73 lines
2.3 KiB
Rust
73 lines
2.3 KiB
Rust
#![feature(rustc_attrs)]
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#![warn(clippy::eager_transmute)]
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#![allow(clippy::transmute_int_to_non_zero)]
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use std::num::NonZeroU8;
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#[repr(u8)]
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enum Opcode {
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Add = 0,
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Sub = 1,
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Mul = 2,
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Div = 3,
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}
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fn int_to_opcode(op: u8) -> Option<Opcode> {
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(op < 4).then(|| unsafe { std::mem::transmute(op) })
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}
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fn f(op: u8, unrelated: u8) {
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true.then_some(unsafe { std::mem::transmute::<_, Opcode>(op) });
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(unrelated < 4).then_some(unsafe { std::mem::transmute::<_, Opcode>(op) });
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(op < 4).then(|| unsafe { std::mem::transmute::<_, Opcode>(op) });
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(op > 4).then(|| unsafe { std::mem::transmute::<_, Opcode>(op) });
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(op == 0).then(|| unsafe { std::mem::transmute::<_, Opcode>(op) });
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}
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unsafe fn f2(op: u8) {
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(op < 4).then(|| std::mem::transmute::<_, Opcode>(op));
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}
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#[rustc_layout_scalar_valid_range_end(254)]
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struct NonMaxU8(u8);
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#[rustc_layout_scalar_valid_range_end(254)]
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#[rustc_layout_scalar_valid_range_start(1)]
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struct NonZeroNonMaxU8(u8);
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macro_rules! impls {
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($($t:ty),*) => {
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$(
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impl PartialEq<u8> for $t {
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fn eq(&self, other: &u8) -> bool {
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self.0 == *other
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}
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}
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impl PartialOrd<u8> for $t {
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fn partial_cmp(&self, other: &u8) -> Option<std::cmp::Ordering> {
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self.0.partial_cmp(other)
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}
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}
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)*
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};
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}
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impls!(NonMaxU8, NonZeroNonMaxU8);
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fn niche_tests(v1: u8, v2: NonZeroU8, v3: NonZeroNonMaxU8) {
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// u8 -> NonZeroU8, do lint
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let _: Option<NonZeroU8> = (v1 > 0).then(|| unsafe { std::mem::transmute(v1) });
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// NonZeroU8 -> u8, don't lint, target type has no niche and therefore a higher validity range
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let _: Option<u8> = (v2 > NonZeroU8::new(1).unwrap()).then_some(unsafe { std::mem::transmute(v2) });
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// NonZeroU8 -> NonMaxU8, do lint, different niche
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let _: Option<NonMaxU8> = (v2 < NonZeroU8::new(255).unwrap()).then(|| unsafe { std::mem::transmute(v2) });
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// NonZeroNonMaxU8 -> NonMaxU8, don't lint, target type has more validity
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let _: Option<NonMaxU8> = (v3 < 255).then_some(unsafe { std::mem::transmute(v2) });
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// NonZeroU8 -> NonZeroNonMaxU8, do lint, target type has less validity
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let _: Option<NonZeroNonMaxU8> = (v2 < NonZeroU8::new(255).unwrap()).then(|| unsafe { std::mem::transmute(v2) });
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}
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fn main() {}
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