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reduce false positives on some common cases from if-let-rescope

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This commit is contained in:
Ding Xiang Fei 2024-12-02 18:27:09 +08:00
parent 76f3ff6059
commit 2d61c0906a
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GPG key ID: 3CD748647EEF6359
4 changed files with 47 additions and 40 deletions
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7
compiler/rustc_lint/src/if_let_rescope.rs
View file

@ -103,8 +103,11 @@ fn expr_parent_is_else(tcx: TyCtxt<'_>, hir_id: hir::HirId) -> bool {
}
fn expr_parent_is_stmt(tcx: TyCtxt<'_>, hir_id: hir::HirId) -> bool {
let Some((_, hir::Node::Stmt(stmt))) = tcx.hir().parent_iter(hir_id).next() else {
return false;
let mut parents = tcx.hir().parent_iter(hir_id);
let stmt = match parents.next() {
Some((_, hir::Node::Stmt(stmt))) => stmt,
Some((_, hir::Node::Block(_) | hir::Node::Arm(_))) => return true,
_ => return false,
};
let (hir::StmtKind::Semi(expr) | hir::StmtKind::Expr(expr)) = stmt.kind else { return false };
expr.hir_id == hir_id

24
tests/ui/drop/lint-if-let-rescope.fixed
View file

@ -14,7 +14,7 @@ impl Drop for Droppy {
}
}
impl Droppy {
fn get(&self) -> Option<u8> {
const fn get(&self) -> Option<u8> {
None
}
}
@ -62,11 +62,10 @@ fn main() {
//~| HELP: a `match` with a single arm can preserve the drop order up to Edition 2021
}
if let () = { match Droppy.get() { Some(_value) => {} _ => {}} } {
//~^ ERROR: `if let` assigns a shorter lifetime since Edition 2024
//~| WARN: this changes meaning in Rust 2024
//~| 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 let () = { if let Some(_value) = Droppy.get() {} } {
// This should not lint.
// This `if let` sits is a tail expression of a block.
// In Edition 2024, the temporaries are dropped before exiting the surrounding block.
}
#[rustfmt::skip]
@ -94,4 +93,17 @@ 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
}
// We want to keep the `if let`s below as direct descendents of match arms,
// so the formatting is suppressed.
#[rustfmt::skip]
match droppy().get() {
_ => if let Some(_value) = droppy().get() {},
// Should not lint
// There is implicitly a block surrounding the `if let`.
// Given that it is a tail expression, the temporaries are dropped duly before
// the execution is exiting the `match`.
}
if let Some(_value) = droppy().get() {}
}

22
tests/ui/drop/lint-if-let-rescope.rs
View file

@ -14,7 +14,7 @@ impl Drop for Droppy {
}
}
impl Droppy {
fn get(&self) -> Option<u8> {
const fn get(&self) -> Option<u8> {
None
}
}
@ -63,10 +63,9 @@ fn main() {
}
if let () = { if let Some(_value) = Droppy.get() {} } {
//~^ ERROR: `if let` assigns a shorter lifetime since Edition 2024
//~| WARN: this changes meaning in Rust 2024
//~| 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
// This should not lint.
// This `if let` sits is a tail expression of a block.
// In Edition 2024, the temporaries are dropped before exiting the surrounding block.
}
#[rustfmt::skip]
@ -94,4 +93,17 @@ 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
}
// We want to keep the `if let`s below as direct descendents of match arms,
// so the formatting is suppressed.
#[rustfmt::skip]
match droppy().get() {
_ => if let Some(_value) = droppy().get() {},
// Should not lint
// There is implicitly a block surrounding the `if let`.
// Given that it is a tail expression, the temporaries are dropped duly before
// the execution is exiting the `match`.
}
if let Some(_value) = droppy().get() {}
}

34
tests/ui/drop/lint-if-let-rescope.stderr
View file

@ -112,27 +112,7 @@ LL | if let Some(1) = { match Droppy.get() { Some(_value) => { Some(1) } _ =
| ~~~~~ +++++++++++++++++ ~~~~ +
error: `if let` assigns a shorter lifetime since Edition 2024
--> $DIR/lint-if-let-rescope.rs:65:22
|
LL | if let () = { if let Some(_value) = Droppy.get() {} } {
| ^^^^^^^^^^^^^^^^^^^------^^^^^^
| |
| 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:65:55
|
LL | if let () = { if let Some(_value) = Droppy.get() {} } {
| ^
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: `if let` assigns a shorter lifetime since Edition 2024
--> $DIR/lint-if-let-rescope.rs:73:12
--> $DIR/lint-if-let-rescope.rs:72:12
|
LL | if (if let Some(_value) = droppy().get() { true } else { false }) {
| ^^^^^^^^^^^^^^^^^^^--------^^^^^^
@ -142,7 +122,7 @@ LL | if (if let Some(_value) = droppy().get() { true } else { false }) {
= 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:73:53
--> $DIR/lint-if-let-rescope.rs:72:53
|
LL | if (if let Some(_value) = droppy().get() { true } else { false }) {
| ^
@ -152,7 +132,7 @@ LL | if (match droppy().get() { Some(_value) => { true } _ => { false }}) {
| ~~~~~ +++++++++++++++++ ~~~~ +
error: `if let` assigns a shorter lifetime since Edition 2024
--> $DIR/lint-if-let-rescope.rs:79:21
--> $DIR/lint-if-let-rescope.rs:78:21
|
LL | } else if (((if let Some(_value) = droppy().get() { true } else { false }))) {
| ^^^^^^^^^^^^^^^^^^^--------^^^^^^
@ -162,7 +142,7 @@ LL | } else if (((if let Some(_value) = droppy().get() { true } else { false
= 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:79:62
--> $DIR/lint-if-let-rescope.rs:78:62
|
LL | } else if (((if let Some(_value) = droppy().get() { true } else { false }))) {
| ^
@ -172,7 +152,7 @@ LL | } else if (((match droppy().get() { Some(_value) => { true } _ => { fal
| ~~~~~ +++++++++++++++++ ~~~~ +
error: `if let` assigns a shorter lifetime since Edition 2024
--> $DIR/lint-if-let-rescope.rs:91:15
--> $DIR/lint-if-let-rescope.rs:90:15
|
LL | while (if let Some(_value) = droppy().get() { false } else { true }) {
| ^^^^^^^^^^^^^^^^^^^--------^^^^^^
@ -182,7 +162,7 @@ LL | while (if let Some(_value) = droppy().get() { false } else { true }) {
= 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:91:57
--> $DIR/lint-if-let-rescope.rs:90:57
|
LL | while (if let Some(_value) = droppy().get() { false } else { true }) {
| ^
@ -191,5 +171,5 @@ help: a `match` with a single arm can preserve the drop order up to Edition 2021
LL | while (match droppy().get() { Some(_value) => { false } _ => { true }}) {
| ~~~~~ +++++++++++++++++ ~~~~ +
error: aborting due to 8 previous errors
error: aborting due to 7 previous errors