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preserve brackets around if-lets and skip while-lets

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This commit is contained in:
Ding Xiang Fei 2024-09-30 03:40:48 +08:00
parent 329e7b4d4e
commit 6d1a25ad7e
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GPG Key ID: 3CD748647EEF6359
4 changed files with 76 additions and 5 deletions
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29
compiler/rustc_lint/src/if_let_rescope.rs
View File

@ -122,7 +122,11 @@ fn probe_if_cascade<'tcx>(&mut self, cx: &LateContext<'tcx>, mut expr: &'tcx hir
}
let tcx = cx.tcx;
let source_map = tcx.sess.source_map();
let expr_end = expr.span.shrink_to_hi();
let expr_end = match expr.kind {
hir::ExprKind::If(_cond, conseq, None) => conseq.span.shrink_to_hi(),
hir::ExprKind::If(_cond, _conseq, Some(alt)) => alt.span.shrink_to_hi(),
_ => return,
};
let mut add_bracket_to_match_head = match_head_needs_bracket(tcx, expr);
let mut significant_droppers = vec![];
let mut lifetime_ends = vec![];
@ -145,7 +149,10 @@ fn probe_if_cascade<'tcx>(&mut self, cx: &LateContext<'tcx>, mut expr: &'tcx hir
recovered: Recovered::No,
}) = cond.kind
{
let if_let_pat = expr.span.shrink_to_lo().between(init.span);
// Peel off round braces
let if_let_pat = source_map
.span_take_while(expr.span, |&ch| ch == '(' || ch.is_whitespace())
.between(init.span);
// The consequent fragment is always a block.
let before_conseq = conseq.span.shrink_to_lo();
let lifetime_end = source_map.end_point(conseq.span);
@ -159,6 +166,8 @@ fn probe_if_cascade<'tcx>(&mut self, cx: &LateContext<'tcx>, mut expr: &'tcx hir
if ty_ascription.is_some()
|| !expr.span.can_be_used_for_suggestions()
|| !pat.span.can_be_used_for_suggestions()
|| !if_let_pat.can_be_used_for_suggestions()
|| !before_conseq.can_be_used_for_suggestions()
{
// Our `match` rewrites does not support type ascription,
// so we just bail.
@ -240,6 +249,22 @@ fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'tcx>) {
if let (Level::Allow, _) = cx.tcx.lint_level_at_node(IF_LET_RESCOPE, expr.hir_id) {
return;
}
if let hir::ExprKind::Loop(block, _label, hir::LoopSource::While, _span) = expr.kind
&& let Some(value) = block.expr
&& let hir::ExprKind::If(cond, _conseq, _alt) = value.kind
&& let hir::ExprKind::Let(..) = cond.kind
{
// Recall that `while let` is lowered into this:
// ```
// loop {
// if let .. { body } else { break; }
// }
// ```
// There is no observable from the `{ break; }` block so the edition change
// means nothing substantial to this `while` statement.
self.skip.insert(value.hir_id);
return;
}
if expr_parent_is_stmt(cx.tcx, expr.hir_id)
&& matches!(expr.kind, hir::ExprKind::If(_cond, _conseq, None))
{

15
tests/ui/drop/lint-if-let-rescope.fixed
View File

@ -2,7 +2,7 @@
#![deny(if_let_rescope)]
#![feature(if_let_rescope)]
#![allow(irrefutable_let_patterns)]
#![allow(irrefutable_let_patterns, unused_parens)]
fn droppy() -> Droppy {
Droppy
@ -68,4 +68,17 @@ fn main() {
//~| HELP: the value is now dropped here in Edition 2024
//~| HELP: a `match` with a single arm can preserve the drop order up to Edition 2021
}
if (match droppy().get() { Some(_value) => { true } _ => { false }}) {
//~^ ERROR: `if let` assigns a shorter lifetime since Edition 2024
//~| WARN: this changes meaning in Rust 2024
//~| HELP: a `match` with a single arm can preserve the drop order up to Edition 2021
//~| HELP: the value is now dropped here in Edition 2024
// do something
}
while let Some(_value) = droppy().get() {
// Should not lint
break;
}
}

15
tests/ui/drop/lint-if-let-rescope.rs
View File

@ -2,7 +2,7 @@
#![deny(if_let_rescope)]
#![feature(if_let_rescope)]
#![allow(irrefutable_let_patterns)]
#![allow(irrefutable_let_patterns, unused_parens)]
fn droppy() -> Droppy {
Droppy
@ -68,4 +68,17 @@ fn main() {
//~| HELP: the value is now dropped here in Edition 2024
//~| HELP: a `match` with a single arm can preserve the drop order up to Edition 2021
}
if (if let Some(_value) = droppy().get() { true } else { false }) {
//~^ ERROR: `if let` assigns a shorter lifetime since Edition 2024
//~| WARN: this changes meaning in Rust 2024
//~| HELP: a `match` with a single arm can preserve the drop order up to Edition 2021
//~| HELP: the value is now dropped here in Edition 2024
// do something
}
while let Some(_value) = droppy().get() {
// Should not lint
break;
}
}

22
tests/ui/drop/lint-if-let-rescope.stderr
View File

@ -131,5 +131,25 @@ help: a `match` with a single arm can preserve the drop order up to Edition 2021
LL | if let () = { match Droppy.get() { Some(_value) => {} _ => {}} } {
| ~~~~~ +++++++++++++++++ ++++++++
error: aborting due to 5 previous errors
error: `if let` assigns a shorter lifetime since Edition 2024
--> $DIR/lint-if-let-rescope.rs:72:12
|
LL | if (if let Some(_value) = droppy().get() { true } else { false }) {
| ^^^^^^^^^^^^^^^^^^^--------^^^^^^
| |
| this value has a significant drop implementation which may observe a major change in drop order and requires your discretion
|
= warning: this changes meaning in Rust 2024
= note: for more information, see issue #124085 <https://github.com/rust-lang/rust/issues/124085>
help: the value is now dropped here in Edition 2024
--> $DIR/lint-if-let-rescope.rs:72:53
|
LL | if (if let Some(_value) = droppy().get() { true } else { false }) {
| ^
help: a `match` with a single arm can preserve the drop order up to Edition 2021
|
LL | if (match droppy().get() { Some(_value) => { true } _ => { false }}) {
| ~~~~~ +++++++++++++++++ ~~~~ +
error: aborting due to 6 previous errors