refactor(natu): remove single-use binding rule

src/natu/rules/single_use_binding.rs

@@ -1,46 +0,0 @@
-use crate::{
-    ast,
-    scope_graph::{Binding, LetScope, ScopeGraph},
-};
-
-pub struct Finding {
-    pub range: ast::SourceRange,
-    pub name: String,
-}
-
-pub fn check(graph: &ScopeGraph) -> Vec<Finding> {
-    graph
-        .let_scopes()
-        .iter()
-        .flat_map(|let_scope| {
-            let_scope.bindings.iter().filter_map(|binding| {
-                is_single_use(graph, let_scope, binding).then(|| Finding {
-                    range: binding.range,
-                    name: binding.name.clone(),
-                })
-            })
-        })
-        .collect()
-}
-
-fn is_single_use(graph: &ScopeGraph, let_scope: &LetScope, binding: &Binding) -> bool {
-    let self_references = binding
-        .references
-        .iter()
-        .filter(|reference| graph.resolve(**reference).contains(&binding.declaration))
-        .count();
-    let external_references = let_scope
-        .bindings
-        .iter()
-        .filter(|candidate| candidate.declaration != binding.declaration)
-        .flat_map(|candidate| candidate.references.iter())
-        .chain(let_scope.entry_references.iter())
-        .filter(|reference| graph.resolve(**reference).contains(&binding.declaration))
-        .collect::<Vec<_>>();
-
-    !binding.is_import
-        && self_references == 0
-        && external_references.len() == 1
-        && (binding.is_lambda
-            || !graph.crosses_lambda_scope(*external_references[0], binding.declaration))
-}