1. The Unstable Book
  2. 1. Compiler flags
    1. 1.1. branch_protection
    2. 1.2. cf_protection
    3. 1.3. check_cfg
    4. 1.4. codegen_backend
    5. 1.5. control_flow_guard
    6. 1.6. debug_info_for_profiling
    7. 1.7. emit_stack_sizes
    8. 1.8. extern_location
    9. 1.9. location_detail
    10. 1.10. move_size_limit
    11. 1.11. no_unique_section_names
    12. 1.12. profile
    13. 1.13. profile_sample_use
    14. 1.14. remap_cwd_prefix
    15. 1.15. report_time
    16. 1.16. sanitizer
    17. 1.17. self_profile
    18. 1.18. self_profile_events
    19. 1.19. src_hash_algorithm
    20. 1.20. temps_dir
    21. 1.21. tls_model
    22. 1.22. unsound_mir_opts
  3. 2. Language features
    1. 2.1. aarch64_ver_target_feature
    2. 2.2. abi_amdgpu_kernel
    3. 2.3. abi_avr_interrupt
    4. 2.4. abi_c_cmse_nonsecure_call
    5. 2.5. abi_efiapi
    6. 2.6. abi_msp430_interrupt
    7. 2.7. abi_ptx
    8. 2.8. abi_thiscall
    9. 2.9. abi_unadjusted
    10. 2.10. abi_vectorcall
    11. 2.11. abi_x86_interrupt
    12. 2.12. adt_const_params
    13. 2.13. alloc_error_handler
    14. 2.14. allocator_internals
    15. 2.15. allow_internal_unsafe
    16. 2.16. allow_internal_unstable
    17. 2.17. arbitrary_enum_discriminant
    18. 2.18. arbitrary_self_types
    19. 2.19. arm_target_feature
    20. 2.20. asm_const
    21. 2.21. asm_experimental_arch
    22. 2.22. asm_sym
    23. 2.23. asm_unwind
    24. 2.24. associated_const_equality
    25. 2.25. associated_type_bounds
    26. 2.26. associated_type_defaults
    27. 2.27. async_closure
    28. 2.28. auto_traits
    29. 2.29. avx512_target_feature
    30. 2.30. box_patterns
    31. 2.31. box_syntax
    32. 2.32. bpf_target_feature
    33. 2.33. c_unwind
    34. 2.34. c_variadic
    35. 2.35. capture_disjoint_fields
    36. 2.36. cfg_sanitize
    37. 2.37. cfg_target_abi
    38. 2.38. cfg_target_has_atomic
    39. 2.39. cfg_target_has_atomic_equal_alignment
    40. 2.40. cfg_target_thread_local
    41. 2.41. cfg_version
    42. 2.42. closure_track_caller
    43. 2.43. cmpxchg16b_target_feature
    44. 2.44. cmse_nonsecure_entry
    45. 2.45. compiler_builtins
    46. 2.46. const_async_blocks
    47. 2.47. const_eval_limit
    48. 2.48. const_extern_fn
    49. 2.49. const_fn_floating_point_arithmetic
    50. 2.50. const_for
    51. 2.51. const_mut_refs
    52. 2.52. const_precise_live_drops
    53. 2.53. const_refs_to_cell
    54. 2.54. const_trait_impl
    55. 2.55. const_try
    56. 2.56. crate_visibility_modifier
    57. 2.57. custom_inner_attributes
    58. 2.58. custom_test_frameworks
    59. 2.59. decl_macro
    60. 2.60. default_alloc_error_handler
    61. 2.61. default_type_parameter_fallback
    62. 2.62. deprecated_safe
    63. 2.63. deprecated_suggestion
    64. 2.64. derive_default_enum
    65. 2.65. doc_auto_cfg
    66. 2.66. doc_cfg
    67. 2.67. doc_cfg_hide
    68. 2.68. doc_masked
    69. 2.69. doc_notable_trait
    70. 2.70. dropck_eyepatch
    71. 2.71. ermsb_target_feature
    72. 2.72. exclusive_range_pattern
    73. 2.73. exhaustive_patterns
    74. 2.74. explicit_generic_args_with_impl_trait
    75. 2.75. extern_types
    76. 2.76. f16c_target_feature
    77. 2.77. ffi_const
    78. 2.78. ffi_pure
    79. 2.79. ffi_returns_twice
    80. 2.80. fn_align
    81. 2.81. fundamental
    82. 2.82. generators
    83. 2.83. generic_arg_infer
    84. 2.84. generic_associated_types
    85. 2.85. generic_associated_types_extended
    86. 2.86. generic_const_exprs
    87. 2.87. half_open_range_patterns
    88. 2.88. hexagon_target_feature
    89. 2.89. if_let_guard
    90. 2.90. imported_main
    91. 2.91. infer_static_outlives_requirements
    92. 2.92. inherent_associated_types
    93. 2.93. inline_const
    94. 2.94. inline_const_pat
    95. 2.95. intra_doc_pointers
    96. 2.96. intrinsics
    97. 2.97. isa_attribute
    98. 2.98. label_break_value
    99. 2.99. lang_items
    100. 2.100. large_assignments
    101. 2.101. let_chains
    102. 2.102. let_else
    103. 2.103. link_cfg
    104. 2.104. link_llvm_intrinsics
    105. 2.105. linkage
    106. 2.106. lint_reasons
    107. 2.107. macro_metavar_expr
    108. 2.108. marker_trait_attr
    109. 2.109. min_specialization
    110. 2.110. mips_target_feature
    111. 2.111. more_qualified_paths
    112. 2.112. movbe_target_feature
    113. 2.113. must_not_suspend
    114. 2.114. naked_functions
    115. 2.115. native_link_modifiers_as_needed
    116. 2.116. native_link_modifiers_bundle
    117. 2.117. native_link_modifiers_verbatim
    118. 2.118. needs_panic_runtime
    119. 2.119. negative_impls
    120. 2.120. never_type
    121. 2.121. never_type_fallback
    122. 2.122. nll
    123. 2.123. no_core
    124. 2.124. no_coverage
    125. 2.125. no_niche
    126. 2.126. no_sanitize
    127. 2.127. non_exhaustive_omitted_patterns_lint
    128. 2.128. object_safe_for_dispatch
    129. 2.129. omit_gdb_pretty_printer_section
    130. 2.130. optimize_attribute
    131. 2.131. panic_runtime
    132. 2.132. platform_intrinsics
    133. 2.133. plugin
    134. 2.134. powerpc_target_feature
    135. 2.135. precise_pointer_size_matching
    136. 2.136. prelude_import
    137. 2.137. proc_macro_hygiene
    138. 2.138. profiler_runtime
    139. 2.139. raw_dylib
    140. 2.140. raw_ref_op
    141. 2.141. register_attr
    142. 2.142. register_tool
    143. 2.143. repr_simd
    144. 2.144. repr128
    145. 2.145. riscv_target_feature
    146. 2.146. rtm_target_feature
    147. 2.147. rustc_allow_const_fn_unstable
    148. 2.148. rustc_attrs
    149. 2.149. rustc_private
    150. 2.150. rustdoc_internals
    151. 2.151. simd_ffi
    152. 2.152. specialization
    153. 2.153. sse4a_target_feature
    154. 2.154. staged_api
    155. 2.155. start
    156. 2.156. static_nobundle
    157. 2.157. stmt_expr_attributes
    158. 2.158. structural_match
    159. 2.159. target_feature_11
    160. 2.160. tbm_target_feature
    161. 2.161. test_2018_feature
    162. 2.162. test_unstable_lint
    163. 2.163. thread_local
    164. 2.164. trait_alias
    165. 2.165. trait_upcasting
    166. 2.166. transparent_unions
    167. 2.167. trivial_bounds
    168. 2.168. try_blocks
    169. 2.169. type_alias_impl_trait
    170. 2.170. type_ascription
    171. 2.171. type_changing_struct_update
    172. 2.172. unboxed_closures
    173. 2.173. unsafe_pin_internals
    174. 2.174. unsized_fn_params
    175. 2.175. unsized_locals
    176. 2.176. unsized_tuple_coercion
    177. 2.177. untagged_unions
    178. 2.178. used_with_arg
    179. 2.179. wasm_abi
    180. 2.180. wasm_target_feature
    181. 2.181. with_negative_coherence
  4. 3. Library Features
    1. 3.1. absolute_path
    2. 3.2. alloc_error_hook
    3. 3.3. alloc_internals
    4. 3.4. alloc_layout_extra
    5. 3.5. allocator_api
    6. 3.6. arc_unwrap_or_clone
    7. 3.7. array_chunks
    8. 3.8. array_error_internals
    9. 3.9. array_from_fn
    10. 3.10. array_into_iter_constructors
    11. 3.11. array_methods
    12. 3.12. array_try_map
    13. 3.13. array_windows
    14. 3.14. array_zip
    15. 3.15. as_array_of_cells
    16. 3.16. assert_matches
    17. 3.17. async_iter_from_iter
    18. 3.18. async_iterator
    19. 3.19. atomic_from_mut
    20. 3.20. atomic_mut_ptr
    21. 3.21. backtrace
    22. 3.22. backtrace_frames
    23. 3.23. bench_black_box
    24. 3.24. bigint_helper_methods
    25. 3.25. binary_heap_as_slice
    26. 3.26. binary_heap_drain_sorted
    27. 3.27. binary_heap_into_iter_sorted
    28. 3.28. binary_heap_retain
    29. 3.29. bool_to_option
    30. 3.30. bound_as_ref
    31. 3.31. bound_map
    32. 3.32. box_into_boxed_slice
    33. 3.33. box_into_inner
    34. 3.34. box_into_pin
    35. 3.35. btree_drain_filter
    36. 3.36. buf_read_has_data_left
    37. 3.37. build_hasher_simple_hash_one
    38. 3.38. byte_slice_trim_ascii
    39. 3.39. c_size_t
    40. 3.40. c_void_variant
    41. 3.41. can_vector
    42. 3.42. cell_filter_map
    43. 3.43. cell_leak
    44. 3.44. cell_update
    45. 3.45. cfg_accessible
    46. 3.46. cfg_eval
    47. 3.47. char_error_internals
    48. 3.48. char_indices_offset
    49. 3.49. char_internals
    50. 3.50. coerce_unsized
    51. 3.51. concat_bytes
    52. 3.52. concat_idents
    53. 3.53. const_align_of_val
    54. 3.54. const_align_of_val_raw
    55. 3.55. const_align_offset
    56. 3.56. const_alloc_error
    57. 3.57. const_alloc_layout
    58. 3.58. const_arguments_as_str
    59. 3.59. const_array_from_ref
    60. 3.60. const_array_into_iter_constructors
    61. 3.61. const_assert_type2
    62. 3.62. const_assume
    63. 3.63. const_bigint_helper_methods
    64. 3.64. const_black_box
    65. 3.65. const_bool_to_option
    66. 3.66. const_borrow
    67. 3.67. const_box
    68. 3.68. const_btree_new
    69. 3.69. const_caller_location
    70. 3.70. const_cell_into_inner
    71. 3.71. const_char_convert
    72. 3.72. const_clone
    73. 3.73. const_convert
    74. 3.74. const_cow_is_borrowed
    75. 3.75. const_default_impls
    76. 3.76. const_deref
    77. 3.77. const_discriminant
    78. 3.78. const_eval_select
    79. 3.79. const_float_bits_conv
    80. 3.80. const_float_classify
    81. 3.81. const_fmt_arguments_new
    82. 3.82. const_format_args
    83. 3.83. const_heap
    84. 3.84. const_inherent_unchecked_arith
    85. 3.85. const_int_unchecked_arith
    86. 3.86. const_intrinsic_copy
    87. 3.87. const_intrinsic_forget
    88. 3.88. const_intrinsic_raw_eq
    89. 3.89. const_io_structs
    90. 3.90. const_ip
    91. 3.91. const_ipv4
    92. 3.92. const_ipv6
    93. 3.93. const_is_char_boundary
    94. 3.94. const_likely
    95. 3.95. const_maybe_uninit_as_mut_ptr
    96. 3.96. const_maybe_uninit_assume_init
    97. 3.97. const_maybe_uninit_assume_init_read
    98. 3.98. const_maybe_uninit_write
    99. 3.99. const_maybe_uninit_zeroed
    100. 3.100. const_nonnull_new
    101. 3.101. const_nonnull_slice_from_raw_parts
    102. 3.102. const_num_from_num
    103. 3.103. const_ops
    104. 3.104. const_option
    105. 3.105. const_option_cloned
    106. 3.106. const_option_ext
    107. 3.107. const_pin
    108. 3.108. const_pref_align_of
    109. 3.109. const_ptr_as_ref
    110. 3.110. const_ptr_is_null
    111. 3.111. const_ptr_offset_from
    112. 3.112. const_ptr_read
    113. 3.113. const_ptr_write
    114. 3.114. const_raw_ptr_comparison
    115. 3.115. const_replace
    116. 3.116. const_result
    117. 3.117. const_result_drop
    118. 3.118. const_size_of_val
    119. 3.119. const_size_of_val_raw
    120. 3.120. const_slice_first_last
    121. 3.121. const_slice_from_raw_parts
    122. 3.122. const_slice_from_ref
    123. 3.123. const_slice_index
    124. 3.124. const_slice_ptr_len
    125. 3.125. const_socketaddr
    126. 3.126. const_str_from_utf8
    127. 3.127. const_str_from_utf8_unchecked_mut
    128. 3.128. const_swap
    129. 3.129. const_transmute_copy
    130. 3.130. const_type_id
    131. 3.131. const_type_name
    132. 3.132. const_unsafecell_get_mut
    133. 3.133. const_weak_new
    134. 3.134. container_error_extra
    135. 3.135. control_flow_enum
    136. 3.136. convert_float_to_int
    137. 3.137. core_ffi_c
    138. 3.138. core_intrinsics
    139. 3.139. core_panic
    140. 3.140. core_private_bignum
    141. 3.141. core_private_diy_float
    142. 3.142. cow_is_borrowed
    143. 3.143. cstr_from_bytes_until_nul
    144. 3.144. cursor_remaining
    145. 3.145. deadline_api
    146. 3.146. dec2flt
    147. 3.147. default_free_fn
    148. 3.148. derive_clone_copy
    149. 3.149. derive_eq
    150. 3.150. dir_entry_ext2
    151. 3.151. discriminant_kind
    152. 3.152. dispatch_from_dyn
    153. 3.153. div_duration
    154. 3.154. downcast_unchecked
    155. 3.155. drain_filter
    156. 3.156. duration_checked_float
    157. 3.157. duration_constants
    158. 3.158. duration_consts_float
    159. 3.159. edition_panic
    160. 3.160. entry_insert
    161. 3.161. error_iter
    162. 3.162. error_reporter
    163. 3.163. error_type_id
    164. 3.164. exact_size_is_empty
    165. 3.165. exit_status_error
    166. 3.166. extend_one
    167. 3.167. fd
    168. 3.168. fd_read
    169. 3.169. float_minimum_maximum
    170. 3.170. flt2dec
    171. 3.171. fmt_internals
    172. 3.172. fn_traits
    173. 3.173. forget_unsized
    174. 3.174. format_args_nl
    175. 3.175. future_join
    176. 3.176. future_poll_fn
    177. 3.177. gen_future
    178. 3.178. generator_trait
    179. 3.179. get_mut_unchecked
    180. 3.180. hash_drain_filter
    181. 3.181. hash_raw_entry
    182. 3.182. hash_set_entry
    183. 3.183. hashmap_internals
    184. 3.184. hint_must_use
    185. 3.185. inplace_iteration
    186. 3.186. int_error_internals
    187. 3.187. int_log
    188. 3.188. int_roundings
    189. 3.189. integer_atomics
    190. 3.190. internal_output_capture
    191. 3.191. into_future
    192. 3.192. io_error_more
    193. 3.193. io_error_other
    194. 3.194. io_error_uncategorized
    195. 3.195. io_read_to_string
    196. 3.196. io_safety
    197. 3.197. io_slice_advance
    198. 3.198. ip
    199. 3.199. is_some_with
    200. 3.200. is_sorted
    201. 3.201. iter_advance_by
    202. 3.202. iter_collect_into
    203. 3.203. iter_intersperse
    204. 3.204. iter_is_partitioned
    205. 3.205. iter_order_by
    206. 3.206. iter_partition_in_place
    207. 3.207. iterator_try_collect
    208. 3.208. iterator_try_reduce
    209. 3.209. layout_for_ptr
    210. 3.210. liballoc_internals
    211. 3.211. libstd_sys_internals
    212. 3.212. libstd_thread_internals
    213. 3.213. linked_list_cursors
    214. 3.214. linked_list_remove
    215. 3.215. linux_pidfd
    216. 3.216. local_key_cell_methods
    217. 3.217. log_syntax
    218. 3.218. main_separator_str
    219. 3.219. map_entry_replace
    220. 3.220. map_first_last
    221. 3.221. map_try_insert
    222. 3.222. maybe_uninit_array_assume_init
    223. 3.223. maybe_uninit_as_bytes
    224. 3.224. maybe_uninit_slice
    225. 3.225. maybe_uninit_uninit_array
    226. 3.226. maybe_uninit_write_slice
    227. 3.227. mixed_integer_ops
    228. 3.228. mutex_unlock
    229. 3.229. new_uninit
    230. 3.230. nonnull_slice_from_raw_parts
    231. 3.231. nonzero_bits
    232. 3.232. nonzero_min_max
    233. 3.233. nonzero_ops
    234. 3.234. numfmt
    235. 3.235. once_cell
    236. 3.236. one_sided_range
    237. 3.237. option_get_or_insert_default
    238. 3.238. option_result_contains
    239. 3.239. option_zip
    240. 3.240. panic_abort
    241. 3.241. panic_always_abort
    242. 3.242. panic_backtrace_config
    243. 3.243. panic_can_unwind
    244. 3.244. panic_info_message
    245. 3.245. panic_internals
    246. 3.246. panic_unwind
    247. 3.247. panic_update_hook
    248. 3.248. path_file_prefix
    249. 3.249. path_try_exists
    250. 3.250. pattern
    251. 3.251. peer_credentials_unix_socket
    252. 3.252. pin_deref_mut
    253. 3.253. pin_macro
    254. 3.254. poll_ready
    255. 3.255. portable_simd
    256. 3.256. print_internals
    257. 3.257. proc_macro_def_site
    258. 3.258. proc_macro_diagnostic
    259. 3.259. proc_macro_expand
    260. 3.260. proc_macro_internals
    261. 3.261. proc_macro_quote
    262. 3.262. proc_macro_span
    263. 3.263. proc_macro_span_shrink
    264. 3.264. proc_macro_tracked_env
    265. 3.265. process_exitcode_internals
    266. 3.266. process_internals
    267. 3.267. process_set_process_group
    268. 3.268. profiler_runtime_lib
    269. 3.269. ptr_as_uninit
    270. 3.270. ptr_const_cast
    271. 3.271. ptr_internals
    272. 3.272. ptr_metadata
    273. 3.273. ptr_to_from_bits
    274. 3.274. pub_crate_should_not_need_unstable_attr
    275. 3.275. raw_os_nonzero
    276. 3.276. raw_vec_internals
    277. 3.277. read_buf
    278. 3.278. ready_macro
    279. 3.279. receiver_trait
    280. 3.280. restricted_std
    281. 3.281. result_contains_err
    282. 3.282. result_flattening
    283. 3.283. result_into_ok_or_err
    284. 3.284. result_option_inspect
    285. 3.285. round_char_boundary
    286. 3.286. rt
    287. 3.287. saturating_int_assign_impl
    288. 3.288. saturating_int_impl
    289. 3.289. scoped_threads
    290. 3.290. sealed
    291. 3.291. seek_stream_len
    292. 3.292. set_ptr_value
    293. 3.293. setgroups
    294. 3.294. sgx_platform
    295. 3.295. slice_as_chunks
    296. 3.296. slice_concat_ext
    297. 3.297. slice_concat_trait
    298. 3.298. slice_from_ptr_range
    299. 3.299. slice_group_by
    300. 3.300. slice_index_methods
    301. 3.301. slice_internals
    302. 3.302. slice_partition_dedup
    303. 3.303. slice_pattern
    304. 3.304. slice_ptr_get
    305. 3.305. slice_ptr_len
    306. 3.306. slice_range
    307. 3.307. slice_split_at_unchecked
    308. 3.308. slice_swap_unchecked
    309. 3.309. slice_take
    310. 3.310. solid_ext
    311. 3.311. sort_internals
    312. 3.312. split_array
    313. 3.313. std_internals
    314. 3.314. stdin_forwarders
    315. 3.315. stdsimd
    316. 3.316. step_trait
    317. 3.317. str_internals
    318. 3.318. str_split_as_str
    319. 3.319. str_split_inclusive_as_str
    320. 3.320. str_split_whitespace_as_str
    321. 3.321. strict_provenance
    322. 3.322. string_extend_from_within
    323. 3.323. string_remove_matches
    324. 3.324. tcp_linger
    325. 3.325. tcplistener_into_incoming
    326. 3.326. test
    327. 3.327. thread_id_value
    328. 3.328. thread_local_internals
    329. 3.329. thread_spawn_unchecked
    330. 3.330. toowned_clone_into
    331. 3.331. total_cmp
    332. 3.332. trace_macros
    333. 3.333. track_path
    334. 3.334. trusted_len
    335. 3.335. trusted_random_access
    336. 3.336. trusted_step
    337. 3.337. try_find
    338. 3.338. try_reserve_2
    339. 3.339. try_reserve_kind
    340. 3.340. try_trait_v2
    341. 3.341. try_trait_v2_residual
    342. 3.342. type_name_of_val
    343. 3.343. unchecked_math
    344. 3.344. unicode_internals
    345. 3.345. unix_chown
    346. 3.346. unix_socket_abstract
    347. 3.347. unix_socket_ancillary_data
    348. 3.348. unix_socket_peek
    349. 3.349. unsize
    350. 3.350. unwrap_infallible
    351. 3.351. unzip_option
    352. 3.352. update_panic_count
    353. 3.353. utf16_extra
    354. 3.354. utf16_extra_const
    355. 3.355. variant_count
    356. 3.356. vec_into_raw_parts
    357. 3.357. vec_split_at_spare
    358. 3.358. waker_getters
    359. 3.359. wasi_ext
    360. 3.360. windows_by_handle
    361. 3.361. windows_c
    362. 3.362. windows_file_type_ext
    363. 3.363. windows_handle
    364. 3.364. windows_net
    365. 3.365. windows_process_extensions_force_quotes
    366. 3.366. windows_process_extensions_raw_arg
    367. 3.367. windows_stdio
    368. 3.368. wrapping_int_impl
    369. 3.369. wrapping_next_power_of_two
    370. 3.370. write_all_vectored

The Rust Unstable Book

Language features