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Precedence improvements: closures and jumps #133782

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Precedence improvements: closures and jumps #133782

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f3ac64a
Add test of closure vs jump precedence
dtolnay Dec 3, 2024
193d827
Squash closures and jumps into a single precedence level
dtolnay Dec 3, 2024
4df47a0
Add test of closure precedence with return type
dtolnay Dec 3, 2024
72ac961
Raise precedence of closure that has explicit return type
dtolnay Dec 3, 2024
fe06c5d
Never parenthesize `continue`
dtolnay Dec 3, 2024
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11 changes: 8 additions & 3 deletions compiler/rustc_ast/src/ast.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1316,11 +1316,15 @@ impl Expr {
}

pub fn precedence(&self) -> ExprPrecedence {
match self.kind {
ExprKind::Closure(..) => ExprPrecedence::Closure,
match &self.kind {
ExprKind::Closure(closure) => {
match closure.fn_decl.output {
FnRetTy::Default(_) => ExprPrecedence::Jump,
FnRetTy::Ty(_) => ExprPrecedence::Unambiguous,
}
}

ExprKind::Break(..)
| ExprKind::Continue(..)
| ExprKind::Ret(..)
| ExprKind::Yield(..)
| ExprKind::Yeet(..)
Expand Down Expand Up @@ -1354,6 +1358,7 @@ impl Expr {
| ExprKind::Block(..)
| ExprKind::Call(..)
| ExprKind::ConstBlock(_)
| ExprKind::Continue(..)
| ExprKind::Field(..)
| ExprKind::ForLoop { .. }
| ExprKind::FormatArgs(..)
Expand Down
3 changes: 1 addition & 2 deletions compiler/rustc_ast/src/util/parser.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -231,8 +231,7 @@ impl AssocOp {

#[derive(Clone, Copy, PartialEq, PartialOrd)]
pub enum ExprPrecedence {
Closure,
// return, break, yield
// return, break, yield, closures
Jump,
// = += -= *= /= %= &= |= ^= <<= >>=
Assign,
Expand Down
13 changes: 9 additions & 4 deletions compiler/rustc_hir/src/hir.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1696,11 +1696,15 @@ pub struct Expr<'hir> {

impl Expr<'_> {
pub fn precedence(&self) -> ExprPrecedence {
match self.kind {
ExprKind::Closure { .. } => ExprPrecedence::Closure,
match &self.kind {
ExprKind::Closure(closure) => {
match closure.fn_decl.output {
FnRetTy::DefaultReturn(_) => ExprPrecedence::Jump,
FnRetTy::Return(_) => ExprPrecedence::Unambiguous,
}
}

ExprKind::Break(..)
| ExprKind::Continue(..)
| ExprKind::Ret(..)
| ExprKind::Yield(..)
| ExprKind::Become(..) => ExprPrecedence::Jump,
Expand All @@ -1726,6 +1730,7 @@ impl Expr<'_> {
| ExprKind::Block(..)
| ExprKind::Call(..)
| ExprKind::ConstBlock(_)
| ExprKind::Continue(..)
| ExprKind::Field(..)
| ExprKind::If(..)
| ExprKind::Index(..)
Expand All @@ -1742,7 +1747,7 @@ impl Expr<'_> {
| ExprKind::Type(..)
| ExprKind::Err(_) => ExprPrecedence::Unambiguous,

ExprKind::DropTemps(ref expr, ..) => expr.precedence(),
ExprKind::DropTemps(expr, ..) => expr.precedence(),
}
}

Expand Down
6 changes: 6 additions & 0 deletions tests/ui-fulldeps/pprust-parenthesis-insertion.rs
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Expand Up @@ -70,6 +70,12 @@ static EXPRS: &[&str] = &[
// These mean different things.
"return - 2",
"(return) - 2",
// Closures and jumps have equal precedence.
"|| return break 2",
"return break || 2",
// Closures with a return type have especially high precedence.
"|| -> T { x } + 1",
"(|| { x }) + 1",
// These mean different things.
"if let _ = true && false {}",
"if let _ = (true && false) {}",
Expand Down
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