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Adjust assoc-oddities-3.rs

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- Include the original MCVE as reported in
  <https://github.com/rust-lang/rust/issues/28777>.
- Document the intention of the test.
This commit is contained in:
许杰友 Jieyou Xu (Joe) 2024-12-08 14:45:24 +08:00
parent b815a93614
commit 3a33522ca8
1 changed files with 28 additions and 0 deletions
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28
tests/ui/parser/assoc/assoc-oddities-3.rs
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@ -1,3 +1,10 @@
//! Check that braces has the expected precedence in relation to index op and some arithmetic
//! bin-ops involving nested braces.
//!
//! This is a regression test for [Wrapping expr in curly braces changes the operator precedence
//! #28777](https://github.com/rust-lang/rust/issues/28777), which was fixed by
//! <https://github.com/rust-lang/rust/pull/30375>.
//@ run-pass
fn that_odd_parse(c: bool, n: usize) -> u32 {
@ -7,7 +14,28 @@ fn that_odd_parse(c: bool, n: usize) -> u32 {
x + if c { a } else { b }[n]
}
/// See [Wrapping expr in curly braces changes the operator precedence
/// #28777](https://github.com/rust-lang/rust/issues/28777). This was fixed by
/// <https://github.com/rust-lang/rust/pull/30375>. #30375 added the `that_odd_parse` example above,
/// but that is not *quite* the same original example as reported in #28777, so we also include the
/// original example here.
fn check_issue_28777() {
// Before #30375 fixed the precedence...
// ... `v1` evaluated to 9, indicating a parse of `(1 + 2) * 3`, while
let v1 = { 1 + { 2 } * { 3 } };
// `v2` evaluated to 7, indicating a parse of `1 + (2 * 3)`.
let v2 = 1 + { 2 } * { 3 };
// Check that both now evaluate to 7, as was fixed by #30375.
assert_eq!(v1, 7);
assert_eq!(v2, 7);
}
fn main() {
assert_eq!(4, that_odd_parse(true, 1));
assert_eq!(8, that_odd_parse(false, 1));
check_issue_28777();
}