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. llvm_writable
    40. location_detail
    41. macro_stats
    42. min_function_alignment
    43. min_recursive_limit
    44. move_size_limit
    45. no_parallel_llvm
    46. no_steal_thir
    47. no_unique_section_names
    48. offload
    49. on_broken_pipe
    50. patchable_function_entry
    51. print_check_cfg
    52. print_crate_root_lint_levels
    53. print_supported_crate_types
    54. profile_sample_use
    55. randomize_layout
    56. reg_struct_return
    57. regparm
    58. remap_cwd_prefix
    59. report_time
    60. sanitizer
    61. self_profile
    62. self_profile_events
    63. shell_argfiles
    64. small_data_threshold
    65. split_dwarf_out_dir
    66. src_hash_algorithm
    67. temps_dir
    68. terminal_urls
    69. tiny_const_eval_limit
    70. tls_model
    71. track_diagnostics
    72. treat_err_as_bug
    73. ub_checks
    74. unsound_mir_opts
    75. verbose_asm
    76. virtual_function_elimination
    77. 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_object_format
    52. cfg_target_thread_local
    53. cfg_ub_checks
    54. cfg_version
    55. cfi_encoding
    56. closure_lifetime_binder
    57. closure_track_caller
    58. cmse_nonsecure_entry
    59. compiler_builtins
    60. const_async_blocks
    61. const_block_items
    62. const_c_variadic
    63. const_closures
    64. const_destruct
    65. const_for
    66. const_precise_live_drops
    67. const_trait_impl
    68. const_try
    69. contracts
    70. contracts_internals
    71. coroutine_clone
    72. coroutines
    73. coverage_attribute
    74. csky_target_feature
    75. custom_inner_attributes
    76. custom_mir
    77. custom_test_frameworks
    78. decl_macro
    79. default_field_values
    80. deprecated_suggestion
    81. deref_patterns
    82. derive_from
    83. diagnostic_on_const
    84. diagnostic_on_move
    85. diagnostic_on_unknown
    86. doc_cfg
    87. doc_masked
    88. doc_notable_trait
    89. dropck_eyepatch
    90. effective_target_features
    91. eii_internals
    92. ergonomic_clones
    93. ermsb_target_feature
    94. exhaustive_patterns
    95. explicit_extern_abis
    96. explicit_tail_calls
    97. export_stable
    98. extern_item_impls
    99. extern_types
    100. f128
    101. f16
    102. ffi_const
    103. ffi_pure
    104. field_projections
    105. field_representing_type_raw
    106. final_associated_functions
    107. fma4_target_feature
    108. fmt_debug
    109. fn_align
    110. fn_delegation
    111. freeze_impls
    112. frontmatter
    113. fundamental
    114. gen_blocks
    115. generic_assert
    116. generic_const_args
    117. generic_const_exprs
    118. generic_const_items
    119. generic_const_parameter_types
    120. generic_pattern_types
    121. global_registration
    122. guard_patterns
    123. half_open_range_patterns_in_slices
    124. hexagon_target_feature
    125. impl_restriction
    126. impl_trait_in_assoc_type
    127. impl_trait_in_bindings
    128. impl_trait_in_fn_trait_return
    129. import_trait_associated_functions
    130. inherent_associated_types
    131. intra_doc_pointers
    132. intrinsics
    133. lahfsahf_target_feature
    134. lang_items
    135. large_assignments
    136. lazy_type_alias
    137. link_arg_attribute
    138. link_cfg
    139. link_llvm_intrinsics
    140. linkage
    141. loongarch_target_feature
    142. loop_match
    143. m68k_target_feature
    144. macro_attr
    145. macro_derive
    146. macro_guard_matcher
    147. macro_metavar_expr
    148. macro_metavar_expr_concat
    149. marker_trait_attr
    150. mgca_type_const_syntax
    151. min_adt_const_params
    152. min_generic_const_args
    153. min_specialization
    154. mips_target_feature
    155. more_maybe_bounds
    156. more_qualified_paths
    157. movrs_target_feature
    158. multiple_supertrait_upcastable
    159. must_not_suspend
    160. mut_ref
    161. naked_functions_rustic_abi
    162. naked_functions_target_feature
    163. native_link_modifiers_as_needed
    164. needs_panic_runtime
    165. negative_bounds
    166. negative_impls
    167. never_patterns
    168. never_type
    169. new_range
    170. no_core
    171. non_exhaustive_omitted_patterns_lint
    172. non_lifetime_binders
    173. nvptx_target_feature
    174. offset_of_enum
    175. offset_of_slice
    176. optimize_attribute
    177. panic_runtime
    178. patchable_function_entry
    179. pattern_complexity_limit
    180. pattern_types
    181. pin_ergonomics
    182. postfix_match
    183. powerpc_target_feature
    184. prelude_import
    185. prfchw_target_feature
    186. proc_macro_hygiene
    187. profiler_runtime
    188. raw_dylib_elf
    189. reborrow
    190. ref_pat_eat_one_layer_2024
    191. ref_pat_eat_one_layer_2024_structural
    192. register_tool
    193. repr_simd
    194. return_type_notation
    195. riscv_target_feature
    196. rtm_target_feature
    197. rust_cold_cc
    198. rust_preserve_none_cc
    199. rustc_attrs
    200. rustc_private
    201. rustdoc_internals
    202. rustdoc_missing_doc_code_examples
    203. s390x_target_feature
    204. sanitize
    205. simd_ffi
    206. sized_hierarchy
    207. sparc_target_feature
    208. specialization
    209. staged_api
    210. static_align
    211. stmt_expr_attributes
    212. strict_provenance_lints
    213. structural_match
    214. super_let
    215. supertrait_item_shadowing
    216. target_feature_inline_always
    217. test_incomplete_feature
    218. test_unstable_lint
    219. thread_local
    220. trait_alias
    221. transmute_generic_consts
    222. transparent_unions
    223. trivial_bounds
    224. try_blocks
    225. try_blocks_heterogeneous
    226. type_alias_impl_trait
    227. type_changing_struct_update
    228. unboxed_closures
    229. unqualified_local_imports
    230. unsafe_binders
    231. unsafe_fields
    232. unsized_const_params
    233. unsized_fn_params
    234. used_with_arg
    235. wasm_target_feature
    236. where_clause_attrs
    237. with_negative_coherence
    238. x86_amx_intrinsics
    239. x87_target_feature
    240. xop_target_feature
    241. yeet_expr
    242. yield_expr
  5. Library Features
    1. abort_immediate
    2. abort_unwind
    3. acceptfilter
    4. addr_parse_ascii
    5. align_to_uninit_mut
    6. alloc_error_hook
    7. alloc_internals
    8. alloc_slice_into_array
    9. allocator_api
    10. alloctests
    11. arc_is_unique
    12. array_into_iter_constructors
    13. array_ptr_get
    14. array_try_from_fn
    15. array_try_map
    16. ascii_char
    17. ascii_char_variants
    18. async_fn_traits
    19. async_gen_internals
    20. async_iter_from_iter
    21. async_iterator
    22. atomic_from_mut
    23. atomic_internals
    24. atomic_ptr_null
    25. autodiff
    26. backtrace_frames
    27. bikeshed_guaranteed_no_drop
    28. binary_heap_as_mut_slice
    29. binary_heap_drain_sorted
    30. binary_heap_from_raw_vec
    31. binary_heap_into_iter_sorted
    32. binary_heap_peek_mut_refresh
    33. binary_heap_pop_if
    34. bool_to_result
    35. borrowed_buf_init
    36. bound_as_ref
    37. bound_copied
    38. box_as_ptr
    39. box_into_boxed_slice
    40. box_into_inner
    41. box_take
    42. box_vec_non_null
    43. breakpoint
    44. bstr
    45. bstr_internals
    46. btree_cursors
    47. btree_merge
    48. btree_set_entry
    49. btreemap_alloc
    50. buf_read_has_data_left
    51. bufreader_peek
    52. c_size_t
    53. c_void_variant
    54. can_vector
    55. case_ignorable
    56. cast_maybe_uninit
    57. cell_get_cloned
    58. cell_leak
    59. cfg_accessible
    60. cfg_eval
    61. char_internals
    62. clamp_magnitude
    63. clone_from_ref
    64. clone_to_uninit
    65. cmp_minmax
    66. coerce_pointee_validated
    67. coerce_unsized
    68. command_resolved_envs
    69. concat_bytes
    70. const_alloc_error
    71. const_array
    72. const_bool
    73. const_btree_len
    74. const_carrying_mul_add
    75. const_cell_traits
    76. const_clone
    77. const_cmp
    78. const_control_flow
    79. const_convert
    80. const_default
    81. const_drop_guard
    82. const_drop_in_place
    83. const_eval_select
    84. const_format_args
    85. const_heap
    86. const_index
    87. const_iter
    88. const_manually_drop_take
    89. const_never_short_circuit
    90. const_nonnull_with_exposed_provenance
    91. const_ops
    92. const_option_ops
    93. const_param_ty_trait
    94. const_path_separators
    95. const_range
    96. const_range_bounds
    97. const_raw_ptr_comparison
    98. const_ref_cell
    99. const_result_trait_fn
    100. const_result_unwrap_unchecked
    101. const_select_unpredictable
    102. const_slice_from_mut_ptr_range
    103. const_slice_from_ptr_range
    104. const_slice_make_iter
    105. const_split_off_first_last
    106. const_swap_with_slice
    107. const_try_residual
    108. const_type_name
    109. const_unsigned_bigint_helpers
    110. container_error_extra
    111. context_ext
    112. control_flow_into_value
    113. convert_float_to_int
    114. copied_into_inner
    115. core_float_math
    116. core_intrinsics
    117. core_intrinsics_fallbacks
    118. core_io
    119. core_io_borrowed_buf
    120. core_io_internals
    121. core_private_bignum
    122. core_private_diy_float
    123. coroutine_trait
    124. cow_is_borrowed
    125. cstr_bytes
    126. cstr_display
    127. cstr_internals
    128. current_thread_id
    129. cursor_split
    130. darwin_objc
    131. deadline_api
    132. debug_closure_helpers
    133. dec2flt
    134. deque_extend_front
    135. deref_pure_trait
    136. derive_clone_copy_internals
    137. derive_coerce_pointee
    138. derive_const
    139. derive_eq_internals
    140. derive_macro_global_path
    141. dir_entry_ext2
    142. dirfd
    143. dirhandle
    144. discriminant_kind
    145. disjoint_bitor
    146. dispatch_from_dyn
    147. downcast_unchecked
    148. drain_keep_rest
    149. drop_guard
    150. duration_constants
    151. duration_constructors
    152. duration_integer_division
    153. duration_millis_float
    154. duration_units
    155. edition_panic
    156. error_generic_member_access
    157. error_iter
    158. error_reporter
    159. error_type_id
    160. exact_bitshifts
    161. exact_div
    162. exact_size_is_empty
    163. exclusive_wrapper
    164. exit_status_error
    165. exitcode_exit_method
    166. extend_one
    167. extend_one_unchecked
    168. f32_from_f16
    169. fd
    170. file_buffered
    171. float_algebraic
    172. float_bits_const
    173. float_erf
    174. float_exact_integer_constants
    175. float_gamma
    176. float_minimum_maximum
    177. flt2dec
    178. fmt_arguments_from_str
    179. fmt_helpers_for_derive
    180. fmt_internals
    181. fn_ptr_trait
    182. fn_traits
    183. forget_unsized
    184. format_args_nl
    185. formatting_options
    186. freeze
    187. fs_set_times
    188. funnel_shifts
    189. future_join
    190. gen_future
    191. generic_assert_internals
    192. generic_atomic
    193. get_disjoint_mut_helpers
    194. get_mut_unchecked
    195. gethostname
    196. gpu_intrinsics
    197. hash_map_internals
    198. hash_map_macro
    199. hash_set_entry
    200. hasher_prefixfree_extras
    201. hashmap_internals
    202. hint_must_use
    203. hint_prefetch
    204. inplace_iteration
    205. int_format_into
    206. int_from_ascii
    207. int_roundings
    208. integer_atomics
    209. integer_cast_extras
    210. integer_extend_truncate
    211. internal_output_capture
    212. io_const_error
    213. io_const_error_internals
    214. io_error_inprogress
    215. io_error_more
    216. io_error_uncategorized
    217. io_slice_as_bytes
    218. ip
    219. ip_as_octets
    220. ip_multicast_reserved
    221. is_ascii_octdigit
    222. is_loongarch_feature_detected
    223. is_riscv_feature_detected
    224. iter_advance_by
    225. iter_array_chunks
    226. iter_collect_into
    227. iter_from_coroutine
    228. iter_intersperse
    229. iter_is_partitioned
    230. iter_macro
    231. iter_map_windows
    232. iter_next_chunk
    233. iter_order_by
    234. iter_partition_in_place
    235. iterator_try_collect
    236. iterator_try_reduce
    237. junction_point
    238. layout_for_ptr
    239. lazy_cell_into_inner
    240. legacy_receiver_trait
    241. liballoc_internals
    242. libstd_sys_internals
    243. likely_unlikely
    244. linked_list_cursors
    245. linked_list_remove
    246. linked_list_retain
    247. linux_pidfd
    248. local_key_cell_update
    249. local_waker
    250. lock_value_accessors
    251. log_syntax
    252. map_try_insert
    253. mapped_lock_guards
    254. maybe_dangling
    255. maybe_uninit_array_assume_init
    256. maybe_uninit_as_bytes
    257. maybe_uninit_fill
    258. maybe_uninit_uninit_array_transpose
    259. mem_conjure_zst
    260. mem_copy_fn
    261. more_float_constants
    262. motor_ext
    263. mpmc_channel
    264. mpsc_is_disconnected
    265. mutex_data_ptr
    266. new_range_api_legacy
    267. new_range_remainder
    268. next_index
    269. nonpoison_condvar
    270. nonpoison_mutex
    271. nonpoison_rwlock
    272. nonzero_bitwise
    273. nonzero_from_mut
    274. nonzero_from_str_radix
    275. nonzero_internals
    276. nonzero_ops
    277. normalize_lexically
    278. num_internals
    279. numfmt
    280. objc_class_variant
    281. objc_selector_variant
    282. once_cell_get_mut
    283. once_cell_try
    284. once_cell_try_insert
    285. one_sided_range
    286. oneshot_channel
    287. option_array_transpose
    288. option_get_or_try_insert_with
    289. option_into_flat_iter
    290. option_reduce
    291. option_reference_flattening
    292. option_zip
    293. os_str_slice
    294. os_string_truncate
    295. panic_abort
    296. panic_always_abort
    297. panic_backtrace_config
    298. panic_can_unwind
    299. panic_internals
    300. panic_unwind
    301. panic_update_hook
    302. partial_ord_chaining_methods
    303. path_absolute_method
    304. path_is_empty
    305. path_trailing_sep
    306. pattern
    307. pattern_type_macro
    308. pattern_type_range_trait
    309. peer_credentials_unix_socket
    310. phantom_variance_markers
    311. pin_coerce_unsized_trait
    312. pin_derefmut_internals
    313. pointer_is_aligned_to
    314. pointer_try_cast_aligned
    315. portable_simd
    316. prelude_future
    317. prelude_next
    318. print_internals
    319. proc_macro_def_site
    320. proc_macro_diagnostic
    321. proc_macro_expand
    322. proc_macro_internals
    323. proc_macro_quote
    324. proc_macro_span
    325. proc_macro_totokens
    326. proc_macro_tracked_env
    327. proc_macro_tracked_path
    328. proc_macro_value
    329. process_chroot
    330. process_exitcode_internals
    331. process_internals
    332. process_setsid
    333. profiler_runtime_lib
    334. profiling_marker_api
    335. ptr_alignment_type
    336. ptr_as_uninit
    337. ptr_cast_array
    338. ptr_cast_slice
    339. ptr_internals
    340. ptr_mask
    341. ptr_metadata
    342. pub_crate_should_not_need_unstable_attr
    343. random
    344. range_bounds_is_empty
    345. range_into_bounds
    346. raw_os_error_ty
    347. raw_slice_split
    348. raw_vec_internals
    349. read_array
    350. read_buf
    351. read_buf_at
    352. reentrant_lock
    353. reentrant_lock_data_ptr
    354. refcell_try_map
    355. restricted_std
    356. result_option_map_or_default
    357. rev_into_inner
    358. rt
    359. rwlock_data_ptr
    360. sealed
    361. seek_io_take_position
    362. seek_stream_len
    363. set_permissions_nofollow
    364. set_ptr_value
    365. setgroups
    366. sgx_platform
    367. signed_bigint_helpers
    368. sized_type_properties
    369. slice_concat_ext
    370. slice_concat_trait
    371. slice_from_ptr_range
    372. slice_index_methods
    373. slice_internals
    374. slice_iter_mut_as_mut_slice
    375. slice_partial_sort_unstable
    376. slice_partition_dedup
    377. slice_pattern
    378. slice_ptr_get
    379. slice_range
    380. slice_shift
    381. slice_split_once
    382. slice_swap_unchecked
    383. sliceindex_wrappers
    384. smart_pointer_try_map
    385. solid_ext
    386. sort_floats
    387. split_array
    388. split_as_slice
    389. std_internals
    390. stdarch_aarch64_feature_detection
    391. stdarch_arm_feature_detection
    392. stdarch_internal
    393. stdarch_loongarch_feature_detection
    394. stdarch_mips_feature_detection
    395. stdarch_powerpc_feature_detection
    396. stdarch_riscv_feature_detection
    397. stdio_fd_consts
    398. stdio_makes_pipe
    399. stdio_swap
    400. step_trait
    401. str_as_str
    402. str_from_raw_parts
    403. str_from_utf16_endian
    404. str_internals
    405. str_lines_remainder
    406. str_split_inclusive_remainder
    407. str_split_remainder
    408. str_split_whitespace_remainder
    409. string_from_utf8_lossy_owned
    410. string_into_chars
    411. string_remove_matches
    412. string_replace_in_place
    413. strip_circumfix
    414. substr_range
    415. sync_nonpoison
    416. sync_poison_mod
    417. sync_unsafe_cell
    418. tcp_deferaccept
    419. tcp_linger
    420. tcplistener_into_incoming
    421. temporary_niche_types
    422. test
    423. thin_box
    424. thread_id_value
    425. thread_local_internals
    426. thread_raw
    427. thread_sleep_until
    428. thread_spawn_hook
    429. time_saturating_systemtime
    430. time_systemtime_limits
    431. titlecase
    432. trace_macros
    433. transmutability
    434. transmute_neo
    435. transmute_prefix
    436. trim_prefix_suffix
    437. trivial_clone
    438. trusted_fused
    439. trusted_len
    440. trusted_len_next_unchecked
    441. trusted_random_access
    442. trusted_step
    443. try_as_dyn
    444. try_find
    445. try_from_int_error_kind
    446. try_reserve_kind
    447. try_trait_v2
    448. try_trait_v2_residual
    449. try_trait_v2_yeet
    450. try_with_capacity
    451. tuple_trait
    452. type_ascription
    453. type_info
    454. ub_checks
    455. uefi_std
    456. uint_carryless_mul
    457. uint_gather_scatter_bits
    458. unicode_internals
    459. unique_rc_arc
    460. unix_file_vectored_at
    461. unix_mkfifo
    462. unix_send_signal
    463. unix_set_mark
    464. unix_socket_ancillary_data
    465. unix_socket_exclbind
    466. unix_socket_peek
    467. unsafe_cell_access
    468. unsafe_pinned
    469. unsafe_unpin
    470. unsize
    471. unwrap_infallible
    472. update_panic_count
    473. utf16_extra
    474. variant_count
    475. vec_deque_extract_if
    476. vec_deque_iter_as_slices
    477. vec_deque_truncate_front
    478. vec_fallible_shrink
    479. vec_from_fn
    480. vec_into_chunks
    481. vec_peek_mut
    482. vec_push_within_capacity
    483. vec_recycle
    484. vec_split_at_spare
    485. vec_try_remove
    486. waker_fn
    487. waker_from_fn_ptr
    488. wasi_ext
    489. widening_mul
    490. windows_by_handle
    491. windows_c
    492. windows_change_time
    493. windows_freeze_file_times
    494. windows_handle
    495. windows_net
    496. windows_process_exit_code_from
    497. windows_process_extensions_async_pipes
    498. windows_process_extensions_force_quotes
    499. windows_process_extensions_inherit_handles
    500. windows_process_extensions_main_thread_handle
    501. windows_process_extensions_raw_attribute
    502. windows_process_extensions_show_window
    503. windows_process_extensions_startupinfo
    504. windows_stdio
    505. windows_unix_domain_sockets
    506. wrapping_int_impl
    507. wrapping_next_power_of_two
    508. write_all_vectored
    509. wtf8_internals
    510. yeet_desugar_details