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_hidden_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.
src_hash_algorithm
1.46.
temps_dir
1.47.
tiny_const_eval_limit
1.48.
tls_model
1.49.
ub_checks
1.50.
unsound_mir_opts
1.51.
verbose_asm
1.52.
virtual_function_elimination
1.53.
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.
arm_target_feature
2.19.
asm_experimental_arch
2.20.
asm_goto
2.21.
asm_unwind
2.22.
associated_const_equality
2.23.
associated_type_defaults
2.24.
async_closure
2.25.
async_fn_track_caller
2.26.
async_for_loop
2.27.
auto_traits
2.28.
avx512_target_feature
2.29.
box_patterns
2.30.
bpf_target_feature
2.31.
builtin_syntax
2.32.
c_variadic
2.33.
cfg_overflow_checks
2.34.
cfg_relocation_model
2.35.
cfg_sanitize
2.36.
cfg_sanitizer_cfi
2.37.
cfg_target_compact
2.38.
cfg_target_has_atomic
2.39.
cfg_target_has_atomic_equal_alignment
2.40.
cfg_target_thread_local
2.41.
cfg_ub_checks
2.42.
cfg_version
2.43.
cfi_encoding
2.44.
closure_lifetime_binder
2.45.
closure_track_caller
2.46.
cmse_nonsecure_entry
2.47.
compiler_builtins
2.48.
const_arg_path
2.49.
const_async_blocks
2.50.
const_closures
2.51.
const_extern_fn
2.52.
const_for
2.53.
const_mut_refs
2.54.
const_precise_live_drops
2.55.
const_refs_to_cell
2.56.
const_refs_to_static
2.57.
const_trait_impl
2.58.
const_try
2.59.
coroutine_clone
2.60.
coroutines
2.61.
coverage_attribute
2.62.
csky_target_feature
2.63.
custom_inner_attributes
2.64.
custom_mir
2.65.
custom_test_frameworks
2.66.
decl_macro
2.67.
deprecated_safe
2.68.
deprecated_suggestion
2.69.
deref_patterns
2.70.
derive_smart_pointer
2.71.
do_not_recommend
2.72.
doc_auto_cfg
2.73.
doc_cfg
2.74.
doc_cfg_hide
2.75.
doc_masked
2.76.
doc_notable_trait
2.77.
dropck_eyepatch
2.78.
dyn_star
2.79.
effects
2.80.
ermsb_target_feature
2.81.
exhaustive_patterns
2.82.
explicit_tail_calls
2.83.
expr_fragment_specifier_2024
2.84.
extended_varargs_abi_support
2.85.
extern_types
2.86.
f128
2.87.
f16
2.88.
ffi_const
2.89.
ffi_pure
2.90.
fmt_debug
2.91.
fn_align
2.92.
fn_delegation
2.93.
freeze_impls
2.94.
fundamental
2.95.
gen_blocks
2.96.
generic_arg_infer
2.97.
generic_assert
2.98.
generic_associated_types_extended
2.99.
generic_const_exprs
2.100.
generic_const_items
2.101.
global_registration
2.102.
half_open_range_patterns_in_slices
2.103.
hexagon_target_feature
2.104.
if_let_guard
2.105.
impl_trait_in_assoc_type
2.106.
impl_trait_in_fn_trait_return
2.107.
inherent_associated_types
2.108.
inline_const_pat
2.109.
intra_doc_pointers
2.110.
intrinsics
2.111.
lahfsahf_target_feature
2.112.
lang_items
2.113.
large_assignments
2.114.
lazy_type_alias
2.115.
let_chains
2.116.
lifetime_capture_rules_2024
2.117.
link_arg_attribute
2.118.
link_cfg
2.119.
link_llvm_intrinsics
2.120.
linkage
2.121.
loongarch_target_feature
2.122.
macro_metavar_expr
2.123.
macro_metavar_expr_concat
2.124.
marker_trait_attr
2.125.
min_specialization
2.126.
mips_target_feature
2.127.
more_maybe_bounds
2.128.
more_qualified_paths
2.129.
multiple_supertrait_upcastable
2.130.
must_not_suspend
2.131.
mut_ref
2.132.
naked_functions
2.133.
native_link_modifiers_as_needed
2.134.
needs_panic_runtime
2.135.
negative_bounds
2.136.
negative_impls
2.137.
never_patterns
2.138.
never_type
2.139.
never_type_fallback
2.140.
no_core
2.141.
no_sanitize
2.142.
non_exhaustive_omitted_patterns_lint
2.143.
non_lifetime_binders
2.144.
object_safe_for_dispatch
2.145.
offset_of_enum
2.146.
offset_of_slice
2.147.
omit_gdb_pretty_printer_section
2.148.
optimize_attribute
2.149.
panic_runtime
2.150.
patchable_function_entry
2.151.
pattern_complexity
2.152.
pattern_types
2.153.
postfix_match
2.154.
powerpc_target_feature
2.155.
prelude_import
2.156.
prfchw_target_feature
2.157.
proc_macro_hygiene
2.158.
profiler_runtime
2.159.
ref_pat_eat_one_layer_2024
2.160.
ref_pat_eat_one_layer_2024_structural
2.161.
register_tool
2.162.
repr_simd
2.163.
repr128
2.164.
result_ffi_guarantees
2.165.
return_type_notation
2.166.
riscv_target_feature
2.167.
rtm_target_feature
2.168.
rust_cold_cc
2.169.
rustc_allow_const_fn_unstable
2.170.
rustc_attrs
2.171.
rustc_private
2.172.
rustdoc_internals
2.173.
rustdoc_missing_doc_code_examples
2.174.
s390x_target_feature
2.175.
sha512_sm_x86
2.176.
shorter_tail_lifetimes
2.177.
simd_ffi
2.178.
specialization
2.179.
sse4a_target_feature
2.180.
staged_api
2.181.
start
2.182.
stmt_expr_attributes
2.183.
strict_provenance
2.184.
string_deref_patterns
2.185.
struct_target_features
2.186.
structural_match
2.187.
target_feature_11
2.188.
tbm_target_feature
2.189.
test_unstable_lint
2.190.
thread_local
2.191.
trait_alias
2.192.
trait_upcasting
2.193.
transmute_generic_consts
2.194.
transparent_unions
2.195.
trivial_bounds
2.196.
try_blocks
2.197.
type_alias_impl_trait
2.198.
type_changing_struct_update
2.199.
unboxed_closures
2.200.
unnamed_fields
2.201.
unsized_const_params
2.202.
unsized_fn_params
2.203.
unsized_locals
2.204.
unsized_tuple_coercion
2.205.
used_with_arg
2.206.
wasm_target_feature
2.207.
with_negative_coherence
2.208.
x86_amx_intrinsics
2.209.
xop_target_feature
2.210.
yeet_expr
3.
Library Features
3.1.
acceptfilter
3.2.
addr_parse_ascii
3.3.
alloc_error_hook
3.4.
alloc_internals
3.5.
alloc_layout_extra
3.6.
allocator_api
3.7.
anonymous_pipe
3.8.
array_chunks
3.9.
array_into_iter_constructors
3.10.
array_ptr_get
3.11.
array_repeat
3.12.
array_try_from_fn
3.13.
array_try_map
3.14.
array_windows
3.15.
as_array_of_cells
3.16.
ascii_char
3.17.
ascii_char_variants
3.18.
assert_matches
3.19.
async_drop
3.20.
async_fn_traits
3.21.
async_gen_internals
3.22.
async_iter_from_iter
3.23.
async_iterator
3.24.
atomic_from_mut
3.25.
backtrace_frames
3.26.
bigint_helper_methods
3.27.
binary_heap_drain_sorted
3.28.
binary_heap_into_iter_sorted
3.29.
bound_as_ref
3.30.
box_as_ptr
3.31.
box_into_boxed_slice
3.32.
box_into_inner
3.33.
box_uninit_write
3.34.
btree_cursors
3.35.
btree_extract_if
3.36.
btreemap_alloc
3.37.
buf_read_has_data_left
3.38.
bufread_skip_until
3.39.
bufreader_peek
3.40.
build_hasher_default_const_new
3.41.
c_size_t
3.42.
c_str_module
3.43.
c_void_variant
3.44.
can_vector
3.45.
cell_leak
3.46.
cell_update
3.47.
cfg_accessible
3.48.
cfg_eval
3.49.
cfg_match
3.50.
char_internals
3.51.
char_min
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_from_ref
3.64.
const_array_into_iter_constructors
3.65.
const_atomic_from_ptr
3.66.
const_bigint_helper_methods
3.67.
const_binary_heap_new_in
3.68.
const_black_box
3.69.
const_box
3.70.
const_btree_len
3.71.
const_cell_into_inner
3.72.
const_collections_with_hasher
3.73.
const_cow_is_borrowed
3.74.
const_eval_select
3.75.
const_exact_div
3.76.
const_float_bits_conv
3.77.
const_float_classify
3.78.
const_fmt_arguments_new
3.79.
const_format_args
3.80.
const_hash
3.81.
const_heap
3.82.
const_index_range_slice_index
3.83.
const_intoiterator_identity
3.84.
const_intrinsic_compare_bytes
3.85.
const_intrinsic_copy
3.86.
const_intrinsic_forget
3.87.
const_intrinsic_raw_eq
3.88.
const_ip
3.89.
const_ipv4
3.90.
const_ipv6
3.91.
const_likely
3.92.
const_maybe_uninit_array_assume_init
3.93.
const_maybe_uninit_as_mut_ptr
3.94.
const_maybe_uninit_assume_init
3.95.
const_maybe_uninit_uninit_array
3.96.
const_maybe_uninit_write
3.97.
const_nonnull_new
3.98.
const_num_midpoint
3.99.
const_option
3.100.
const_option_ext
3.101.
const_pin
3.102.
const_pointer_is_aligned
3.103.
const_pref_align_of
3.104.
const_ptr_as_ref
3.105.
const_ptr_is_null
3.106.
const_ptr_sub_ptr
3.107.
const_ptr_write
3.108.
const_range_bounds
3.109.
const_raw_ptr_comparison
3.110.
const_replace
3.111.
const_result
3.112.
const_size_of_val
3.113.
const_size_of_val_raw
3.114.
const_slice_first_last
3.115.
const_slice_first_last_chunk
3.116.
const_slice_flatten
3.117.
const_slice_from_mut_ptr_range
3.118.
const_slice_from_ptr_range
3.119.
const_slice_from_raw_parts_mut
3.120.
const_slice_from_ref
3.121.
const_slice_index
3.122.
const_slice_split_at_mut
3.123.
const_str_from_raw_parts_mut
3.124.
const_str_from_utf8
3.125.
const_str_from_utf8_unchecked_mut
3.126.
const_strict_overflow_ops
3.127.
const_swap
3.128.
const_three_way_compare
3.129.
const_type_id
3.130.
const_type_name
3.131.
const_typed_swap
3.132.
const_ub_checks
3.133.
const_unbounded_shifts
3.134.
const_unicode_case_lookup
3.135.
const_unsafecell_get_mut
3.136.
container_error_extra
3.137.
context_ext
3.138.
control_flow_enum
3.139.
convert_float_to_int
3.140.
core_intrinsics
3.141.
core_io_borrowed_buf
3.142.
core_pattern_type
3.143.
core_pattern_types
3.144.
core_private_bignum
3.145.
core_private_diy_float
3.146.
coroutine_trait
3.147.
cow_is_borrowed
3.148.
cstr_bytes
3.149.
cstr_internals
3.150.
cursor_split
3.151.
deadline_api
3.152.
debug_closure_helpers
3.153.
debug_more_non_exhaustive
3.154.
dec2flt
3.155.
deref_pure_trait
3.156.
derive_clone_copy
3.157.
derive_const
3.158.
derive_eq
3.159.
dir_entry_ext2
3.160.
discriminant_kind
3.161.
dispatch_from_dyn
3.162.
downcast_unchecked
3.163.
drain_keep_rest
3.164.
duration_constants
3.165.
duration_constructors
3.166.
duration_consts_float
3.167.
duration_millis_float
3.168.
duration_units
3.169.
edition_panic
3.170.
effect_types
3.171.
entry_insert
3.172.
error_generic_member_access
3.173.
error_iter
3.174.
error_reporter
3.175.
error_type_id
3.176.
exact_size_is_empty
3.177.
exclusive_wrapper
3.178.
exit_status_error
3.179.
exitcode_exit_method
3.180.
exposed_provenance
3.181.
extend_one
3.182.
extend_one_unchecked
3.183.
extract_if
3.184.
fd
3.185.
fd_read
3.186.
float_gamma
3.187.
float_minimum_maximum
3.188.
float_next_up_down
3.189.
flt2dec
3.190.
fmt_helpers_for_derive
3.191.
fmt_internals
3.192.
fn_ptr_trait
3.193.
fn_traits
3.194.
forget_unsized
3.195.
format_args_nl
3.196.
freeze
3.197.
future_join
3.198.
gen_future
3.199.
generic_assert_internals
3.200.
get_many_mut
3.201.
get_mut_unchecked
3.202.
hash_extract_if
3.203.
hash_raw_entry
3.204.
hash_set_entry
3.205.
hasher_prefixfree_extras
3.206.
hashmap_internals
3.207.
hint_must_use
3.208.
inplace_iteration
3.209.
int_roundings
3.210.
integer_atomics
3.211.
integer_sign_cast
3.212.
internal_impls_macro
3.213.
internal_output_capture
3.214.
io_error_more
3.215.
io_error_uncategorized
3.216.
ip
3.217.
is_ascii_octdigit
3.218.
is_riscv_feature_detected
3.219.
is_val_statically_known
3.220.
isqrt
3.221.
iter_advance_by
3.222.
iter_array_chunks
3.223.
iter_chain
3.224.
iter_collect_into
3.225.
iter_from_coroutine
3.226.
iter_intersperse
3.227.
iter_is_partitioned
3.228.
iter_map_windows
3.229.
iter_next_chunk
3.230.
iter_order_by
3.231.
iter_partition_in_place
3.232.
iterator_try_collect
3.233.
iterator_try_reduce
3.234.
junction_point
3.235.
layout_for_ptr
3.236.
lazy_cell_into_inner
3.237.
liballoc_internals
3.238.
libstd_sys_internals
3.239.
linked_list_cursors
3.240.
linked_list_remove
3.241.
linked_list_retain
3.242.
linux_pidfd
3.243.
local_waker
3.244.
log_syntax
3.245.
map_entry_replace
3.246.
map_many_mut
3.247.
map_try_insert
3.248.
mapped_lock_guards
3.249.
maybe_uninit_array_assume_init
3.250.
maybe_uninit_as_bytes
3.251.
maybe_uninit_fill
3.252.
maybe_uninit_slice
3.253.
maybe_uninit_uninit_array
3.254.
maybe_uninit_uninit_array_transpose
3.255.
maybe_uninit_write_slice
3.256.
mem_copy_fn
3.257.
more_float_constants
3.258.
new_range_api
3.259.
new_zeroed_alloc
3.260.
non_zero_count_ones
3.261.
nonzero_bitwise
3.262.
nonzero_from_mut
3.263.
nonzero_internals
3.264.
nonzero_ops
3.265.
noop_waker
3.266.
num_midpoint
3.267.
numfmt
3.268.
once_cell_get_mut
3.269.
once_cell_try
3.270.
once_cell_try_insert
3.271.
once_wait
3.272.
one_sided_range
3.273.
option_get_or_insert_default
3.274.
option_zip
3.275.
os_str_display
3.276.
os_str_slice
3.277.
os_string_pathbuf_leak
3.278.
panic_abort
3.279.
panic_always_abort
3.280.
panic_backtrace_config
3.281.
panic_can_unwind
3.282.
panic_internals
3.283.
panic_payload_as_str
3.284.
panic_unwind
3.285.
panic_update_hook
3.286.
path_add_extension
3.287.
path_file_prefix
3.288.
pattern
3.289.
peer_credentials_unix_socket
3.290.
pin_coerce_unsized_trait
3.291.
pin_deref_mut
3.292.
pointer_is_aligned_to
3.293.
pointer_like_trait
3.294.
portable_simd
3.295.
prelude_2024
3.296.
print_internals
3.297.
proc_macro_def_site
3.298.
proc_macro_diagnostic
3.299.
proc_macro_expand
3.300.
proc_macro_internals
3.301.
proc_macro_quote
3.302.
proc_macro_span
3.303.
proc_macro_tracked_env
3.304.
process_exitcode_internals
3.305.
process_internals
3.306.
profiler_runtime_lib
3.307.
ptr_alignment_type
3.308.
ptr_as_ref_unchecked
3.309.
ptr_as_uninit
3.310.
ptr_fn_addr_eq
3.311.
ptr_internals
3.312.
ptr_mask
3.313.
ptr_metadata
3.314.
ptr_sub_ptr
3.315.
pub_crate_should_not_need_unstable_attr
3.316.
raw_os_error_ty
3.317.
raw_slice_split
3.318.
raw_vec_internals
3.319.
read_buf
3.320.
receiver_trait
3.321.
reentrant_lock
3.322.
restricted_std
3.323.
result_flattening
3.324.
round_char_boundary
3.325.
rt
3.326.
rustc_encodable_decodable
3.327.
sealed
3.328.
seek_stream_len
3.329.
set_ptr_value
3.330.
setgroups
3.331.
sgx_platform
3.332.
sized_type_properties
3.333.
slice_as_chunks
3.334.
slice_concat_ext
3.335.
slice_concat_trait
3.336.
slice_from_ptr_range
3.337.
slice_index_methods
3.338.
slice_internals
3.339.
slice_iter_mut_as_mut_slice
3.340.
slice_partition_dedup
3.341.
slice_pattern
3.342.
slice_ptr_get
3.343.
slice_range
3.344.
slice_split_once
3.345.
slice_swap_unchecked
3.346.
slice_take
3.347.
solid_ext
3.348.
sort_floats
3.349.
split_array
3.350.
split_as_slice
3.351.
std_internals
3.352.
stdarch_arm_feature_detection
3.353.
stdarch_mips_feature_detection
3.354.
stdarch_powerpc_feature_detection
3.355.
stdio_makes_pipe
3.356.
step_trait
3.357.
str_from_raw_parts
3.358.
str_from_utf16_endian
3.359.
str_internals
3.360.
str_lines_remainder
3.361.
str_split_inclusive_remainder
3.362.
str_split_remainder
3.363.
str_split_whitespace_remainder
3.364.
strict_overflow_ops
3.365.
strict_provenance_atomic_ptr
3.366.
string_extend_from_within
3.367.
string_remove_matches
3.368.
substr_range
3.369.
sync_unsafe_cell
3.370.
tcp_deferaccept
3.371.
tcp_linger
3.372.
tcp_quickack
3.373.
tcplistener_into_incoming
3.374.
test
3.375.
thin_box
3.376.
thread_id_value
3.377.
thread_local_internals
3.378.
thread_sleep_until
3.379.
trace_macros
3.380.
track_path
3.381.
transmutability
3.382.
trusted_fused
3.383.
trusted_len
3.384.
trusted_len_next_unchecked
3.385.
trusted_random_access
3.386.
trusted_step
3.387.
try_find
3.388.
try_reserve_kind
3.389.
try_trait_v2
3.390.
try_trait_v2_residual
3.391.
try_trait_v2_yeet
3.392.
try_with_capacity
3.393.
tuple_trait
3.394.
type_ascription
3.395.
ub_checks
3.396.
uefi_std
3.397.
unbounded_shifts
3.398.
unchecked_neg
3.399.
unchecked_shifts
3.400.
unicode_internals
3.401.
unique_rc_arc
3.402.
unix_file_vectored_at
3.403.
unix_set_mark
3.404.
unix_socket_ancillary_data
3.405.
unix_socket_peek
3.406.
unsafe_cell_from_mut
3.407.
unsafe_pin_internals
3.408.
unsigned_is_multiple_of
3.409.
unsigned_signed_diff
3.410.
unsize
3.411.
unwrap_infallible
3.412.
update_panic_count
3.413.
utf16_extra
3.414.
utf16_extra_const
3.415.
variant_count
3.416.
vec_into_raw_parts
3.417.
vec_pop_if
3.418.
vec_push_within_capacity
3.419.
vec_split_at_spare
3.420.
waker_getters
3.421.
wasi_ext
3.422.
windows_by_handle
3.423.
windows_c
3.424.
windows_change_time
3.425.
windows_handle
3.426.
windows_net
3.427.
windows_process_exit_code_from
3.428.
windows_process_extensions_async_pipes
3.429.
windows_process_extensions_force_quotes
3.430.
windows_process_extensions_main_thread_handle
3.431.
windows_process_extensions_raw_attribute
3.432.
windows_process_extensions_show_window
3.433.
windows_stdio
3.434.
wrapping_int_impl
3.435.
wrapping_next_power_of_two
3.436.
write_all_vectored
3.437.
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