The Unstable Book
1.
Compiler flags
1.1.
branch_protection
1.2.
cf_protection
1.3.
codegen_backend
1.4.
codegen_options
1.5.
control_flow_guard
1.6.
coverage_options
1.7.
debug_info_for_profiling
1.8.
default_visibility
1.9.
direct_access_external_data
1.10.
dump_mono_stats
1.11.
dump_mono_stats_format
1.12.
dwarf_version
1.13.
dylib_lto
1.14.
embed_source
1.15.
emit_stack_sizes
1.16.
env_set
1.17.
export_executable_symbols
1.18.
extern_options
1.19.
external_clangrt
1.20.
fixed_x18
1.21.
fmt_debug
1.22.
function_return
1.23.
instrument_xray
1.24.
link_native_libraries
1.25.
linker_features
1.26.
lint_llvm_ir
1.27.
llvm_module_flag
1.28.
location_detail
1.29.
move_size_limit
1.30.
no_jump_tables
1.31.
no_parallel_llvm
1.32.
no_unique_section_names
1.33.
on_broken_pipe
1.34.
patchable_function_entry
1.35.
print_check_cfg
1.36.
profile
1.37.
profile_sample_use
1.38.
remap_cwd_prefix
1.39.
remap_path_scope
1.40.
report_time
1.41.
sanitizer
1.42.
self_profile
1.43.
self_profile_events
1.44.
shell_argfiles
1.45.
small_data_threshold
1.46.
src_hash_algorithm
1.47.
temps_dir
1.48.
tiny_const_eval_limit
1.49.
tls_model
1.50.
ub_checks
1.51.
unsound_mir_opts
1.52.
verbose_asm
1.53.
virtual_function_elimination
1.54.
wasm_c_abi
2.
Language features
2.1.
aarch64_unstable_target_feature
2.2.
aarch64_ver_target_feature
2.3.
abi_avr_interrupt
2.4.
abi_c_cmse_nonsecure_call
2.5.
abi_msp430_interrupt
2.6.
abi_ptx
2.7.
abi_riscv_interrupt
2.8.
abi_unadjusted
2.9.
abi_vectorcall
2.10.
abi_x86_interrupt
2.11.
adt_const_params
2.12.
alloc_error_handler
2.13.
allocator_internals
2.14.
allow_internal_unsafe
2.15.
allow_internal_unstable
2.16.
anonymous_lifetime_in_impl_trait
2.17.
arbitrary_self_types
2.18.
arbitrary_self_types_pointers
2.19.
arm_target_feature
2.20.
asm_experimental_arch
2.21.
asm_goto
2.22.
asm_unwind
2.23.
associated_const_equality
2.24.
associated_type_defaults
2.25.
async_closure
2.26.
async_fn_track_caller
2.27.
async_for_loop
2.28.
auto_traits
2.29.
avx512_target_feature
2.30.
box_patterns
2.31.
bpf_target_feature
2.32.
builtin_syntax
2.33.
c_variadic
2.34.
cfg_boolean_literals
2.35.
cfg_overflow_checks
2.36.
cfg_relocation_model
2.37.
cfg_sanitize
2.38.
cfg_sanitizer_cfi
2.39.
cfg_target_compact
2.40.
cfg_target_has_atomic
2.41.
cfg_target_has_atomic_equal_alignment
2.42.
cfg_target_thread_local
2.43.
cfg_ub_checks
2.44.
cfg_version
2.45.
cfi_encoding
2.46.
closure_lifetime_binder
2.47.
closure_track_caller
2.48.
cmse_nonsecure_entry
2.49.
compiler_builtins
2.50.
const_async_blocks
2.51.
const_closures
2.52.
const_for
2.53.
const_precise_live_drops
2.54.
const_trait_impl
2.55.
const_try
2.56.
coroutine_clone
2.57.
coroutines
2.58.
coverage_attribute
2.59.
csky_target_feature
2.60.
custom_inner_attributes
2.61.
custom_mir
2.62.
custom_test_frameworks
2.63.
decl_macro
2.64.
deprecated_safe
2.65.
deprecated_suggestion
2.66.
deref_patterns
2.67.
derive_smart_pointer
2.68.
do_not_recommend
2.69.
doc_auto_cfg
2.70.
doc_cfg
2.71.
doc_cfg_hide
2.72.
doc_masked
2.73.
doc_notable_trait
2.74.
dropck_eyepatch
2.75.
dyn_compatible_for_dispatch
2.76.
dyn_star
2.77.
effects
2.78.
ermsb_target_feature
2.79.
exhaustive_patterns
2.80.
explicit_tail_calls
2.81.
extended_varargs_abi_support
2.82.
extern_types
2.83.
f128
2.84.
f16
2.85.
ffi_const
2.86.
ffi_pure
2.87.
fmt_debug
2.88.
fn_align
2.89.
fn_delegation
2.90.
freeze_impls
2.91.
fundamental
2.92.
gen_blocks
2.93.
generic_arg_infer
2.94.
generic_assert
2.95.
generic_associated_types_extended
2.96.
generic_const_exprs
2.97.
generic_const_items
2.98.
global_registration
2.99.
half_open_range_patterns_in_slices
2.100.
hexagon_target_feature
2.101.
if_let_guard
2.102.
if_let_rescope
2.103.
impl_trait_in_assoc_type
2.104.
impl_trait_in_fn_trait_return
2.105.
inherent_associated_types
2.106.
inline_const_pat
2.107.
intra_doc_pointers
2.108.
intrinsics
2.109.
lahfsahf_target_feature
2.110.
lang_items
2.111.
large_assignments
2.112.
lazy_type_alias
2.113.
let_chains
2.114.
lifetime_capture_rules_2024
2.115.
link_arg_attribute
2.116.
link_cfg
2.117.
link_llvm_intrinsics
2.118.
linkage
2.119.
loongarch_target_feature
2.120.
macro_metavar_expr
2.121.
macro_metavar_expr_concat
2.122.
marker_trait_attr
2.123.
min_specialization
2.124.
mips_target_feature
2.125.
more_maybe_bounds
2.126.
more_qualified_paths
2.127.
multiple_supertrait_upcastable
2.128.
must_not_suspend
2.129.
mut_ref
2.130.
naked_functions
2.131.
native_link_modifiers_as_needed
2.132.
needs_panic_runtime
2.133.
negative_bounds
2.134.
negative_impls
2.135.
never_patterns
2.136.
never_type
2.137.
never_type_fallback
2.138.
no_core
2.139.
no_sanitize
2.140.
non_exhaustive_omitted_patterns_lint
2.141.
non_lifetime_binders
2.142.
offset_of_enum
2.143.
offset_of_slice
2.144.
omit_gdb_pretty_printer_section
2.145.
optimize_attribute
2.146.
panic_runtime
2.147.
patchable_function_entry
2.148.
pattern_complexity
2.149.
pattern_types
2.150.
pin_ergonomics
2.151.
postfix_match
2.152.
powerpc_target_feature
2.153.
precise_capturing_in_traits
2.154.
prelude_import
2.155.
prfchw_target_feature
2.156.
proc_macro_hygiene
2.157.
profiler_runtime
2.158.
ref_pat_eat_one_layer_2024
2.159.
ref_pat_eat_one_layer_2024_structural
2.160.
register_tool
2.161.
repr_simd
2.162.
repr128
2.163.
result_ffi_guarantees
2.164.
return_type_notation
2.165.
riscv_target_feature
2.166.
rtm_target_feature
2.167.
rust_cold_cc
2.168.
rustc_allow_const_fn_unstable
2.169.
rustc_attrs
2.170.
rustc_private
2.171.
rustdoc_internals
2.172.
rustdoc_missing_doc_code_examples
2.173.
s390x_target_feature
2.174.
sha512_sm_x86
2.175.
shorter_tail_lifetimes
2.176.
simd_ffi
2.177.
specialization
2.178.
sse4a_target_feature
2.179.
staged_api
2.180.
start
2.181.
stmt_expr_attributes
2.182.
strict_provenance
2.183.
string_deref_patterns
2.184.
structural_match
2.185.
target_feature_11
2.186.
tbm_target_feature
2.187.
test_unstable_lint
2.188.
thread_local
2.189.
trait_alias
2.190.
trait_upcasting
2.191.
transmute_generic_consts
2.192.
transparent_unions
2.193.
trivial_bounds
2.194.
try_blocks
2.195.
type_alias_impl_trait
2.196.
type_changing_struct_update
2.197.
unboxed_closures
2.198.
unqualified_local_imports
2.199.
unsized_const_params
2.200.
unsized_fn_params
2.201.
unsized_locals
2.202.
unsized_tuple_coercion
2.203.
used_with_arg
2.204.
wasm_target_feature
2.205.
with_negative_coherence
2.206.
x86_amx_intrinsics
2.207.
xop_target_feature
2.208.
yeet_expr
3.
Library Features
3.1.
abort_unwind
3.2.
acceptfilter
3.3.
addr_parse_ascii
3.4.
alloc_error_hook
3.5.
alloc_internals
3.6.
alloc_layout_extra
3.7.
allocator_api
3.8.
anonymous_pipe
3.9.
array_chunks
3.10.
array_into_iter_constructors
3.11.
array_ptr_get
3.12.
array_repeat
3.13.
array_try_from_fn
3.14.
array_try_map
3.15.
array_windows
3.16.
as_array_of_cells
3.17.
ascii_char
3.18.
ascii_char_variants
3.19.
assert_matches
3.20.
async_drop
3.21.
async_fn_traits
3.22.
async_gen_internals
3.23.
async_iter_from_iter
3.24.
async_iterator
3.25.
atomic_from_mut
3.26.
backtrace_frames
3.27.
bigint_helper_methods
3.28.
binary_heap_drain_sorted
3.29.
binary_heap_into_iter_sorted
3.30.
bound_as_ref
3.31.
box_as_ptr
3.32.
box_into_boxed_slice
3.33.
box_into_inner
3.34.
box_uninit_write
3.35.
box_vec_non_null
3.36.
btree_cursors
3.37.
btree_extract_if
3.38.
btreemap_alloc
3.39.
buf_read_has_data_left
3.40.
bufreader_peek
3.41.
build_hasher_default_const_new
3.42.
c_size_t
3.43.
c_str_module
3.44.
c_void_variant
3.45.
can_vector
3.46.
cell_leak
3.47.
cell_update
3.48.
cfg_accessible
3.49.
cfg_eval
3.50.
cfg_match
3.51.
char_internals
3.52.
clone_to_uninit
3.53.
cmp_minmax
3.54.
coerce_unsized
3.55.
concat_bytes
3.56.
concat_idents
3.57.
const_align_of_val
3.58.
const_align_of_val_raw
3.59.
const_align_offset
3.60.
const_alloc_error
3.61.
const_alloc_layout
3.62.
const_arguments_as_str
3.63.
const_array_into_iter_constructors
3.64.
const_atomic_from_ptr
3.65.
const_bigint_helper_methods
3.66.
const_binary_heap_new_in
3.67.
const_black_box
3.68.
const_box
3.69.
const_btree_len
3.70.
const_cell
3.71.
const_char_encode_utf16
3.72.
const_collections_with_hasher
3.73.
const_eval_select
3.74.
const_exact_div
3.75.
const_fmt_arguments_new
3.76.
const_format_args
3.77.
const_hash
3.78.
const_heap
3.79.
const_index_range_slice_index
3.80.
const_intoiterator_identity
3.81.
const_intrinsic_compare_bytes
3.82.
const_intrinsic_raw_eq
3.83.
const_ip
3.84.
const_ipv4
3.85.
const_ipv6
3.86.
const_likely
3.87.
const_make_ascii
3.88.
const_maybe_uninit_array_assume_init
3.89.
const_maybe_uninit_assume_init
3.90.
const_maybe_uninit_uninit_array
3.91.
const_maybe_uninit_write
3.92.
const_nonnull_new
3.93.
const_num_midpoint
3.94.
const_option_ext
3.95.
const_pin
3.96.
const_pointer_is_aligned
3.97.
const_pref_align_of
3.98.
const_ptr_is_null
3.99.
const_ptr_sub_ptr
3.100.
const_range_bounds
3.101.
const_raw_ptr_comparison
3.102.
const_size_of_val
3.103.
const_size_of_val_raw
3.104.
const_slice_flatten
3.105.
const_slice_from_mut_ptr_range
3.106.
const_slice_from_ptr_range
3.107.
const_str_from_raw_parts_mut
3.108.
const_str_from_utf8
3.109.
const_strict_overflow_ops
3.110.
const_swap
3.111.
const_three_way_compare
3.112.
const_type_id
3.113.
const_type_name
3.114.
const_typed_swap
3.115.
const_ub_checks
3.116.
const_unbounded_shifts
3.117.
const_unicode_case_lookup
3.118.
const_vec_string_slice
3.119.
container_error_extra
3.120.
context_ext
3.121.
convert_float_to_int
3.122.
core_intrinsics
3.123.
core_io_borrowed_buf
3.124.
core_pattern_type
3.125.
core_pattern_types
3.126.
core_private_bignum
3.127.
core_private_diy_float
3.128.
coroutine_trait
3.129.
cow_is_borrowed
3.130.
cstr_bytes
3.131.
cstr_internals
3.132.
cursor_split
3.133.
deadline_api
3.134.
debug_closure_helpers
3.135.
dec2flt
3.136.
deref_pure_trait
3.137.
derive_clone_copy
3.138.
derive_const
3.139.
derive_eq
3.140.
dir_entry_ext2
3.141.
discriminant_kind
3.142.
dispatch_from_dyn
3.143.
downcast_unchecked
3.144.
drain_keep_rest
3.145.
duration_constants
3.146.
duration_constructors
3.147.
duration_millis_float
3.148.
duration_units
3.149.
edition_panic
3.150.
effect_types
3.151.
error_generic_member_access
3.152.
error_iter
3.153.
error_reporter
3.154.
error_type_id
3.155.
exact_size_is_empty
3.156.
exclusive_wrapper
3.157.
exit_status_error
3.158.
exitcode_exit_method
3.159.
exposed_provenance
3.160.
extend_one
3.161.
extend_one_unchecked
3.162.
extract_if
3.163.
fd
3.164.
fd_read
3.165.
file_buffered
3.166.
float_gamma
3.167.
float_minimum_maximum
3.168.
float_next_up_down
3.169.
flt2dec
3.170.
fmt_helpers_for_derive
3.171.
fmt_internals
3.172.
fn_ptr_trait
3.173.
fn_traits
3.174.
forget_unsized
3.175.
format_args_nl
3.176.
freeze
3.177.
future_join
3.178.
gen_future
3.179.
generic_assert_internals
3.180.
get_many_mut
3.181.
get_mut_unchecked
3.182.
hash_extract_if
3.183.
hash_raw_entry
3.184.
hash_set_entry
3.185.
hasher_prefixfree_extras
3.186.
hashmap_internals
3.187.
hint_must_use
3.188.
inplace_iteration
3.189.
int_roundings
3.190.
integer_atomics
3.191.
integer_sign_cast
3.192.
internal_impls_macro
3.193.
internal_output_capture
3.194.
io_error_inprogress
3.195.
io_error_more
3.196.
io_error_uncategorized
3.197.
ip
3.198.
is_ascii_octdigit
3.199.
is_riscv_feature_detected
3.200.
is_val_statically_known
3.201.
isqrt
3.202.
iter_advance_by
3.203.
iter_array_chunks
3.204.
iter_chain
3.205.
iter_collect_into
3.206.
iter_from_coroutine
3.207.
iter_intersperse
3.208.
iter_is_partitioned
3.209.
iter_map_windows
3.210.
iter_next_chunk
3.211.
iter_order_by
3.212.
iter_partition_in_place
3.213.
iterator_try_collect
3.214.
iterator_try_reduce
3.215.
junction_point
3.216.
layout_for_ptr
3.217.
lazy_cell_into_inner
3.218.
lazy_get
3.219.
liballoc_internals
3.220.
libstd_sys_internals
3.221.
linked_list_cursors
3.222.
linked_list_remove
3.223.
linked_list_retain
3.224.
linux_pidfd
3.225.
local_waker
3.226.
log_syntax
3.227.
map_many_mut
3.228.
map_try_insert
3.229.
mapped_lock_guards
3.230.
maybe_uninit_array_assume_init
3.231.
maybe_uninit_as_bytes
3.232.
maybe_uninit_fill
3.233.
maybe_uninit_slice
3.234.
maybe_uninit_uninit_array
3.235.
maybe_uninit_uninit_array_transpose
3.236.
maybe_uninit_write_slice
3.237.
mem_copy_fn
3.238.
more_float_constants
3.239.
mpmc_channel
3.240.
new_range_api
3.241.
new_zeroed_alloc
3.242.
non_zero_count_ones
3.243.
nonzero_bitwise
3.244.
nonzero_from_mut
3.245.
nonzero_internals
3.246.
nonzero_ops
3.247.
noop_waker
3.248.
num_midpoint
3.249.
numfmt
3.250.
once_cell_get_mut
3.251.
once_cell_try
3.252.
once_cell_try_insert
3.253.
once_wait
3.254.
one_sided_range
3.255.
option_array_transpose
3.256.
option_zip
3.257.
os_str_display
3.258.
os_str_slice
3.259.
os_string_pathbuf_leak
3.260.
panic_abort
3.261.
panic_always_abort
3.262.
panic_backtrace_config
3.263.
panic_can_unwind
3.264.
panic_internals
3.265.
panic_payload_as_str
3.266.
panic_unwind
3.267.
panic_update_hook
3.268.
path_add_extension
3.269.
path_file_prefix
3.270.
pattern
3.271.
peer_credentials_unix_socket
3.272.
pin_coerce_unsized_trait
3.273.
pin_deref_mut
3.274.
pointer_is_aligned_to
3.275.
pointer_like_trait
3.276.
portable_simd
3.277.
prelude_2024
3.278.
print_internals
3.279.
proc_macro_def_site
3.280.
proc_macro_diagnostic
3.281.
proc_macro_expand
3.282.
proc_macro_internals
3.283.
proc_macro_quote
3.284.
proc_macro_span
3.285.
proc_macro_tracked_env
3.286.
process_exitcode_internals
3.287.
process_internals
3.288.
profiler_runtime_lib
3.289.
ptr_alignment_type
3.290.
ptr_as_ref_unchecked
3.291.
ptr_as_uninit
3.292.
ptr_fn_addr_eq
3.293.
ptr_internals
3.294.
ptr_mask
3.295.
ptr_metadata
3.296.
ptr_sub_ptr
3.297.
pub_crate_should_not_need_unstable_attr
3.298.
random
3.299.
raw_os_error_ty
3.300.
raw_slice_split
3.301.
raw_vec_internals
3.302.
read_buf
3.303.
receiver_trait
3.304.
reentrant_lock
3.305.
restricted_std
3.306.
result_flattening
3.307.
round_char_boundary
3.308.
rt
3.309.
rustc_encodable_decodable
3.310.
sealed
3.311.
seek_stream_len
3.312.
set_ptr_value
3.313.
setgroups
3.314.
sgx_platform
3.315.
sized_type_properties
3.316.
slice_as_chunks
3.317.
slice_concat_ext
3.318.
slice_concat_trait
3.319.
slice_from_ptr_range
3.320.
slice_index_methods
3.321.
slice_internals
3.322.
slice_iter_mut_as_mut_slice
3.323.
slice_partition_dedup
3.324.
slice_pattern
3.325.
slice_ptr_get
3.326.
slice_range
3.327.
slice_split_once
3.328.
slice_swap_unchecked
3.329.
slice_take
3.330.
solid_ext
3.331.
sort_floats
3.332.
split_array
3.333.
split_as_slice
3.334.
std_internals
3.335.
stdarch_arm_feature_detection
3.336.
stdarch_mips_feature_detection
3.337.
stdarch_powerpc_feature_detection
3.338.
stdio_makes_pipe
3.339.
step_trait
3.340.
str_as_str
3.341.
str_from_raw_parts
3.342.
str_from_utf16_endian
3.343.
str_internals
3.344.
str_lines_remainder
3.345.
str_split_inclusive_remainder
3.346.
str_split_remainder
3.347.
str_split_whitespace_remainder
3.348.
strict_overflow_ops
3.349.
strict_provenance_atomic_ptr
3.350.
string_extend_from_within
3.351.
string_from_utf8_lossy_owned
3.352.
string_remove_matches
3.353.
substr_range
3.354.
sync_unsafe_cell
3.355.
tcp_deferaccept
3.356.
tcp_linger
3.357.
tcp_quickack
3.358.
tcplistener_into_incoming
3.359.
test
3.360.
thin_box
3.361.
thread_id_value
3.362.
thread_local_internals
3.363.
thread_raw
3.364.
thread_sleep_until
3.365.
trace_macros
3.366.
track_path
3.367.
transmutability
3.368.
trusted_fused
3.369.
trusted_len
3.370.
trusted_len_next_unchecked
3.371.
trusted_random_access
3.372.
trusted_step
3.373.
try_find
3.374.
try_reserve_kind
3.375.
try_trait_v2
3.376.
try_trait_v2_residual
3.377.
try_trait_v2_yeet
3.378.
try_with_capacity
3.379.
tuple_trait
3.380.
type_ascription
3.381.
ub_checks
3.382.
uefi_std
3.383.
unbounded_shifts
3.384.
unchecked_neg
3.385.
unchecked_shifts
3.386.
unicode_internals
3.387.
unique_rc_arc
3.388.
unix_file_vectored_at
3.389.
unix_set_mark
3.390.
unix_socket_ancillary_data
3.391.
unix_socket_peek
3.392.
unsafe_cell_from_mut
3.393.
unsafe_pin_internals
3.394.
unsigned_is_multiple_of
3.395.
unsigned_signed_diff
3.396.
unsize
3.397.
unwrap_infallible
3.398.
update_panic_count
3.399.
utf16_extra
3.400.
utf16_extra_const
3.401.
variant_count
3.402.
vec_into_raw_parts
3.403.
vec_pop_if
3.404.
vec_push_within_capacity
3.405.
vec_split_at_spare
3.406.
wasi_ext
3.407.
windows_by_handle
3.408.
windows_c
3.409.
windows_change_time
3.410.
windows_handle
3.411.
windows_net
3.412.
windows_process_exit_code_from
3.413.
windows_process_extensions_async_pipes
3.414.
windows_process_extensions_force_quotes
3.415.
windows_process_extensions_main_thread_handle
3.416.
windows_process_extensions_raw_attribute
3.417.
windows_process_extensions_show_window
3.418.
windows_stdio
3.419.
wrapping_int_impl
3.420.
wrapping_next_power_of_two
3.421.
write_all_vectored
3.422.
yeet_desugar_details
Light
Rust
Coal
Navy
Ayu
The Rust Unstable Book
impl_trait_in_fn_trait_return
The tracking issue for this feature is:
#99697