feat(linter) eslint plugin unicorn: prefer optional catch binding (#1188)

crates/oxc_linter/src/rules.rs

@@ -163,6 +163,7 @@ mod unicorn {
     pub mod prefer_code_point;
     pub mod prefer_date_now;
     pub mod prefer_logical_operator_over_ternary;
+    pub mod prefer_optional_catch_binding;
     pub mod prefer_query_selector;
     pub mod prefer_regexp_test;
     pub mod prefer_string_trim_start_end;
@@ -301,6 +302,7 @@ oxc_macros::declare_all_lint_rules! {
     unicorn::prefer_code_point,
     unicorn::prefer_date_now,
     unicorn::prefer_logical_operator_over_ternary,
+    unicorn::prefer_optional_catch_binding,
     unicorn::prefer_query_selector,
     unicorn::prefer_regexp_test,
     unicorn::prefer_string_trim_start_end,

crates/oxc_linter/src/rules/unicorn/prefer_optional_catch_binding.rs

@@ -0,0 +1,119 @@
+use oxc_ast::{
+    ast::{BindingPattern, BindingPatternKind},
+    AstKind,
+};
+use oxc_diagnostics::{
+    miette::{self, Diagnostic},
+    thiserror::Error,
+};
+use oxc_macros::declare_oxc_lint;
+use oxc_span::{GetSpan, Span};
+
+use crate::{context::LintContext, rule::Rule, AstNode};
+
+#[derive(Debug, Error, Diagnostic)]
+#[error("eslint-plugin-unicorn(prefer-optional-catch-binding): Prefer omitting the catch binding parameter if it is unused")]
+#[diagnostic(severity(warning))]
+struct PreferOptionalCatchBindingDiagnostic(#[label] pub Span);
+
+#[derive(Debug, Default, Clone)]
+pub struct PreferOptionalCatchBinding;
+
+declare_oxc_lint!(
+    /// ### What it does
+    ///
+    /// Prefers omitting the catch binding parameter if it is unused
+    ///
+    /// ### Why is this bad?
+    ///
+    /// It is unnecessary to bind the error to a variable if it is not used.
+    ///
+    /// ### Example
+    /// ```javascript
+    /// // Bad
+    /// try {
+    ///  // ...
+    /// } catch (e) { }
+    ///
+    /// // Good
+    /// try {
+    ///  // ...
+    /// } catch { }
+    /// ```
+    PreferOptionalCatchBinding,
+    style
+);
+
+impl Rule for PreferOptionalCatchBinding {
+    fn run<'a>(&self, node: &AstNode<'a>, ctx: &LintContext<'a>) {
+        let AstKind::CatchClause(catch_clause) = node.kind() else { return };
+
+        let Some(catch_param) = &catch_clause.param else { return };
+
+        let references_count = get_param_references_count(catch_param, ctx);
+
+        if references_count != 0 {
+            return;
+        }
+
+        ctx.diagnostic(PreferOptionalCatchBindingDiagnostic(catch_param.span()));
+    }
+}
+
+fn get_param_references_count(binding_pat: &BindingPattern, ctx: &LintContext) -> usize {
+    match &binding_pat.kind {
+        BindingPatternKind::BindingIdentifier(binding_ident) => {
+            ctx.semantic().symbol_references(binding_ident.symbol_id.get().unwrap()).count()
+        }
+        BindingPatternKind::ObjectPattern(object_pat) => {
+            let mut count = 0;
+
+            for prop in &object_pat.properties {
+                count += get_param_references_count(&prop.value, ctx);
+            }
+
+            if let Some(rest) = &object_pat.rest {
+                count += get_param_references_count(&rest.argument, ctx);
+            }
+
+            count
+        }
+        BindingPatternKind::AssignmentPattern(_) => 1,
+        BindingPatternKind::ArrayPattern(array_pat) => {
+            let mut count = 0;
+
+            for element in (&array_pat.elements).into_iter().flatten() {
+                count += get_param_references_count(element, ctx);
+            }
+
+            count
+        }
+    }
+}
+
+#[test]
+fn test() {
+    use crate::tester::Tester;
+
+    let pass = vec![
+        r#"try {} catch {}"#,
+        r#"try {} catch ({message}) {alert(message)}"#,
+        r#"try {} catch ({cause: {message}}) {alert(message)}"#,
+        r#"try {} catch({nonExistsProperty = thisWillExecute()}) {}"#,
+    ];
+
+    let fail = vec![
+        r#"try {} catch (_) {}"#,
+        r#"try {} catch (theRealErrorName) {}"#,
+        r#"try    {    } catch    (e)  
+			  	  {    }"#,
+        r#"try {} catch(e) {}"#,
+        r#"try {} catch (e){}"#,
+        r#"try {} catch ({}) {}"#,
+        r#"try {} catch ({message}) {}"#,
+        r#"try {} catch ({message: notUsedMessage}) {}"#,
+        r#"try {} catch ({cause: {message}}) {}"#,
+    ];
+
+    Tester::new_without_config(PreferOptionalCatchBinding::NAME, pass, fail).test_and_snapshot();
+}

crates/oxc_linter/src/snapshots/prefer_optional_catch_binding.snap

@@ -0,0 +1,60 @@
+---
+source: crates/oxc_linter/src/tester.rs
+expression: prefer_optional_catch_binding
+---
+  ⚠ eslint-plugin-unicorn(prefer-optional-catch-binding): Prefer omitting the catch binding parameter if it is unused
+   ╭─[prefer_optional_catch_binding.tsx:1:1]
+ 1 │ try {} catch (_) {}
+   ·               ─
+   ╰────
+
+  ⚠ eslint-plugin-unicorn(prefer-optional-catch-binding): Prefer omitting the catch binding parameter if it is unused
+   ╭─[prefer_optional_catch_binding.tsx:1:1]
+ 1 │ try {} catch (theRealErrorName) {}
+   ·               ────────────────
+   ╰────
+
+  ⚠ eslint-plugin-unicorn(prefer-optional-catch-binding): Prefer omitting the catch binding parameter if it is unused
+   ╭─[prefer_optional_catch_binding.tsx:1:1]
+ 1 │ try    {    } catch    (e)  
+   ·                         ─
+ 2 │                   {    }
+   ╰────
+
+  ⚠ eslint-plugin-unicorn(prefer-optional-catch-binding): Prefer omitting the catch binding parameter if it is unused
+   ╭─[prefer_optional_catch_binding.tsx:1:1]
+ 1 │ try {} catch(e) {}
+   ·              ─
+   ╰────
+
+  ⚠ eslint-plugin-unicorn(prefer-optional-catch-binding): Prefer omitting the catch binding parameter if it is unused
+   ╭─[prefer_optional_catch_binding.tsx:1:1]
+ 1 │ try {} catch (e){}
+   ·               ─
+   ╰────
+
+  ⚠ eslint-plugin-unicorn(prefer-optional-catch-binding): Prefer omitting the catch binding parameter if it is unused
+   ╭─[prefer_optional_catch_binding.tsx:1:1]
+ 1 │ try {} catch ({}) {}
+   ·               ──
+   ╰────
+
+  ⚠ eslint-plugin-unicorn(prefer-optional-catch-binding): Prefer omitting the catch binding parameter if it is unused
+   ╭─[prefer_optional_catch_binding.tsx:1:1]
+ 1 │ try {} catch ({message}) {}
+   ·               ─────────
+   ╰────
+
+  ⚠ eslint-plugin-unicorn(prefer-optional-catch-binding): Prefer omitting the catch binding parameter if it is unused
+   ╭─[prefer_optional_catch_binding.tsx:1:1]
+ 1 │ try {} catch ({message: notUsedMessage}) {}
+   ·               ─────────────────────────
+   ╰────
+
+  ⚠ eslint-plugin-unicorn(prefer-optional-catch-binding): Prefer omitting the catch binding parameter if it is unused
+   ╭─[prefer_optional_catch_binding.tsx:1:1]
+ 1 │ try {} catch ({cause: {message}}) {}
+   ·               ──────────────────
+   ╰────
+
+