use crate::{make, Metadata, Report, Rule, Suggestion}; use if_chain::if_chain; use macros::lint; use rnix::{ types::{Pattern, TypedNode}, NodeOrToken, SyntaxElement, SyntaxKind, }; /// ## What it does /// Checks for an empty variadic pattern: `{...}`, in a function /// argument. /// /// ## Why is this bad? /// The intention with empty patterns is not instantly obvious. Prefer /// an underscore identifier instead, to indicate that the argument /// is being ignored. /// /// ## Example /// /// ``` /// client = { ... }: { /// imports = [ self.nixosModules.irmaseal-pkg ]; /// services.irmaseal-pkg.enable = true; /// }; /// ``` /// /// Replace the empty variadic pattern with `_` to indicate that you /// intend to ignore the argument: /// /// ``` /// client = _: { /// imports = [ self.nixosModules.irmaseal-pkg ]; /// services.irmaseal-pkg.enable = true; /// }; /// ``` #[lint( name = "empty pattern", note = "Found empty pattern in function argument", code = 10, match_with = SyntaxKind::NODE_PATTERN )] struct EmptyPattern; impl Rule for EmptyPattern { fn validate(&self, node: &SyntaxElement) -> Option { if_chain! { if let NodeOrToken::Node(node) = node; if let Some(pattern) = Pattern::cast(node.clone()); // no patterns within `{ }` if pattern.entries().count() == 0; // pattern is not bound if pattern.at().is_none(); then { let at = node.text_range(); let message = "This pattern is empty, use `_` instead"; let replacement = make::ident("_").node().clone(); Some(self.report().suggest(at, message, Suggestion::new(at, replacement))) } else { None } } } }