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Merge pull request #21465 from A4-Tacks/prec-cast-before-angle

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Fix false positive precedence in `(2 as i32) < 3`
This commit is contained in:
Shoyu Vanilla (Flint) 2026-01-15 09:09:18 +00:00 • committed by GitHub
commit 70f4111d67
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2 changed files with 26 additions and 4 deletions
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6
src/tools/rust-analyzer/crates/ide-assists/src/handlers/remove_parentheses.rs
View file

@ -321,6 +321,12 @@ mod tests {
);
}
#[test]
fn remove_parens_conflict_cast_before_l_angle() {
check_assist_not_applicable(remove_parentheses, r#"fn f() { _ = $0(1 as u32) << 10; }"#);
check_assist_not_applicable(remove_parentheses, r#"fn f() { _ = $0(1 as u32) < 10; }"#);
}
#[test]
fn remove_parens_double_paren_stmt() {
check_assist(

24
src/tools/rust-analyzer/crates/syntax/src/ast/prec.rs
View file

@ -154,6 +154,11 @@ fn check_ancestry(ancestor: &SyntaxNode, descendent: &SyntaxNode) -> bool {
bail()
}
fn next_token_of(node: &SyntaxNode) -> Option<ast::SyntaxToken> {
let last = node.last_token()?;
skip_trivia_token(last.next_token()?, Direction::Next)
}
impl Expr {
pub fn precedence(&self) -> ExprPrecedence {
precedence(self)
@ -197,6 +202,8 @@ impl Expr {
if is_parent_call_expr && is_field_expr {
return true;
}
let place_of_parent =
|| place_of.ancestors().find(|it| it.parent().is_none_or(|p| &p == parent.syntax()));
// Special-case block weirdness
if parent.child_is_followed_by_a_block() {
@ -226,15 +233,24 @@ impl Expr {
// For `&&`, we avoid introducing `<ret-like> && <expr>` into a binary chain.
if self.precedence() == ExprPrecedence::Jump
&& let Some(node) =
place_of.ancestors().find(|it| it.parent().is_none_or(|p| &p == parent.syntax()))
&& let Some(next) =
node.last_token().and_then(|t| skip_trivia_token(t.next_token()?, Direction::Next))
&& let Some(node) = place_of_parent()
&& let Some(next) = next_token_of(&node)
&& matches!(next.kind(), T![||] | T![&&])
{
return true;
}
// Special-case `2 as x < 3`
if let ast::Expr::CastExpr(it) = self
&& let Some(ty) = it.ty()
&& ty.syntax().last_token().and_then(|it| ast::NameLike::cast(it.parent()?)).is_some()
&& let Some(node) = place_of_parent()
&& let Some(next) = next_token_of(&node)
&& matches!(next.kind(), T![<] | T![<<])
{
return true;
}
if self.is_paren_like()
|| parent.is_paren_like()
|| self.is_prefix()