1. The Unstable Book
  2. 1. Compiler flags
    1. 1.1. codegen_backend
    2. 1.2. control_flow_guard
    3. 1.3. emit_stack_sizes
    4. 1.4. profile
    5. 1.5. report_time
    6. 1.6. sanitizer
    7. 1.7. self_profile
    8. 1.8. self_profile_events
    9. 1.9. source_based_code_coverage
    10. 1.10. src_hash_algorithm
    11. 1.11. strip
    12. 1.12. tls_model
    13. 1.13. unsound_mir_opts
  3. 2. Language features
    1. 2.1. aarch64_target_feature
    2. 2.2. abi_amdgpu_kernel
    3. 2.3. abi_avr_interrupt
    4. 2.4. abi_efiapi
    5. 2.5. abi_msp430_interrupt
    6. 2.6. abi_ptx
    7. 2.7. abi_thiscall
    8. 2.8. abi_unadjusted
    9. 2.9. abi_vectorcall
    10. 2.10. abi_x86_interrupt
    11. 2.11. adx_target_feature
    12. 2.12. alloc_error_handler
    13. 2.13. allocator_internals
    14. 2.14. allow_fail
    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. associated_type_bounds
    21. 2.21. associated_type_defaults
    22. 2.22. async_closure
    23. 2.23. avx512_target_feature
    24. 2.24. bindings_after_at
    25. 2.25. box_patterns
    26. 2.26. box_syntax
    27. 2.27. c_variadic
    28. 2.28. cfg_panic
    29. 2.29. cfg_sanitize
    30. 2.30. cfg_target_has_atomic
    31. 2.31. cfg_target_thread_local
    32. 2.32. cfg_version
    33. 2.33. cmpxchg16b_target_feature
    34. 2.34. cmse_nonsecure_entry
    35. 2.35. compiler_builtins
    36. 2.36. const_eval_limit
    37. 2.37. const_evaluatable_checked
    38. 2.38. const_extern_fn
    39. 2.39. const_fn
    40. 2.40. const_fn_floating_point_arithmetic
    41. 2.41. const_fn_fn_ptr_basics
    42. 2.42. const_fn_transmute
    43. 2.43. const_fn_union
    44. 2.44. const_generics
    45. 2.45. const_impl_trait
    46. 2.46. const_in_array_repeat_expressions
    47. 2.47. const_mut_refs
    48. 2.48. const_panic
    49. 2.49. const_precise_live_drops
    50. 2.50. const_raw_ptr_deref
    51. 2.51. const_raw_ptr_to_usize_cast
    52. 2.52. const_trait_bound_opt_out
    53. 2.53. const_trait_impl
    54. 2.54. crate_visibility_modifier
    55. 2.55. custom_inner_attributes
    56. 2.56. custom_test_frameworks
    57. 2.57. decl_macro
    58. 2.58. default_alloc_error_handler
    59. 2.59. default_type_parameter_fallback
    60. 2.60. destructuring_assignment
    61. 2.61. doc_cfg
    62. 2.62. doc_keyword
    63. 2.63. doc_masked
    64. 2.64. doc_spotlight
    65. 2.65. dropck_eyepatch
    66. 2.66. ermsb_target_feature
    67. 2.67. exclusive_range_pattern
    68. 2.68. exhaustive_patterns
    69. 2.69. extern_types
    70. 2.70. external_doc
    71. 2.71. f16c_target_feature
    72. 2.72. ffi_const
    73. 2.73. ffi_pure
    74. 2.74. ffi_returns_twice
    75. 2.75. format_args_capture
    76. 2.76. fundamental
    77. 2.77. generators
    78. 2.78. generic_associated_types
    79. 2.79. half_open_range_patterns
    80. 2.80. hexagon_target_feature
    81. 2.81. if_let_guard
    82. 2.82. impl_trait_in_bindings
    83. 2.83. in_band_lifetimes
    84. 2.84. infer_static_outlives_requirements
    85. 2.85. inline_const
    86. 2.86. intrinsics
    87. 2.87. isa_attribute
    88. 2.88. label_break_value
    89. 2.89. lang_items
    90. 2.90. lazy_normalization_consts
    91. 2.91. let_chains
    92. 2.92. link_args
    93. 2.93. link_cfg
    94. 2.94. link_llvm_intrinsics
    95. 2.95. linkage
    96. 2.96. lint_reasons
    97. 2.97. main
    98. 2.98. marker_trait_attr
    99. 2.99. member_constraints
    100. 2.100. min_const_generics
    101. 2.101. min_specialization
    102. 2.102. mips_target_feature
    103. 2.103. movbe_target_feature
    104. 2.104. naked_functions
    105. 2.105. needs_panic_runtime
    106. 2.106. negative_impls
    107. 2.107. never_type
    108. 2.108. never_type_fallback
    109. 2.109. nll
    110. 2.110. no_core
    111. 2.111. no_niche
    112. 2.112. no_sanitize
    113. 2.113. non_ascii_idents
    114. 2.114. object_safe_for_dispatch
    115. 2.115. omit_gdb_pretty_printer_section
    116. 2.116. optimize_attribute
    117. 2.117. optin_builtin_traits
    118. 2.118. or_patterns
    119. 2.119. panic_runtime
    120. 2.120. platform_intrinsics
    121. 2.121. plugin
    122. 2.122. plugin_registrar
    123. 2.123. powerpc_target_feature
    124. 2.124. precise_pointer_size_matching
    125. 2.125. prelude_import
    126. 2.126. proc_macro_hygiene
    127. 2.127. profiler_runtime
    128. 2.128. raw_dylib
    129. 2.129. raw_ref_op
    130. 2.130. register_attr
    131. 2.131. register_tool
    132. 2.132. repr_simd
    133. 2.133. repr128
    134. 2.134. riscv_target_feature
    135. 2.135. rtm_target_feature
    136. 2.136. rustc_allow_const_fn_unstable
    137. 2.137. rustc_attrs
    138. 2.138. rustc_private
    139. 2.139. simd_ffi
    140. 2.140. specialization
    141. 2.141. sse4a_target_feature
    142. 2.142. staged_api
    143. 2.143. start
    144. 2.144. static_nobundle
    145. 2.145. stmt_expr_attributes
    146. 2.146. structural_match
    147. 2.147. target_feature_11
    148. 2.148. tbm_target_feature
    149. 2.149. test_2018_feature
    150. 2.150. thread_local
    151. 2.151. trait_alias
    152. 2.152. transparent_unions
    153. 2.153. trivial_bounds
    154. 2.154. try_blocks
    155. 2.155. type_alias_impl_trait
    156. 2.156. type_ascription
    157. 2.157. unboxed_closures
    158. 2.158. unsafe_block_in_unsafe_fn
    159. 2.159. unsized_fn_params
    160. 2.160. unsized_locals
    161. 2.161. unsized_tuple_coercion
    162. 2.162. untagged_unions
    163. 2.163. unwind_attributes
    164. 2.164. wasm_target_feature
  4. 3. Library Features
    1. 3.1. alloc_error_hook
    2. 3.2. alloc_internals
    3. 3.3. alloc_layout_extra
    4. 3.4. alloc_prelude
    5. 3.5. allocator_api
    6. 3.6. arc_mutate_strong_count
    7. 3.7. arc_new_cyclic
    8. 3.8. array_chunks
    9. 3.9. array_error_internals
    10. 3.10. array_from_ref
    11. 3.11. array_map
    12. 3.12. array_methods
    13. 3.13. array_value_iter
    14. 3.14. array_windows
    15. 3.15. asm
    16. 3.16. assoc_char_consts
    17. 3.17. assoc_char_funcs
    18. 3.18. atomic_fetch_update
    19. 3.19. atomic_from_mut
    20. 3.20. atomic_mut_ptr
    21. 3.21. available_concurrency
    22. 3.22. backtrace
    23. 3.23. binary_heap_drain_sorted
    24. 3.24. binary_heap_into_iter_sorted
    25. 3.25. binary_heap_retain
    26. 3.26. bool_to_option
    27. 3.27. bound_cloned
    28. 3.28. box_into_boxed_slice
    29. 3.29. box_into_pin
    30. 3.30. btree_drain_filter
    31. 3.31. bufreader_seek_relative
    32. 3.32. c_void_variant
    33. 3.33. can_vector
    34. 3.34. cell_leak
    35. 3.35. cell_update
    36. 3.36. cfg_accessible
    37. 3.37. char_error_internals
    38. 3.38. char_internals
    39. 3.39. clamp
    40. 3.40. cmp_min_max_by
    41. 3.41. coerce_unsized
    42. 3.42. command_access
    43. 3.43. concat_idents
    44. 3.44. const_align_of_val
    45. 3.45. const_alloc_layout
    46. 3.46. const_assume
    47. 3.47. const_btree_new
    48. 3.48. const_caller_location
    49. 3.49. const_cell_into_inner
    50. 3.50. const_checked_int_methods
    51. 3.51. const_cow_is_borrowed
    52. 3.52. const_cstr_unchecked
    53. 3.53. const_cttz
    54. 3.54. const_discriminant
    55. 3.55. const_euclidean_int_methods
    56. 3.56. const_float_bits_conv
    57. 3.57. const_float_classify
    58. 3.58. const_int_pow
    59. 3.59. const_int_unchecked_arith
    60. 3.60. const_io_structs
    61. 3.61. const_ip
    62. 3.62. const_ipv4
    63. 3.63. const_ipv6
    64. 3.64. const_likely
    65. 3.65. const_maybe_uninit_as_ptr
    66. 3.66. const_nonnull_slice_from_raw_parts
    67. 3.67. const_option
    68. 3.68. const_overflowing_int_methods
    69. 3.69. const_pin
    70. 3.70. const_pref_align_of
    71. 3.71. const_ptr_is_null
    72. 3.72. const_ptr_offset
    73. 3.73. const_ptr_offset_from
    74. 3.74. const_raw_ptr_comparison
    75. 3.75. const_size_of_val
    76. 3.76. const_slice_from_raw_parts
    77. 3.77. const_slice_ptr_len
    78. 3.78. const_str_from_utf8_unchecked
    79. 3.79. const_type_id
    80. 3.80. const_type_name
    81. 3.81. const_unreachable_unchecked
    82. 3.82. const_wrapping_int_methods
    83. 3.83. constctlz
    84. 3.84. container_error_extra
    85. 3.85. control_flow_enum
    86. 3.86. convert_float_to_int
    87. 3.87. core_intrinsics
    88. 3.88. core_panic
    89. 3.89. core_private_bignum
    90. 3.90. core_private_diy_float
    91. 3.91. cow_is_borrowed
    92. 3.92. cstring_from_vec_with_nul
    93. 3.93. deadline_api
    94. 3.94. debug_non_exhaustive
    95. 3.95. dec2flt
    96. 3.96. default_free_fn
    97. 3.97. deque_range
    98. 3.98. derive_clone_copy
    99. 3.99. derive_eq
    100. 3.100. discriminant_kind
    101. 3.101. dispatch_from_dyn
    102. 3.102. div_duration
    103. 3.103. drain_filter
    104. 3.104. duration_constants
    105. 3.105. duration_consts_2
    106. 3.106. duration_saturating_ops
    107. 3.107. duration_zero
    108. 3.108. entry_insert
    109. 3.109. error_iter
    110. 3.110. error_type_id
    111. 3.111. exact_size_is_empty
    112. 3.112. extend_one
    113. 3.113. fd
    114. 3.114. fd_read
    115. 3.115. fixed_size_array
    116. 3.116. flt2dec
    117. 3.117. fmt_as_str
    118. 3.118. fmt_internals
    119. 3.119. fn_traits
    120. 3.120. foo
    121. 3.121. forget_unsized
    122. 3.122. format_args_nl
    123. 3.123. future_poll_fn
    124. 3.124. gen_future
    125. 3.125. generator_trait
    126. 3.126. get_mut_unchecked
    127. 3.127. global_asm
    128. 3.128. hash_drain_filter
    129. 3.129. hash_raw_entry
    130. 3.130. hash_set_entry
    131. 3.131. hashmap_internals
    132. 3.132. inplace_iteration
    133. 3.133. int_bits_const
    134. 3.134. int_error_internals
    135. 3.135. int_error_matching
    136. 3.136. integer_atomics
    137. 3.137. into_future
    138. 3.138. io_slice_advance
    139. 3.139. ip
    140. 3.140. is_sorted
    141. 3.141. iter_advance_by
    142. 3.142. iter_is_partitioned
    143. 3.143. iter_map_while
    144. 3.144. iter_order_by
    145. 3.145. iter_partition_in_place
    146. 3.146. iterator_fold_self
    147. 3.147. layout_for_ptr
    148. 3.148. liballoc_internals
    149. 3.149. libstd_io_internals
    150. 3.150. libstd_sys_internals
    151. 3.151. libstd_thread_internals
    152. 3.152. linked_list_cursors
    153. 3.153. linked_list_extras
    154. 3.154. linked_list_prepend
    155. 3.155. linked_list_remove
    156. 3.156. llvm_asm
    157. 3.157. log_syntax
    158. 3.158. map_entry_replace
    159. 3.159. map_first_last
    160. 3.160. map_into_keys_values
    161. 3.161. maybe_uninit_extra
    162. 3.162. maybe_uninit_ref
    163. 3.163. maybe_uninit_slice
    164. 3.164. maybe_uninit_uninit_array
    165. 3.165. new_uninit
    166. 3.166. nonnull_slice_from_raw_parts
    167. 3.167. num_as_ne_bytes
    168. 3.168. once_cell
    169. 3.169. once_poison
    170. 3.170. option_expect_none
    171. 3.171. option_insert
    172. 3.172. option_result_contains
    173. 3.173. option_unwrap_none
    174. 3.174. option_zip
    175. 3.175. or_insert_with_key
    176. 3.176. osstring_ascii
    177. 3.177. panic_abort
    178. 3.178. panic_any
    179. 3.179. panic_info_message
    180. 3.180. panic_internals
    181. 3.181. panic_unwind
    182. 3.182. partition_point
    183. 3.183. pattern
    184. 3.184. peekable_next_if
    185. 3.185. peer_credentials_unix_socket
    186. 3.186. pin_static_ref
    187. 3.187. poll_map
    188. 3.188. print_internals
    189. 3.189. proc_macro_def_site
    190. 3.190. proc_macro_diagnostic
    191. 3.191. proc_macro_internals
    192. 3.192. proc_macro_is_available
    193. 3.193. proc_macro_quote
    194. 3.194. proc_macro_span
    195. 3.195. proc_macro_tracked_env
    196. 3.196. process_exitcode_placeholder
    197. 3.197. process_internals
    198. 3.198. profiler_runtime_lib
    199. 3.199. ptr_as_uninit
    200. 3.200. ptr_internals
    201. 3.201. range_bounds_assert_len
    202. 3.202. raw
    203. 3.203. raw_ref_macros
    204. 3.204. raw_vec_internals
    205. 3.205. read_initializer
    206. 3.206. ready_macro
    207. 3.207. receiver_trait
    208. 3.208. refcell_take
    209. 3.209. result_cloned
    210. 3.210. result_contains_err
    211. 3.211. result_copied
    212. 3.212. result_flattening
    213. 3.213. rt
    214. 3.214. seek_convenience
    215. 3.215. set_ptr_value
    216. 3.216. set_stdio
    217. 3.217. sgx_platform
    218. 3.218. shrink_to
    219. 3.219. slice_as_chunks
    220. 3.220. slice_concat_ext
    221. 3.221. slice_concat_trait
    222. 3.222. slice_fill
    223. 3.223. slice_index_methods
    224. 3.224. slice_internals
    225. 3.225. slice_iter_mut_as_slice
    226. 3.226. slice_partition_at_index
    227. 3.227. slice_partition_dedup
    228. 3.228. slice_ptr_get
    229. 3.229. slice_ptr_len
    230. 3.230. slice_split_at_unchecked
    231. 3.231. slice_strip
    232. 3.232. sort_internals
    233. 3.233. split_inclusive
    234. 3.234. std_internals
    235. 3.235. stdsimd
    236. 3.236. step_trait
    237. 3.237. step_trait_ext
    238. 3.238. str_internals
    239. 3.239. str_split_as_str
    240. 3.240. str_split_inclusive_as_str
    241. 3.241. str_split_once
    242. 3.242. string_drain_as_str
    243. 3.243. termination_trait_lib
    244. 3.244. test
    245. 3.245. thread_id_value
    246. 3.246. thread_local_internals
    247. 3.247. thread_spawn_unchecked
    248. 3.248. toowned_clone_into
    249. 3.249. total_cmp
    250. 3.250. trace_macros
    251. 3.251. trusted_len
    252. 3.252. trusted_random_access
    253. 3.253. try_find
    254. 3.254. try_reserve
    255. 3.255. try_trait
    256. 3.256. type_name_of_val
    257. 3.257. unchecked_math
    258. 3.258. unicode_internals
    259. 3.259. unix_socket_peek
    260. 3.260. unsafe_cell_get_mut
    261. 3.261. unsafe_cell_raw_get
    262. 3.262. unsigned_abs
    263. 3.263. unsize
    264. 3.264. unwrap_infallible
    265. 3.265. update_panic_count
    266. 3.266. variant_count
    267. 3.267. vec_into_raw_parts
    268. 3.268. vec_remove_item
    269. 3.269. vec_spare_capacity
    270. 3.270. vecdeque_binary_search
    271. 3.271. wake_trait
    272. 3.272. wasi_ext
    273. 3.273. windows_by_handle
    274. 3.274. windows_c
    275. 3.275. windows_file_type_ext
    276. 3.276. windows_handle
    277. 3.277. windows_net
    278. 3.278. windows_stdio
    279. 3.279. with_options
    280. 3.280. wrapping_int_impl
    281. 3.281. wrapping_next_power_of_two
    282. 3.282. write_all_vectored

The Rust Unstable Book

Library Features