Skip to content

Commit

Permalink
const-stabilize the unchecked_{add,sub,mul} *intrinsics*
Browse files Browse the repository at this point in the history 
This is only the intrinsics, which aren't exposed anywhere, so I think we can just do this without an FCP.

The behaviour of these is well understood, have been implemented for ages, and don't offer any new functionality to `const fn`s -- it would be completely legal for them to be implemented via `wrapping_add`, since we don't promise to catch all UB.
  • Loading branch information
@scottmcm
scottmcm committed Jun 8, 2022
1 parent 09d52bc commit d8198ca
Show file tree
Hide file tree
Showing 4 changed files with 52 additions and 54 deletions.
6 changes: 3 additions & 3 deletions library/core/src/intrinsics.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1760,21 +1760,21 @@ extern "rust-intrinsic" {
/// undefined behavior when `x + y > T::MAX` or `x + y < T::MIN`.
///
/// This intrinsic does not have a stable counterpart.
#[rustc_const_unstable(feature = "const_int_unchecked_arith", issue = "none")]
#[rustc_const_stable(feature = "const_int_unchecked_arith", since = "1.63.0")]
pub fn unchecked_add<T: Copy>(x: T, y: T) -> T;

/// Returns the result of an unchecked subtraction, resulting in
/// undefined behavior when `x - y > T::MAX` or `x - y < T::MIN`.
///
/// This intrinsic does not have a stable counterpart.
#[rustc_const_unstable(feature = "const_int_unchecked_arith", issue = "none")]
#[rustc_const_stable(feature = "const_int_unchecked_arith", since = "1.63.0")]
pub fn unchecked_sub<T: Copy>(x: T, y: T) -> T;

/// Returns the result of an unchecked multiplication, resulting in
/// undefined behavior when `x * y > T::MAX` or `x * y < T::MIN`.
///
/// This intrinsic does not have a stable counterpart.
#[rustc_const_unstable(feature = "const_int_unchecked_arith", issue = "none")]
#[rustc_const_stable(feature = "const_int_unchecked_arith", since = "1.63.0")]
pub fn unchecked_mul<T: Copy>(x: T, y: T) -> T;

/// Performs rotate left.
Expand Down
1 change: 0 additions & 1 deletion library/core/src/lib.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -113,7 +113,6 @@
#![feature(const_heap)]
#![feature(const_convert)]
#![feature(const_inherent_unchecked_arith)]
#![feature(const_int_unchecked_arith)]
#![feature(const_intrinsic_forget)]
#![feature(const_likely)]
#![feature(const_maybe_uninit_uninit_array)]
Expand Down
1 change: 0 additions & 1 deletion src/test/ui/consts/const-int-unchecked.rs
View file
Original file line number Diff line number Diff line change
@@ -1,5 +1,4 @@
#![feature(core_intrinsics)]
#![feature(const_int_unchecked_arith)]

use std::intrinsics;

Expand Down
98 changes: 49 additions & 49 deletions src/test/ui/consts/const-int-unchecked.stderr
View file
Original file line number Diff line number Diff line change
@@ -1,293 +1,293 @@
error[E0080]: evaluation of constant value failed
--> $DIR/const-int-unchecked.rs:15:29
--> $DIR/const-int-unchecked.rs:14:29
|
LL | const SHL_U8: u8 = unsafe { intrinsics::unchecked_shl(5_u8, 8) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ overflowing shift by 8 in `unchecked_shl`

error[E0080]: evaluation of constant value failed
--> $DIR/const-int-unchecked.rs:17:31
--> $DIR/const-int-unchecked.rs:16:31
|
LL | const SHL_U16: u16 = unsafe { intrinsics::unchecked_shl(5_u16, 16) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ overflowing shift by 16 in `unchecked_shl`

error[E0080]: evaluation of constant value failed
--> $DIR/const-int-unchecked.rs:19:31
--> $DIR/const-int-unchecked.rs:18:31
|
LL | const SHL_U32: u32 = unsafe { intrinsics::unchecked_shl(5_u32, 32) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ overflowing shift by 32 in `unchecked_shl`

error[E0080]: evaluation of constant value failed
--> $DIR/const-int-unchecked.rs:21:31
--> $DIR/const-int-unchecked.rs:20:31
|
LL | const SHL_U64: u64 = unsafe { intrinsics::unchecked_shl(5_u64, 64) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ overflowing shift by 64 in `unchecked_shl`

error[E0080]: evaluation of constant value failed
--> $DIR/const-int-unchecked.rs:23:33
--> $DIR/const-int-unchecked.rs:22:33
|
LL | const SHL_U128: u128 = unsafe { intrinsics::unchecked_shl(5_u128, 128) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ overflowing shift by 128 in `unchecked_shl`

error[E0080]: evaluation of constant value failed
--> $DIR/const-int-unchecked.rs:28:29
--> $DIR/const-int-unchecked.rs:27:29
|
LL | const SHL_I8: i8 = unsafe { intrinsics::unchecked_shl(5_i8, 8) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ overflowing shift by 8 in `unchecked_shl`

error[E0080]: evaluation of constant value failed
--> $DIR/const-int-unchecked.rs:30:31
--> $DIR/const-int-unchecked.rs:29:31
|
LL | const SHL_I16: i16 = unsafe { intrinsics::unchecked_shl(5_16, 16) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ overflowing shift by 16 in `unchecked_shl`

error[E0080]: evaluation of constant value failed
--> $DIR/const-int-unchecked.rs:32:31
--> $DIR/const-int-unchecked.rs:31:31
|
LL | const SHL_I32: i32 = unsafe { intrinsics::unchecked_shl(5_i32, 32) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ overflowing shift by 32 in `unchecked_shl`

error[E0080]: evaluation of constant value failed
--> $DIR/const-int-unchecked.rs:34:31
--> $DIR/const-int-unchecked.rs:33:31
|
LL | const SHL_I64: i64 = unsafe { intrinsics::unchecked_shl(5_i64, 64) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ overflowing shift by 64 in `unchecked_shl`

error[E0080]: evaluation of constant value failed
--> $DIR/const-int-unchecked.rs:36:33
--> $DIR/const-int-unchecked.rs:35:33
|
LL | const SHL_I128: i128 = unsafe { intrinsics::unchecked_shl(5_i128, 128) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ overflowing shift by 128 in `unchecked_shl`

error[E0080]: evaluation of constant value failed
--> $DIR/const-int-unchecked.rs:41:33
--> $DIR/const-int-unchecked.rs:40:33
|
LL | const SHL_I8_NEG: i8 = unsafe { intrinsics::unchecked_shl(5_i8, -1) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ overflowing shift by 255 in `unchecked_shl`

error[E0080]: evaluation of constant value failed
--> $DIR/const-int-unchecked.rs:43:35
--> $DIR/const-int-unchecked.rs:42:35
|
LL | const SHL_I16_NEG: i16 = unsafe { intrinsics::unchecked_shl(5_16, -1) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ overflowing shift by 65535 in `unchecked_shl`

error[E0080]: evaluation of constant value failed
--> $DIR/const-int-unchecked.rs:45:35
--> $DIR/const-int-unchecked.rs:44:35
|
LL | const SHL_I32_NEG: i32 = unsafe { intrinsics::unchecked_shl(5_i32, -1) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ overflowing shift by 4294967295 in `unchecked_shl`

error[E0080]: evaluation of constant value failed
--> $DIR/const-int-unchecked.rs:47:35
--> $DIR/const-int-unchecked.rs:46:35
|
LL | const SHL_I64_NEG: i64 = unsafe { intrinsics::unchecked_shl(5_i64, -1) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ overflowing shift by 18446744073709551615 in `unchecked_shl`

error[E0080]: evaluation of constant value failed
--> $DIR/const-int-unchecked.rs:49:37
--> $DIR/const-int-unchecked.rs:48:37
|
LL | const SHL_I128_NEG: i128 = unsafe { intrinsics::unchecked_shl(5_i128, -1) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ overflowing shift by 340282366920938463463374607431768211455 in `unchecked_shl`

error[E0080]: evaluation of constant value failed
--> $DIR/const-int-unchecked.rs:55:40
--> $DIR/const-int-unchecked.rs:54:40
|
LL | const SHL_I8_NEG_RANDOM: i8 = unsafe { intrinsics::unchecked_shl(5_i8, -6) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ overflowing shift by 250 in `unchecked_shl`

error[E0080]: evaluation of constant value failed
--> $DIR/const-int-unchecked.rs:57:42
--> $DIR/const-int-unchecked.rs:56:42
|
LL | const SHL_I16_NEG_RANDOM: i16 = unsafe { intrinsics::unchecked_shl(5_16, -13) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ overflowing shift by 65523 in `unchecked_shl`

error[E0080]: evaluation of constant value failed
--> $DIR/const-int-unchecked.rs:59:42
--> $DIR/const-int-unchecked.rs:58:42
|
LL | const SHL_I32_NEG_RANDOM: i32 = unsafe { intrinsics::unchecked_shl(5_i32, -25) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ overflowing shift by 4294967271 in `unchecked_shl`

error[E0080]: evaluation of constant value failed
--> $DIR/const-int-unchecked.rs:61:42
--> $DIR/const-int-unchecked.rs:60:42
|
LL | const SHL_I64_NEG_RANDOM: i64 = unsafe { intrinsics::unchecked_shl(5_i64, -30) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ overflowing shift by 18446744073709551586 in `unchecked_shl`

error[E0080]: evaluation of constant value failed
--> $DIR/const-int-unchecked.rs:63:44
--> $DIR/const-int-unchecked.rs:62:44
|
LL | const SHL_I128_NEG_RANDOM: i128 = unsafe { intrinsics::unchecked_shl(5_i128, -93) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ overflowing shift by 340282366920938463463374607431768211363 in `unchecked_shl`

error[E0080]: evaluation of constant value failed
--> $DIR/const-int-unchecked.rs:70:29
--> $DIR/const-int-unchecked.rs:69:29
|
LL | const SHR_U8: u8 = unsafe { intrinsics::unchecked_shr(5_u8, 8) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ overflowing shift by 8 in `unchecked_shr`

error[E0080]: evaluation of constant value failed
--> $DIR/const-int-unchecked.rs:72:31
--> $DIR/const-int-unchecked.rs:71:31
|
LL | const SHR_U16: u16 = unsafe { intrinsics::unchecked_shr(5_u16, 16) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ overflowing shift by 16 in `unchecked_shr`

error[E0080]: evaluation of constant value failed
--> $DIR/const-int-unchecked.rs:74:31
--> $DIR/const-int-unchecked.rs:73:31
|
LL | const SHR_U32: u32 = unsafe { intrinsics::unchecked_shr(5_u32, 32) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ overflowing shift by 32 in `unchecked_shr`

error[E0080]: evaluation of constant value failed
--> $DIR/const-int-unchecked.rs:76:31
--> $DIR/const-int-unchecked.rs:75:31
|
LL | const SHR_U64: u64 = unsafe { intrinsics::unchecked_shr(5_u64, 64) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ overflowing shift by 64 in `unchecked_shr`

error[E0080]: evaluation of constant value failed
--> $DIR/const-int-unchecked.rs:78:33
--> $DIR/const-int-unchecked.rs:77:33
|
LL | const SHR_U128: u128 = unsafe { intrinsics::unchecked_shr(5_u128, 128) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ overflowing shift by 128 in `unchecked_shr`

error[E0080]: evaluation of constant value failed
--> $DIR/const-int-unchecked.rs:83:29
--> $DIR/const-int-unchecked.rs:82:29
|
LL | const SHR_I8: i8 = unsafe { intrinsics::unchecked_shr(5_i8, 8) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ overflowing shift by 8 in `unchecked_shr`

error[E0080]: evaluation of constant value failed
--> $DIR/const-int-unchecked.rs:85:31
--> $DIR/const-int-unchecked.rs:84:31
|
LL | const SHR_I16: i16 = unsafe { intrinsics::unchecked_shr(5_16, 16) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ overflowing shift by 16 in `unchecked_shr`

error[E0080]: evaluation of constant value failed
--> $DIR/const-int-unchecked.rs:87:31
--> $DIR/const-int-unchecked.rs:86:31
|
LL | const SHR_I32: i32 = unsafe { intrinsics::unchecked_shr(5_i32, 32) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ overflowing shift by 32 in `unchecked_shr`

error[E0080]: evaluation of constant value failed
--> $DIR/const-int-unchecked.rs:89:31
--> $DIR/const-int-unchecked.rs:88:31
|
LL | const SHR_I64: i64 = unsafe { intrinsics::unchecked_shr(5_i64, 64) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ overflowing shift by 64 in `unchecked_shr`

error[E0080]: evaluation of constant value failed
--> $DIR/const-int-unchecked.rs:91:33
--> $DIR/const-int-unchecked.rs:90:33
|
LL | const SHR_I128: i128 = unsafe { intrinsics::unchecked_shr(5_i128, 128) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ overflowing shift by 128 in `unchecked_shr`

error[E0080]: evaluation of constant value failed
--> $DIR/const-int-unchecked.rs:96:33
--> $DIR/const-int-unchecked.rs:95:33
|
LL | const SHR_I8_NEG: i8 = unsafe { intrinsics::unchecked_shr(5_i8, -1) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ overflowing shift by 255 in `unchecked_shr`

error[E0080]: evaluation of constant value failed
--> $DIR/const-int-unchecked.rs:98:35
--> $DIR/const-int-unchecked.rs:97:35
|
LL | const SHR_I16_NEG: i16 = unsafe { intrinsics::unchecked_shr(5_16, -1) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ overflowing shift by 65535 in `unchecked_shr`

error[E0080]: evaluation of constant value failed
--> $DIR/const-int-unchecked.rs:100:35
--> $DIR/const-int-unchecked.rs:99:35
|
LL | const SHR_I32_NEG: i32 = unsafe { intrinsics::unchecked_shr(5_i32, -1) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ overflowing shift by 4294967295 in `unchecked_shr`

error[E0080]: evaluation of constant value failed
--> $DIR/const-int-unchecked.rs:102:35
--> $DIR/const-int-unchecked.rs:101:35
|
LL | const SHR_I64_NEG: i64 = unsafe { intrinsics::unchecked_shr(5_i64, -1) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ overflowing shift by 18446744073709551615 in `unchecked_shr`

error[E0080]: evaluation of constant value failed
--> $DIR/const-int-unchecked.rs:104:37
--> $DIR/const-int-unchecked.rs:103:37
|
LL | const SHR_I128_NEG: i128 = unsafe { intrinsics::unchecked_shr(5_i128, -1) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ overflowing shift by 340282366920938463463374607431768211455 in `unchecked_shr`

error[E0080]: evaluation of constant value failed
--> $DIR/const-int-unchecked.rs:110:40
--> $DIR/const-int-unchecked.rs:109:40
|
LL | const SHR_I8_NEG_RANDOM: i8 = unsafe { intrinsics::unchecked_shr(5_i8, -6) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ overflowing shift by 250 in `unchecked_shr`

error[E0080]: evaluation of constant value failed
--> $DIR/const-int-unchecked.rs:112:42
--> $DIR/const-int-unchecked.rs:111:42
|
LL | const SHR_I16_NEG_RANDOM: i16 = unsafe { intrinsics::unchecked_shr(5_16, -13) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ overflowing shift by 65523 in `unchecked_shr`

error[E0080]: evaluation of constant value failed
--> $DIR/const-int-unchecked.rs:114:42
--> $DIR/const-int-unchecked.rs:113:42
|
LL | const SHR_I32_NEG_RANDOM: i32 = unsafe { intrinsics::unchecked_shr(5_i32, -25) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ overflowing shift by 4294967271 in `unchecked_shr`

error[E0080]: evaluation of constant value failed
--> $DIR/const-int-unchecked.rs:116:42
--> $DIR/const-int-unchecked.rs:115:42
|
LL | const SHR_I64_NEG_RANDOM: i64 = unsafe { intrinsics::unchecked_shr(5_i64, -30) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ overflowing shift by 18446744073709551586 in `unchecked_shr`

error[E0080]: evaluation of constant value failed
--> $DIR/const-int-unchecked.rs:118:44
--> $DIR/const-int-unchecked.rs:117:44
|
LL | const SHR_I128_NEG_RANDOM: i128 = unsafe { intrinsics::unchecked_shr(5_i128, -93) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ overflowing shift by 340282366920938463463374607431768211363 in `unchecked_shr`

error[E0080]: evaluation of constant value failed
--> $DIR/const-int-unchecked.rs:123:25
--> $DIR/const-int-unchecked.rs:122:25
|
LL | const _: u16 = unsafe { std::intrinsics::unchecked_add(40000u16, 30000) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ overflow executing `unchecked_add`

error[E0080]: evaluation of constant value failed
--> $DIR/const-int-unchecked.rs:126:25
--> $DIR/const-int-unchecked.rs:125:25
|
LL | const _: u32 = unsafe { std::intrinsics::unchecked_sub(14u32, 22) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ overflow executing `unchecked_sub`

error[E0080]: evaluation of constant value failed
--> $DIR/const-int-unchecked.rs:129:25
--> $DIR/const-int-unchecked.rs:128:25
|
LL | const _: u16 = unsafe { std::intrinsics::unchecked_mul(300u16, 250u16) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ overflow executing `unchecked_mul`

error[E0080]: evaluation of constant value failed
--> $DIR/const-int-unchecked.rs:132:25
--> $DIR/const-int-unchecked.rs:131:25
|
LL | const _: i32 = unsafe { std::intrinsics::unchecked_div(1, 0) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ dividing by zero

error[E0080]: evaluation of constant value failed
--> $DIR/const-int-unchecked.rs:134:25
--> $DIR/const-int-unchecked.rs:133:25
|
LL | const _: i32 = unsafe { std::intrinsics::unchecked_div(i32::MIN, -1) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ overflow in signed division (dividing MIN by -1)

error[E0080]: evaluation of constant value failed
--> $DIR/const-int-unchecked.rs:137:25
--> $DIR/const-int-unchecked.rs:136:25
|
LL | const _: i32 = unsafe { std::intrinsics::unchecked_rem(1, 0) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ calculating the remainder with a divisor of zero

error[E0080]: evaluation of constant value failed
--> $DIR/const-int-unchecked.rs:139:25
--> $DIR/const-int-unchecked.rs:138:25
|
LL | const _: i32 = unsafe { std::intrinsics::unchecked_rem(i32::MIN, -1) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ overflow in signed remainder (dividing MIN by -1)

error[E0080]: evaluation of constant value failed
--> $DIR/const-int-unchecked.rs:144:25
--> $DIR/const-int-unchecked.rs:143:25
|
LL | const _: u32 = unsafe { std::intrinsics::ctlz_nonzero(0) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `ctlz_nonzero` called on 0

error[E0080]: evaluation of constant value failed
--> $DIR/const-int-unchecked.rs:146:25
--> $DIR/const-int-unchecked.rs:145:25
|
LL | const _: u32 = unsafe { std::intrinsics::cttz_nonzero(0) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `cttz_nonzero` called on 0
Expand Down

0 comments on commit d8198ca

Please sign in to comment.