1. The Unstable Book
  2. Compiler environment variables
    1. COLORTERM
    2. QNX_TARGET
    3. RUSTC_BLESS
    4. RUSTC_BOOTSTRAP
    5. RUSTC_BREAK_ON_ICE
    6. RUSTC_CTFE_BACKTRACE
    7. RUSTC_FORCE_RUSTC_VERSION
    8. RUSTC_GRAPHVIZ_FONT
    9. RUSTC_ICE
    10. RUSTC_LOG
    11. RUSTC_OVERRIDE_VERSION_STRING
    12. RUSTC_WINDOWS_RC
    13. RUST_BACKTRACE
    14. RUST_DEP_GRAPH
    15. RUST_DEP_GRAPH_FILTER
    16. RUST_FORBID_DEP_GRAPH_EDGE
    17. RUST_MIN_STACK
    18. RUST_TARGET_PATH
    19. SDKROOT
    20. TERM
    21. UNSTABLE_RUSTDOC_TEST_LINE
    22. UNSTABLE_RUSTDOC_TEST_PATH
  3. Compiler flags
    1. allow_features
    2. annotate_moves
    3. autodiff
    4. branch_protection
    5. cache_proc_macros
    6. cf_protection
    7. codegen_backend
    8. codegen_options
    9. codegen_source_order
    10. control_flow_guard
    11. coverage_options
    12. crate_attr
    13. debug_info_for_profiling
    14. debug_info_type_line_numbers
    15. default_visibility
    16. direct_access_external_data
    17. dump_mono_stats
    18. dump_mono_stats_format
    19. dylib_lto
    20. eagerly_emit_delayed_bugs
    21. embed_metadata
    22. embed_source
    23. emit_stack_sizes
    24. emscripten_wasm_eh
    25. env_set
    26. export_executable_symbols
    27. extern_options
    28. external_clangrt
    29. fixed_x18
    30. fmt_debug
    31. function_return
    32. hint_mostly_unused
    33. indirect_branch_cs_prefix
    34. instrument_xray
    35. large_data_threshold
    36. link_native_libraries
    37. lint_llvm_ir
    38. llvm_module_flag
    39. location_detail
    40. macro_stats
    41. min_function_alignment
    42. move_size_limit
    43. no_parallel_llvm
    44. no_steal_thir
    45. no_unique_section_names
    46. offload
    47. on_broken_pipe
    48. patchable_function_entry
    49. print_check_cfg
    50. print_crate_root_lint_levels
    51. print_supported_crate_types
    52. profile_sample_use
    53. randomize_layout
    54. reg_struct_return
    55. regparm
    56. remap_cwd_prefix
    57. report_time
    58. sanitizer
    59. self_profile
    60. self_profile_events
    61. shell_argfiles
    62. small_data_threshold
    63. split_dwarf_out_dir
    64. src_hash_algorithm
    65. temps_dir
    66. terminal_urls
    67. tiny_const_eval_limit
    68. tls_model
    69. track_diagnostics
    70. treat_err_as_bug
    71. ub_checks
    72. unsound_mir_opts
    73. verbose_asm
    74. virtual_function_elimination
    75. wasm_c_abi
  4. Language features
    1. aarch64_unstable_target_feature
    2. aarch64_ver_target_feature
    3. abi_avr_interrupt
    4. abi_cmse_nonsecure_call
    5. abi_custom
    6. abi_gpu_kernel
    7. abi_msp430_interrupt
    8. abi_ptx
    9. abi_riscv_interrupt
    10. abi_unadjusted
    11. abi_vectorcall
    12. abi_x86_interrupt
    13. adt_const_params
    14. alloc_error_handler
    15. allocator_internals
    16. allow_internal_unsafe
    17. allow_internal_unstable
    18. anonymous_lifetime_in_impl_trait
    19. apx_target_feature
    20. arbitrary_self_types
    21. arbitrary_self_types_pointers
    22. arm_target_feature
    23. asm_experimental_arch
    24. asm_experimental_reg
    25. asm_goto_with_outputs
    26. asm_unwind
    27. associated_type_defaults
    28. async_drop
    29. async_fn_in_dyn_trait
    30. async_fn_track_caller
    31. async_for_loop
    32. async_trait_bounds
    33. auto_traits
    34. avr_target_feature
    35. avx10_target_feature
    36. box_patterns
    37. bpf_target_feature
    38. builtin_syntax
    39. c_variadic
    40. c_variadic_naked_functions
    41. cfg_contract_checks
    42. cfg_emscripten_wasm_eh
    43. cfg_overflow_checks
    44. cfg_relocation_model
    45. cfg_sanitize
    46. cfg_sanitizer_cfi
    47. cfg_target_compact
    48. cfg_target_has_atomic
    49. cfg_target_has_atomic_equal_alignment
    50. cfg_target_has_reliable_f16_f128
    51. cfg_target_thread_local
    52. cfg_ub_checks
    53. cfg_version
    54. cfi_encoding
    55. closure_lifetime_binder
    56. closure_track_caller
    57. cmse_nonsecure_entry
    58. compiler_builtins
    59. const_async_blocks
    60. const_block_items
    61. const_c_variadic
    62. const_closures
    63. const_destruct
    64. const_for
    65. const_precise_live_drops
    66. const_trait_impl
    67. const_try
    68. contracts
    69. contracts_internals
    70. coroutine_clone
    71. coroutines
    72. coverage_attribute
    73. csky_target_feature
    74. custom_inner_attributes
    75. custom_mir
    76. custom_test_frameworks
    77. decl_macro
    78. default_field_values
    79. deprecated_suggestion
    80. deref_patterns
    81. derive_from
    82. diagnostic_on_const
    83. doc_cfg
    84. doc_masked
    85. doc_notable_trait
    86. dropck_eyepatch
    87. effective_target_features
    88. eii_internals
    89. ergonomic_clones
    90. ermsb_target_feature
    91. exhaustive_patterns
    92. explicit_extern_abis
    93. explicit_tail_calls
    94. export_stable
    95. extern_item_impls
    96. extern_types
    97. f128
    98. f16
    99. ffi_const
    100. ffi_pure
    101. final_associated_functions
    102. fmt_debug
    103. fn_align
    104. fn_delegation
    105. freeze_impls
    106. frontmatter
    107. fundamental
    108. gen_blocks
    109. generic_assert
    110. generic_const_exprs
    111. generic_const_items
    112. generic_const_parameter_types
    113. generic_pattern_types
    114. global_registration
    115. guard_patterns
    116. half_open_range_patterns_in_slices
    117. hexagon_target_feature
    118. impl_trait_in_assoc_type
    119. impl_trait_in_bindings
    120. impl_trait_in_fn_trait_return
    121. import_trait_associated_functions
    122. inherent_associated_types
    123. intra_doc_pointers
    124. intrinsics
    125. lahfsahf_target_feature
    126. lang_items
    127. large_assignments
    128. lazy_type_alias
    129. link_arg_attribute
    130. link_cfg
    131. link_llvm_intrinsics
    132. linkage
    133. loongarch_target_feature
    134. loop_match
    135. m68k_target_feature
    136. macro_attr
    137. macro_derive
    138. macro_metavar_expr
    139. macro_metavar_expr_concat
    140. marker_trait_attr
    141. mgca_type_const_syntax
    142. min_generic_const_args
    143. min_specialization
    144. mips_target_feature
    145. more_maybe_bounds
    146. more_qualified_paths
    147. movrs_target_feature
    148. multiple_supertrait_upcastable
    149. must_not_suspend
    150. mut_ref
    151. naked_functions_rustic_abi
    152. naked_functions_target_feature
    153. native_link_modifiers_as_needed
    154. needs_panic_runtime
    155. negative_bounds
    156. negative_impls
    157. never_patterns
    158. never_type
    159. new_range
    160. no_core
    161. non_exhaustive_omitted_patterns_lint
    162. non_lifetime_binders
    163. nvptx_target_feature
    164. offset_of_enum
    165. offset_of_slice
    166. opaque_generic_const_args
    167. optimize_attribute
    168. panic_runtime
    169. patchable_function_entry
    170. pattern_complexity_limit
    171. pattern_types
    172. pin_ergonomics
    173. postfix_match
    174. powerpc_target_feature
    175. prelude_import
    176. prfchw_target_feature
    177. proc_macro_hygiene
    178. profiler_runtime
    179. raw_dylib_elf
    180. reborrow
    181. ref_pat_eat_one_layer_2024
    182. ref_pat_eat_one_layer_2024_structural
    183. register_tool
    184. repr_simd
    185. return_type_notation
    186. riscv_target_feature
    187. rtm_target_feature
    188. rust_cold_cc
    189. rust_preserve_none_cc
    190. rustc_attrs
    191. rustc_private
    192. rustdoc_internals
    193. rustdoc_missing_doc_code_examples
    194. s390x_target_feature
    195. sanitize
    196. simd_ffi
    197. sized_hierarchy
    198. sparc_target_feature
    199. specialization
    200. staged_api
    201. static_align
    202. stmt_expr_attributes
    203. strict_provenance_lints
    204. structural_match
    205. super_let
    206. supertrait_item_shadowing
    207. target_feature_inline_always
    208. test_unstable_lint
    209. thread_local
    210. trait_alias
    211. transmute_generic_consts
    212. transparent_unions
    213. trivial_bounds
    214. try_blocks
    215. try_blocks_heterogeneous
    216. type_alias_impl_trait
    217. type_changing_struct_update
    218. unboxed_closures
    219. unqualified_local_imports
    220. unsafe_binders
    221. unsafe_fields
    222. unsized_const_params
    223. unsized_fn_params
    224. used_with_arg
    225. wasm_target_feature
    226. where_clause_attrs
    227. with_negative_coherence
    228. x86_amx_intrinsics
    229. x87_target_feature
    230. xop_target_feature
    231. yeet_expr
    232. yield_expr
  5. Library Features
    1. abort_unwind
    2. acceptfilter
    3. addr_parse_ascii
    4. align_to_uninit_mut
    5. alloc_error_hook
    6. alloc_internals
    7. alloc_slice_into_array
    8. allocator_api
    9. alloctests
    10. arc_is_unique
    11. array_into_iter_constructors
    12. array_ptr_get
    13. array_try_from_fn
    14. array_try_map
    15. ascii_char
    16. ascii_char_variants
    17. async_fn_traits
    18. async_gen_internals
    19. async_iter_from_iter
    20. async_iterator
    21. atomic_from_mut
    22. atomic_internals
    23. atomic_ptr_null
    24. autodiff
    25. backtrace_frames
    26. bikeshed_guaranteed_no_drop
    27. binary_heap_drain_sorted
    28. binary_heap_from_raw_vec
    29. binary_heap_into_iter_sorted
    30. binary_heap_peek_mut_refresh
    31. binary_heap_pop_if
    32. bool_to_result
    33. bound_as_ref
    34. bound_copied
    35. box_as_ptr
    36. box_into_boxed_slice
    37. box_into_inner
    38. box_take
    39. box_vec_non_null
    40. breakpoint
    41. bstr
    42. bstr_internals
    43. btree_cursors
    44. btree_merge
    45. btree_set_entry
    46. btreemap_alloc
    47. buf_read_has_data_left
    48. bufreader_peek
    49. c_size_t
    50. c_void_variant
    51. can_vector
    52. cast_maybe_uninit
    53. cell_get_cloned
    54. cell_leak
    55. cfg_accessible
    56. cfg_eval
    57. char_internals
    58. char_max_len
    59. clamp_magnitude
    60. clone_from_ref
    61. clone_to_uninit
    62. cmp_minmax
    63. coerce_pointee_validated
    64. coerce_unsized
    65. command_resolved_envs
    66. concat_bytes
    67. const_alloc_error
    68. const_array
    69. const_bool
    70. const_btree_len
    71. const_carrying_mul_add
    72. const_cell_traits
    73. const_clone
    74. const_cmp
    75. const_control_flow
    76. const_convert
    77. const_default
    78. const_drop_guard
    79. const_drop_in_place
    80. const_eval_select
    81. const_format_args
    82. const_heap
    83. const_index
    84. const_iter
    85. const_manually_drop_take
    86. const_never_short_circuit
    87. const_ops
    88. const_option_ops
    89. const_range
    90. const_range_bounds
    91. const_raw_ptr_comparison
    92. const_ref_cell
    93. const_result_trait_fn
    94. const_result_unwrap_unchecked
    95. const_select_unpredictable
    96. const_slice_from_mut_ptr_range
    97. const_slice_from_ptr_range
    98. const_slice_make_iter
    99. const_split_off_first_last
    100. const_swap_with_slice
    101. const_try_residual
    102. const_type_name
    103. const_unsigned_bigint_helpers
    104. container_error_extra
    105. context_ext
    106. control_flow_into_value
    107. control_flow_ok
    108. convert_float_to_int
    109. copied_into_inner
    110. core_float_math
    111. core_intrinsics
    112. core_intrinsics_fallbacks
    113. core_io_borrowed_buf
    114. core_private_bignum
    115. core_private_diy_float
    116. coroutine_trait
    117. cow_is_borrowed
    118. cstr_bytes
    119. cstr_display
    120. cstr_internals
    121. current_thread_id
    122. cursor_split
    123. darwin_objc
    124. deadline_api
    125. debug_closure_helpers
    126. dec2flt
    127. deque_extend_front
    128. deref_pure_trait
    129. derive_clone_copy_internals
    130. derive_coerce_pointee
    131. derive_const
    132. derive_eq_internals
    133. dir_entry_ext2
    134. dirfd
    135. dirhandle
    136. discriminant_kind
    137. disjoint_bitor
    138. dispatch_from_dyn
    139. downcast_unchecked
    140. drain_keep_rest
    141. drop_guard
    142. duration_constants
    143. duration_constructors
    144. duration_integer_division
    145. duration_millis_float
    146. duration_units
    147. edition_panic
    148. error_generic_member_access
    149. error_iter
    150. error_reporter
    151. error_type_id
    152. exact_bitshifts
    153. exact_div
    154. exact_size_is_empty
    155. exclusive_wrapper
    156. exit_status_error
    157. exitcode_exit_method
    158. extend_one
    159. extend_one_unchecked
    160. fd
    161. file_buffered
    162. float_algebraic
    163. float_bits_const
    164. float_erf
    165. float_exact_integer_constants
    166. float_gamma
    167. float_minimum_maximum
    168. flt2dec
    169. fmt_arguments_from_str
    170. fmt_helpers_for_derive
    171. fmt_internals
    172. fn_ptr_trait
    173. fn_traits
    174. forget_unsized
    175. format_args_nl
    176. formatting_options
    177. freeze
    178. fs_set_times
    179. funnel_shifts
    180. future_join
    181. gen_future
    182. generic_assert_internals
    183. generic_atomic
    184. get_disjoint_mut_helpers
    185. get_mut_unchecked
    186. gethostname
    187. gpu_intrinsics
    188. hash_set_entry
    189. hasher_prefixfree_extras
    190. hashmap_internals
    191. hint_must_use
    192. hint_prefetch
    193. inplace_iteration
    194. int_format_into
    195. int_from_ascii
    196. int_lowest_highest_one
    197. int_roundings
    198. integer_atomics
    199. internal_impls_macro
    200. internal_output_capture
    201. io_const_error
    202. io_const_error_internals
    203. io_error_inprogress
    204. io_error_more
    205. io_error_uncategorized
    206. io_slice_as_bytes
    207. ip
    208. ip_as_octets
    209. is_ascii_octdigit
    210. is_loongarch_feature_detected
    211. is_riscv_feature_detected
    212. isolate_most_least_significant_one
    213. iter_advance_by
    214. iter_array_chunks
    215. iter_collect_into
    216. iter_from_coroutine
    217. iter_intersperse
    218. iter_is_partitioned
    219. iter_macro
    220. iter_map_windows
    221. iter_next_chunk
    222. iter_order_by
    223. iter_partition_in_place
    224. iterator_try_collect
    225. iterator_try_reduce
    226. junction_point
    227. layout_for_ptr
    228. lazy_cell_into_inner
    229. legacy_receiver_trait
    230. liballoc_internals
    231. libstd_sys_internals
    232. likely_unlikely
    233. linked_list_cursors
    234. linked_list_remove
    235. linked_list_retain
    236. linux_pidfd
    237. local_key_cell_update
    238. local_waker
    239. lock_value_accessors
    240. log_syntax
    241. map_try_insert
    242. mapped_lock_guards
    243. maybe_dangling
    244. maybe_uninit_array_assume_init
    245. maybe_uninit_as_bytes
    246. maybe_uninit_fill
    247. maybe_uninit_uninit_array_transpose
    248. mem_conjure_zst
    249. mem_copy_fn
    250. more_float_constants
    251. motor_ext
    252. mpmc_channel
    253. mutex_data_ptr
    254. new_range_api
    255. next_index
    256. nonpoison_condvar
    257. nonpoison_mutex
    258. nonpoison_rwlock
    259. nonzero_bitwise
    260. nonzero_from_mut
    261. nonzero_from_str_radix
    262. nonzero_internals
    263. nonzero_ops
    264. normalize_lexically
    265. numfmt
    266. objc_class_variant
    267. objc_selector_variant
    268. once_cell_get_mut
    269. once_cell_try
    270. once_cell_try_insert
    271. one_sided_range
    272. oneshot_channel
    273. option_array_transpose
    274. option_get_or_try_insert_with
    275. option_into_flat_iter
    276. option_reduce
    277. option_reference_flattening
    278. option_zip
    279. os_str_slice
    280. os_string_truncate
    281. panic_abort
    282. panic_always_abort
    283. panic_backtrace_config
    284. panic_can_unwind
    285. panic_internals
    286. panic_unwind
    287. panic_update_hook
    288. partial_ord_chaining_methods
    289. path_is_empty
    290. path_trailing_sep
    291. pattern
    292. pattern_type_macro
    293. pattern_type_range_trait
    294. peer_credentials_unix_socket
    295. phantom_variance_markers
    296. pin_coerce_unsized_trait
    297. pin_derefmut_internals
    298. pointer_is_aligned_to
    299. pointer_try_cast_aligned
    300. portable_simd
    301. prelude_future
    302. prelude_next
    303. print_internals
    304. proc_macro_def_site
    305. proc_macro_diagnostic
    306. proc_macro_expand
    307. proc_macro_internals
    308. proc_macro_quote
    309. proc_macro_span
    310. proc_macro_totokens
    311. proc_macro_tracked_env
    312. proc_macro_tracked_path
    313. proc_macro_value
    314. process_chroot
    315. process_exitcode_internals
    316. process_internals
    317. process_setsid
    318. profiler_runtime_lib
    319. profiling_marker_api
    320. ptr_alignment_type
    321. ptr_as_uninit
    322. ptr_cast_array
    323. ptr_cast_slice
    324. ptr_internals
    325. ptr_mask
    326. ptr_metadata
    327. pub_crate_should_not_need_unstable_attr
    328. random
    329. range_bounds_is_empty
    330. range_into_bounds
    331. raw_os_error_ty
    332. raw_slice_split
    333. raw_vec_internals
    334. read_array
    335. read_buf
    336. read_buf_at
    337. reentrant_lock
    338. reentrant_lock_data_ptr
    339. refcell_try_map
    340. restricted_std
    341. result_option_map_or_default
    342. rev_into_inner
    343. rt
    344. rwlock_data_ptr
    345. sealed
    346. seek_io_take_position
    347. seek_stream_len
    348. set_permissions_nofollow
    349. set_ptr_value
    350. setgroups
    351. sgx_platform
    352. signed_bigint_helpers
    353. sized_type_properties
    354. slice_concat_ext
    355. slice_concat_trait
    356. slice_from_ptr_range
    357. slice_index_methods
    358. slice_internals
    359. slice_iter_mut_as_mut_slice
    360. slice_partial_sort_unstable
    361. slice_partition_dedup
    362. slice_pattern
    363. slice_ptr_get
    364. slice_range
    365. slice_shift
    366. slice_split_once
    367. slice_swap_unchecked
    368. sliceindex_wrappers
    369. smart_pointer_try_map
    370. solid_ext
    371. sort_floats
    372. split_array
    373. split_as_slice
    374. std_internals
    375. stdarch_aarch64_feature_detection
    376. stdarch_arm_feature_detection
    377. stdarch_internal
    378. stdarch_loongarch_feature_detection
    379. stdarch_mips_feature_detection
    380. stdarch_powerpc_feature_detection
    381. stdarch_riscv_feature_detection
    382. stdio_fd_consts
    383. stdio_makes_pipe
    384. stdio_swap
    385. step_trait
    386. str_as_str
    387. str_from_raw_parts
    388. str_from_utf16_endian
    389. str_internals
    390. str_lines_remainder
    391. str_split_inclusive_remainder
    392. str_split_remainder
    393. str_split_whitespace_remainder
    394. string_from_utf8_lossy_owned
    395. string_into_chars
    396. string_remove_matches
    397. string_replace_in_place
    398. strip_circumfix
    399. substr_range
    400. sync_nonpoison
    401. sync_poison_mod
    402. sync_unsafe_cell
    403. tcp_deferaccept
    404. tcp_linger
    405. tcplistener_into_incoming
    406. temporary_niche_types
    407. test
    408. thin_box
    409. thread_id_value
    410. thread_local_internals
    411. thread_raw
    412. thread_sleep_until
    413. thread_spawn_hook
    414. time_saturating_systemtime
    415. time_systemtime_limits
    416. trace_macros
    417. transmutability
    418. trim_prefix_suffix
    419. trivial_clone
    420. trusted_fused
    421. trusted_len
    422. trusted_len_next_unchecked
    423. trusted_random_access
    424. trusted_step
    425. try_as_dyn
    426. try_find
    427. try_reserve_kind
    428. try_trait_v2
    429. try_trait_v2_residual
    430. try_trait_v2_yeet
    431. try_with_capacity
    432. tuple_trait
    433. type_ascription
    434. type_info
    435. ub_checks
    436. uefi_std
    437. uint_bit_width
    438. uint_carryless_mul
    439. uint_gather_scatter_bits
    440. unicode_internals
    441. unique_rc_arc
    442. unix_file_vectored_at
    443. unix_mkfifo
    444. unix_send_signal
    445. unix_set_mark
    446. unix_socket_ancillary_data
    447. unix_socket_exclbind
    448. unix_socket_peek
    449. unsafe_cell_access
    450. unsafe_pinned
    451. unsafe_unpin
    452. unsize
    453. unwrap_infallible
    454. update_panic_count
    455. utf16_extra
    456. variant_count
    457. vec_deque_extract_if
    458. vec_deque_iter_as_slices
    459. vec_deque_truncate_front
    460. vec_fallible_shrink
    461. vec_from_fn
    462. vec_into_chunks
    463. vec_peek_mut
    464. vec_push_within_capacity
    465. vec_recycle
    466. vec_split_at_spare
    467. vec_try_remove
    468. waker_fn
    469. waker_from_fn_ptr
    470. wasi_ext
    471. widening_mul
    472. windows_by_handle
    473. windows_c
    474. windows_change_time
    475. windows_freeze_file_times
    476. windows_handle
    477. windows_net
    478. windows_process_exit_code_from
    479. windows_process_extensions_async_pipes
    480. windows_process_extensions_force_quotes
    481. windows_process_extensions_inherit_handles
    482. windows_process_extensions_main_thread_handle
    483. windows_process_extensions_raw_attribute
    484. windows_process_extensions_show_window
    485. windows_process_extensions_startupinfo
    486. windows_stdio
    487. windows_unix_domain_sockets
    488. wrapping_int_impl
    489. wrapping_next_power_of_two
    490. write_all_vectored
    491. wtf8_internals
    492. yeet_desugar_details