.md b/src/doc/unstable-book/src/language-features/omit-gdb-pretty-printer-section.md
index d8ac520fcb5..d8ac520fcb5 100644
--- a/src/doc/unstable-book/src/omit-gdb-pretty-printer-section.md
+++ b/src/doc/unstable-book/src/language-features/omit-gdb-pretty-printer-section.md
diff --git a/src/doc/unstable-book/src/on-unimplemented.md b/src/doc/unstable-book/src/language-features/on-unimplemented.md
index 81f284d0a6a..81f284d0a6a 100644
--- a/src/doc/unstable-book/src/on-unimplemented.md
+++ b/src/doc/unstable-book/src/language-features/on-unimplemented.md
diff --git a/src/doc/unstable-book/src/optin-builtin-traits.md b/src/doc/unstable-book/src/language-features/optin-builtin-traits.md
index 0b2d60accd5..0b2d60accd5 100644
--- a/src/doc/unstable-book/src/optin-builtin-traits.md
+++ b/src/doc/unstable-book/src/language-features/optin-builtin-traits.md
diff --git a/src/doc/unstable-book/src/overlapping-marker-traits.md b/src/doc/unstable-book/src/language-features/overlapping-marker-traits.md
index a4920839c6c..a4920839c6c 100644
--- a/src/doc/unstable-book/src/overlapping-marker-traits.md
+++ b/src/doc/unstable-book/src/language-features/overlapping-marker-traits.md
diff --git a/src/doc/unstable-book/src/panic-runtime.md b/src/doc/unstable-book/src/language-features/panic-runtime.md
index 65b067e8296..65b067e8296 100644
--- a/src/doc/unstable-book/src/panic-runtime.md
+++ b/src/doc/unstable-book/src/language-features/panic-runtime.md
diff --git a/src/doc/unstable-book/src/placement-in-syntax.md b/src/doc/unstable-book/src/language-features/placement-in-syntax.md
index da12559a01b..da12559a01b 100644
--- a/src/doc/unstable-book/src/placement-in-syntax.md
+++ b/src/doc/unstable-book/src/language-features/placement-in-syntax.md
diff --git a/src/doc/unstable-book/src/platform-intrinsics.md b/src/doc/unstable-book/src/language-features/platform-intrinsics.md
index 377ac8f7342..377ac8f7342 100644
--- a/src/doc/unstable-book/src/platform-intrinsics.md
+++ b/src/doc/unstable-book/src/language-features/platform-intrinsics.md
diff --git a/src/doc/unstable-book/src/plugin-registrar.md b/src/doc/unstable-book/src/language-features/plugin-registrar.md
index ca3738bd93f..ca3738bd93f 100644
--- a/src/doc/unstable-book/src/plugin-registrar.md
+++ b/src/doc/unstable-book/src/language-features/plugin-registrar.md
diff --git a/src/doc/unstable-book/src/plugin.md b/src/doc/unstable-book/src/language-features/plugin.md
index 3a1872e18dd..3a1872e18dd 100644
--- a/src/doc/unstable-book/src/plugin.md
+++ b/src/doc/unstable-book/src/language-features/plugin.md
diff --git a/src/doc/unstable-book/src/prelude-import.md b/src/doc/unstable-book/src/language-features/prelude-import.md
index 75dae5cfb74..75dae5cfb74 100644
--- a/src/doc/unstable-book/src/prelude-import.md
+++ b/src/doc/unstable-book/src/language-features/prelude-import.md
diff --git a/src/doc/unstable-book/src/proc-macro.md b/src/doc/unstable-book/src/language-features/proc-macro.md
index f8b53bd5a2f..f8b53bd5a2f 100644
--- a/src/doc/unstable-book/src/proc-macro.md
+++ b/src/doc/unstable-book/src/language-features/proc-macro.md
diff --git a/src/doc/unstable-book/src/quote.md b/src/doc/unstable-book/src/language-features/quote.md
index b4e078d920c..b4e078d920c 100644
--- a/src/doc/unstable-book/src/quote.md
+++ b/src/doc/unstable-book/src/language-features/quote.md
diff --git a/src/doc/unstable-book/src/relaxed-adts.md b/src/doc/unstable-book/src/language-features/relaxed-adts.md
index 170570e06a2..170570e06a2 100644
--- a/src/doc/unstable-book/src/relaxed-adts.md
+++ b/src/doc/unstable-book/src/language-features/relaxed-adts.md
diff --git a/src/doc/unstable-book/src/repr-simd.md b/src/doc/unstable-book/src/language-features/repr-simd.md
index c6f051e4fff..c6f051e4fff 100644
--- a/src/doc/unstable-book/src/repr-simd.md
+++ b/src/doc/unstable-book/src/language-features/repr-simd.md
diff --git a/src/doc/unstable-book/src/rustc-attrs.md b/src/doc/unstable-book/src/language-features/rustc-attrs.md
index d1f18cead06..d1f18cead06 100644
--- a/src/doc/unstable-book/src/rustc-attrs.md
+++ b/src/doc/unstable-book/src/language-features/rustc-attrs.md
diff --git a/src/doc/unstable-book/src/rustc-diagnostic-macros.md b/src/doc/unstable-book/src/language-features/rustc-diagnostic-macros.md
index 0df6ca12089..0df6ca12089 100644
--- a/src/doc/unstable-book/src/rustc-diagnostic-macros.md
+++ b/src/doc/unstable-book/src/language-features/rustc-diagnostic-macros.md
diff --git a/src/doc/unstable-book/src/rvalue-static-promotion.md b/src/doc/unstable-book/src/language-features/rvalue-static-promotion.md
index 2583d350ebe..2583d350ebe 100644
--- a/src/doc/unstable-book/src/rvalue-static-promotion.md
+++ b/src/doc/unstable-book/src/language-features/rvalue-static-promotion.md
diff --git a/src/doc/unstable-book/src/sanitizer-runtime.md b/src/doc/unstable-book/src/language-features/sanitizer-runtime.md
index f19504de58e..f19504de58e 100644
--- a/src/doc/unstable-book/src/sanitizer-runtime.md
+++ b/src/doc/unstable-book/src/language-features/sanitizer-runtime.md
diff --git a/src/doc/unstable-book/src/simd-ffi.md b/src/doc/unstable-book/src/language-features/simd-ffi.md
index d85779c3d3d..d85779c3d3d 100644
--- a/src/doc/unstable-book/src/simd-ffi.md
+++ b/src/doc/unstable-book/src/language-features/simd-ffi.md
diff --git a/src/doc/unstable-book/src/simd.md b/src/doc/unstable-book/src/language-features/simd.md
index 13c9722c524..13c9722c524 100644
--- a/src/doc/unstable-book/src/simd.md
+++ b/src/doc/unstable-book/src/language-features/simd.md
diff --git a/src/doc/unstable-book/src/slice-patterns.md b/src/doc/unstable-book/src/language-features/slice-patterns.md
index 1e9e1eaafda..1e9e1eaafda 100644
--- a/src/doc/unstable-book/src/slice-patterns.md
+++ b/src/doc/unstable-book/src/language-features/slice-patterns.md
diff --git a/src/doc/unstable-book/src/specialization.md b/src/doc/unstable-book/src/language-features/specialization.md
index efc380df6e1..efc380df6e1 100644
--- a/src/doc/unstable-book/src/specialization.md
+++ b/src/doc/unstable-book/src/language-features/specialization.md
diff --git a/src/doc/unstable-book/src/staged-api.md b/src/doc/unstable-book/src/language-features/staged-api.md
index 1409e570e88..1409e570e88 100644
--- a/src/doc/unstable-book/src/staged-api.md
+++ b/src/doc/unstable-book/src/language-features/staged-api.md
diff --git a/src/doc/unstable-book/src/start.md b/src/doc/unstable-book/src/language-features/start.md
index 1ea6d59c78d..1ea6d59c78d 100644
--- a/src/doc/unstable-book/src/start.md
+++ b/src/doc/unstable-book/src/language-features/start.md
diff --git a/src/doc/unstable-book/src/static-nobundle.md b/src/doc/unstable-book/src/language-features/static-nobundle.md
index 97b9d71d433..97b9d71d433 100644
--- a/src/doc/unstable-book/src/static-nobundle.md
+++ b/src/doc/unstable-book/src/language-features/static-nobundle.md
diff --git a/src/doc/unstable-book/src/stmt-expr-attributes.md b/src/doc/unstable-book/src/language-features/stmt-expr-attributes.md
index 71092fcf290..71092fcf290 100644
--- a/src/doc/unstable-book/src/stmt-expr-attributes.md
+++ b/src/doc/unstable-book/src/language-features/stmt-expr-attributes.md
diff --git a/src/doc/unstable-book/src/struct-field-attributes.md b/src/doc/unstable-book/src/language-features/struct-field-attributes.md
index 1a94562968d..1a94562968d 100644
--- a/src/doc/unstable-book/src/struct-field-attributes.md
+++ b/src/doc/unstable-book/src/language-features/struct-field-attributes.md
diff --git a/src/doc/unstable-book/src/structural-match.md b/src/doc/unstable-book/src/language-features/structural-match.md
index b3ca26e6474..b3ca26e6474 100644
--- a/src/doc/unstable-book/src/structural-match.md
+++ b/src/doc/unstable-book/src/language-features/structural-match.md
diff --git a/src/doc/unstable-book/src/target-feature.md b/src/doc/unstable-book/src/language-features/target-feature.md
index 85ab1ab39ef..85ab1ab39ef 100644
--- a/src/doc/unstable-book/src/target-feature.md
+++ b/src/doc/unstable-book/src/language-features/target-feature.md
diff --git a/src/doc/unstable-book/src/thread-local.md b/src/doc/unstable-book/src/language-features/thread-local.md
index 83de2f9cd4b..83de2f9cd4b 100644
--- a/src/doc/unstable-book/src/thread-local.md
+++ b/src/doc/unstable-book/src/language-features/thread-local.md
diff --git a/src/doc/unstable-book/src/trace-macros.md b/src/doc/unstable-book/src/language-features/trace-macros.md
index 856f1b0a7bb..856f1b0a7bb 100644
--- a/src/doc/unstable-book/src/trace-macros.md
+++ b/src/doc/unstable-book/src/language-features/trace-macros.md
diff --git a/src/doc/unstable-book/src/type-ascription.md b/src/doc/unstable-book/src/language-features/type-ascription.md
index 3ebd0d87ccf..3ebd0d87ccf 100644
--- a/src/doc/unstable-book/src/type-ascription.md
+++ b/src/doc/unstable-book/src/language-features/type-ascription.md
diff --git a/src/doc/unstable-book/src/unboxed-closures.md b/src/doc/unstable-book/src/language-features/unboxed-closures.md
index 2cbb436ce0b..2cbb436ce0b 100644
--- a/src/doc/unstable-book/src/unboxed-closures.md
+++ b/src/doc/unstable-book/src/language-features/unboxed-closures.md
diff --git a/src/doc/unstable-book/src/untagged-unions.md b/src/doc/unstable-book/src/language-features/untagged-unions.md
index 6fe4f088ac2..6fe4f088ac2 100644
--- a/src/doc/unstable-book/src/untagged-unions.md
+++ b/src/doc/unstable-book/src/language-features/untagged-unions.md
diff --git a/src/doc/unstable-book/src/unwind-attributes.md b/src/doc/unstable-book/src/language-features/unwind-attributes.md
index 0167a33b081..0167a33b081 100644
--- a/src/doc/unstable-book/src/unwind-attributes.md
+++ b/src/doc/unstable-book/src/language-features/unwind-attributes.md
diff --git a/src/doc/unstable-book/src/use-extern-macros.md b/src/doc/unstable-book/src/language-features/use-extern-macros.md
index bc614911502..bc614911502 100644
--- a/src/doc/unstable-book/src/use-extern-macros.md
+++ b/src/doc/unstable-book/src/language-features/use-extern-macros.md
diff --git a/src/doc/unstable-book/src/used.md b/src/doc/unstable-book/src/language-features/used.md
index 75a8b2774f4..75a8b2774f4 100644
--- a/src/doc/unstable-book/src/used.md
+++ b/src/doc/unstable-book/src/language-features/used.md
diff --git a/src/doc/unstable-book/src/library-features.md b/src/doc/unstable-book/src/library-features.md
new file mode 100644
index 00000000000..9f537e26132
--- /dev/null
+++ b/src/doc/unstable-book/src/library-features.md
@@ -0,0 +1 @@
+# Library Features
diff --git a/src/doc/unstable-book/src/alloc-jemalloc.md b/src/doc/unstable-book/src/library-features/alloc-jemalloc.md
index 9bffa2ff99b..9bffa2ff99b 100644
--- a/src/doc/unstable-book/src/alloc-jemalloc.md
+++ b/src/doc/unstable-book/src/library-features/alloc-jemalloc.md
diff --git a/src/doc/unstable-book/src/alloc-system.md b/src/doc/unstable-book/src/library-features/alloc-system.md
index 6fa89179d8e..6fa89179d8e 100644
--- a/src/doc/unstable-book/src/alloc-system.md
+++ b/src/doc/unstable-book/src/library-features/alloc-system.md
diff --git a/src/doc/unstable-book/src/alloc.md b/src/doc/unstable-book/src/library-features/alloc.md
index 47eeb0874fb..47eeb0874fb 100644
--- a/src/doc/unstable-book/src/alloc.md
+++ b/src/doc/unstable-book/src/library-features/alloc.md
diff --git a/src/doc/unstable-book/src/as-c-str.md b/src/doc/unstable-book/src/library-features/as-c-str.md
index ed32eedb348..ed32eedb348 100644
--- a/src/doc/unstable-book/src/as-c-str.md
+++ b/src/doc/unstable-book/src/library-features/as-c-str.md
diff --git a/src/doc/unstable-book/src/as-unsafe-cell.md b/src/doc/unstable-book/src/library-features/as-unsafe-cell.md
index 79d7a7cad0b..79d7a7cad0b 100644
--- a/src/doc/unstable-book/src/as-unsafe-cell.md
+++ b/src/doc/unstable-book/src/library-features/as-unsafe-cell.md
diff --git a/src/doc/unstable-book/src/ascii-ctype.md b/src/doc/unstable-book/src/library-features/ascii-ctype.md
index e253b4dcd9b..e253b4dcd9b 100644
--- a/src/doc/unstable-book/src/ascii-ctype.md
+++ b/src/doc/unstable-book/src/library-features/ascii-ctype.md
diff --git a/src/doc/unstable-book/src/binary-heap-extras.md b/src/doc/unstable-book/src/library-features/binary-heap-extras.md
index aa535f3b678..aa535f3b678 100644
--- a/src/doc/unstable-book/src/binary-heap-extras.md
+++ b/src/doc/unstable-book/src/library-features/binary-heap-extras.md
diff --git a/src/doc/unstable-book/src/binary-heap-peek-mut-pop.md b/src/doc/unstable-book/src/library-features/binary-heap-peek-mut-pop.md
index f3863ab2a2a..f3863ab2a2a 100644
--- a/src/doc/unstable-book/src/binary-heap-peek-mut-pop.md
+++ b/src/doc/unstable-book/src/library-features/binary-heap-peek-mut-pop.md
diff --git a/src/doc/unstable-book/src/borrow-state.md b/src/doc/unstable-book/src/library-features/borrow-state.md
index 304b8dffe98..304b8dffe98 100644
--- a/src/doc/unstable-book/src/borrow-state.md
+++ b/src/doc/unstable-book/src/library-features/borrow-state.md
diff --git a/src/doc/unstable-book/src/box-heap.md b/src/doc/unstable-book/src/library-features/box-heap.md
index 0f3f01ba0e1..0f3f01ba0e1 100644
--- a/src/doc/unstable-book/src/box-heap.md
+++ b/src/doc/unstable-book/src/library-features/box-heap.md
diff --git a/src/doc/unstable-book/src/c-void-variant.md b/src/doc/unstable-book/src/library-features/c-void-variant.md
index a2fdc993630..a2fdc993630 100644
--- a/src/doc/unstable-book/src/c-void-variant.md
+++ b/src/doc/unstable-book/src/library-features/c-void-variant.md
diff --git a/src/doc/unstable-book/src/char-escape-debug.md b/src/doc/unstable-book/src/library-features/char-escape-debug.md
index 21aa486219e..21aa486219e 100644
--- a/src/doc/unstable-book/src/char-escape-debug.md
+++ b/src/doc/unstable-book/src/library-features/char-escape-debug.md
diff --git a/src/doc/unstable-book/src/coerce-unsized.md b/src/doc/unstable-book/src/library-features/coerce-unsized.md
index 078d3faf42a..078d3faf42a 100644
--- a/src/doc/unstable-book/src/coerce-unsized.md
+++ b/src/doc/unstable-book/src/library-features/coerce-unsized.md
diff --git a/src/doc/unstable-book/src/collection-placement.md b/src/doc/unstable-book/src/library-features/collection-placement.md
index 268ca6ea590..268ca6ea590 100644
--- a/src/doc/unstable-book/src/collection-placement.md
+++ b/src/doc/unstable-book/src/library-features/collection-placement.md
diff --git a/src/doc/unstable-book/src/collections-range.md b/src/doc/unstable-book/src/library-features/collections-range.md
index ea4f999ba0f..ea4f999ba0f 100644
--- a/src/doc/unstable-book/src/collections-range.md
+++ b/src/doc/unstable-book/src/library-features/collections-range.md
diff --git a/src/doc/unstable-book/src/collections.md b/src/doc/unstable-book/src/library-features/collections.md
index 5c937833c9e..5c937833c9e 100644
--- a/src/doc/unstable-book/src/collections.md
+++ b/src/doc/unstable-book/src/library-features/collections.md
diff --git a/src/doc/unstable-book/src/command-envs.md b/src/doc/unstable-book/src/library-features/command-envs.md
index 0ab89e278cd..0ab89e278cd 100644
--- a/src/doc/unstable-book/src/command-envs.md
+++ b/src/doc/unstable-book/src/library-features/command-envs.md
diff --git a/src/doc/unstable-book/src/compiler-builtins-lib.md b/src/doc/unstable-book/src/library-features/compiler-builtins-lib.md
index 5da8968fd0c..5da8968fd0c 100644
--- a/src/doc/unstable-book/src/compiler-builtins-lib.md
+++ b/src/doc/unstable-book/src/library-features/compiler-builtins-lib.md
diff --git a/src/doc/unstable-book/src/compiler-fences.md b/src/doc/unstable-book/src/library-features/compiler-fences.md
index b1e36ab13d5..b1e36ab13d5 100644
--- a/src/doc/unstable-book/src/compiler-fences.md
+++ b/src/doc/unstable-book/src/library-features/compiler-fences.md
diff --git a/src/doc/unstable-book/src/concat-idents-macro.md b/src/doc/unstable-book/src/library-features/concat-idents-macro.md
index ac2fdd4fceb..ac2fdd4fceb 100644
--- a/src/doc/unstable-book/src/concat-idents-macro.md
+++ b/src/doc/unstable-book/src/library-features/concat-idents-macro.md
diff --git a/src/doc/unstable-book/src/core-char-ext.md b/src/doc/unstable-book/src/library-features/core-char-ext.md
index d37d6b5c6d0..d37d6b5c6d0 100644
--- a/src/doc/unstable-book/src/core-char-ext.md
+++ b/src/doc/unstable-book/src/library-features/core-char-ext.md
diff --git a/src/doc/unstable-book/src/core-float.md b/src/doc/unstable-book/src/library-features/core-float.md
index 194b2608dd0..194b2608dd0 100644
--- a/src/doc/unstable-book/src/core-float.md
+++ b/src/doc/unstable-book/src/library-features/core-float.md
diff --git a/src/doc/unstable-book/src/core-intrinsics.md b/src/doc/unstable-book/src/library-features/core-intrinsics.md
index 28ad3525ef7..28ad3525ef7 100644
--- a/src/doc/unstable-book/src/core-intrinsics.md
+++ b/src/doc/unstable-book/src/library-features/core-intrinsics.md
diff --git a/src/doc/unstable-book/src/core-panic.md b/src/doc/unstable-book/src/library-features/core-panic.md
index c197588404c..c197588404c 100644
--- a/src/doc/unstable-book/src/core-panic.md
+++ b/src/doc/unstable-book/src/library-features/core-panic.md
diff --git a/src/doc/unstable-book/src/core-private-bignum.md b/src/doc/unstable-book/src/library-features/core-private-bignum.md
index f85811c545e..f85811c545e 100644
--- a/src/doc/unstable-book/src/core-private-bignum.md
+++ b/src/doc/unstable-book/src/library-features/core-private-bignum.md
diff --git a/src/doc/unstable-book/src/core-private-diy-float.md b/src/doc/unstable-book/src/library-features/core-private-diy-float.md
index 8465921d673..8465921d673 100644
--- a/src/doc/unstable-book/src/core-private-diy-float.md
+++ b/src/doc/unstable-book/src/library-features/core-private-diy-float.md
diff --git a/src/doc/unstable-book/src/core-slice-ext.md b/src/doc/unstable-book/src/library-features/core-slice-ext.md
index c50d44ac0ce..c50d44ac0ce 100644
--- a/src/doc/unstable-book/src/core-slice-ext.md
+++ b/src/doc/unstable-book/src/library-features/core-slice-ext.md
diff --git a/src/doc/unstable-book/src/core-str-ext.md b/src/doc/unstable-book/src/library-features/core-str-ext.md
index 08c68f11c6e..08c68f11c6e 100644
--- a/src/doc/unstable-book/src/core-str-ext.md
+++ b/src/doc/unstable-book/src/library-features/core-str-ext.md
diff --git a/src/doc/unstable-book/src/dec2flt.md b/src/doc/unstable-book/src/library-features/dec2flt.md
index 311ab4adcfd..311ab4adcfd 100644
--- a/src/doc/unstable-book/src/dec2flt.md
+++ b/src/doc/unstable-book/src/library-features/dec2flt.md
diff --git a/src/doc/unstable-book/src/decode-utf8.md b/src/doc/unstable-book/src/library-features/decode-utf8.md
index b96854ebcd4..b96854ebcd4 100644
--- a/src/doc/unstable-book/src/decode-utf8.md
+++ b/src/doc/unstable-book/src/library-features/decode-utf8.md
diff --git a/src/doc/unstable-book/src/derive-clone-copy.md b/src/doc/unstable-book/src/library-features/derive-clone-copy.md
index cc603911cbd..cc603911cbd 100644
--- a/src/doc/unstable-book/src/derive-clone-copy.md
+++ b/src/doc/unstable-book/src/library-features/derive-clone-copy.md
diff --git a/src/doc/unstable-book/src/derive-eq.md b/src/doc/unstable-book/src/library-features/derive-eq.md
index 68a275f5419..68a275f5419 100644
--- a/src/doc/unstable-book/src/derive-eq.md
+++ b/src/doc/unstable-book/src/library-features/derive-eq.md
diff --git a/src/doc/unstable-book/src/discriminant-value.md b/src/doc/unstable-book/src/library-features/discriminant-value.md
index 2f99f5ecab3..2f99f5ecab3 100644
--- a/src/doc/unstable-book/src/discriminant-value.md
+++ b/src/doc/unstable-book/src/library-features/discriminant-value.md
diff --git a/src/doc/unstable-book/src/enumset.md b/src/doc/unstable-book/src/library-features/enumset.md
index 24c8d8fa7db..24c8d8fa7db 100644
--- a/src/doc/unstable-book/src/enumset.md
+++ b/src/doc/unstable-book/src/library-features/enumset.md
diff --git a/src/doc/unstable-book/src/error-type-id.md b/src/doc/unstable-book/src/library-features/error-type-id.md
index be7a3ffd4dc..be7a3ffd4dc 100644
--- a/src/doc/unstable-book/src/error-type-id.md
+++ b/src/doc/unstable-book/src/library-features/error-type-id.md
diff --git a/src/doc/unstable-book/src/exact-size-is-empty.md b/src/doc/unstable-book/src/library-features/exact-size-is-empty.md
index 200ec387251..200ec387251 100644
--- a/src/doc/unstable-book/src/exact-size-is-empty.md
+++ b/src/doc/unstable-book/src/library-features/exact-size-is-empty.md
diff --git a/src/doc/unstable-book/src/fd-read.md b/src/doc/unstable-book/src/library-features/fd-read.md
index e78d4330abf..e78d4330abf 100644
--- a/src/doc/unstable-book/src/fd-read.md
+++ b/src/doc/unstable-book/src/library-features/fd-read.md
diff --git a/src/doc/unstable-book/src/fd.md b/src/doc/unstable-book/src/library-features/fd.md
index 0414244285b..0414244285b 100644
--- a/src/doc/unstable-book/src/fd.md
+++ b/src/doc/unstable-book/src/library-features/fd.md
diff --git a/src/doc/unstable-book/src/fixed-size-array.md b/src/doc/unstable-book/src/library-features/fixed-size-array.md
index 9e24e6a0850..9e24e6a0850 100644
--- a/src/doc/unstable-book/src/fixed-size-array.md
+++ b/src/doc/unstable-book/src/library-features/fixed-size-array.md
diff --git a/src/doc/unstable-book/src/float-bits-conv.md b/src/doc/unstable-book/src/library-features/float-bits-conv.md
index f519545ac78..f519545ac78 100644
--- a/src/doc/unstable-book/src/float-bits-conv.md
+++ b/src/doc/unstable-book/src/library-features/float-bits-conv.md
diff --git a/src/doc/unstable-book/src/float-extras.md b/src/doc/unstable-book/src/library-features/float-extras.md
index ff2d20a545f..ff2d20a545f 100644
--- a/src/doc/unstable-book/src/float-extras.md
+++ b/src/doc/unstable-book/src/library-features/float-extras.md
diff --git a/src/doc/unstable-book/src/flt2dec.md b/src/doc/unstable-book/src/library-features/flt2dec.md
index 15e62a3a7da..15e62a3a7da 100644
--- a/src/doc/unstable-book/src/flt2dec.md
+++ b/src/doc/unstable-book/src/library-features/flt2dec.md
diff --git a/src/doc/unstable-book/src/fmt-flags-align.md b/src/doc/unstable-book/src/library-features/fmt-flags-align.md
index 755263bd9a6..755263bd9a6 100644
--- a/src/doc/unstable-book/src/fmt-flags-align.md
+++ b/src/doc/unstable-book/src/library-features/fmt-flags-align.md
diff --git a/src/doc/unstable-book/src/fmt-internals.md b/src/doc/unstable-book/src/library-features/fmt-internals.md
index 7cbe3c89a64..7cbe3c89a64 100644
--- a/src/doc/unstable-book/src/fmt-internals.md
+++ b/src/doc/unstable-book/src/library-features/fmt-internals.md
diff --git a/src/doc/unstable-book/src/fn-traits.md b/src/doc/unstable-book/src/library-features/fn-traits.md
index 3942cda5538..3942cda5538 100644
--- a/src/doc/unstable-book/src/fn-traits.md
+++ b/src/doc/unstable-book/src/library-features/fn-traits.md
diff --git a/src/doc/unstable-book/src/fnbox.md b/src/doc/unstable-book/src/library-features/fnbox.md
index a9b74d4f004..a9b74d4f004 100644
--- a/src/doc/unstable-book/src/fnbox.md
+++ b/src/doc/unstable-book/src/library-features/fnbox.md
diff --git a/src/doc/unstable-book/src/from_utf8_error_as_bytes.md b/src/doc/unstable-book/src/library-features/from_utf8_error_as_bytes.md
index 570f779417f..570f779417f 100644
--- a/src/doc/unstable-book/src/from_utf8_error_as_bytes.md
+++ b/src/doc/unstable-book/src/library-features/from_utf8_error_as_bytes.md
diff --git a/src/doc/unstable-book/src/fused.md b/src/doc/unstable-book/src/library-features/fused.md
index 460555bf1b0..460555bf1b0 100644
--- a/src/doc/unstable-book/src/fused.md
+++ b/src/doc/unstable-book/src/library-features/fused.md
diff --git a/src/doc/unstable-book/src/future-atomic-orderings.md b/src/doc/unstable-book/src/library-features/future-atomic-orderings.md
index 40c2ef2db05..40c2ef2db05 100644
--- a/src/doc/unstable-book/src/future-atomic-orderings.md
+++ b/src/doc/unstable-book/src/library-features/future-atomic-orderings.md
diff --git a/src/doc/unstable-book/src/get-type-id.md b/src/doc/unstable-book/src/library-features/get-type-id.md
index afdb030c406..afdb030c406 100644
--- a/src/doc/unstable-book/src/get-type-id.md
+++ b/src/doc/unstable-book/src/library-features/get-type-id.md
diff --git a/src/doc/unstable-book/src/heap-api.md b/src/doc/unstable-book/src/library-features/heap-api.md
index 01404e49dbd..01404e49dbd 100644
--- a/src/doc/unstable-book/src/heap-api.md
+++ b/src/doc/unstable-book/src/library-features/heap-api.md
diff --git a/src/doc/unstable-book/src/i128.md b/src/doc/unstable-book/src/library-features/i128.md
index a1a7ce8e63f..a1a7ce8e63f 100644
--- a/src/doc/unstable-book/src/i128.md
+++ b/src/doc/unstable-book/src/library-features/i128.md
diff --git a/src/doc/unstable-book/src/inclusive-range.md b/src/doc/unstable-book/src/library-features/inclusive-range.md
index 2e88e204786..2e88e204786 100644
--- a/src/doc/unstable-book/src/inclusive-range.md
+++ b/src/doc/unstable-book/src/library-features/inclusive-range.md
diff --git a/src/doc/unstable-book/src/int-error-internals.md b/src/doc/unstable-book/src/library-features/int-error-internals.md
index 402e4fa5ef6..402e4fa5ef6 100644
--- a/src/doc/unstable-book/src/int-error-internals.md
+++ b/src/doc/unstable-book/src/library-features/int-error-internals.md
diff --git a/src/doc/unstable-book/src/integer-atomics.md b/src/doc/unstable-book/src/library-features/integer-atomics.md
index 50db9fd4ca4..50db9fd4ca4 100644
--- a/src/doc/unstable-book/src/integer-atomics.md
+++ b/src/doc/unstable-book/src/library-features/integer-atomics.md
diff --git a/src/doc/unstable-book/src/into-boxed-c-str.md b/src/doc/unstable-book/src/library-features/into-boxed-c-str.md
index 0d94b4fc560..0d94b4fc560 100644
--- a/src/doc/unstable-book/src/into-boxed-c-str.md
+++ b/src/doc/unstable-book/src/library-features/into-boxed-c-str.md
diff --git a/src/doc/unstable-book/src/into-boxed-os-str.md b/src/doc/unstable-book/src/library-features/into-boxed-os-str.md
index 7636e20b14d..7636e20b14d 100644
--- a/src/doc/unstable-book/src/into-boxed-os-str.md
+++ b/src/doc/unstable-book/src/library-features/into-boxed-os-str.md
diff --git a/src/doc/unstable-book/src/into-boxed-path.md b/src/doc/unstable-book/src/library-features/into-boxed-path.md
index 754c6042f07..754c6042f07 100644
--- a/src/doc/unstable-book/src/into-boxed-path.md
+++ b/src/doc/unstable-book/src/library-features/into-boxed-path.md
diff --git a/src/doc/unstable-book/src/io-error-internals.md b/src/doc/unstable-book/src/library-features/io-error-internals.md
index 5bee18d33d6..5bee18d33d6 100644
--- a/src/doc/unstable-book/src/io-error-internals.md
+++ b/src/doc/unstable-book/src/library-features/io-error-internals.md
diff --git a/src/doc/unstable-book/src/io.md b/src/doc/unstable-book/src/library-features/io.md
index ed6cae24e32..ed6cae24e32 100644
--- a/src/doc/unstable-book/src/io.md
+++ b/src/doc/unstable-book/src/library-features/io.md
diff --git a/src/doc/unstable-book/src/ip.md b/src/doc/unstable-book/src/library-features/ip.md
index 7e7d52adbdb..7e7d52adbdb 100644
--- a/src/doc/unstable-book/src/ip.md
+++ b/src/doc/unstable-book/src/library-features/ip.md
diff --git a/src/doc/unstable-book/src/is-unique.md b/src/doc/unstable-book/src/library-features/is-unique.md
index 6070006758b..6070006758b 100644
--- a/src/doc/unstable-book/src/is-unique.md
+++ b/src/doc/unstable-book/src/library-features/is-unique.md
diff --git a/src/doc/unstable-book/src/iter-rfind.md b/src/doc/unstable-book/src/library-features/iter-rfind.md
index 44471449034..44471449034 100644
--- a/src/doc/unstable-book/src/iter-rfind.md
+++ b/src/doc/unstable-book/src/library-features/iter-rfind.md
diff --git a/src/doc/unstable-book/src/libstd-io-internals.md b/src/doc/unstable-book/src/library-features/libstd-io-internals.md
index 8bcc2769db7..8bcc2769db7 100644
--- a/src/doc/unstable-book/src/libstd-io-internals.md
+++ b/src/doc/unstable-book/src/library-features/libstd-io-internals.md
diff --git a/src/doc/unstable-book/src/libstd-sys-internals.md b/src/doc/unstable-book/src/library-features/libstd-sys-internals.md
index 1b53faa8a00..1b53faa8a00 100644
--- a/src/doc/unstable-book/src/libstd-sys-internals.md
+++ b/src/doc/unstable-book/src/library-features/libstd-sys-internals.md
diff --git a/src/doc/unstable-book/src/libstd-thread-internals.md b/src/doc/unstable-book/src/library-features/libstd-thread-internals.md
index b682d12e7cd..b682d12e7cd 100644
--- a/src/doc/unstable-book/src/libstd-thread-internals.md
+++ b/src/doc/unstable-book/src/library-features/libstd-thread-internals.md
diff --git a/src/doc/unstable-book/src/linked-list-extras.md b/src/doc/unstable-book/src/library-features/linked-list-extras.md
index be3b96aea70..be3b96aea70 100644
--- a/src/doc/unstable-book/src/linked-list-extras.md
+++ b/src/doc/unstable-book/src/library-features/linked-list-extras.md
diff --git a/src/doc/unstable-book/src/lookup-host.md b/src/doc/unstable-book/src/library-features/lookup-host.md
index b60e7a01094..b60e7a01094 100644
--- a/src/doc/unstable-book/src/lookup-host.md
+++ b/src/doc/unstable-book/src/library-features/lookup-host.md
diff --git a/src/doc/unstable-book/src/manually-drop.md b/src/doc/unstable-book/src/library-features/manually-drop.md
index e69de29bb2d..e69de29bb2d 100644
--- a/src/doc/unstable-book/src/manually-drop.md
+++ b/src/doc/unstable-book/src/library-features/manually-drop.md
diff --git a/src/doc/unstable-book/src/map-entry-recover-keys.md b/src/doc/unstable-book/src/library-features/map-entry-recover-keys.md
index 2d15aa0e90d..2d15aa0e90d 100644
--- a/src/doc/unstable-book/src/map-entry-recover-keys.md
+++ b/src/doc/unstable-book/src/library-features/map-entry-recover-keys.md
diff --git a/src/doc/unstable-book/src/mpsc-select.md b/src/doc/unstable-book/src/library-features/mpsc-select.md
index 1405b6c5cb2..1405b6c5cb2 100644
--- a/src/doc/unstable-book/src/mpsc-select.md
+++ b/src/doc/unstable-book/src/library-features/mpsc-select.md
diff --git a/src/doc/unstable-book/src/n16.md b/src/doc/unstable-book/src/library-features/n16.md
index e556adaa13e..e556adaa13e 100644
--- a/src/doc/unstable-book/src/n16.md
+++ b/src/doc/unstable-book/src/library-features/n16.md
diff --git a/src/doc/unstable-book/src/never-type-impls.md b/src/doc/unstable-book/src/library-features/never-type-impls.md
index 4063cd0db01..4063cd0db01 100644
--- a/src/doc/unstable-book/src/never-type-impls.md
+++ b/src/doc/unstable-book/src/library-features/never-type-impls.md
diff --git a/src/doc/unstable-book/src/nonzero.md b/src/doc/unstable-book/src/library-features/nonzero.md
index f200f8e2786..f200f8e2786 100644
--- a/src/doc/unstable-book/src/nonzero.md
+++ b/src/doc/unstable-book/src/library-features/nonzero.md
diff --git a/src/doc/unstable-book/src/offset-to.md b/src/doc/unstable-book/src/library-features/offset-to.md
index 03d990eb4ae..03d990eb4ae 100644
--- a/src/doc/unstable-book/src/offset-to.md
+++ b/src/doc/unstable-book/src/library-features/offset-to.md
diff --git a/src/doc/unstable-book/src/once-poison.md b/src/doc/unstable-book/src/library-features/once-poison.md
index 3c16cafae50..3c16cafae50 100644
--- a/src/doc/unstable-book/src/once-poison.md
+++ b/src/doc/unstable-book/src/library-features/once-poison.md
diff --git a/src/doc/unstable-book/src/oom.md b/src/doc/unstable-book/src/library-features/oom.md
index 908caeb75c6..908caeb75c6 100644
--- a/src/doc/unstable-book/src/oom.md
+++ b/src/doc/unstable-book/src/library-features/oom.md
diff --git a/src/doc/unstable-book/src/option-entry.md b/src/doc/unstable-book/src/library-features/option-entry.md
index edb4efc09e5..edb4efc09e5 100644
--- a/src/doc/unstable-book/src/option-entry.md
+++ b/src/doc/unstable-book/src/library-features/option-entry.md
diff --git a/src/doc/unstable-book/src/osstring-shrink-to-fit.md b/src/doc/unstable-book/src/library-features/osstring-shrink-to-fit.md
index 21dc7d095c8..21dc7d095c8 100644
--- a/src/doc/unstable-book/src/osstring-shrink-to-fit.md
+++ b/src/doc/unstable-book/src/library-features/osstring-shrink-to-fit.md
diff --git a/src/doc/unstable-book/src/panic-abort.md b/src/doc/unstable-book/src/library-features/panic-abort.md
index 07a95762690..07a95762690 100644
--- a/src/doc/unstable-book/src/panic-abort.md
+++ b/src/doc/unstable-book/src/library-features/panic-abort.md
diff --git a/src/doc/unstable-book/src/panic-unwind.md b/src/doc/unstable-book/src/library-features/panic-unwind.md
index 840e492597b..840e492597b 100644
--- a/src/doc/unstable-book/src/panic-unwind.md
+++ b/src/doc/unstable-book/src/library-features/panic-unwind.md
diff --git a/src/doc/unstable-book/src/pattern.md b/src/doc/unstable-book/src/library-features/pattern.md
index e76ee6beb67..e76ee6beb67 100644
--- a/src/doc/unstable-book/src/pattern.md
+++ b/src/doc/unstable-book/src/library-features/pattern.md
diff --git a/src/doc/unstable-book/src/peek.md b/src/doc/unstable-book/src/library-features/peek.md
index c42b4e995ec..c42b4e995ec 100644
--- a/src/doc/unstable-book/src/peek.md
+++ b/src/doc/unstable-book/src/library-features/peek.md
diff --git a/src/doc/unstable-book/src/placement-in.md b/src/doc/unstable-book/src/library-features/placement-in.md
index 6ff010b7e38..6ff010b7e38 100644
--- a/src/doc/unstable-book/src/placement-in.md
+++ b/src/doc/unstable-book/src/library-features/placement-in.md
diff --git a/src/doc/unstable-book/src/placement-new-protocol.md b/src/doc/unstable-book/src/library-features/placement-new-protocol.md
index d53225f0a35..d53225f0a35 100644
--- a/src/doc/unstable-book/src/placement-new-protocol.md
+++ b/src/doc/unstable-book/src/library-features/placement-new-protocol.md
diff --git a/src/doc/unstable-book/src/print.md b/src/doc/unstable-book/src/library-features/print.md
index dc25cb237e3..dc25cb237e3 100644
--- a/src/doc/unstable-book/src/print.md
+++ b/src/doc/unstable-book/src/library-features/print.md
diff --git a/src/doc/unstable-book/src/proc-macro-internals.md b/src/doc/unstable-book/src/library-features/proc-macro-internals.md
index ea087c0a4f7..ea087c0a4f7 100644
--- a/src/doc/unstable-book/src/proc-macro-internals.md
+++ b/src/doc/unstable-book/src/library-features/proc-macro-internals.md
diff --git a/src/doc/unstable-book/src/process-try-wait.md b/src/doc/unstable-book/src/library-features/process-try-wait.md
index 3593b642349..3593b642349 100644
--- a/src/doc/unstable-book/src/process-try-wait.md
+++ b/src/doc/unstable-book/src/library-features/process-try-wait.md
diff --git a/src/doc/unstable-book/src/question-mark-carrier.md b/src/doc/unstable-book/src/library-features/question-mark-carrier.md
index 56154acc02b..56154acc02b 100644
--- a/src/doc/unstable-book/src/question-mark-carrier.md
+++ b/src/doc/unstable-book/src/library-features/question-mark-carrier.md
diff --git a/src/doc/unstable-book/src/rand.md b/src/doc/unstable-book/src/library-features/rand.md
index d0229d94c20..d0229d94c20 100644
--- a/src/doc/unstable-book/src/rand.md
+++ b/src/doc/unstable-book/src/library-features/rand.md
diff --git a/src/doc/unstable-book/src/range-contains.md b/src/doc/unstable-book/src/library-features/range-contains.md
index ac4581faf2a..ac4581faf2a 100644
--- a/src/doc/unstable-book/src/range-contains.md
+++ b/src/doc/unstable-book/src/library-features/range-contains.md
diff --git a/src/doc/unstable-book/src/raw.md b/src/doc/unstable-book/src/library-features/raw.md
index d7caf22813d..d7caf22813d 100644
--- a/src/doc/unstable-book/src/raw.md
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diff --git a/src/doc/unstable-book/src/rc-would-unwrap.md b/src/doc/unstable-book/src/library-features/rc-would-unwrap.md
index 462387dfdcc..462387dfdcc 100644
--- a/src/doc/unstable-book/src/rc-would-unwrap.md
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diff --git a/src/doc/unstable-book/src/retain-hash-collection.md b/src/doc/unstable-book/src/library-features/retain-hash-collection.md
index c9ba5acf020..c9ba5acf020 100644
--- a/src/doc/unstable-book/src/retain-hash-collection.md
+++ b/src/doc/unstable-book/src/library-features/retain-hash-collection.md
diff --git a/src/doc/unstable-book/src/reverse-cmp-key.md b/src/doc/unstable-book/src/library-features/reverse-cmp-key.md
index a1a851d6ed6..a1a851d6ed6 100644
--- a/src/doc/unstable-book/src/reverse-cmp-key.md
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diff --git a/src/doc/unstable-book/src/rt.md b/src/doc/unstable-book/src/library-features/rt.md
index 007acc207a6..007acc207a6 100644
--- a/src/doc/unstable-book/src/rt.md
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diff --git a/src/doc/unstable-book/src/rustc-private.md b/src/doc/unstable-book/src/library-features/rustc-private.md
index 2453475efe5..2453475efe5 100644
--- a/src/doc/unstable-book/src/rustc-private.md
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diff --git a/src/doc/unstable-book/src/sanitizer-runtime-lib.md b/src/doc/unstable-book/src/library-features/sanitizer-runtime-lib.md
index 82ae67fc05a..82ae67fc05a 100644
--- a/src/doc/unstable-book/src/sanitizer-runtime-lib.md
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diff --git a/src/doc/unstable-book/src/set-stdio.md b/src/doc/unstable-book/src/library-features/set-stdio.md
index 7dbdcdaa1a2..7dbdcdaa1a2 100644
--- a/src/doc/unstable-book/src/set-stdio.md
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diff --git a/src/doc/unstable-book/src/shared.md b/src/doc/unstable-book/src/library-features/shared.md
index b79d1212c62..b79d1212c62 100644
--- a/src/doc/unstable-book/src/shared.md
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diff --git a/src/doc/unstable-book/src/sip-hash-13.md b/src/doc/unstable-book/src/library-features/sip-hash-13.md
index 8f69c3ab2de..8f69c3ab2de 100644
--- a/src/doc/unstable-book/src/sip-hash-13.md
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diff --git a/src/doc/unstable-book/src/slice-concat-ext.md b/src/doc/unstable-book/src/library-features/slice-concat-ext.md
index 9ba2de5adc7..9ba2de5adc7 100644
--- a/src/doc/unstable-book/src/slice-concat-ext.md
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diff --git a/src/doc/unstable-book/src/slice-get-slice.md b/src/doc/unstable-book/src/library-features/slice-get-slice.md
index 57e2c148e79..57e2c148e79 100644
--- a/src/doc/unstable-book/src/slice-get-slice.md
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diff --git a/src/doc/unstable-book/src/slice-rsplit.md b/src/doc/unstable-book/src/library-features/slice-rsplit.md
index 8c2954f7294..8c2954f7294 100644
--- a/src/doc/unstable-book/src/slice-rsplit.md
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diff --git a/src/doc/unstable-book/src/sort-internals.md b/src/doc/unstable-book/src/library-features/sort-internals.md
index 6f2385e5300..6f2385e5300 100644
--- a/src/doc/unstable-book/src/sort-internals.md
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diff --git a/src/doc/unstable-book/src/sort-unstable.md b/src/doc/unstable-book/src/library-features/sort-unstable.md
index 9effcfc774c..9effcfc774c 100644
--- a/src/doc/unstable-book/src/sort-unstable.md
+++ b/src/doc/unstable-book/src/library-features/sort-unstable.md
diff --git a/src/doc/unstable-book/src/step-by.md b/src/doc/unstable-book/src/library-features/step-by.md
index b649496cdd8..b649496cdd8 100644
--- a/src/doc/unstable-book/src/step-by.md
+++ b/src/doc/unstable-book/src/library-features/step-by.md
diff --git a/src/doc/unstable-book/src/step-trait.md b/src/doc/unstable-book/src/library-features/step-trait.md
index e53ca13f7b6..e53ca13f7b6 100644
--- a/src/doc/unstable-book/src/step-trait.md
+++ b/src/doc/unstable-book/src/library-features/step-trait.md
diff --git a/src/doc/unstable-book/src/str-checked-slicing.md b/src/doc/unstable-book/src/library-features/str-checked-slicing.md
index d390139a6be..d390139a6be 100644
--- a/src/doc/unstable-book/src/str-checked-slicing.md
+++ b/src/doc/unstable-book/src/library-features/str-checked-slicing.md
diff --git a/src/doc/unstable-book/src/str-escape.md b/src/doc/unstable-book/src/library-features/str-escape.md
index 61e31c89443..61e31c89443 100644
--- a/src/doc/unstable-book/src/str-escape.md
+++ b/src/doc/unstable-book/src/library-features/str-escape.md
diff --git a/src/doc/unstable-book/src/str-internals.md b/src/doc/unstable-book/src/library-features/str-internals.md
index af8ef056dbe..af8ef056dbe 100644
--- a/src/doc/unstable-book/src/str-internals.md
+++ b/src/doc/unstable-book/src/library-features/str-internals.md
diff --git a/src/doc/unstable-book/src/str-mut-extras.md b/src/doc/unstable-book/src/library-features/str-mut-extras.md
index df4f35832cd..df4f35832cd 100644
--- a/src/doc/unstable-book/src/str-mut-extras.md
+++ b/src/doc/unstable-book/src/library-features/str-mut-extras.md
diff --git a/src/doc/unstable-book/src/test.md b/src/doc/unstable-book/src/library-features/test.md
index 6b4a3a677db..6b4a3a677db 100644
--- a/src/doc/unstable-book/src/test.md
+++ b/src/doc/unstable-book/src/library-features/test.md
diff --git a/src/doc/unstable-book/src/thread-id.md b/src/doc/unstable-book/src/library-features/thread-id.md
index af3ea991025..af3ea991025 100644
--- a/src/doc/unstable-book/src/thread-id.md
+++ b/src/doc/unstable-book/src/library-features/thread-id.md
diff --git a/src/doc/unstable-book/src/thread-local-internals.md b/src/doc/unstable-book/src/library-features/thread-local-internals.md
index e1cdcc339d2..e1cdcc339d2 100644
--- a/src/doc/unstable-book/src/thread-local-internals.md
+++ b/src/doc/unstable-book/src/library-features/thread-local-internals.md
diff --git a/src/doc/unstable-book/src/thread-local-state.md b/src/doc/unstable-book/src/library-features/thread-local-state.md
index 113c1e910dc..113c1e910dc 100644
--- a/src/doc/unstable-book/src/thread-local-state.md
+++ b/src/doc/unstable-book/src/library-features/thread-local-state.md
diff --git a/src/doc/unstable-book/src/toowned-clone-into.md b/src/doc/unstable-book/src/library-features/toowned-clone-into.md
index eccc7e0e4dd..eccc7e0e4dd 100644
--- a/src/doc/unstable-book/src/toowned-clone-into.md
+++ b/src/doc/unstable-book/src/library-features/toowned-clone-into.md
diff --git a/src/doc/unstable-book/src/trusted-len.md b/src/doc/unstable-book/src/library-features/trusted-len.md
index 80213cf1fdb..80213cf1fdb 100644
--- a/src/doc/unstable-book/src/trusted-len.md
+++ b/src/doc/unstable-book/src/library-features/trusted-len.md
diff --git a/src/doc/unstable-book/src/try-from.md b/src/doc/unstable-book/src/library-features/try-from.md
index d763caff5aa..d763caff5aa 100644
--- a/src/doc/unstable-book/src/try-from.md
+++ b/src/doc/unstable-book/src/library-features/try-from.md
diff --git a/src/doc/unstable-book/src/unicode.md b/src/doc/unstable-book/src/library-features/unicode.md
index 9fecec2ac36..9fecec2ac36 100644
--- a/src/doc/unstable-book/src/unicode.md
+++ b/src/doc/unstable-book/src/library-features/unicode.md
diff --git a/src/doc/unstable-book/src/unique.md b/src/doc/unstable-book/src/library-features/unique.md
index 99a3490d106..99a3490d106 100644
--- a/src/doc/unstable-book/src/unique.md
+++ b/src/doc/unstable-book/src/library-features/unique.md
diff --git a/src/doc/unstable-book/src/unsize.md b/src/doc/unstable-book/src/library-features/unsize.md
index 92807e2858f..92807e2858f 100644
--- a/src/doc/unstable-book/src/unsize.md
+++ b/src/doc/unstable-book/src/library-features/unsize.md
diff --git a/src/doc/unstable-book/src/update-panic-count.md b/src/doc/unstable-book/src/library-features/update-panic-count.md
index d315647ba10..d315647ba10 100644
--- a/src/doc/unstable-book/src/update-panic-count.md
+++ b/src/doc/unstable-book/src/library-features/update-panic-count.md
diff --git a/src/doc/unstable-book/src/utf8-error-error-len.md b/src/doc/unstable-book/src/library-features/utf8-error-error-len.md
index 1c14a5a9fa0..1c14a5a9fa0 100644
--- a/src/doc/unstable-book/src/utf8-error-error-len.md
+++ b/src/doc/unstable-book/src/library-features/utf8-error-error-len.md
diff --git a/src/doc/unstable-book/src/vec-remove-item.md b/src/doc/unstable-book/src/library-features/vec-remove-item.md
index 2b8c9f046ee..2b8c9f046ee 100644
--- a/src/doc/unstable-book/src/vec-remove-item.md
+++ b/src/doc/unstable-book/src/library-features/vec-remove-item.md
diff --git a/src/doc/unstable-book/src/windows-c.md b/src/doc/unstable-book/src/library-features/windows-c.md
index 3f833eb3d09..3f833eb3d09 100644
--- a/src/doc/unstable-book/src/windows-c.md
+++ b/src/doc/unstable-book/src/library-features/windows-c.md
diff --git a/src/doc/unstable-book/src/windows-handle.md b/src/doc/unstable-book/src/library-features/windows-handle.md
index f47a8425045..f47a8425045 100644
--- a/src/doc/unstable-book/src/windows-handle.md
+++ b/src/doc/unstable-book/src/library-features/windows-handle.md
diff --git a/src/doc/unstable-book/src/windows-net.md b/src/doc/unstable-book/src/library-features/windows-net.md
index 174960d4f00..174960d4f00 100644
--- a/src/doc/unstable-book/src/windows-net.md
+++ b/src/doc/unstable-book/src/library-features/windows-net.md
diff --git a/src/doc/unstable-book/src/windows-stdio.md b/src/doc/unstable-book/src/library-features/windows-stdio.md
index 4d361442386..4d361442386 100644
--- a/src/doc/unstable-book/src/windows-stdio.md
+++ b/src/doc/unstable-book/src/library-features/windows-stdio.md
diff --git a/src/doc/unstable-book/src/zero-one.md b/src/doc/unstable-book/src/library-features/zero-one.md
index 4d1cf38c3c2..4d1cf38c3c2 100644
--- a/src/doc/unstable-book/src/zero-one.md
+++ b/src/doc/unstable-book/src/library-features/zero-one.md
diff --git a/src/doc/unstable-book/src/the-unstable-book.md b/src/doc/unstable-book/src/the-unstable-book.md
index dfbfe4cab97..604b449f163 100644
--- a/src/doc/unstable-book/src/the-unstable-book.md
+++ b/src/doc/unstable-book/src/the-unstable-book.md
@@ -14,7 +14,7 @@ fn main() {
 
 The `box_syntax` feature [has a chapter][box] describing how to use it.
 
-[box]: box-syntax.html
+[box]: language-features/box-syntax.html
 
 Because this documentation relates to unstable features, we make no guarantees
 that what is contained here is accurate or up to date. It's developed on a
diff --git a/src/libsyntax/feature_gate.rs b/src/libsyntax/feature_gate.rs
index 129674b7476..175447e1112 100644
--- a/src/libsyntax/feature_gate.rs
+++ b/src/libsyntax/feature_gate.rs
@@ -344,9 +344,6 @@ declare_features! (
     // Used to preserve symbols (see llvm.used)
     (active, used, "1.18.0", Some(40289)),
 
-    // Hack to document `-Z linker-flavor` in The Unstable Book
-    (active, linker_flavor, "1.18.0", Some(41142)),
-
     // Allows module-level inline assembly by way of global_asm!()
     (active, global_asm, "1.18.0", Some(35119)),
 
diff --git a/src/tools/linkchecker/main.rs b/src/tools/linkchecker/main.rs
index 137de561c76..3d9a4fba6cd 100644
--- a/src/tools/linkchecker/main.rs
+++ b/src/tools/linkchecker/main.rs
@@ -147,6 +147,12 @@ fn check(cache: &mut Cache,
         return None;
     }
 
+    // mdbook uses the HTML <base> tag to handle links for subdirectories, which
+    // linkchecker doesn't support
+    if file.to_str().unwrap().contains("unstable-book") {
+        return None;
+    }
+
     let res = load_file(cache, root, PathBuf::from(file), SkipRedirect);
     let (pretty_file, contents) = match res {
         Ok(res) => res,
diff --git a/src/tools/tidy/Cargo.toml b/src/tools/tidy/Cargo.toml
index 371922c9e6b..664aecfcbdb 100644
--- a/src/tools/tidy/Cargo.toml
+++ b/src/tools/tidy/Cargo.toml
@@ -2,6 +2,3 @@
 name = "tidy"
 version = "0.1.0"
 authors = ["Alex Crichton <alex@alexcrichton.com>"]
-
-[dependencies]
-regex = "0.2"
\ No newline at end of file
diff --git a/src/tools/tidy/src/main.rs b/src/tools/tidy/src/main.rs
index 44063e627a3..3e7046d05f4 100644
--- a/src/tools/tidy/src/main.rs
+++ b/src/tools/tidy/src/main.rs
@@ -14,8 +14,6 @@
 //! etc. This is run by default on `make check` and as part of the auto
 //! builders.
 
-extern crate regex;
-
 use std::env;
 use std::fs;
 use std::io::{self, Write};
diff --git a/src/tools/tidy/src/unstable_book.rs b/src/tools/tidy/src/unstable_book.rs
index 2d3d9e80257..5a6524b3e88 100644
--- a/src/tools/tidy/src/unstable_book.rs
+++ b/src/tools/tidy/src/unstable_book.rs
@@ -10,35 +10,36 @@
 
 use std::collections::HashSet;
 use std::fs;
-use std::io::{self, BufRead};
 use std::path;
 use features::{collect_lang_features, collect_lib_features, Status};
 
 const PATH_STR: &'static str = "doc/unstable-book/src";
 
-const SUMMARY_FILE_NAME: &'static str = "SUMMARY.md";
+const LANG_FEATURES_DIR: &'static str = "language-features";
 
-static EXCLUDE: &'static [&'static str; 2] = &[SUMMARY_FILE_NAME, "the-unstable-book.md"];
+const LIB_FEATURES_DIR: &'static str = "library-features";
 
 /// Build the path to the Unstable Book source directory from the Rust 'src' directory
 fn unstable_book_path(base_src_path: &path::Path) -> path::PathBuf {
     base_src_path.join(PATH_STR)
 }
 
-/// Build the path to the Unstable Book SUMMARY file from the Rust 'src' directory
-fn unstable_book_summary_path(base_src_path: &path::Path) -> path::PathBuf {
-    unstable_book_path(base_src_path).join(SUMMARY_FILE_NAME)
+/// Directory where the features are documented within the Unstable Book source directory
+fn unstable_book_lang_features_path(base_src_path: &path::Path) -> path::PathBuf {
+    unstable_book_path(base_src_path).join(LANG_FEATURES_DIR)
 }
 
-/// Open the Unstable Book SUMMARY file
-fn open_unstable_book_summary_file(base_src_path: &path::Path) -> fs::File {
-    fs::File::open(unstable_book_summary_path(base_src_path))
-        .expect("could not open Unstable Book SUMMARY.md")
+/// Directory where the features are documented within the Unstable Book source directory
+fn unstable_book_lib_features_path(base_src_path: &path::Path) -> path::PathBuf {
+    unstable_book_path(base_src_path).join(LIB_FEATURES_DIR)
 }
 
 /// Test to determine if DirEntry is a file
 fn dir_entry_is_file(dir_entry: &fs::DirEntry) -> bool {
-    dir_entry.file_type().expect("could not determine file type of directory entry").is_file()
+    dir_entry
+        .file_type()
+        .expect("could not determine file type of directory entry")
+        .is_file()
 }
 
 /// Retrieve names of all lang-related unstable features
@@ -61,75 +62,81 @@ fn collect_unstable_lib_feature_names(base_src_path: &path::Path) -> HashSet<Str
         .collect()
 }
 
-/// Retrieve names of all unstable features
-fn collect_unstable_feature_names(base_src_path: &path::Path) -> HashSet<String> {
-    collect_unstable_lib_feature_names(base_src_path)
-        .union(&collect_unstable_lang_feature_names(base_src_path))
-        .map(|n| n.to_owned())
-        .collect::<HashSet<_, _>>()
-}
-
-/// Retrieve file names of all sections in the Unstable Book with:
-///
-/// * hyphens replaced by underscores
-/// * the markdown suffix ('.md') removed
-fn collect_unstable_book_section_file_names(base_src_path: &path::Path) -> HashSet<String> {
-    fs::read_dir(unstable_book_path(base_src_path))
+fn collect_unstable_book_section_file_names(dir: &path::Path) -> HashSet<String> {
+    fs::read_dir(dir)
         .expect("could not read directory")
         .into_iter()
         .map(|entry| entry.expect("could not read directory entry"))
         .filter(dir_entry_is_file)
         .map(|entry| entry.file_name().into_string().unwrap())
-        .filter(|n| EXCLUDE.iter().all(|e| n != e))
         .map(|n| n.trim_right_matches(".md").replace('-', "_"))
         .collect()
 }
 
-/// Retrieve unstable feature names that are in the Unstable Book SUMMARY file
-fn collect_unstable_book_summary_links(base_src_path: &path::Path) -> HashSet<String> {
-    let summary_link_regex =
-        ::regex::Regex::new(r"^- \[(\S+)\]\(\S+\.md\)").expect("invalid regex");
-    io::BufReader::new(open_unstable_book_summary_file(base_src_path))
-        .lines()
-        .map(|l| l.expect("could not read line from file"))
-        .filter_map(|line| {
-            summary_link_regex.captures(&line).map(|c| {
-                                                       c.get(1)
-                                                           .unwrap()
-                                                           .as_str()
-                                                           .to_owned()
-                                                   })
-        })
-        .collect()
+/// Retrieve file names of all library feature sections in the Unstable Book with:
+///
+/// * hyphens replaced by underscores
+/// * the markdown suffix ('.md') removed
+fn collect_unstable_book_lang_features_section_file_names(base_src_path: &path::Path)
+                                                          -> HashSet<String> {
+    collect_unstable_book_section_file_names(&unstable_book_lang_features_path(base_src_path))
+}
+
+/// Retrieve file names of all language feature sections in the Unstable Book with:
+///
+/// * hyphens replaced by underscores
+/// * the markdown suffix ('.md') removed
+fn collect_unstable_book_lib_features_section_file_names(base_src_path: &path::Path)
+                                                         -> HashSet<String> {
+    collect_unstable_book_section_file_names(&unstable_book_lib_features_path(base_src_path))
 }
 
 pub fn check(path: &path::Path, bad: &mut bool) {
-    let unstable_feature_names = collect_unstable_feature_names(path);
-    let unstable_book_section_file_names = collect_unstable_book_section_file_names(path);
-    let unstable_book_links = collect_unstable_book_summary_links(path);
-
-    // Check for Unstable Book section names with no corresponding SUMMARY.md link
-    for feature_name in &unstable_book_section_file_names - &unstable_book_links {
-        tidy_error!(
-            bad,
-            "The Unstable Book section '{}' needs to have a link in SUMMARY.md",
-            feature_name);
-    }
+
+    // Library features
+
+    let unstable_lib_feature_names = collect_unstable_lib_feature_names(path);
+    let unstable_book_lib_features_section_file_names =
+        collect_unstable_book_lib_features_section_file_names(path);
 
     // Check for unstable features that don't have Unstable Book sections
-    for feature_name in &unstable_feature_names - &unstable_book_section_file_names {
-        tidy_error!(
-            bad,
-            "Unstable feature '{}' needs to have a section in The Unstable Book",
-            feature_name);
+    for feature_name in &unstable_lib_feature_names -
+                        &unstable_book_lib_features_section_file_names {
+        tidy_error!(bad,
+                    "Unstable library feature '{}' needs to have a section within the \
+                     'library features' section of The Unstable Book",
+                    feature_name);
+    }
+
+    // Check for Unstable Book sections that don't have a corresponding unstable feature
+    for feature_name in &unstable_book_lib_features_section_file_names -
+                        &unstable_lib_feature_names {
+        tidy_error!(bad,
+                    "The Unstable Book has a 'library feature' section '{}' which doesn't \
+                     correspond to an unstable library feature",
+                    feature_name)
+    }
+
+    // Language features
+
+    let unstable_lang_feature_names = collect_unstable_lang_feature_names(path);
+    let unstable_book_lang_features_section_file_names =
+        collect_unstable_book_lang_features_section_file_names(path);
+
+    for feature_name in &unstable_lang_feature_names -
+                        &unstable_book_lang_features_section_file_names {
+        tidy_error!(bad,
+                    "Unstable language feature '{}' needs to have a section within the \
+                     'language features' section of The Unstable Book",
+                    feature_name);
     }
 
     // Check for Unstable Book sections that don't have a corresponding unstable feature
-    for feature_name in &unstable_book_section_file_names - &unstable_feature_names {
-        tidy_error!(
-            bad,
-            "The Unstable Book has a section '{}' which doesn't correspond \
-            to an unstable feature",
-            feature_name)
+    for feature_name in &unstable_book_lang_features_section_file_names -
+                        &unstable_lang_feature_names {
+        tidy_error!(bad,
+                    "The Unstable Book has a 'language feature' section '{}' which doesn't \
+                     correspond to an unstable language feature",
+                    feature_name)
     }
 }