The Unstable Book
1.
Compiler flags
1.1.
control_flow_guard
1.2.
emit_stack_sizes
1.3.
profile
1.4.
report_time
1.5.
sanitizer
1.6.
self_profile
1.7.
self_profile_events
1.8.
src_hash_algorithm
1.9.
strip
1.10.
tls_model
1.11.
unsound_mir_opts
2.
Language features
2.1.
aarch64_target_feature
2.2.
abi_amdgpu_kernel
2.3.
abi_avr_interrupt
2.4.
abi_efiapi
2.5.
abi_msp430_interrupt
2.6.
abi_ptx
2.7.
abi_thiscall
2.8.
abi_unadjusted
2.9.
abi_vectorcall
2.10.
abi_x86_interrupt
2.11.
adx_target_feature
2.12.
alloc_error_handler
2.13.
allocator_internals
2.14.
allow_fail
2.15.
allow_internal_unsafe
2.16.
allow_internal_unstable
2.17.
arbitrary_enum_discriminant
2.18.
arbitrary_self_types
2.19.
arm_target_feature
2.20.
associated_type_bounds
2.21.
associated_type_defaults
2.22.
async_closure
2.23.
avx512_target_feature
2.24.
bindings_after_at
2.25.
box_patterns
2.26.
box_syntax
2.27.
c_variadic
2.28.
cfg_sanitize
2.29.
cfg_target_has_atomic
2.30.
cfg_target_thread_local
2.31.
cfg_version
2.32.
cmpxchg16b_target_feature
2.33.
cmse_nonsecure_entry
2.34.
compiler_builtins
2.35.
const_eval_limit
2.36.
const_evaluatable_checked
2.37.
const_extern_fn
2.38.
const_fn
2.39.
const_fn_floating_point_arithmetic
2.40.
const_fn_fn_ptr_basics
2.41.
const_fn_transmute
2.42.
const_fn_union
2.43.
const_generics
2.44.
const_in_array_repeat_expressions
2.45.
const_mut_refs
2.46.
const_panic
2.47.
const_precise_live_drops
2.48.
const_raw_ptr_deref
2.49.
const_raw_ptr_to_usize_cast
2.50.
const_trait_bound_opt_out
2.51.
const_trait_impl
2.52.
crate_visibility_modifier
2.53.
custom_inner_attributes
2.54.
custom_test_frameworks
2.55.
decl_macro
2.56.
default_type_parameter_fallback
2.57.
doc_cfg
2.58.
doc_keyword
2.59.
doc_masked
2.60.
doc_spotlight
2.61.
dropck_eyepatch
2.62.
exclusive_range_pattern
2.63.
exhaustive_patterns
2.64.
extern_types
2.65.
external_doc
2.66.
f16c_target_feature
2.67.
ffi_const
2.68.
ffi_pure
2.69.
ffi_returns_twice
2.70.
format_args_capture
2.71.
fundamental
2.72.
generators
2.73.
generic_associated_types
2.74.
half_open_range_patterns
2.75.
hexagon_target_feature
2.76.
if_let_guard
2.77.
impl_trait_in_bindings
2.78.
in_band_lifetimes
2.79.
infer_static_outlives_requirements
2.80.
intrinsics
2.81.
label_break_value
2.82.
lang_items
2.83.
lazy_normalization_consts
2.84.
let_chains
2.85.
link_args
2.86.
link_cfg
2.87.
link_llvm_intrinsics
2.88.
linkage
2.89.
lint_reasons
2.90.
main
2.91.
marker_trait_attr
2.92.
member_constraints
2.93.
min_const_generics
2.94.
min_specialization
2.95.
mips_target_feature
2.96.
movbe_target_feature
2.97.
move_ref_pattern
2.98.
naked_functions
2.99.
needs_panic_runtime
2.100.
negative_impls
2.101.
never_type
2.102.
never_type_fallback
2.103.
nll
2.104.
no_core
2.105.
no_niche
2.106.
no_sanitize
2.107.
non_ascii_idents
2.108.
object_safe_for_dispatch
2.109.
omit_gdb_pretty_printer_section
2.110.
optimize_attribute
2.111.
optin_builtin_traits
2.112.
or_patterns
2.113.
panic_runtime
2.114.
platform_intrinsics
2.115.
plugin
2.116.
plugin_registrar
2.117.
powerpc_target_feature
2.118.
precise_pointer_size_matching
2.119.
prelude_import
2.120.
proc_macro_hygiene
2.121.
profiler_runtime
2.122.
raw_dylib
2.123.
raw_ref_op
2.124.
register_attr
2.125.
register_tool
2.126.
repr_simd
2.127.
repr128
2.128.
riscv_target_feature
2.129.
rtm_target_feature
2.130.
rustc_attrs
2.131.
rustc_private
2.132.
simd_ffi
2.133.
specialization
2.134.
sse4a_target_feature
2.135.
staged_api
2.136.
start
2.137.
static_nobundle
2.138.
stmt_expr_attributes
2.139.
structural_match
2.140.
target_feature_11
2.141.
tbm_target_feature
2.142.
test_2018_feature
2.143.
thread_local
2.144.
trait_alias
2.145.
transparent_unions
2.146.
trivial_bounds
2.147.
try_blocks
2.148.
type_alias_impl_trait
2.149.
type_ascription
2.150.
unboxed_closures
2.151.
unsafe_block_in_unsafe_fn
2.152.
unsized_locals
2.153.
unsized_tuple_coercion
2.154.
untagged_unions
2.155.
unwind_attributes
2.156.
wasm_target_feature
3.
Library Features
3.1.
alloc_error_hook
3.2.
alloc_internals
3.3.
alloc_layout_extra
3.4.
alloc_prelude
3.5.
allocator_api
3.6.
arc_mutate_strong_count
3.7.
arc_new_cyclic
3.8.
array_chunks
3.9.
array_error_internals
3.10.
array_from_ref
3.11.
array_map
3.12.
array_methods
3.13.
array_value_iter
3.14.
array_windows
3.15.
asm
3.16.
assoc_char_consts
3.17.
assoc_char_funcs
3.18.
atomic_from_mut
3.19.
atomic_mut_ptr
3.20.
backtrace
3.21.
binary_heap_drain_sorted
3.22.
binary_heap_into_iter_sorted
3.23.
binary_heap_retain
3.24.
bool_to_option
3.25.
bound_cloned
3.26.
box_into_boxed_slice
3.27.
box_into_pin
3.28.
btree_drain_filter
3.29.
bufreader_seek_relative
3.30.
c_void_variant
3.31.
can_vector
3.32.
cell_leak
3.33.
cell_update
3.34.
cfg_accessible
3.35.
char_error_internals
3.36.
char_internals
3.37.
clamp
3.38.
cmp_min_max_by
3.39.
coerce_unsized
3.40.
command_access
3.41.
concat_idents
3.42.
const_align_of_val
3.43.
const_alloc_layout
3.44.
const_assume
3.45.
const_btree_new
3.46.
const_caller_location
3.47.
const_checked_int_methods
3.48.
const_cow_is_borrowed
3.49.
const_cstr_unchecked
3.50.
const_cttz
3.51.
const_discriminant
3.52.
const_euclidean_int_methods
3.53.
const_float_bits_conv
3.54.
const_float_classify
3.55.
const_int_pow
3.56.
const_int_unchecked_arith
3.57.
const_ip
3.58.
const_ipv4
3.59.
const_ipv6
3.60.
const_likely
3.61.
const_maybe_uninit_as_ptr
3.62.
const_nonnull_slice_from_raw_parts
3.63.
const_option
3.64.
const_overflowing_int_methods
3.65.
const_pin
3.66.
const_pref_align_of
3.67.
const_ptr_is_null
3.68.
const_ptr_offset
3.69.
const_ptr_offset_from
3.70.
const_raw_ptr_comparison
3.71.
const_size_of_val
3.72.
const_slice_from_raw_parts
3.73.
const_slice_ptr_len
3.74.
const_str_from_utf8_unchecked
3.75.
const_type_id
3.76.
const_type_name
3.77.
const_unreachable_unchecked
3.78.
const_wrapping_int_methods
3.79.
constctlz
3.80.
container_error_extra
3.81.
control_flow_enum
3.82.
convert_float_to_int
3.83.
core_intrinsics
3.84.
core_panic
3.85.
core_private_bignum
3.86.
core_private_diy_float
3.87.
cow_is_borrowed
3.88.
cstring_from_vec_with_nul
3.89.
deadline_api
3.90.
debug_non_exhaustive
3.91.
dec2flt
3.92.
default_free_fn
3.93.
deque_range
3.94.
derive_clone_copy
3.95.
derive_eq
3.96.
discriminant_kind
3.97.
dispatch_from_dyn
3.98.
div_duration
3.99.
drain_filter
3.100.
duration_constants
3.101.
duration_consts_2
3.102.
duration_saturating_ops
3.103.
duration_zero
3.104.
entry_insert
3.105.
error_iter
3.106.
error_type_id
3.107.
exact_size_is_empty
3.108.
extend_one
3.109.
fd
3.110.
fd_read
3.111.
fixed_size_array
3.112.
flt2dec
3.113.
fmt_as_str
3.114.
fmt_internals
3.115.
fn_traits
3.116.
foo
3.117.
forget_unsized
3.118.
format_args_nl
3.119.
future_poll_fn
3.120.
gen_future
3.121.
generator_trait
3.122.
get_mut_unchecked
3.123.
global_asm
3.124.
hash_drain_filter
3.125.
hash_raw_entry
3.126.
hash_set_entry
3.127.
hashmap_internals
3.128.
inplace_iteration
3.129.
int_bits_const
3.130.
int_error_internals
3.131.
int_error_matching
3.132.
integer_atomics
3.133.
into_future
3.134.
io_slice_advance
3.135.
ip
3.136.
is_sorted
3.137.
iter_advance_by
3.138.
iter_is_partitioned
3.139.
iter_map_while
3.140.
iter_order_by
3.141.
iter_partition_in_place
3.142.
iterator_fold_self
3.143.
layout_for_ptr
3.144.
liballoc_internals
3.145.
libstd_io_internals
3.146.
libstd_sys_internals
3.147.
libstd_thread_internals
3.148.
linked_list_cursors
3.149.
linked_list_extras
3.150.
linked_list_prepend
3.151.
linked_list_remove
3.152.
llvm_asm
3.153.
log_syntax
3.154.
map_entry_replace
3.155.
map_first_last
3.156.
map_into_keys_values
3.157.
maybe_uninit_extra
3.158.
maybe_uninit_ref
3.159.
maybe_uninit_slice
3.160.
maybe_uninit_uninit_array
3.161.
new_uninit
3.162.
nonnull_slice_from_raw_parts
3.163.
once_cell
3.164.
once_poison
3.165.
option_expect_none
3.166.
option_result_contains
3.167.
option_unwrap_none
3.168.
option_zip
3.169.
or_insert_with_key
3.170.
osstring_ascii
3.171.
panic_abort
3.172.
panic_info_message
3.173.
panic_internals
3.174.
panic_unwind
3.175.
partition_point
3.176.
pattern
3.177.
peekable_next_if
3.178.
peer_credentials_unix_socket
3.179.
pin_static_ref
3.180.
poll_map
3.181.
print_internals
3.182.
proc_macro_def_site
3.183.
proc_macro_diagnostic
3.184.
proc_macro_internals
3.185.
proc_macro_is_available
3.186.
proc_macro_quote
3.187.
proc_macro_span
3.188.
proc_macro_tracked_env
3.189.
process_exitcode_placeholder
3.190.
process_internals
3.191.
profiler_runtime_lib
3.192.
ptr_as_uninit
3.193.
ptr_internals
3.194.
raw
3.195.
raw_ref_macros
3.196.
raw_vec_internals
3.197.
read_initializer
3.198.
ready_macro
3.199.
receiver_trait
3.200.
refcell_take
3.201.
renamed_spin_loop
3.202.
result_cloned
3.203.
result_contains_err
3.204.
result_copied
3.205.
result_flattening
3.206.
rt
3.207.
seek_convenience
3.208.
set_ptr_value
3.209.
set_stdio
3.210.
sgx_platform
3.211.
shrink_to
3.212.
slice_check_range
3.213.
slice_concat_ext
3.214.
slice_concat_trait
3.215.
slice_fill
3.216.
slice_index_methods
3.217.
slice_internals
3.218.
slice_iter_mut_as_slice
3.219.
slice_partition_at_index
3.220.
slice_partition_dedup
3.221.
slice_ptr_get
3.222.
slice_ptr_len
3.223.
slice_split_at_unchecked
3.224.
slice_strip
3.225.
sort_internals
3.226.
split_inclusive
3.227.
std_internals
3.228.
stdsimd
3.229.
step_trait
3.230.
step_trait_ext
3.231.
str_internals
3.232.
str_split_once
3.233.
string_drain_as_str
3.234.
termination_trait_lib
3.235.
test
3.236.
thread_id_value
3.237.
thread_local_internals
3.238.
thread_spawn_unchecked
3.239.
toowned_clone_into
3.240.
total_cmp
3.241.
trace_macros
3.242.
trusted_len
3.243.
trusted_random_access
3.244.
try_find
3.245.
try_reserve
3.246.
try_trait
3.247.
type_name_of_val
3.248.
unchecked_math
3.249.
unicode_internals
3.250.
unix_socket_peek
3.251.
unsafe_cell_get_mut
3.252.
unsafe_cell_raw_get
3.253.
unsigned_abs
3.254.
unsize
3.255.
unwrap_infallible
3.256.
update_panic_count
3.257.
variant_count
3.258.
vec_into_raw_parts
3.259.
vec_remove_item
3.260.
vec_resize_default
3.261.
vec_spare_capacity
3.262.
wake_trait
3.263.
wasi_ext
3.264.
windows_by_handle
3.265.
windows_c
3.266.
windows_file_type_ext
3.267.
windows_handle
3.268.
windows_net
3.269.
windows_stdio
3.270.
with_options
3.271.
wrapping_int_impl
3.272.
wrapping_next_power_of_two
3.273.
write_all_vectored
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The Rust Unstable Book
or_insert_with_key
The tracking issue for this feature is:
#71024