bjoernager/rust
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Stabilize let_chains

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This commit is contained in:
Caio 2022-07-12 15:36:59 -03:00
parent d5e7f4782e
commit 3266460749
58 changed files with 470 additions and 821 deletions
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30
compiler/rustc_parse/src/parser/expr.rs
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@ -2341,16 +2341,9 @@ impl<'a> Parser<'a> {
/// Parses the condition of a `if` or `while` expression.
fn parse_cond_expr(&mut self) -> PResult<'a, P<Expr>> {
let cond = self.with_let_management(true, |local_self| {
self.with_let_management(true, |local_self| {
local_self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)
})?;
if let ExprKind::Let(..) = cond.kind {
// Remove the last feature gating of a `let` expression since it's stable.
self.sess.gated_spans.ungate_last(sym::let_chains, cond.span);
}
Ok(cond)
})
}
// Checks if `let` is in an invalid position like `let x = let y = 1;` or
@ -2389,7 +2382,6 @@ impl<'a> Parser<'a> {
this.parse_assoc_expr_with(1 + prec_let_scrutinee_needs_par(), None.into())
})?;
let span = lo.to(expr.span);
self.sess.gated_spans.gate(sym::let_chains, span);
Ok(self.mk_expr(span, ExprKind::Let(pat, expr, span), attrs))
}
@ -2695,15 +2687,11 @@ impl<'a> Parser<'a> {
pub(super) fn parse_arm(&mut self) -> PResult<'a, Arm> {
// Used to check the `let_chains` and `if_let_guard` features mostly by scaning
// `&&` tokens.
fn check_let_expr(expr: &Expr) -> (bool, bool) {
fn check_let_expr(expr: &Expr) -> bool {
match expr.kind {
ExprKind::Binary(_, ref lhs, ref rhs) => {
let lhs_rslt = check_let_expr(lhs);
let rhs_rslt = check_let_expr(rhs);
(lhs_rslt.0 || rhs_rslt.0, false)
}
ExprKind::Let(..) => (true, true),
_ => (false, true),
ExprKind::Binary(_, ref lhs, ref rhs) => check_let_expr(lhs) || check_let_expr(rhs),
ExprKind::Let(..) => true,
_ => false,
}
}
let attrs = self.parse_outer_attributes()?;
@ -2718,12 +2706,8 @@ impl<'a> Parser<'a> {
let guard = if this.eat_keyword(kw::If) {
let if_span = this.prev_token.span;
let cond = this.with_let_management(true, |local_this| local_this.parse_expr())?;
let (has_let_expr, does_not_have_bin_op) = check_let_expr(&cond);
let has_let_expr = check_let_expr(&cond);
if has_let_expr {
if does_not_have_bin_op {
// Remove the last feature gating of a `let` expression since it's stable.
this.sess.gated_spans.ungate_last(sym::let_chains, cond.span);
}
let span = if_span.to(cond.span);
this.sess.gated_spans.gate(sym::if_let_guard, span);
}