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Insert parentheses around binary operation with attribute

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This commit is contained in:
David Tolnay
2025-06-13 13:00:46 -07:00
parent cbef8f6e07
commit 12a855d2c8
1 changed files with 38 additions and 12 deletions
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50
compiler/rustc_ast_pretty/src/pprust/state/expr.rs
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@@ -386,18 +386,44 @@ impl<'a> State<'a> {
let ib = self.ibox(INDENT_UNIT);
// The Match subexpression in `match x {} - 1` must be parenthesized if
// it is the leftmost subexpression in a statement:
//
// (match x {}) - 1;
//
// But not otherwise:
//
// let _ = match x {} - 1;
//
// Same applies to a small set of other expression kinds which eagerly
// terminate a statement which opens with them.
let needs_par = fixup.would_cause_statement_boundary(expr);
let needs_par = {
// The Match subexpression in `match x {} - 1` must be parenthesized
// if it is the leftmost subexpression in a statement:
//
// (match x {}) - 1;
//
// But not otherwise:
//
// let _ = match x {} - 1;
//
// Same applies to a small set of other expression kinds which
// eagerly terminate a statement which opens with them.
fixup.would_cause_statement_boundary(expr)
} || {
// If a binary operation ends up with an attribute, such as
// resulting from the following macro expansion, then parentheses
// are required so that the attribute encompasses the right
// subexpression and not just the left one.
//
// #![feature(stmt_expr_attributes)]
//
// macro_rules! add_attr {
// ($e:expr) => { #[attr] $e };
// }
//
// let _ = add_attr!(1 + 1);
//
// We must pretty-print `#[attr] (1 + 1)` not `#[attr] 1 + 1`.
!attrs.is_empty()
&& matches!(
expr.kind,
ast::ExprKind::Binary(..)
| ast::ExprKind::Cast(..)
| ast::ExprKind::Assign(..)
| ast::ExprKind::AssignOp(..)
| ast::ExprKind::Range(..)
)
};
if needs_par {
self.popen();
fixup = FixupContext::default();