From 2993b205dbad0f7fd3755f9f3cfb3003c79a8b5a Mon Sep 17 00:00:00 2001 From: Akshay Date: Fri, 15 Oct 2021 13:06:59 +0530 Subject: new lint: useless_parens --- lib/src/lints/useless_parens.rs | 99 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 99 insertions(+) create mode 100644 lib/src/lints/useless_parens.rs (limited to 'lib/src/lints') diff --git a/lib/src/lints/useless_parens.rs b/lib/src/lints/useless_parens.rs new file mode 100644 index 0000000..d93f06c --- /dev/null +++ b/lib/src/lints/useless_parens.rs @@ -0,0 +1,99 @@ +use crate::{Lint, Metadata, Report, Rule, Suggestion, Diagnostic}; + +use if_chain::if_chain; +use macros::lint; +use rnix::{ + types::{ParsedType, KeyValue, Paren, TypedNode, Wrapper}, + NodeOrToken, SyntaxElement, SyntaxKind, +}; + +#[lint( + name = "useless parens", + note = "These parentheses can be omitted", + code = 8, + match_with = [ + SyntaxKind::NODE_KEY_VALUE, + SyntaxKind::NODE_PAREN, + SyntaxKind::NODE_LET_IN, + ] +)] +struct UselessParens; + +impl Rule for UselessParens { + fn validate(&self, node: &SyntaxElement) -> Option { + if_chain! { + if let NodeOrToken::Node(node) = node; + if let Some(parsed_type_node) = ParsedType::cast(node.clone()); + + if let Some(diagnostic) = do_thing(parsed_type_node); + then { + let mut report = Self::report(); + report.diagnostics.push(diagnostic); + Some(report) + } else { + None + } + } + } +} + +fn do_thing(parsed_type_node: ParsedType) -> Option { + match parsed_type_node { + ParsedType::KeyValue(kv) => if_chain! { + if let Some(value_node) = kv.value(); + let value_range = value_node.text_range(); + if let Some(value_in_parens) = Paren::cast(value_node); + if let Some(inner) = value_in_parens.inner(); + then { + let at = value_range; + let message = "Useless parentheses around value in `let` binding"; + let replacement = inner; + Some(Diagnostic::suggest(at, message, Suggestion::new(at, replacement))) + } else { + None + } + }, + ParsedType::LetIn(let_in) => if_chain! { + if let Some(body_node) = let_in.body(); + let body_range = body_node.text_range(); + if let Some(body_as_parens) = Paren::cast(body_node); + if let Some(inner) = body_as_parens.inner(); + then { + let at = body_range; + let message = "Useless parentheses around body of `let` expression"; + let replacement = inner; + Some(Diagnostic::suggest(at, message, Suggestion::new(at, replacement))) + } else { + None + } + }, + ParsedType::Paren(paren_expr) => if_chain! { + let paren_expr_range = paren_expr.node().text_range(); + if let Some(father_node) = paren_expr.node().parent(); + + // ensure that we don't lint inside let-in statements + // we already lint such cases in previous match stmt + if KeyValue::cast(father_node).is_none(); + + if let Some(inner_node) = paren_expr.inner(); + if let Some(parsed_inner) = ParsedType::cast(inner_node); + if matches!( + parsed_inner, + ParsedType::List(_) + | ParsedType::Paren(_) + | ParsedType::Str(_) + | ParsedType::AttrSet(_) + | ParsedType::Select(_) + ); + then { + let at = paren_expr_range; + let message = "Useless parentheses around primitive expression"; + let replacement = parsed_inner.node().clone(); + Some(Diagnostic::suggest(at, message, Suggestion::new(at, replacement))) + } else { + None + } + }, + _ => None + } +} -- cgit v1.2.3