bitwise operation takes wrong value #11580
Comments
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This doesn't appear to be a problem anymore, can it be closed? |
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This still reproduces for me when compiling with optimizations. |
fn main() {
let m : [u8, ..1] = [ 0u8 ];
println!("{}", ((m[0] >> 8) | 0) as u16);
println!("{}", ((m[0] >> 8) | m[0]) as u16);
assert!((((m[0] >> 8) | 0) as u16) == 0);
assert!((((m[0] >> 8) | m[0]) as u16) == 255);
} |
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Bit shifts with a RHS equal to or larger than the width of the type in bytes have undefined behaviour in C and LLVM. The code here is shifting an 8-bit integer by 8 bits. This issue is reported as #10183 already. |
flip1995
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Oct 6, 2023
[`manual_let_else`]: only omit block if span is from same ctxt Fixes rust-lang#11579. The lint already had logic for omitting a block in `else` if a block is already present, however this didn't handle the case where the block is from a different expansion/syntax context. E.g. ```rs macro_rules! panic_in_block { () => { { panic!() } } } let _ = match Some(1) { Some(v) => v, _ => panic_in_block!() }; ``` It would see this in its expanded form as `_ => { panic!() }` and think it doesn't have to include a block in its suggestion because it is already there, however that's not true if it's from a different expansion like in this case. changelog: [`manual_let_else`]: only omit block in suggestion if the block is from the same expansion
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I'm on caf316a
Found a strange value calculation when bitwising with wrong casting:
https://gist.github.com/ya-mouse/8444726
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