arity 0.3.0

An LSP, formatter, and linter for R
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//! `undefined-symbol`: an identifier read that doesn't resolve to any
//! in-scope binding nor any known package export.
//!
//! On by default, but gated: the rule only runs when *every* `library()`-
//! attached package is indexed (a default package, or harvested into the
//! introspection cache). If any attached package's exports are unknown, the
//! rule stays silent for the whole file — an un-indexed package could export
//! any of the otherwise-unresolved names, so flagging them would be a false
//! positive.

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

pub struct UndefinedSymbol;

impl Rule for UndefinedSymbol {
    fn id(&self) -> &'static str {
        "undefined-symbol"
    }

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

    fn default_enabled(&self) -> bool {
        true
    }

    fn run(&self, ctx: &RuleContext<'_>) -> Vec<Diagnostic> {
        match ctx.resolution {
            // Cross-file path: the salsa `external_resolution` query already
            // applied the conservative gates and the project + package masking,
            // memoized and backdated across edits. We only re-apply the cheap,
            // always-fresh per-occurrence local-binding check and re-attach the
            // diagnostic span — the resolved set is range-free.
            Some(resolution) => ctx
                .model
                .idents()
                .iter()
                .filter(|ident| ctx.model.resolve_local(ident).is_none())
                .filter(|ident| resolution.unresolved.contains(ident.name.as_str()))
                .map(|ident| undefined(&ident.name, ident.range))
                .collect(),
            // Single-file fallback (no project / no manifest): resolve inline
            // against the provided `SymbolProvider`, preserving the historical
            // behavior for one-shot checks and the LSP per-document path.
            None => self.run_standalone(ctx),
        }
    }
}

impl UndefinedSymbol {
    /// Inline resolution used when no salsa-backed [`ExternalResolution`] is
    /// available (single-file paths). Mirrors the cross-file path's logic using
    /// the [`RuleContext::symbols`] provider directly.
    fn run_standalone(&self, ctx: &RuleContext<'_>) -> Vec<Diagnostic> {
        let mut out = Vec::new();
        let loaded = ctx.model.loaded_packages();
        // Conservative gate: bail out entirely if any attached package's exports
        // are unknown, since such a package could define the unresolved names.
        if loaded.iter().any(|p| !ctx.symbols.package_indexed(&p.name)) {
            return out;
        }
        // Conservative gate: incomplete cross-file visibility (an unresolved
        // `source()`, or a wholesale `import(pkg)`) could define any of the
        // names below.
        if ctx.project.is_some_and(|p| p.resolution_incomplete) {
            return out;
        }
        for ident in ctx.model.idents() {
            // Skip if it resolves to a local binding.
            if ctx.model.resolve_local(ident).is_some() {
                continue;
            }
            // Skip if a sibling file in the same package or source-closure binds
            // it at top level.
            if ctx.project.is_some_and(|p| p.resolves(&ident.name)) {
                continue;
            }
            // Skip if the symbol provider can place it.
            if !matches!(
                ctx.symbols.origin(&ident.name, loaded),
                PackageOrigin::Unknown
            ) {
                continue;
            }
            out.push(undefined(&ident.name, ident.range));
        }
        out
    }
}

/// Build an `undefined-symbol` diagnostic for `name` at `range`.
fn undefined(name: &str, range: rowan::TextRange) -> Diagnostic {
    Diagnostic {
        rule: "undefined-symbol",
        severity: Severity::Warning,
        path: Default::default(),
        range,
        message: ViolationData::new(
            "undefined-symbol",
            format!("no in-scope binding or attached package exports `{name}`"),
        ),
        fix: None,
    }
}