Skip to content

Commit

Permalink
Auto merge of #90040 - nbdd0121:issue-90038, r=oli-obk
Browse files Browse the repository at this point in the history
Fix wrong niche calculation when 2+ niches are placed at the start

When the niche is at the start, existing code incorrectly uses 1 instead of count for subtraction.

Fix #90038

`@rustbot` label: T-compiler
  • Loading branch information
bors committed Oct 19, 2021
2 parents 2f22e63 + 7dbd5bb commit d45ed75
Show file tree
Hide file tree
Showing 2 changed files with 22 additions and 1 deletion.
2 changes: 1 addition & 1 deletion compiler/rustc_target/src/abi/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1117,7 +1117,7 @@ impl Niche {
// In practice this means that enums with `count > 1` are unlikely to claim niche zero, since they have to fit perfectly.
// If niche zero is already reserved, the selection of bounds are of little interest.
let move_start = |v: WrappingRange| {
let start = v.start.wrapping_sub(1) & max_value;
let start = v.start.wrapping_sub(count) & max_value;
Some((start, Scalar { value, valid_range: v.with_start(start) }))
};
let move_end = |v: WrappingRange| {
Expand Down
21 changes: 21 additions & 0 deletions src/test/ui/enum-discriminant/issue-90038.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,21 @@
// run-pass

#[repr(u32)]
pub enum Foo {
// Greater than or equal to 2
A = 2,
}

pub enum Bar {
A(Foo),
// More than two const variants
B,
C,
}

fn main() {
match Bar::A(Foo::A) {
Bar::A(_) => (),
_ => unreachable!(),
}
}

0 comments on commit d45ed75

Please sign in to comment.