diff options
Diffstat (limited to 'compiler/rustc_builtin_macros/src/deriving/cmp/partial_eq.rs')
| -rw-r--r-- | compiler/rustc_builtin_macros/src/deriving/cmp/partial_eq.rs | 25 |
1 files changed, 20 insertions, 5 deletions
diff --git a/compiler/rustc_builtin_macros/src/deriving/cmp/partial_eq.rs b/compiler/rustc_builtin_macros/src/deriving/cmp/partial_eq.rs index 9051fe0b2..bad47db0d 100644 --- a/compiler/rustc_builtin_macros/src/deriving/cmp/partial_eq.rs +++ b/compiler/rustc_builtin_macros/src/deriving/cmp/partial_eq.rs @@ -29,16 +29,30 @@ pub fn expand_deriving_partial_eq( cx.span_bug(field.span, "not exactly 2 arguments in `derive(PartialEq)`"); }; - // We received `&T` arguments. Convert them to `T` by - // stripping `&` or adding `*`. This isn't necessary for - // type checking, but it results in much better error - // messages if something goes wrong. + // We received arguments of type `&T`. Convert them to type `T` by stripping + // any leading `&` or adding `*`. This isn't necessary for type checking, but + // it results in better error messages if something goes wrong. + // + // Note: for arguments that look like `&{ x }`, which occur with packed + // structs, this would cause expressions like `{ self.x } == { other.x }`, + // which isn't valid Rust syntax. This wouldn't break compilation because these + // AST nodes are constructed within the compiler. But it would mean that code + // printed by `-Zunpretty=expanded` (or `cargo expand`) would have invalid + // syntax, which would be suboptimal. So we wrap these in parens, giving + // `({ self.x }) == ({ other.x })`, which is valid syntax. let convert = |expr: &P<Expr>| { if let ExprKind::AddrOf(BorrowKind::Ref, Mutability::Not, inner) = &expr.kind { - inner.clone() + if let ExprKind::Block(..) = &inner.kind { + // `&{ x }` form: remove the `&`, add parens. + cx.expr_paren(field.span, inner.clone()) + } else { + // `&x` form: remove the `&`. + inner.clone() + } } else { + // No leading `&`: add a leading `*`. cx.expr_deref(field.span, expr.clone()) } }; @@ -84,6 +98,7 @@ pub fn expand_deriving_partial_eq( span, path: path_std!(cmp::PartialEq), skip_path_as_bound: false, + needs_copy_as_bound_if_packed: true, additional_bounds: Vec::new(), supports_unions: false, methods, |