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_TRANSLATION_NO_DEBUG_ASSERT
    13. RUSTC_WINDOWS_RC
    14. RUST_BACKTRACE
    15. RUST_DEP_GRAPH
    16. RUST_DEP_GRAPH_FILTER
    17. RUST_FORBID_DEP_GRAPH_EDGE
    18. RUST_MIN_STACK
    19. RUST_TARGET_PATH
    20. SDKROOT
    21. TERM
    22. UNSTABLE_RUSTDOC_TEST_LINE
    23. UNSTABLE_RUSTDOC_TEST_PATH
  3. Compiler flags
    1. allow_features
    2. annotate_moves
    3. autodiff
    4. branch_protection
    5. cf_protection
    6. codegen_backend
    7. codegen_options
    8. codegen_source_order
    9. control_flow_guard
    10. coverage_options
    11. crate_attr
    12. debug_info_for_profiling
    13. debug_info_type_line_numbers
    14. default_visibility
    15. direct_access_external_data
    16. dump_mono_stats
    17. dump_mono_stats_format
    18. dylib_lto
    19. eagerly_emit_delayed_bugs
    20. embed_metadata
    21. embed_source
    22. emit_stack_sizes
    23. emscripten_wasm_eh
    24. env_set
    25. export_executable_symbols
    26. extern_options
    27. external_clangrt
    28. fixed_x18
    29. fmt_debug
    30. function_return
    31. hint_mostly_unused
    32. indirect_branch_cs_prefix
    33. instrument_xray
    34. large_data_threshold
    35. link_native_libraries
    36. lint_llvm_ir
    37. llvm_module_flag
    38. location_detail
    39. macro_stats
    40. min_function_alignment
    41. move_size_limit
    42. no_parallel_llvm
    43. no_steal_thir
    44. no_unique_section_names
    45. offload
    46. on_broken_pipe
    47. patchable_function_entry
    48. print_check_cfg
    49. print_crate_root_lint_levels
    50. print_supported_crate_types
    51. profile_sample_use
    52. randomize_layout
    53. reg_struct_return
    54. regparm
    55. remap_cwd_prefix
    56. report_time
    57. sanitizer
    58. self_profile
    59. self_profile_events
    60. shell_argfiles
    61. small_data_threshold
    62. split_dwarf_out_dir
    63. src_hash_algorithm
    64. temps_dir
    65. terminal_urls
    66. tiny_const_eval_limit
    67. tls_model
    68. track_diagnostics
    69. treat_err_as_bug
    70. ub_checks
    71. unsound_mir_opts
    72. verbose_asm
    73. virtual_function_elimination
    74. 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. avx10_target_feature
    35. box_patterns
    36. bpf_target_feature
    37. builtin_syntax
    38. c_variadic
    39. c_variadic_naked_functions
    40. cfg_contract_checks
    41. cfg_emscripten_wasm_eh
    42. cfg_overflow_checks
    43. cfg_relocation_model
    44. cfg_sanitize
    45. cfg_sanitizer_cfi
    46. cfg_target_compact
    47. cfg_target_has_atomic
    48. cfg_target_has_atomic_equal_alignment
    49. cfg_target_has_reliable_f16_f128
    50. cfg_target_thread_local
    51. cfg_ub_checks
    52. cfg_version
    53. cfi_encoding
    54. closure_lifetime_binder
    55. closure_track_caller
    56. cmse_nonsecure_entry
    57. compiler_builtins
    58. const_async_blocks
    59. const_block_items
    60. const_closures
    61. const_destruct
    62. const_for
    63. const_precise_live_drops
    64. const_trait_impl
    65. const_try
    66. contracts
    67. contracts_internals
    68. coroutine_clone
    69. coroutines
    70. coverage_attribute
    71. csky_target_feature
    72. custom_inner_attributes
    73. custom_mir
    74. custom_test_frameworks
    75. decl_macro
    76. default_field_values
    77. deprecated_safe
    78. deprecated_suggestion
    79. deref_patterns
    80. derive_from
    81. diagnostic_on_const
    82. doc_cfg
    83. doc_masked
    84. doc_notable_trait
    85. dropck_eyepatch
    86. effective_target_features
    87. eii_internals
    88. ergonomic_clones
    89. ermsb_target_feature
    90. exhaustive_patterns
    91. explicit_extern_abis
    92. explicit_tail_calls
    93. export_stable
    94. extern_item_impls
    95. extern_types
    96. f128
    97. f16
    98. ffi_const
    99. ffi_pure
    100. fmt_debug
    101. fn_align
    102. fn_delegation
    103. freeze_impls
    104. frontmatter
    105. fundamental
    106. gen_blocks
    107. generic_assert
    108. generic_const_exprs
    109. generic_const_items
    110. generic_const_parameter_types
    111. generic_pattern_types
    112. global_registration
    113. guard_patterns
    114. half_open_range_patterns_in_slices
    115. hexagon_target_feature
    116. if_let_guard
    117. impl_trait_in_assoc_type
    118. impl_trait_in_bindings
    119. impl_trait_in_fn_trait_return
    120. import_trait_associated_functions
    121. inherent_associated_types
    122. intra_doc_pointers
    123. intrinsics
    124. lahfsahf_target_feature
    125. lang_items
    126. large_assignments
    127. lazy_type_alias
    128. link_arg_attribute
    129. link_cfg
    130. link_llvm_intrinsics
    131. linkage
    132. loongarch_target_feature
    133. loop_match
    134. m68k_target_feature
    135. macro_attr
    136. macro_derive
    137. macro_metavar_expr
    138. macro_metavar_expr_concat
    139. marker_trait_attr
    140. min_generic_const_args
    141. min_specialization
    142. mips_target_feature
    143. more_maybe_bounds
    144. more_qualified_paths
    145. movrs_target_feature
    146. multiple_supertrait_upcastable
    147. must_not_suspend
    148. mut_ref
    149. naked_functions_rustic_abi
    150. naked_functions_target_feature
    151. native_link_modifiers_as_needed
    152. needs_panic_runtime
    153. negative_bounds
    154. negative_impls
    155. never_patterns
    156. never_type
    157. new_range
    158. no_core
    159. non_exhaustive_omitted_patterns_lint
    160. non_lifetime_binders
    161. nvptx_target_feature
    162. offset_of_enum
    163. offset_of_slice
    164. optimize_attribute
    165. panic_runtime
    166. patchable_function_entry
    167. pattern_complexity_limit
    168. pattern_types
    169. pin_ergonomics
    170. postfix_match
    171. powerpc_target_feature
    172. prelude_import
    173. prfchw_target_feature
    174. proc_macro_hygiene
    175. profiler_runtime
    176. raw_dylib_elf
    177. reborrow
    178. ref_pat_eat_one_layer_2024
    179. ref_pat_eat_one_layer_2024_structural
    180. register_tool
    181. repr_simd
    182. return_type_notation
    183. riscv_target_feature
    184. rtm_target_feature
    185. rust_cold_cc
    186. rust_preserve_none_cc
    187. rustc_allow_const_fn_unstable
    188. rustc_attrs
    189. rustc_private
    190. rustdoc_internals
    191. rustdoc_missing_doc_code_examples
    192. s390x_target_feature
    193. sanitize
    194. simd_ffi
    195. sized_hierarchy
    196. sparc_target_feature
    197. specialization
    198. staged_api
    199. static_align
    200. stmt_expr_attributes
    201. strict_provenance_lints
    202. structural_match
    203. super_let
    204. supertrait_item_shadowing
    205. target_feature_inline_always
    206. test_unstable_lint
    207. thread_local
    208. trait_alias
    209. transmute_generic_consts
    210. transparent_unions
    211. trivial_bounds
    212. try_blocks
    213. try_blocks_heterogeneous
    214. type_alias_impl_trait
    215. type_changing_struct_update
    216. unboxed_closures
    217. unqualified_local_imports
    218. unsafe_binders
    219. unsafe_fields
    220. unsized_const_params
    221. unsized_fn_params
    222. used_with_arg
    223. wasm_target_feature
    224. where_clause_attrs
    225. with_negative_coherence
    226. x86_amx_intrinsics
    227. x87_target_feature
    228. xop_target_feature
    229. yeet_expr
    230. 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. assert_matches
    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. atomic_try_update
    26. autodiff
    27. backtrace_frames
    28. bikeshed_guaranteed_no_drop
    29. binary_heap_drain_sorted
    30. binary_heap_into_iter_sorted
    31. binary_heap_peek_mut_refresh
    32. binary_heap_pop_if
    33. bool_to_result
    34. bound_as_ref
    35. bound_copied
    36. box_as_ptr
    37. box_into_boxed_slice
    38. box_into_inner
    39. box_take
    40. box_vec_non_null
    41. breakpoint
    42. bstr
    43. bstr_internals
    44. btree_cursors
    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. cfg_select
    58. char_internals
    59. char_max_len
    60. clamp_magnitude
    61. clone_from_ref
    62. clone_to_uninit
    63. cmp_minmax
    64. coerce_pointee_validated
    65. coerce_unsized
    66. cold_path
    67. command_resolved_envs
    68. concat_bytes
    69. const_alloc_error
    70. const_array
    71. const_bool
    72. const_btree_len
    73. const_carrying_mul_add
    74. const_cell_traits
    75. const_clone
    76. const_cmp
    77. const_control_flow
    78. const_convert
    79. const_default
    80. const_drop_guard
    81. const_drop_in_place
    82. const_eval_select
    83. const_format_args
    84. const_heap
    85. const_index
    86. const_iter
    87. const_manually_drop_take
    88. const_never_short_circuit
    89. const_ops
    90. const_option_ops
    91. const_range
    92. const_range_bounds
    93. const_raw_ptr_comparison
    94. const_ref_cell
    95. const_result_trait_fn
    96. const_result_unwrap_unchecked
    97. const_select_unpredictable
    98. const_slice_from_mut_ptr_range
    99. const_slice_from_ptr_range
    100. const_slice_make_iter
    101. const_split_off_first_last
    102. const_swap_with_slice
    103. const_try_residual
    104. const_type_name
    105. const_unsigned_bigint_helpers
    106. container_error_extra
    107. context_ext
    108. control_flow_into_value
    109. control_flow_ok
    110. convert_float_to_int
    111. copied_into_inner
    112. core_float_math
    113. core_intrinsics
    114. core_intrinsics_fallbacks
    115. core_io_borrowed_buf
    116. core_private_bignum
    117. core_private_diy_float
    118. coroutine_trait
    119. cow_is_borrowed
    120. cstr_bytes
    121. cstr_display
    122. cstr_internals
    123. current_thread_id
    124. cursor_split
    125. darwin_objc
    126. deadline_api
    127. debug_closure_helpers
    128. dec2flt
    129. deque_extend_front
    130. deref_pure_trait
    131. derive_clone_copy_internals
    132. derive_coerce_pointee
    133. derive_const
    134. derive_eq_internals
    135. dir_entry_ext2
    136. dirfd
    137. dirhandle
    138. discriminant_kind
    139. disjoint_bitor
    140. dispatch_from_dyn
    141. downcast_unchecked
    142. drain_keep_rest
    143. drop_guard
    144. duration_constants
    145. duration_constructors
    146. duration_integer_division
    147. duration_millis_float
    148. duration_units
    149. edition_panic
    150. error_generic_member_access
    151. error_iter
    152. error_reporter
    153. error_type_id
    154. exact_bitshifts
    155. exact_div
    156. exact_size_is_empty
    157. exclusive_wrapper
    158. exit_status_error
    159. exitcode_exit_method
    160. extend_one
    161. extend_one_unchecked
    162. fd
    163. file_buffered
    164. float_algebraic
    165. float_bits_const
    166. float_erf
    167. float_gamma
    168. float_minimum_maximum
    169. flt2dec
    170. fmt_arguments_from_str
    171. fmt_helpers_for_derive
    172. fmt_internals
    173. fn_ptr_trait
    174. fn_traits
    175. forget_unsized
    176. format_args_nl
    177. formatting_options
    178. freeze
    179. fs_set_times
    180. funnel_shifts
    181. future_join
    182. gen_future
    183. generic_assert_internals
    184. generic_atomic
    185. get_disjoint_mut_helpers
    186. get_mut_unchecked
    187. gethostname
    188. gpu_intrinsics
    189. hash_set_entry
    190. hasher_prefixfree_extras
    191. hashmap_internals
    192. hint_must_use
    193. hint_prefetch
    194. inplace_iteration
    195. int_format_into
    196. int_from_ascii
    197. int_lowest_highest_one
    198. int_roundings
    199. integer_atomics
    200. internal_impls_macro
    201. internal_output_capture
    202. io_const_error
    203. io_const_error_internals
    204. io_error_inprogress
    205. io_error_more
    206. io_error_uncategorized
    207. io_slice_as_bytes
    208. ip
    209. ip_as_octets
    210. is_ascii_octdigit
    211. is_loongarch_feature_detected
    212. is_riscv_feature_detected
    213. isolate_most_least_significant_one
    214. iter_advance_by
    215. iter_array_chunks
    216. iter_collect_into
    217. iter_from_coroutine
    218. iter_intersperse
    219. iter_is_partitioned
    220. iter_macro
    221. iter_map_windows
    222. iter_next_chunk
    223. iter_order_by
    224. iter_partition_in_place
    225. iterator_try_collect
    226. iterator_try_reduce
    227. junction_point
    228. layout_for_ptr
    229. lazy_cell_into_inner
    230. legacy_receiver_trait
    231. liballoc_internals
    232. libstd_sys_internals
    233. likely_unlikely
    234. linked_list_cursors
    235. linked_list_remove
    236. linked_list_retain
    237. linux_pidfd
    238. local_key_cell_update
    239. local_waker
    240. lock_value_accessors
    241. log_syntax
    242. map_try_insert
    243. mapped_lock_guards
    244. maybe_dangling
    245. maybe_uninit_array_assume_init
    246. maybe_uninit_as_bytes
    247. maybe_uninit_fill
    248. maybe_uninit_uninit_array_transpose
    249. mem_conjure_zst
    250. mem_copy_fn
    251. min_const_control_flow
    252. more_float_constants
    253. motor_ext
    254. mpmc_channel
    255. mutex_data_ptr
    256. new_range_api
    257. next_index
    258. nonpoison_condvar
    259. nonpoison_mutex
    260. nonpoison_rwlock
    261. nonzero_bitwise
    262. nonzero_from_mut
    263. nonzero_internals
    264. nonzero_ops
    265. normalize_lexically
    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_is_empty
    291. path_trailing_sep
    292. pattern
    293. pattern_type_macro
    294. pattern_type_range_trait
    295. peer_credentials_unix_socket
    296. phantom_variance_markers
    297. pin_coerce_unsized_trait
    298. pin_derefmut_internals
    299. pointer_is_aligned_to
    300. pointer_try_cast_aligned
    301. portable_simd
    302. prelude_future
    303. prelude_next
    304. print_internals
    305. proc_macro_def_site
    306. proc_macro_diagnostic
    307. proc_macro_expand
    308. proc_macro_internals
    309. proc_macro_quote
    310. proc_macro_span
    311. proc_macro_totokens
    312. proc_macro_tracked_env
    313. proc_macro_tracked_path
    314. proc_macro_value
    315. process_chroot
    316. process_exitcode_internals
    317. process_internals
    318. process_setsid
    319. profiler_runtime_lib
    320. profiling_marker_api
    321. ptr_alignment_type
    322. ptr_as_uninit
    323. ptr_cast_array
    324. ptr_cast_slice
    325. ptr_internals
    326. ptr_mask
    327. ptr_metadata
    328. pub_crate_should_not_need_unstable_attr
    329. random
    330. range_bounds_is_empty
    331. range_into_bounds
    332. raw_os_error_ty
    333. raw_slice_split
    334. raw_vec_internals
    335. read_array
    336. read_buf
    337. read_buf_at
    338. reentrant_lock
    339. reentrant_lock_data_ptr
    340. refcell_try_map
    341. restricted_std
    342. result_option_map_or_default
    343. rev_into_inner
    344. rt
    345. rwlock_data_ptr
    346. sealed
    347. seek_io_take_position
    348. seek_stream_len
    349. set_permissions_nofollow
    350. set_ptr_value
    351. setgroups
    352. sgx_platform
    353. signed_bigint_helpers
    354. sized_type_properties
    355. slice_concat_ext
    356. slice_concat_trait
    357. slice_from_ptr_range
    358. slice_index_methods
    359. slice_internals
    360. slice_iter_mut_as_mut_slice
    361. slice_partial_sort_unstable
    362. slice_partition_dedup
    363. slice_pattern
    364. slice_ptr_get
    365. slice_range
    366. slice_shift
    367. slice_split_once
    368. slice_swap_unchecked
    369. sliceindex_wrappers
    370. smart_pointer_try_map
    371. solid_ext
    372. sort_floats
    373. split_array
    374. split_as_slice
    375. std_internals
    376. stdarch_aarch64_feature_detection
    377. stdarch_arm_feature_detection
    378. stdarch_internal
    379. stdarch_loongarch_feature_detection
    380. stdarch_mips_feature_detection
    381. stdarch_powerpc_feature_detection
    382. stdarch_riscv_feature_detection
    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_gather_scatter_bits
    439. unicode_internals
    440. unique_rc_arc
    441. unix_file_vectored_at
    442. unix_mkfifo
    443. unix_send_signal
    444. unix_set_mark
    445. unix_socket_ancillary_data
    446. unix_socket_exclbind
    447. unix_socket_peek
    448. unsafe_cell_access
    449. unsafe_pinned
    450. unsize
    451. unwrap_infallible
    452. update_panic_count
    453. utf16_extra
    454. variant_count
    455. vec_deque_extract_if
    456. vec_deque_iter_as_slices
    457. vec_deque_truncate_front
    458. vec_from_fn
    459. vec_into_chunks
    460. vec_peek_mut
    461. vec_push_within_capacity
    462. vec_recycle
    463. vec_split_at_spare
    464. vec_try_remove
    465. waker_fn
    466. waker_from_fn_ptr
    467. wasi_ext
    468. widening_mul
    469. windows_by_handle
    470. windows_c
    471. windows_change_time
    472. windows_freeze_file_times
    473. windows_handle
    474. windows_net
    475. windows_process_exit_code_from
    476. windows_process_extensions_async_pipes
    477. windows_process_extensions_force_quotes
    478. windows_process_extensions_inherit_handles
    479. windows_process_extensions_main_thread_handle
    480. windows_process_extensions_raw_attribute
    481. windows_process_extensions_show_window
    482. windows_process_extensions_startupinfo
    483. windows_stdio
    484. windows_unix_domain_sockets
    485. wrapping_int_impl
    486. wrapping_next_power_of_two
    487. write_all_vectored
    488. wtf8_internals
    489. yeet_desugar_details