Skip to content

Navigation Menu

Sign in
Appearance settings

Search code, repositories, users, issues, pull requests...

Provide feedback

We read every piece of feedback, and take your input very seriously.

Saved searches

Use saved searches to filter your results more quickly
Sign up
Appearance settings

Commit 75e87d1

Browse files
Fix syntax in -Zunpretty-expanded output for derived PartialEq.
If you do `derive(PartialEq)` on a packed struct, the output shown by `-Zunpretty=expanded` includes expressions like this: ``` { self.x } == { other.x } ``` This is invalid syntax. This doesn't break compilation, because the AST nodes are constructed within the compiler. But it does mean anyone using `-Zunpretty=expanded` output as a guide for hand-written impls could get a nasty surprise. This commit fixes things by instead using this form: ``` ({ self.x }) == ({ other.x }) ```
1 parent a322848 commit 75e87d1

File tree

3 files changed

+26
-8
lines changed

3 files changed

+26
-8
lines changed

‎compiler/rustc_builtin_macros/src/deriving/cmp/partial_eq.rs‎

Lines changed: 19 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -29,16 +29,30 @@ pub fn expand_deriving_partial_eq(
2929
cx.span_bug(field.span, "not exactly 2 arguments in `derive(PartialEq)`");
3030
};
3131

32-
// We received `&T` arguments. Convert them to `T` by
33-
// stripping `&` or adding `*`. This isn't necessary for
34-
// type checking, but it results in much better error
35-
// messages if something goes wrong.
32+
// We received arguments of type `&T`. Convert them to type `T` by stripping
33+
// any leading `&` or adding `*`. This isn't necessary for type checking, but
34+
// it results in better error messages if something goes wrong.
35+
//
36+
// Note: for arguments that look like `&{ x }`, which occur with packed
37+
// structs, this would cause expressions like `{ self.x } == { other.x }`,
38+
// which isn't valid Rust syntax. This wouldn't break compilation because these
39+
// AST nodes are constructed within the compiler. But it would mean that code
40+
// printed by `-Zunpretty=expanded` (or `cargo expand`) would have invalid
41+
// syntax, which would be suboptimal. So we wrap these in parens, giving
42+
// `({ self.x }) == ({ other.x })`, which is valid syntax.
3643
let convert = |expr: &P<Expr>| {
3744
if let ExprKind::AddrOf(BorrowKind::Ref, Mutability::Not, inner) =
3845
&expr.kind
3946
{
40-
inner.clone()
47+
if let ExprKind::Block(..) = &inner.kind {
48+
// `&{ x }` form: remove the `&`, add parens.
49+
cx.expr_paren(field.span, inner.clone())
50+
} else {
51+
// `&x` form: remove the `&`.
52+
inner.clone()
53+
}
4154
} else {
55+
// No leading `&`: add a leading `*`.
4256
cx.expr_deref(field.span, expr.clone())
4357
}
4458
};

‎compiler/rustc_expand/src/build.rs‎

Lines changed: 4 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -272,6 +272,10 @@ impl<'a> ExtCtxt<'a> {
272272
self.expr(sp, ast::ExprKind::AddrOf(ast::BorrowKind::Ref, ast::Mutability::Not, e))
273273
}
274274

275+
pub fn expr_paren(&self, sp: Span, e: P<ast::Expr>) -> P<ast::Expr> {
276+
self.expr(sp, ast::ExprKind::Paren(e))
277+
}
278+
275279
pub fn expr_call(
276280
&self,
277281
span: Span,

‎tests/ui/deriving/deriving-all-codegen.stdout‎

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -209,7 +209,7 @@ impl ::core::marker::StructuralPartialEq for PackedPoint { }
209209
impl ::core::cmp::PartialEq for PackedPoint {
210210
#[inline]
211211
fn eq(&self, other: &PackedPoint) -> bool {
212-
{ self.x } == { other.x } && { self.y } == { other.y }
212+
({ self.x }) == ({ other.x }) && ({ self.y }) == ({ other.y })
213213
}
214214
}
215215
#[automatically_derived]
@@ -718,8 +718,8 @@ impl<T: ::core::cmp::PartialEq + ::core::marker::Copy + Trait,
718718
::core::marker::Copy {
719719
#[inline]
720720
fn eq(&self, other: &PackedGeneric<T, U>) -> bool {
721-
{ self.0 } == { other.0 } && { self.1 } == { other.1 } &&
722-
{ self.2 } == { other.2 }
721+
({ self.0 }) == ({ other.0 }) && ({ self.1 }) == ({ other.1 }) &&
722+
({ self.2 }) == ({ other.2 })
723723
}
724724
}
725725
#[automatically_derived]

0 commit comments

Comments
(0)

AltStyle によって変換されたページ (->オリジナル) /