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. auto_traits
    24. 2.24. avx512_target_feature
    25. 2.25. bindings_after_at
    26. 2.26. box_patterns
    27. 2.27. box_syntax
    28. 2.28. c_variadic
    29. 2.29. capture_disjoint_fields
    30. 2.30. cfg_panic
    31. 2.31. cfg_sanitize
    32. 2.32. cfg_target_has_atomic
    33. 2.33. cfg_target_thread_local
    34. 2.34. cfg_version
    35. 2.35. cmpxchg16b_target_feature
    36. 2.36. cmse_nonsecure_entry
    37. 2.37. compiler_builtins
    38. 2.38. const_eval_limit
    39. 2.39. const_evaluatable_checked
    40. 2.40. const_extern_fn
    41. 2.41. const_fn
    42. 2.42. const_fn_floating_point_arithmetic
    43. 2.43. const_fn_fn_ptr_basics
    44. 2.44. const_fn_transmute
    45. 2.45. const_fn_union
    46. 2.46. const_generics
    47. 2.47. const_impl_trait
    48. 2.48. const_in_array_repeat_expressions
    49. 2.49. const_mut_refs
    50. 2.50. const_panic
    51. 2.51. const_precise_live_drops
    52. 2.52. const_raw_ptr_deref
    53. 2.53. const_raw_ptr_to_usize_cast
    54. 2.54. const_trait_bound_opt_out
    55. 2.55. const_trait_impl
    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. destructuring_assignment
    63. 2.63. doc_cfg
    64. 2.64. doc_keyword
    65. 2.65. doc_masked
    66. 2.66. doc_spotlight
    67. 2.67. dropck_eyepatch
    68. 2.68. ermsb_target_feature
    69. 2.69. exclusive_range_pattern
    70. 2.70. exhaustive_patterns
    71. 2.71. extended_key_value_attributes
    72. 2.72. extern_types
    73. 2.73. external_doc
    74. 2.74. f16c_target_feature
    75. 2.75. ffi_const
    76. 2.76. ffi_pure
    77. 2.77. ffi_returns_twice
    78. 2.78. format_args_capture
    79. 2.79. fundamental
    80. 2.80. generators
    81. 2.81. generic_associated_types
    82. 2.82. half_open_range_patterns
    83. 2.83. hexagon_target_feature
    84. 2.84. if_let_guard
    85. 2.85. impl_trait_in_bindings
    86. 2.86. in_band_lifetimes
    87. 2.87. infer_static_outlives_requirements
    88. 2.88. inline_const
    89. 2.89. intrinsics
    90. 2.90. isa_attribute
    91. 2.91. label_break_value
    92. 2.92. lang_items
    93. 2.93. lazy_normalization_consts
    94. 2.94. let_chains
    95. 2.95. link_args
    96. 2.96. link_cfg
    97. 2.97. link_llvm_intrinsics
    98. 2.98. linkage
    99. 2.99. lint_reasons
    100. 2.100. main
    101. 2.101. marker_trait_attr
    102. 2.102. member_constraints
    103. 2.103. min_const_generics
    104. 2.104. min_specialization
    105. 2.105. mips_target_feature
    106. 2.106. movbe_target_feature
    107. 2.107. naked_functions
    108. 2.108. needs_panic_runtime
    109. 2.109. negative_impls
    110. 2.110. never_type
    111. 2.111. never_type_fallback
    112. 2.112. nll
    113. 2.113. no_core
    114. 2.114. no_niche
    115. 2.115. no_sanitize
    116. 2.116. non_ascii_idents
    117. 2.117. object_safe_for_dispatch
    118. 2.118. omit_gdb_pretty_printer_section
    119. 2.119. optimize_attribute
    120. 2.120. or_patterns
    121. 2.121. panic_runtime
    122. 2.122. platform_intrinsics
    123. 2.123. plugin
    124. 2.124. plugin_registrar
    125. 2.125. powerpc_target_feature
    126. 2.126. precise_pointer_size_matching
    127. 2.127. prelude_import
    128. 2.128. proc_macro_hygiene
    129. 2.129. profiler_runtime
    130. 2.130. raw_dylib
    131. 2.131. raw_ref_op
    132. 2.132. register_attr
    133. 2.133. register_tool
    134. 2.134. repr_simd
    135. 2.135. repr128
    136. 2.136. riscv_target_feature
    137. 2.137. rtm_target_feature
    138. 2.138. rustc_allow_const_fn_unstable
    139. 2.139. rustc_attrs
    140. 2.140. rustc_private
    141. 2.141. simd_ffi
    142. 2.142. specialization
    143. 2.143. sse4a_target_feature
    144. 2.144. staged_api
    145. 2.145. start
    146. 2.146. static_nobundle
    147. 2.147. stmt_expr_attributes
    148. 2.148. structural_match
    149. 2.149. target_feature_11
    150. 2.150. tbm_target_feature
    151. 2.151. test_2018_feature
    152. 2.152. thread_local
    153. 2.153. trait_alias
    154. 2.154. transparent_unions
    155. 2.155. trivial_bounds
    156. 2.156. try_blocks
    157. 2.157. type_alias_impl_trait
    158. 2.158. type_ascription
    159. 2.159. unboxed_closures
    160. 2.160. unsafe_block_in_unsafe_fn
    161. 2.161. unsized_fn_params
    162. 2.162. unsized_locals
    163. 2.163. unsized_tuple_coercion
    164. 2.164. untagged_unions
    165. 2.165. unwind_attributes
    166. 2.166. 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_value_iter_slice
    15. 3.15. array_windows
    16. 3.16. array_zip
    17. 3.17. asm
    18. 3.18. assoc_char_consts
    19. 3.19. assoc_char_funcs
    20. 3.20. atomic_fetch_update
    21. 3.21. atomic_from_mut
    22. 3.22. atomic_mut_ptr
    23. 3.23. available_concurrency
    24. 3.24. backtrace
    25. 3.25. binary_heap_drain_sorted
    26. 3.26. binary_heap_into_iter_sorted
    27. 3.27. binary_heap_retain
    28. 3.28. bool_to_option
    29. 3.29. bound_cloned
    30. 3.30. box_into_boxed_slice
    31. 3.31. box_into_pin
    32. 3.32. btree_drain_filter
    33. 3.33. btree_retain
    34. 3.34. bufreader_seek_relative
    35. 3.35. c_void_variant
    36. 3.36. can_vector
    37. 3.37. cell_leak
    38. 3.38. cell_update
    39. 3.39. cfg_accessible
    40. 3.40. char_error_internals
    41. 3.41. char_internals
    42. 3.42. cmp_min_max_by
    43. 3.43. coerce_unsized
    44. 3.44. command_access
    45. 3.45. concat_idents
    46. 3.46. const_align_of_val
    47. 3.47. const_alloc_layout
    48. 3.48. const_assert_type
    49. 3.49. const_assume
    50. 3.50. const_btree_new
    51. 3.51. const_caller_location
    52. 3.52. const_cell_into_inner
    53. 3.53. const_checked_int_methods
    54. 3.54. const_cow_is_borrowed
    55. 3.55. const_cstr_unchecked
    56. 3.56. const_cttz
    57. 3.57. const_discriminant
    58. 3.58. const_euclidean_int_methods
    59. 3.59. const_float_bits_conv
    60. 3.60. const_float_classify
    61. 3.61. const_heap
    62. 3.62. const_int_unchecked_arith
    63. 3.63. const_io_structs
    64. 3.64. const_ip
    65. 3.65. const_ipv4
    66. 3.66. const_ipv6
    67. 3.67. const_likely
    68. 3.68. const_maybe_uninit_as_ptr
    69. 3.69. const_maybe_uninit_assume_init
    70. 3.70. const_nonnull_slice_from_raw_parts
    71. 3.71. const_option
    72. 3.72. const_overflowing_int_methods
    73. 3.73. const_pin
    74. 3.74. const_pref_align_of
    75. 3.75. const_ptr_is_null
    76. 3.76. const_ptr_offset
    77. 3.77. const_ptr_offset_from
    78. 3.78. const_raw_ptr_comparison
    79. 3.79. const_size_of_val
    80. 3.80. const_slice_from_raw_parts
    81. 3.81. const_slice_ptr_len
    82. 3.82. const_str_from_utf8_unchecked
    83. 3.83. const_type_id
    84. 3.84. const_type_name
    85. 3.85. const_unreachable_unchecked
    86. 3.86. const_wrapping_int_methods
    87. 3.87. container_error_extra
    88. 3.88. control_flow_enum
    89. 3.89. convert_float_to_int
    90. 3.90. core_intrinsics
    91. 3.91. core_panic
    92. 3.92. core_private_bignum
    93. 3.93. core_private_diy_float
    94. 3.94. cow_is_borrowed
    95. 3.95. cstring_from_vec_with_nul
    96. 3.96. deadline_api
    97. 3.97. debug_non_exhaustive
    98. 3.98. dec2flt
    99. 3.99. default_free_fn
    100. 3.100. deque_range
    101. 3.101. derive_clone_copy
    102. 3.102. derive_eq
    103. 3.103. discriminant_kind
    104. 3.104. dispatch_from_dyn
    105. 3.105. div_duration
    106. 3.106. drain_filter
    107. 3.107. duration_constants
    108. 3.108. duration_consts_2
    109. 3.109. duration_saturating_ops
    110. 3.110. duration_zero
    111. 3.111. entry_insert
    112. 3.112. error_iter
    113. 3.113. error_type_id
    114. 3.114. exact_size_is_empty
    115. 3.115. extend_one
    116. 3.116. fd
    117. 3.117. fd_read
    118. 3.118. fixed_size_array
    119. 3.119. flt2dec
    120. 3.120. fmt_as_str
    121. 3.121. fmt_internals
    122. 3.122. fn_traits
    123. 3.123. foo
    124. 3.124. forget_unsized
    125. 3.125. format_args_nl
    126. 3.126. future_poll_fn
    127. 3.127. gen_future
    128. 3.128. generator_trait
    129. 3.129. get_mut_unchecked
    130. 3.130. global_asm
    131. 3.131. hash_drain_filter
    132. 3.132. hash_raw_entry
    133. 3.133. hash_set_entry
    134. 3.134. hashmap_internals
    135. 3.135. inplace_iteration
    136. 3.136. int_bits_const
    137. 3.137. int_error_internals
    138. 3.138. int_error_matching
    139. 3.139. integer_atomics
    140. 3.140. internal_output_capture
    141. 3.141. into_future
    142. 3.142. io_into_inner_error_parts
    143. 3.143. io_slice_advance
    144. 3.144. ip
    145. 3.145. is_sorted
    146. 3.146. is_subnormal
    147. 3.147. iter_advance_by
    148. 3.148. iter_is_partitioned
    149. 3.149. iter_map_while
    150. 3.150. iter_order_by
    151. 3.151. iter_partition_in_place
    152. 3.152. iterator_fold_self
    153. 3.153. layout_for_ptr
    154. 3.154. liballoc_internals
    155. 3.155. libstd_sys_internals
    156. 3.156. libstd_thread_internals
    157. 3.157. linked_list_cursors
    158. 3.158. linked_list_prepend
    159. 3.159. linked_list_remove
    160. 3.160. llvm_asm
    161. 3.161. log_syntax
    162. 3.162. map_entry_replace
    163. 3.163. map_first_last
    164. 3.164. map_into_keys_values
    165. 3.165. maybe_uninit_extra
    166. 3.166. maybe_uninit_ref
    167. 3.167. maybe_uninit_slice
    168. 3.168. maybe_uninit_uninit_array
    169. 3.169. maybe_uninit_write_slice
    170. 3.170. new_uninit
    171. 3.171. nonnull_slice_from_raw_parts
    172. 3.172. nonzero_leading_trailing_zeros
    173. 3.173. num_as_ne_bytes
    174. 3.174. once_cell
    175. 3.175. once_poison
    176. 3.176. option_expect_none
    177. 3.177. option_insert
    178. 3.178. option_result_contains
    179. 3.179. option_unwrap_none
    180. 3.180. option_zip
    181. 3.181. ordering_helpers
    182. 3.182. osstring_ascii
    183. 3.183. panic_abort
    184. 3.184. panic_any
    185. 3.185. panic_info_message
    186. 3.186. panic_internals
    187. 3.187. panic_unwind
    188. 3.188. partition_point
    189. 3.189. pattern
    190. 3.190. peekable_next_if
    191. 3.191. peekable_peek_mut
    192. 3.192. peer_credentials_unix_socket
    193. 3.193. pin_static_ref
    194. 3.194. poll_map
    195. 3.195. print_internals
    196. 3.196. proc_macro_def_site
    197. 3.197. proc_macro_diagnostic
    198. 3.198. proc_macro_internals
    199. 3.199. proc_macro_is_available
    200. 3.200. proc_macro_quote
    201. 3.201. proc_macro_span
    202. 3.202. proc_macro_tracked_env
    203. 3.203. process_exitcode_placeholder
    204. 3.204. process_internals
    205. 3.205. profiler_runtime_lib
    206. 3.206. ptr_as_uninit
    207. 3.207. ptr_internals
    208. 3.208. range_bounds_assert_len
    209. 3.209. raw
    210. 3.210. raw_ref_macros
    211. 3.211. raw_vec_internals
    212. 3.212. read_initializer
    213. 3.213. ready_macro
    214. 3.214. receiver_trait
    215. 3.215. restricted_std
    216. 3.216. result_cloned
    217. 3.217. result_contains_err
    218. 3.218. result_copied
    219. 3.219. result_flattening
    220. 3.220. rt
    221. 3.221. seek_convenience
    222. 3.222. set_ptr_value
    223. 3.223. sgx_platform
    224. 3.224. shrink_to
    225. 3.225. slice_as_chunks
    226. 3.226. slice_concat_ext
    227. 3.227. slice_concat_trait
    228. 3.228. slice_fill_with
    229. 3.229. slice_index_methods
    230. 3.230. slice_internals
    231. 3.231. slice_iter_mut_as_slice
    232. 3.232. slice_partition_at_index
    233. 3.233. slice_partition_dedup
    234. 3.234. slice_ptr_get
    235. 3.235. slice_ptr_len
    236. 3.236. slice_split_at_unchecked
    237. 3.237. slice_strip
    238. 3.238. sort_internals
    239. 3.239. split_inclusive
    240. 3.240. std_internals
    241. 3.241. stdsimd
    242. 3.242. step_trait
    243. 3.243. step_trait_ext
    244. 3.244. str_internals
    245. 3.245. str_split_as_str
    246. 3.246. str_split_inclusive_as_str
    247. 3.247. str_split_once
    248. 3.248. string_drain_as_str
    249. 3.249. termination_trait_lib
    250. 3.250. test
    251. 3.251. thread_id_value
    252. 3.252. thread_local_internals
    253. 3.253. thread_spawn_unchecked
    254. 3.254. toowned_clone_into
    255. 3.255. total_cmp
    256. 3.256. trace_macros
    257. 3.257. trusted_len
    258. 3.258. trusted_random_access
    259. 3.259. try_find
    260. 3.260. try_reserve
    261. 3.261. try_trait
    262. 3.262. type_name_of_val
    263. 3.263. unchecked_math
    264. 3.264. unicode_internals
    265. 3.265. unix_socket_ancillary_data
    266. 3.266. unix_socket_peek
    267. 3.267. unsafe_cell_raw_get
    268. 3.268. unsigned_abs
    269. 3.269. unsize
    270. 3.270. unwrap_infallible
    271. 3.271. update_panic_count
    272. 3.272. variant_count
    273. 3.273. vec_into_raw_parts
    274. 3.274. vec_remove_item
    275. 3.275. vec_spare_capacity
    276. 3.276. vecdeque_binary_search
    277. 3.277. wake_trait
    278. 3.278. wasi_ext
    279. 3.279. windows_by_handle
    280. 3.280. windows_c
    281. 3.281. windows_file_type_ext
    282. 3.282. windows_handle
    283. 3.283. windows_net
    284. 3.284. windows_stdio
    285. 3.285. with_options
    286. 3.286. wrapping_int_impl
    287. 3.287. wrapping_next_power_of_two
    288. 3.288. write_all_vectored

The Rust Unstable Book

Library Features