mirror of https://github.com/rust-lang/rust.git
26 lines
785 B
Rust
26 lines
785 B
Rust
use std::ptr;
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const IS_NULL: () = {
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assert!(ptr::null::<u8>().is_null());
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};
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const IS_NOT_NULL: () = {
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assert!(!ptr::null::<u8>().wrapping_add(1).is_null());
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};
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const MAYBE_NULL: () = {
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let x = 15;
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let ptr = &x as *const i32;
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// This one is still unambiguous...
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assert!(!ptr.is_null());
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// and in fact, any offset not visible by 4 (the alignment) cannot be null,
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// even if it goes out-of-bounds...
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assert!(!ptr.wrapping_byte_add(13).is_null());
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assert!(!ptr.wrapping_byte_add(18).is_null());
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assert!(!ptr.wrapping_byte_sub(1).is_null());
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// ... but once we shift outside the allocation, with an offset divisible by 4,
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// we might become null.
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assert!(!ptr.wrapping_sub(512).is_null()); //~inside `MAYBE_NULL`
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};
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fn main() {}
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