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use crate::{session::SessionInfo, Metadata, Report, Rule, Suggestion};
use if_chain::if_chain;
use macros::lint;
use rnix::{
types::{Pattern, TokenWrapper, TypedNode},
NodeOrToken, SyntaxElement, SyntaxKind,
};
/// ## What it does
/// Checks for binds of the form `inputs @ { ... }` in function
/// arguments.
///
/// ## Why is this bad?
/// The variadic pattern here is redundant, as it does not capture
/// anything.
///
/// ## Example
///
/// ```nix
/// inputs @ { ... }: inputs.nixpkgs
/// ```
///
/// Remove the pattern altogether:
///
/// ```nix
/// inputs: inputs.nixpkgs
/// ```
#[lint(
name = "redundant_pattern_bind",
note = "Found redundant pattern bind in function argument",
code = 11,
match_with = SyntaxKind::NODE_PATTERN
)]
struct RedundantPatternBind;
impl Rule for RedundantPatternBind {
fn validate(&self, node: &SyntaxElement, _sess: &SessionInfo) -> Option<Report> {
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 just ellipsis
if pattern.ellipsis();
// pattern is bound
if let Some(ident) = pattern.at();
then {
let at = node.text_range();
let message = format!("This pattern bind is redundant, use `{}` instead", ident.as_str());
let replacement = ident.node().clone();
Some(self.report().suggest(at, message, Suggestion::new(at, replacement)))
} else {
None
}
}
}
}
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