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Delete special handling of some expr kinds from print_let

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In all four of Break, Closure, Ret, Yeet, the needs_par_as_let_scrutinee
is guaranteed to return true because the .precedence().order() of those
expr kinds is <= AssocOp::LAnd.precedence().

The relevant functions in rustc_ast::util::parser are:

    fn needs_par_as_let_scrutinee(order: i8) -> bool {
        order <= prec_let_scrutinee_needs_par() as i8
    }

    fn prec_let_scrutinee_needs_par() -> usize {
        AssocOp::LAnd.precedence()
    }

The .precedence().order() of Closure is PREC_CLOSURE (-40) and of Break,
Ret, Yeet is PREC_JUMP (-30).

The value of AssocOp::LAnd.precedence() is 6.

So this commit causes no change in behavior, only potentially
performance by doing a redundant call to contains_exterior_struct_lit in
those four cases. This is fine because Break, Closure, Ret, Yeet should
be exceedingly rare in the position of a let scrutinee.
This commit is contained in:
David Tolnay 2023-11-29 21:19:22 -08:00
parent dc5ec724c0
commit 7f314acc34
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GPG Key ID: F9BA143B95FF6D82
1 changed files with 2 additions and 10 deletions
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12
compiler/rustc_ast_pretty/src/pprust/state.rs
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@ -1161,16 +1161,8 @@ fn print_let(&mut self, pat: &ast::Pat, expr: &ast::Expr) {
self.word_space("=");
self.print_expr_cond_paren(
expr,
match expr.kind {
ast::ExprKind::Break(..)
| ast::ExprKind::Closure(..)
| ast::ExprKind::Ret(..)
| ast::ExprKind::Yeet(..) => true,
_ => {
parser::contains_exterior_struct_lit(expr)
|| parser::needs_par_as_let_scrutinee(expr.precedence().order())
}
},
parser::contains_exterior_struct_lit(expr)
|| parser::needs_par_as_let_scrutinee(expr.precedence().order()),
);
}