arity 0.3.0

An LSP, formatter, and linter for R
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//! `shadowed-builtin`: a binding whose name is exported by a default R package
//! AND that name is later used in a call context in the same scope.
//!
//! Defining `c <- 1` is fine on its own. It's `c <- 1; c(2, 3)` that bites —
//! you think you're calling base `c()`, but R uses your local. The two-step
//! trigger keeps false positives down.

use crate::linter::diagnostic::{Diagnostic, Severity, ViolationData};
use crate::linter::rules::{Rule, RuleContext};
use crate::semantic::BindingKind;

pub struct ShadowedBuiltin;

impl Rule for ShadowedBuiltin {
    fn id(&self) -> &'static str {
        "shadowed-builtin"
    }

    fn default_severity(&self) -> Severity {
        Severity::Warning
    }

    fn run(&self, ctx: &RuleContext<'_>) -> Vec<Diagnostic> {
        let mut out = Vec::new();
        for (binding_idx, binding) in ctx.model.bindings().iter().enumerate() {
            if !matches!(binding.kind, BindingKind::Local | BindingKind::Param) {
                continue;
            }
            if !ctx.symbols.is_base(&binding.name) {
                continue;
            }
            // Look for any read of this name in the same scope (or a descendant
            // scope) that occurs *after* the definition. We approximate "in the
            // same scope" by walking idents and checking that the binding
            // resolves them.
            let id = crate::semantic::BindingId(binding_idx as u32);
            let triggered = ctx.model.idents().iter().any(|ident| {
                ident.name == binding.name
                    && u32::from(ident.range.start()) > u32::from(binding.def_range.end())
                    && ctx.model.resolve_local(ident) == Some(id)
            });
            if !triggered {
                continue;
            }
            out.push(Diagnostic {
                rule: "shadowed-builtin",
                severity: Severity::Warning,
                path: Default::default(),
                range: binding.def_range,
                message: ViolationData::new(
                    "shadowed-builtin",
                    format!(
                        "local binding `{}` shadows a base-R name later used in this scope",
                        binding.name
                    ),
                )
                .with_suggestion(
                    "Rename the local, or fully qualify the base call (e.g. `base::c`).",
                ),
                fix: None,
            });
        }
        out
    }
}