diff --git a/tvix/eval/src/compiler/optimiser.rs b/tvix/eval/src/compiler/optimiser.rs index 615de3235..af0ad2256 100644 --- a/tvix/eval/src/compiler/optimiser.rs +++ b/tvix/eval/src/compiler/optimiser.rs @@ -9,6 +9,7 @@ use ast::Expr; pub(super) fn optimise_expr(c: &mut Compiler, slot: LocalIdx, expr: ast::Expr) -> ast::Expr { match expr { Expr::BinOp(_) => optimise_bin_op(c, slot, expr), + Expr::Paren(_) => optimise_paren(c, expr), _ => expr.to_owned(), } } @@ -123,3 +124,28 @@ fn optimise_bin_op(c: &mut Compiler, slot: LocalIdx, expr: ast::Expr) -> ast::Ex expr } + +/// Detect useless parenthesis around primitive expressions. +fn optimise_paren(c: &mut Compiler, expr: ast::Expr) -> ast::Expr { + if let Expr::Paren(inner) = &expr { + let inner = inner.expr().unwrap(); + + if let Expr::Paren(_) = &inner { + c.emit_warning(&expr, WarningKind::UselessParens); + return optimise_paren(c, inner); + } + + if let Expr::Literal(_) + | Expr::Str(_) + | Expr::Select(_) + | Expr::List(_) + | Expr::AttrSet(_) + | Expr::Ident(_) = &inner + { + c.emit_warning(&expr, WarningKind::UselessParens); + return inner; + } + } + + expr +} diff --git a/tvix/eval/src/warnings.rs b/tvix/eval/src/warnings.rs index cfe5044a8..26efd24d1 100644 --- a/tvix/eval/src/warnings.rs +++ b/tvix/eval/src/warnings.rs @@ -17,6 +17,7 @@ pub enum WarningKind { DeadCode, EmptyInherit, EmptyLet, + UselessParens, /// Tvix internal warning for features triggered by users that are /// not actually implemented yet, but do not cause runtime failures. @@ -105,6 +106,10 @@ impl EvalWarning { format!("this `let`-expression contains no bindings") } + WarningKind::UselessParens => { + format!("these parenthesis can be removed") + } + WarningKind::NotImplemented(what) => { format!("feature not yet implemented in tvix: {}", what) } @@ -125,6 +130,7 @@ impl EvalWarning { WarningKind::DeadCode => "W008", WarningKind::EmptyInherit => "W009", WarningKind::EmptyLet => "W010", + WarningKind::UselessParens => "W011", WarningKind::NotImplemented(_) => "W999", }