arity 0.5.0

An LSP, formatter, and linter for R
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//! `duplicated-arguments`: a call supplying the same argument name twice
//! (`f(a = 1, a = 2)`). The sibling of `duplicate-formal` on the call side.
//! Not always a runtime error (`c(a = 1, a = 2)` is fine — `c` takes `...`), so
//! it is a warning, not an error, and carries no autofix.

use std::collections::HashSet;

use rowan::ast::AstNode as _;

use crate::ast::CallExpr;
use crate::linter::diagnostic::{Diagnostic, Severity, ViolationData};
use crate::linter::rules::matchers;
use crate::linter::rules::{Rule, RuleContext};
use crate::syntax::{SyntaxElement, SyntaxKind};

pub struct DuplicatedArguments;

impl Rule for DuplicatedArguments {
    fn id(&self) -> &'static str {
        "duplicated-arguments"
    }

    fn interests(&self) -> &'static [SyntaxKind] {
        &[SyntaxKind::CALL_EXPR]
    }

    fn check(&self, el: &SyntaxElement, _ctx: &RuleContext<'_>, sink: &mut Vec<Diagnostic>) {
        let Some(call) = el.as_node().cloned().and_then(CallExpr::cast) else {
            return;
        };
        let mut seen: HashSet<String> = HashSet::new();
        for arg in matchers::args(&call) {
            let (Some(name), Some(token)) = (arg.name, arg.name_token) else {
                continue;
            };
            if !seen.insert(name.to_string()) {
                sink.push(Diagnostic {
                    rule: "duplicated-arguments",
                    severity: Severity::Warning,
                    path: Default::default(),
                    range: token.text_range(),
                    message: ViolationData::new(
                        "duplicated-arguments",
                        format!("argument `{name}` is supplied more than once in this call"),
                    )
                    .with_suggestion("Remove or rename the duplicate argument."),
                    fix: None,
                });
            }
        }
    }
}