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_options
    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
    23. 1.23. virtual_function_elimination
  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_compact
    39. 2.39. cfg_target_has_atomic
    40. 2.40. cfg_target_has_atomic_equal_alignment
    41. 2.41. cfg_target_thread_local
    42. 2.42. cfg_version
    43. 2.43. closure_track_caller
    44. 2.44. cmpxchg16b_target_feature
    45. 2.45. cmse_nonsecure_entry
    46. 2.46. compiler_builtins
    47. 2.47. const_async_blocks
    48. 2.48. const_eval_limit
    49. 2.49. const_extern_fn
    50. 2.50. const_fn_floating_point_arithmetic
    51. 2.51. const_for
    52. 2.52. const_mut_refs
    53. 2.53. const_precise_live_drops
    54. 2.54. const_refs_to_cell
    55. 2.55. const_trait_impl
    56. 2.56. const_try
    57. 2.57. custom_inner_attributes
    58. 2.58. custom_test_frameworks
    59. 2.59. debugger_visualizer
    60. 2.60. decl_macro
    61. 2.61. default_alloc_error_handler
    62. 2.62. default_type_parameter_fallback
    63. 2.63. deprecated_safe
    64. 2.64. deprecated_suggestion
    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. extern_types
    75. 2.75. f16c_target_feature
    76. 2.76. ffi_const
    77. 2.77. ffi_pure
    78. 2.78. ffi_returns_twice
    79. 2.79. fn_align
    80. 2.80. fundamental
    81. 2.81. generators
    82. 2.82. generic_arg_infer
    83. 2.83. generic_assert
    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. inherent_associated_types
    92. 2.92. inline_const
    93. 2.93. inline_const_pat
    94. 2.94. intra_doc_pointers
    95. 2.95. intrinsics
    96. 2.96. isa_attribute
    97. 2.97. label_break_value
    98. 2.98. lang_items
    99. 2.99. large_assignments
    100. 2.100. let_chains
    101. 2.101. let_else
    102. 2.102. link_cfg
    103. 2.103. link_llvm_intrinsics
    104. 2.104. linkage
    105. 2.105. lint_reasons
    106. 2.106. macro_metavar_expr
    107. 2.107. marker_trait_attr
    108. 2.108. min_specialization
    109. 2.109. mips_target_feature
    110. 2.110. more_qualified_paths
    111. 2.111. movbe_target_feature
    112. 2.112. must_not_suspend
    113. 2.113. naked_functions
    114. 2.114. native_link_modifiers_as_needed
    115. 2.115. native_link_modifiers_verbatim
    116. 2.116. needs_panic_runtime
    117. 2.117. negative_impls
    118. 2.118. never_type
    119. 2.119. never_type_fallback
    120. 2.120. no_core
    121. 2.121. no_coverage
    122. 2.122. no_niche
    123. 2.123. no_sanitize
    124. 2.124. non_exhaustive_omitted_patterns_lint
    125. 2.125. object_safe_for_dispatch
    126. 2.126. omit_gdb_pretty_printer_section
    127. 2.127. optimize_attribute
    128. 2.128. panic_runtime
    129. 2.129. platform_intrinsics
    130. 2.130. plugin
    131. 2.131. powerpc_target_feature
    132. 2.132. precise_pointer_size_matching
    133. 2.133. prelude_import
    134. 2.134. proc_macro_hygiene
    135. 2.135. profiler_runtime
    136. 2.136. raw_dylib
    137. 2.137. raw_ref_op
    138. 2.138. register_attr
    139. 2.139. register_tool
    140. 2.140. repr_simd
    141. 2.141. repr128
    142. 2.142. riscv_target_feature
    143. 2.143. rtm_target_feature
    144. 2.144. rust_cold_cc
    145. 2.145. rustc_allow_const_fn_unstable
    146. 2.146. rustc_attrs
    147. 2.147. rustc_private
    148. 2.148. rustdoc_internals
    149. 2.149. simd_ffi
    150. 2.150. specialization
    151. 2.151. sse4a_target_feature
    152. 2.152. staged_api
    153. 2.153. start
    154. 2.154. stmt_expr_attributes
    155. 2.155. strict_provenance
    156. 2.156. structural_match
    157. 2.157. target_feature_11
    158. 2.158. tbm_target_feature
    159. 2.159. test_2018_feature
    160. 2.160. test_unstable_lint
    161. 2.161. thread_local
    162. 2.162. trait_alias
    163. 2.163. trait_upcasting
    164. 2.164. transparent_unions
    165. 2.165. trivial_bounds
    166. 2.166. try_blocks
    167. 2.167. type_alias_impl_trait
    168. 2.168. type_ascription
    169. 2.169. type_changing_struct_update
    170. 2.170. unboxed_closures
    171. 2.171. unsafe_pin_internals
    172. 2.172. unsized_fn_params
    173. 2.173. unsized_locals
    174. 2.174. unsized_tuple_coercion
    175. 2.175. untagged_unions
    176. 2.176. used_with_arg
    177. 2.177. wasm_abi
    178. 2.178. wasm_target_feature
    179. 2.179. with_negative_coherence
    180. 2.180. yeet_expr
  4. 3. Library Features
    1. 3.1. absolute_path
    2. 3.2. alloc_c_string
    3. 3.3. alloc_error_hook
    4. 3.4. alloc_ffi
    5. 3.5. alloc_internals
    6. 3.6. alloc_layout_extra
    7. 3.7. allocator_api
    8. 3.8. arc_unwrap_or_clone
    9. 3.9. array_chunks
    10. 3.10. array_error_internals
    11. 3.11. array_into_iter_constructors
    12. 3.12. array_methods
    13. 3.13. array_try_from_fn
    14. 3.14. array_try_map
    15. 3.15. array_windows
    16. 3.16. array_zip
    17. 3.17. as_array_of_cells
    18. 3.18. assert_matches
    19. 3.19. async_iter_from_iter
    20. 3.20. async_iterator
    21. 3.21. atomic_from_mut
    22. 3.22. atomic_mut_ptr
    23. 3.23. backtrace
    24. 3.24. backtrace_frames
    25. 3.25. bench_black_box
    26. 3.26. bigint_helper_methods
    27. 3.27. binary_heap_as_slice
    28. 3.28. binary_heap_drain_sorted
    29. 3.29. binary_heap_into_iter_sorted
    30. 3.30. binary_heap_retain
    31. 3.31. bound_as_ref
    32. 3.32. bound_map
    33. 3.33. box_into_boxed_slice
    34. 3.34. box_into_inner
    35. 3.35. btree_drain_filter
    36. 3.36. btreemap_alloc
    37. 3.37. buf_read_has_data_left
    38. 3.38. build_hasher_simple_hash_one
    39. 3.39. byte_slice_trim_ascii
    40. 3.40. c_size_t
    41. 3.41. c_void_variant
    42. 3.42. can_vector
    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_intoiterator_identity
    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_array_assume_init
    96. 3.96. const_maybe_uninit_as_mut_ptr
    97. 3.97. const_maybe_uninit_assume_init
    98. 3.98. const_maybe_uninit_assume_init_read
    99. 3.99. const_maybe_uninit_uninit_array
    100. 3.100. const_maybe_uninit_write
    101. 3.101. const_maybe_uninit_zeroed
    102. 3.102. const_nonnull_new
    103. 3.103. const_nonnull_slice_from_raw_parts
    104. 3.104. const_num_from_num
    105. 3.105. const_ops
    106. 3.106. const_option
    107. 3.107. const_option_cloned
    108. 3.108. const_option_ext
    109. 3.109. const_pin
    110. 3.110. const_pointer_byte_offsets
    111. 3.111. const_pref_align_of
    112. 3.112. const_ptr_as_ref
    113. 3.113. const_ptr_is_null
    114. 3.114. const_ptr_offset_from
    115. 3.115. const_ptr_read
    116. 3.116. const_ptr_sub_ptr
    117. 3.117. const_ptr_write
    118. 3.118. const_raw_ptr_comparison
    119. 3.119. const_replace
    120. 3.120. const_result
    121. 3.121. const_result_drop
    122. 3.122. const_size_of_val
    123. 3.123. const_size_of_val_raw
    124. 3.124. const_slice_first_last
    125. 3.125. const_slice_from_mut_ptr_range
    126. 3.126. const_slice_from_ptr_range
    127. 3.127. const_slice_from_raw_parts
    128. 3.128. const_slice_from_ref
    129. 3.129. const_slice_index
    130. 3.130. const_slice_ptr_len
    131. 3.131. const_socketaddr
    132. 3.132. const_str_from_utf8
    133. 3.133. const_str_from_utf8_unchecked_mut
    134. 3.134. const_swap
    135. 3.135. const_transmute_copy
    136. 3.136. const_type_id
    137. 3.137. const_type_name
    138. 3.138. const_unsafecell_get_mut
    139. 3.139. const_weak_new
    140. 3.140. container_error_extra
    141. 3.141. control_flow_enum
    142. 3.142. convert_float_to_int
    143. 3.143. core_c_str
    144. 3.144. core_ffi_c
    145. 3.145. core_intrinsics
    146. 3.146. core_panic
    147. 3.147. core_private_bignum
    148. 3.148. core_private_diy_float
    149. 3.149. cow_is_borrowed
    150. 3.150. cstr_from_bytes_until_nul
    151. 3.151. cstr_internals
    152. 3.152. cursor_remaining
    153. 3.153. deadline_api
    154. 3.154. dec2flt
    155. 3.155. default_free_fn
    156. 3.156. derive_clone_copy
    157. 3.157. derive_eq
    158. 3.158. dir_entry_ext2
    159. 3.159. discriminant_kind
    160. 3.160. dispatch_from_dyn
    161. 3.161. div_duration
    162. 3.162. downcast_unchecked
    163. 3.163. drain_filter
    164. 3.164. duration_checked_float
    165. 3.165. duration_constants
    166. 3.166. duration_consts_float
    167. 3.167. edition_panic
    168. 3.168. entry_insert
    169. 3.169. error_iter
    170. 3.170. error_reporter
    171. 3.171. error_type_id
    172. 3.172. exact_size_is_empty
    173. 3.173. exit_status_error
    174. 3.174. exitcode_exit_method
    175. 3.175. extend_one
    176. 3.176. fd
    177. 3.177. fd_read
    178. 3.178. float_minimum_maximum
    179. 3.179. flt2dec
    180. 3.180. fmt_internals
    181. 3.181. fn_traits
    182. 3.182. forget_unsized
    183. 3.183. format_args_nl
    184. 3.184. fs_try_exists
    185. 3.185. future_join
    186. 3.186. future_poll_fn
    187. 3.187. gen_future
    188. 3.188. generator_trait
    189. 3.189. generic_assert_internals
    190. 3.190. get_mut_unchecked
    191. 3.191. hash_drain_filter
    192. 3.192. hash_raw_entry
    193. 3.193. hash_set_entry
    194. 3.194. hasher_prefixfree_extras
    195. 3.195. hashmap_internals
    196. 3.196. hint_must_use
    197. 3.197. inplace_iteration
    198. 3.198. int_error_internals
    199. 3.199. int_log
    200. 3.200. int_roundings
    201. 3.201. integer_atomics
    202. 3.202. internal_output_capture
    203. 3.203. into_future
    204. 3.204. io_error_more
    205. 3.205. io_error_other
    206. 3.206. io_error_uncategorized
    207. 3.207. io_read_to_string
    208. 3.208. io_slice_advance
    209. 3.209. ip
    210. 3.210. is_some_with
    211. 3.211. is_sorted
    212. 3.212. iter_advance_by
    213. 3.213. iter_collect_into
    214. 3.214. iter_from_generator
    215. 3.215. iter_intersperse
    216. 3.216. iter_is_partitioned
    217. 3.217. iter_order_by
    218. 3.218. iter_partition_in_place
    219. 3.219. iterator_try_collect
    220. 3.220. iterator_try_reduce
    221. 3.221. layout_for_ptr
    222. 3.222. liballoc_internals
    223. 3.223. libstd_sys_internals
    224. 3.224. libstd_thread_internals
    225. 3.225. linked_list_cursors
    226. 3.226. linked_list_remove
    227. 3.227. linux_pidfd
    228. 3.228. local_key_cell_methods
    229. 3.229. log_syntax
    230. 3.230. main_separator_str
    231. 3.231. map_entry_replace
    232. 3.232. map_first_last
    233. 3.233. map_many_mut
    234. 3.234. map_try_insert
    235. 3.235. maybe_uninit_array_assume_init
    236. 3.236. maybe_uninit_as_bytes
    237. 3.237. maybe_uninit_slice
    238. 3.238. maybe_uninit_uninit_array
    239. 3.239. maybe_uninit_write_slice
    240. 3.240. mem_copy_fn
    241. 3.241. mixed_integer_ops
    242. 3.242. mutex_unlock
    243. 3.243. mutex_unpoison
    244. 3.244. new_uninit
    245. 3.245. nonnull_slice_from_raw_parts
    246. 3.246. nonzero_bits
    247. 3.247. nonzero_min_max
    248. 3.248. nonzero_ops
    249. 3.249. numfmt
    250. 3.250. once_cell
    251. 3.251. one_sided_range
    252. 3.252. option_get_or_insert_default
    253. 3.253. option_result_contains
    254. 3.254. option_zip
    255. 3.255. panic_abort
    256. 3.256. panic_always_abort
    257. 3.257. panic_backtrace_config
    258. 3.258. panic_can_unwind
    259. 3.259. panic_info_message
    260. 3.260. panic_internals
    261. 3.261. panic_unwind
    262. 3.262. panic_update_hook
    263. 3.263. path_file_prefix
    264. 3.264. pattern
    265. 3.265. peer_credentials_unix_socket
    266. 3.266. pin_deref_mut
    267. 3.267. pin_macro
    268. 3.268. pointer_byte_offsets
    269. 3.269. pointer_is_aligned
    270. 3.270. poll_ready
    271. 3.271. portable_simd
    272. 3.272. prelude_2024
    273. 3.273. print_internals
    274. 3.274. proc_macro_def_site
    275. 3.275. proc_macro_diagnostic
    276. 3.276. proc_macro_expand
    277. 3.277. proc_macro_internals
    278. 3.278. proc_macro_quote
    279. 3.279. proc_macro_span
    280. 3.280. proc_macro_span_shrink
    281. 3.281. proc_macro_tracked_env
    282. 3.282. process_exitcode_internals
    283. 3.283. process_internals
    284. 3.284. process_set_process_group
    285. 3.285. profiler_runtime_lib
    286. 3.286. provide_any
    287. 3.287. ptr_as_uninit
    288. 3.288. ptr_const_cast
    289. 3.289. ptr_internals
    290. 3.290. ptr_metadata
    291. 3.291. ptr_sub_ptr
    292. 3.292. ptr_to_from_bits
    293. 3.293. pub_crate_should_not_need_unstable_attr
    294. 3.294. raw_os_nonzero
    295. 3.295. raw_slice_split
    296. 3.296. raw_vec_internals
    297. 3.297. read_buf
    298. 3.298. ready_macro
    299. 3.299. receiver_trait
    300. 3.300. restricted_std
    301. 3.301. result_contains_err
    302. 3.302. result_flattening
    303. 3.303. result_into_ok_or_err
    304. 3.304. result_option_inspect
    305. 3.305. round_char_boundary
    306. 3.306. rt
    307. 3.307. saturating_int_assign_impl
    308. 3.308. saturating_int_impl
    309. 3.309. sealed
    310. 3.310. seek_stream_len
    311. 3.311. set_ptr_value
    312. 3.312. setgroups
    313. 3.313. sgx_platform
    314. 3.314. slice_as_chunks
    315. 3.315. slice_concat_ext
    316. 3.316. slice_concat_trait
    317. 3.317. slice_flatten
    318. 3.318. slice_from_ptr_range
    319. 3.319. slice_group_by
    320. 3.320. slice_index_methods
    321. 3.321. slice_internals
    322. 3.322. slice_iter_mut_as_mut_slice
    323. 3.323. slice_partition_dedup
    324. 3.324. slice_pattern
    325. 3.325. slice_ptr_get
    326. 3.326. slice_ptr_len
    327. 3.327. slice_range
    328. 3.328. slice_split_at_unchecked
    329. 3.329. slice_swap_unchecked
    330. 3.330. slice_take
    331. 3.331. solid_ext
    332. 3.332. sort_internals
    333. 3.333. split_array
    334. 3.334. split_as_slice
    335. 3.335. std_internals
    336. 3.336. stdio_makes_pipe
    337. 3.337. stdsimd
    338. 3.338. step_trait
    339. 3.339. str_internals
    340. 3.340. str_split_as_str
    341. 3.341. str_split_inclusive_as_str
    342. 3.342. str_split_whitespace_as_str
    343. 3.343. string_extend_from_within
    344. 3.344. string_remove_matches
    345. 3.345. sync_unsafe_cell
    346. 3.346. tcp_linger
    347. 3.347. tcplistener_into_incoming
    348. 3.348. test
    349. 3.349. thin_box
    350. 3.350. thread_id_value
    351. 3.351. thread_local_internals
    352. 3.352. thread_spawn_unchecked
    353. 3.353. trace_macros
    354. 3.354. track_path
    355. 3.355. trusted_len
    356. 3.356. trusted_random_access
    357. 3.357. trusted_step
    358. 3.358. try_find
    359. 3.359. try_reserve_kind
    360. 3.360. try_trait_v2
    361. 3.361. try_trait_v2_residual
    362. 3.362. try_trait_v2_yeet
    363. 3.363. type_name_of_val
    364. 3.364. unchecked_math
    365. 3.365. unicode_internals
    366. 3.366. unix_chown
    367. 3.367. unix_socket_abstract
    368. 3.368. unix_socket_ancillary_data
    369. 3.369. unix_socket_peek
    370. 3.370. unsize
    371. 3.371. unwrap_infallible
    372. 3.372. unzip_option
    373. 3.373. update_panic_count
    374. 3.374. utf16_extra
    375. 3.375. utf16_extra_const
    376. 3.376. variant_count
    377. 3.377. vec_into_raw_parts
    378. 3.378. vec_split_at_spare
    379. 3.379. waker_getters
    380. 3.380. wasi_ext
    381. 3.381. windows_by_handle
    382. 3.382. windows_c
    383. 3.383. windows_file_type_ext
    384. 3.384. windows_handle
    385. 3.385. windows_net
    386. 3.386. windows_process_extensions_async_pipes
    387. 3.387. windows_process_extensions_force_quotes
    388. 3.388. windows_process_extensions_main_thread_handle
    389. 3.389. windows_stdio
    390. 3.390. wrapping_int_impl
    391. 3.391. wrapping_next_power_of_two
    392. 3.392. write_all_vectored
    393. 3.393. yeet_desugar_details

The Rust Unstable Book

Language features