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. min_recursive_limit
    43. move_size_limit
    44. no_parallel_llvm
    45. no_steal_thir
    46. no_unique_section_names
    47. offload
    48. on_broken_pipe
    49. patchable_function_entry
    50. print_check_cfg
    51. print_crate_root_lint_levels
    52. print_supported_crate_types
    53. profile_sample_use
    54. randomize_layout
    55. reg_struct_return
    56. regparm
    57. remap_cwd_prefix
    58. report_time
    59. sanitizer
    60. self_profile
    61. self_profile_events
    62. shell_argfiles
    63. small_data_threshold
    64. split_dwarf_out_dir
    65. src_hash_algorithm
    66. temps_dir
    67. terminal_urls
    68. tiny_const_eval_limit
    69. tls_model
    70. track_diagnostics
    71. treat_err_as_bug
    72. ub_checks
    73. unsound_mir_opts
    74. verbose_asm
    75. virtual_function_elimination
    76. 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. field_projections
    102. field_representing_type_raw
    103. final_associated_functions
    104. fmt_debug
    105. fn_align
    106. fn_delegation
    107. freeze_impls
    108. frontmatter
    109. fundamental
    110. gen_blocks
    111. generic_assert
    112. generic_const_exprs
    113. generic_const_items
    114. generic_const_parameter_types
    115. generic_pattern_types
    116. global_registration
    117. guard_patterns
    118. half_open_range_patterns_in_slices
    119. hexagon_target_feature
    120. impl_restriction
    121. impl_trait_in_assoc_type
    122. impl_trait_in_bindings
    123. impl_trait_in_fn_trait_return
    124. import_trait_associated_functions
    125. inherent_associated_types
    126. intra_doc_pointers
    127. intrinsics
    128. lahfsahf_target_feature
    129. lang_items
    130. large_assignments
    131. lazy_type_alias
    132. link_arg_attribute
    133. link_cfg
    134. link_llvm_intrinsics
    135. linkage
    136. loongarch_target_feature
    137. loop_match
    138. m68k_target_feature
    139. macro_attr
    140. macro_derive
    141. macro_metavar_expr
    142. macro_metavar_expr_concat
    143. marker_trait_attr
    144. mgca_type_const_syntax
    145. min_generic_const_args
    146. min_specialization
    147. mips_target_feature
    148. more_maybe_bounds
    149. more_qualified_paths
    150. movrs_target_feature
    151. multiple_supertrait_upcastable
    152. must_not_suspend
    153. mut_ref
    154. naked_functions_rustic_abi
    155. naked_functions_target_feature
    156. native_link_modifiers_as_needed
    157. needs_panic_runtime
    158. negative_bounds
    159. negative_impls
    160. never_patterns
    161. never_type
    162. new_range
    163. no_core
    164. non_exhaustive_omitted_patterns_lint
    165. non_lifetime_binders
    166. nvptx_target_feature
    167. offset_of_enum
    168. offset_of_slice
    169. opaque_generic_const_args
    170. optimize_attribute
    171. panic_runtime
    172. patchable_function_entry
    173. pattern_complexity_limit
    174. pattern_types
    175. pin_ergonomics
    176. postfix_match
    177. powerpc_target_feature
    178. prelude_import
    179. prfchw_target_feature
    180. proc_macro_hygiene
    181. profiler_runtime
    182. raw_dylib_elf
    183. reborrow
    184. ref_pat_eat_one_layer_2024
    185. ref_pat_eat_one_layer_2024_structural
    186. register_tool
    187. repr_simd
    188. return_type_notation
    189. riscv_target_feature
    190. rtm_target_feature
    191. rust_cold_cc
    192. rust_preserve_none_cc
    193. rustc_attrs
    194. rustc_private
    195. rustdoc_internals
    196. rustdoc_missing_doc_code_examples
    197. s390x_target_feature
    198. sanitize
    199. simd_ffi
    200. sized_hierarchy
    201. sparc_target_feature
    202. specialization
    203. staged_api
    204. static_align
    205. stmt_expr_attributes
    206. strict_provenance_lints
    207. structural_match
    208. super_let
    209. supertrait_item_shadowing
    210. target_feature_inline_always
    211. test_incomplete_feature
    212. test_unstable_lint
    213. thread_local
    214. trait_alias
    215. transmute_generic_consts
    216. transparent_unions
    217. trivial_bounds
    218. try_blocks
    219. try_blocks_heterogeneous
    220. type_alias_impl_trait
    221. type_changing_struct_update
    222. unboxed_closures
    223. unqualified_local_imports
    224. unsafe_binders
    225. unsafe_fields
    226. unsized_const_params
    227. unsized_fn_params
    228. used_with_arg
    229. wasm_target_feature
    230. where_clause_attrs
    231. with_negative_coherence
    232. x86_amx_intrinsics
    233. x87_target_feature
    234. xop_target_feature
    235. yeet_expr
    236. 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_path_separators
    90. const_range
    91. const_range_bounds
    92. const_raw_ptr_comparison
    93. const_ref_cell
    94. const_result_trait_fn
    95. const_result_unwrap_unchecked
    96. const_select_unpredictable
    97. const_slice_from_mut_ptr_range
    98. const_slice_from_ptr_range
    99. const_slice_make_iter
    100. const_split_off_first_last
    101. const_swap_with_slice
    102. const_try_residual
    103. const_type_name
    104. const_unsigned_bigint_helpers
    105. container_error_extra
    106. context_ext
    107. control_flow_into_value
    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. num_internals
    266. numfmt
    267. objc_class_variant
    268. objc_selector_variant
    269. once_cell_get_mut
    270. once_cell_try
    271. once_cell_try_insert
    272. one_sided_range
    273. oneshot_channel
    274. option_array_transpose
    275. option_get_or_try_insert_with
    276. option_into_flat_iter
    277. option_reduce
    278. option_reference_flattening
    279. option_zip
    280. os_str_slice
    281. os_string_truncate
    282. panic_abort
    283. panic_always_abort
    284. panic_backtrace_config
    285. panic_can_unwind
    286. panic_internals
    287. panic_unwind
    288. panic_update_hook
    289. partial_ord_chaining_methods
    290. path_absolute_method
    291. path_is_empty
    292. path_trailing_sep
    293. pattern
    294. pattern_type_macro
    295. pattern_type_range_trait
    296. peer_credentials_unix_socket
    297. phantom_variance_markers
    298. pin_coerce_unsized_trait
    299. pin_derefmut_internals
    300. pointer_is_aligned_to
    301. pointer_try_cast_aligned
    302. portable_simd
    303. prelude_future
    304. prelude_next
    305. print_internals
    306. proc_macro_def_site
    307. proc_macro_diagnostic
    308. proc_macro_expand
    309. proc_macro_internals
    310. proc_macro_quote
    311. proc_macro_span
    312. proc_macro_totokens
    313. proc_macro_tracked_env
    314. proc_macro_tracked_path
    315. proc_macro_value
    316. process_chroot
    317. process_exitcode_internals
    318. process_internals
    319. process_setsid
    320. profiler_runtime_lib
    321. profiling_marker_api
    322. ptr_alignment_type
    323. ptr_as_uninit
    324. ptr_cast_array
    325. ptr_cast_slice
    326. ptr_internals
    327. ptr_mask
    328. ptr_metadata
    329. pub_crate_should_not_need_unstable_attr
    330. random
    331. range_bounds_is_empty
    332. range_into_bounds
    333. raw_os_error_ty
    334. raw_slice_split
    335. raw_vec_internals
    336. read_array
    337. read_buf
    338. read_buf_at
    339. reentrant_lock
    340. reentrant_lock_data_ptr
    341. refcell_try_map
    342. restricted_std
    343. result_option_map_or_default
    344. rev_into_inner
    345. rt
    346. rwlock_data_ptr
    347. sealed
    348. seek_io_take_position
    349. seek_stream_len
    350. set_permissions_nofollow
    351. set_ptr_value
    352. setgroups
    353. sgx_platform
    354. signed_bigint_helpers
    355. sized_type_properties
    356. slice_concat_ext
    357. slice_concat_trait
    358. slice_from_ptr_range
    359. slice_index_methods
    360. slice_internals
    361. slice_iter_mut_as_mut_slice
    362. slice_partial_sort_unstable
    363. slice_partition_dedup
    364. slice_pattern
    365. slice_ptr_get
    366. slice_range
    367. slice_shift
    368. slice_split_once
    369. slice_swap_unchecked
    370. sliceindex_wrappers
    371. smart_pointer_try_map
    372. solid_ext
    373. sort_floats
    374. split_array
    375. split_as_slice
    376. std_internals
    377. stdarch_aarch64_feature_detection
    378. stdarch_arm_feature_detection
    379. stdarch_internal
    380. stdarch_loongarch_feature_detection
    381. stdarch_mips_feature_detection
    382. stdarch_powerpc_feature_detection
    383. stdarch_riscv_feature_detection
    384. stdio_fd_consts
    385. stdio_makes_pipe
    386. stdio_swap
    387. step_trait
    388. str_as_str
    389. str_from_raw_parts
    390. str_from_utf16_endian
    391. str_internals
    392. str_lines_remainder
    393. str_split_inclusive_remainder
    394. str_split_remainder
    395. str_split_whitespace_remainder
    396. string_from_utf8_lossy_owned
    397. string_into_chars
    398. string_remove_matches
    399. string_replace_in_place
    400. strip_circumfix
    401. substr_range
    402. sync_nonpoison
    403. sync_poison_mod
    404. sync_unsafe_cell
    405. tcp_deferaccept
    406. tcp_linger
    407. tcplistener_into_incoming
    408. temporary_niche_types
    409. test
    410. thin_box
    411. thread_id_value
    412. thread_local_internals
    413. thread_raw
    414. thread_sleep_until
    415. thread_spawn_hook
    416. time_saturating_systemtime
    417. time_systemtime_limits
    418. trace_macros
    419. transmutability
    420. trim_prefix_suffix
    421. trivial_clone
    422. trusted_fused
    423. trusted_len
    424. trusted_len_next_unchecked
    425. trusted_random_access
    426. trusted_step
    427. try_as_dyn
    428. try_find
    429. try_reserve_kind
    430. try_trait_v2
    431. try_trait_v2_residual
    432. try_trait_v2_yeet
    433. try_with_capacity
    434. tuple_trait
    435. type_ascription
    436. type_info
    437. ub_checks
    438. uefi_std
    439. uint_bit_width
    440. uint_carryless_mul
    441. uint_gather_scatter_bits
    442. unicode_internals
    443. unique_rc_arc
    444. unix_file_vectored_at
    445. unix_mkfifo
    446. unix_send_signal
    447. unix_set_mark
    448. unix_socket_ancillary_data
    449. unix_socket_exclbind
    450. unix_socket_peek
    451. unsafe_cell_access
    452. unsafe_pinned
    453. unsafe_unpin
    454. unsize
    455. unwrap_infallible
    456. update_panic_count
    457. utf16_extra
    458. variant_count
    459. vec_deque_extract_if
    460. vec_deque_iter_as_slices
    461. vec_deque_truncate_front
    462. vec_fallible_shrink
    463. vec_from_fn
    464. vec_into_chunks
    465. vec_peek_mut
    466. vec_push_within_capacity
    467. vec_recycle
    468. vec_split_at_spare
    469. vec_try_remove
    470. waker_fn
    471. waker_from_fn_ptr
    472. wasi_ext
    473. widening_mul
    474. windows_by_handle
    475. windows_c
    476. windows_change_time
    477. windows_freeze_file_times
    478. windows_handle
    479. windows_net
    480. windows_process_exit_code_from
    481. windows_process_extensions_async_pipes
    482. windows_process_extensions_force_quotes
    483. windows_process_extensions_inherit_handles
    484. windows_process_extensions_main_thread_handle
    485. windows_process_extensions_raw_attribute
    486. windows_process_extensions_show_window
    487. windows_process_extensions_startupinfo
    488. windows_stdio
    489. windows_unix_domain_sockets
    490. wrapping_int_impl
    491. wrapping_next_power_of_two
    492. write_all_vectored
    493. wtf8_internals
    494. yeet_desugar_details