fix(linter/no-shadow): align initializer shadow handling with typescript-eslint

crates/oxc_linter/src/rules/eslint/no_shadow/mod.rs

@@ -107,13 +107,6 @@ impl Rule for NoShadow {
                 continue;
             }
 
-            if let Some(shadowed_span) =
-                Self::function_expression_name_shadow_span(ctx, symbol_id, symbol_name_str)
-            {
-                ctx.diagnostic(no_shadow_diagnostic(symbol_span, symbol_name_str, shadowed_span));
-                continue;
-            }
-
             if let Some(shadowed_symbol_id) = Self::find_shadowed_symbol_id(ctx, symbol_id) {
                 if !self.should_ignore_shadowed_symbol(ctx, symbol_id, shadowed_symbol_id) {
                     let shadowed_span = scoping.symbol_span(shadowed_symbol_id);
@@ -126,6 +119,13 @@ impl Rule for NoShadow {
                 continue;
             }
 
+            if let Some(shadowed_span) =
+                Self::function_expression_name_shadow_span(ctx, symbol_id, symbol_name_str)
+            {
+                ctx.diagnostic(no_shadow_diagnostic(symbol_span, symbol_name_str, shadowed_span));
+                continue;
+            }
+
             let symbol_flags = scoping.symbol_flags(symbol_id);
             if self.is_builtin_global_shadow(ctx, symbol_id, symbol_name_str, symbol_flags) {
                 ctx.diagnostic(no_shadow_global_diagnostic(symbol_span, symbol_name_str));
@@ -485,6 +485,8 @@ impl NoShadow {
 
         let outer_declaration_id = ctx.scoping().symbol_declaration(outer_symbol_id);
         let outer_symbol_span = ctx.scoping().symbol_span(outer_symbol_id);
+        let is_outer_formal_parameter = Self::is_formal_parameter_symbol(ctx, outer_declaration_id);
+
         let Some(initializer) =
             Self::find_initializer_expression(ctx, outer_declaration_id, outer_symbol_span)
         else {
@@ -499,8 +501,16 @@ impl NoShadow {
             return false;
         }
 
-        let unwrapped_expression_id = Self::unwrap_expression(ctx, inner_expression_id);
-        initializer.address() == ctx.nodes().kind(unwrapped_expression_id).address()
+        if is_outer_formal_parameter {
+            let unwrapped_expression_id = Self::unwrap_expression(ctx, inner_expression_id);
+            return initializer.address() == ctx.nodes().kind(unwrapped_expression_id).address();
+        }
+
+        let inner_scope_id = ctx.scoping().symbol_scope_id(inner_symbol_id);
+        let outer_scope_id = ctx.scoping().symbol_scope_id(outer_symbol_id);
+        ctx.scoping()
+            .scope_parent_id(inner_scope_id)
+            .is_some_and(|parent_scope_id| parent_scope_id == outer_scope_id)
     }
 
     fn is_init_pattern_node(
@@ -642,6 +652,20 @@ impl NoShadow {
         None
     }
 
+    fn is_formal_parameter_symbol(ctx: &LintContext, declaration_id: NodeId) -> bool {
+        for node_id in
+            std::iter::once(declaration_id).chain(ctx.nodes().ancestor_ids(declaration_id))
+        {
+            match ctx.nodes().kind(node_id) {
+                AstKind::FormalParameter(_) => return true,
+                kind if is_initializer_sentinel(kind) => break,
+                _ => {}
+            }
+        }
+
+        false
+    }
+
     fn unwrap_expression(ctx: &LintContext, expression_id: NodeId) -> NodeId {
         let mut current_id = expression_id;
 

crates/oxc_linter/src/rules/eslint/no_shadow/tests.rs

@@ -1719,28 +1719,31 @@ fn test_eslint() {
             None,
             None,
         ), // { "ecmaVersion": 6 },
-        (
-            "let x = false; export const a = wrap(function a() { if (!x) { x = true; a(); } });",
-            Some(serde_json::json!([{ "hoist": "all" }])),
-            None,
-            None,
-        ), // { "ecmaVersion": 6, "sourceType": "module" },
-        ("const a = wrap(function a() {});", None, None, None), // { "ecmaVersion": 6 },
-        ("const a = foo || wrap(function a() {});", None, None, None), // { "ecmaVersion": 6 },
-        ("const { a = wrap(function a() {}) } = obj;", None, None, None), // { "ecmaVersion": 6 },
-        ("const { a = foo || wrap(function a() {}) } = obj;", None, None, None), // { "ecmaVersion": 6 },
+        // The following tests are disabled as the behaviour of eslint vs typescript-eslint
+        // differs. We are following typescript-eslint's behaviour, but these tests are left
+        // here for clarity.
+        // (
+        //     "let x = false; export const a = wrap(function a() { if (!x) { x = true; a(); } });",
+        //     Some(serde_json::json!([{ "hoist": "all" }])),
+        //     None,
+        //     None,
+        // ), // { "ecmaVersion": 6, "sourceType": "module" },
+        // ("const a = wrap(function a() {});", None, None, None), // { "ecmaVersion": 6 },
+        // ("const a = foo || wrap(function a() {});", None, None, None), // { "ecmaVersion": 6 },
+        // ("const { a = wrap(function a() {}) } = obj;", None, None, None), // { "ecmaVersion": 6 },
+        // ("const { a = foo || wrap(function a() {}) } = obj;", None, None, None), // { "ecmaVersion": 6 },
         ("const { a = foo, b = function a() {} } = {}", None, None, None), // { "ecmaVersion": 6 },
         ("const { A = Foo, B = class A {} } = {}", None, None, None),      // { "ecmaVersion": 6 },
         ("function foo(a = wrap(function a() {})) {}", None, None, None),  // { "ecmaVersion": 6 },
         ("function foo(a = foo || wrap(function a() {})) {}", None, None, None), // { "ecmaVersion": 6 },
-        ("const A = wrap(class A {});", None, None, None), // { "ecmaVersion": 6 },
-        ("const A = foo || wrap(class A {});", None, None, None), // { "ecmaVersion": 6 },
-        ("const { A = wrap(class A {}) } = obj;", None, None, None), // { "ecmaVersion": 6 },
-        ("const { A = foo || wrap(class A {}) } = obj;", None, None, None), // { "ecmaVersion": 6 },
+        // ("const A = wrap(class A {});", None, None, None), // { "ecmaVersion": 6 },
+        // ("const A = foo || wrap(class A {});", None, None, None), // { "ecmaVersion": 6 },
+        // ("const { A = wrap(class A {}) } = obj;", None, None, None), // { "ecmaVersion": 6 },
+        // ("const { A = foo || wrap(class A {}) } = obj;", None, None, None), // { "ecmaVersion": 6 },
         ("function foo(A = wrap(class A {})) {}", None, None, None), // { "ecmaVersion": 6 },
         ("function foo(A = foo || wrap(class A {})) {}", None, None, None), // { "ecmaVersion": 6 },
-        ("var a = function a() {} ? foo : bar", None, None, None),
-        ("var A = class A {} ? foo : bar", None, None, None), // { "ecmaVersion": 6, },
+        // ("var a = function a() {} ? foo : bar", None, None, None),
+        // ("var A = class A {} ? foo : bar", None, None, None), // { "ecmaVersion": 6, },
         (
             "(function Array() {})",
             Some(serde_json::json!([{ "builtinGlobals": true }])),
@@ -2304,6 +2307,18 @@ fn test_typescript_eslint() {
             None,
             None,
         ),
+        (
+            "
+            import { memo } from 'react';
+
+            const FooBarComponent = memo(function FooBarComponent() {
+              return <div>Foo</div>;
+            });
+                ",
+            None,
+            None,
+            Some(PathBuf::from("test.tsx")),
+        ),
         (
             "
             function foo<T extends (id: string, ...args: any[]) => any>(

crates/oxc_linter/src/snapshots/eslint_no_shadow.snap

@@ -664,51 +664,6 @@ source: crates/oxc_linter/src/tester.rs
    ╰────
   help: Consider renaming 'x' to avoid shadowing the variable from the outer scope.
 
-  ⚠ eslint(no-shadow): 'a' is already declared in the upper scope.
-   ╭─[no_shadow.tsx:1:29]
- 1 │ let x = false; export const a = wrap(function a() { if (!x) { x = true; a(); } });
-   ·                             ┬                 ┬
-   ·                             │                 ╰── 'a' is declared here
-   ·                             ╰── shadowed declaration is here
-   ╰────
-  help: Consider renaming 'a' to avoid shadowing the variable from the outer scope.
-
-  ⚠ eslint(no-shadow): 'a' is already declared in the upper scope.
-   ╭─[no_shadow.tsx:1:7]
- 1 │ const a = wrap(function a() {});
-   ·       ┬                 ┬
-   ·       │                 ╰── 'a' is declared here
-   ·       ╰── shadowed declaration is here
-   ╰────
-  help: Consider renaming 'a' to avoid shadowing the variable from the outer scope.
-
-  ⚠ eslint(no-shadow): 'a' is already declared in the upper scope.
-   ╭─[no_shadow.tsx:1:7]
- 1 │ const a = foo || wrap(function a() {});
-   ·       ┬                        ┬
-   ·       │                        ╰── 'a' is declared here
-   ·       ╰── shadowed declaration is here
-   ╰────
-  help: Consider renaming 'a' to avoid shadowing the variable from the outer scope.
-
-  ⚠ eslint(no-shadow): 'a' is already declared in the upper scope.
-   ╭─[no_shadow.tsx:1:9]
- 1 │ const { a = wrap(function a() {}) } = obj;
-   ·         ┬                 ┬
-   ·         │                 ╰── 'a' is declared here
-   ·         ╰── shadowed declaration is here
-   ╰────
-  help: Consider renaming 'a' to avoid shadowing the variable from the outer scope.
-
-  ⚠ eslint(no-shadow): 'a' is already declared in the upper scope.
-   ╭─[no_shadow.tsx:1:9]
- 1 │ const { a = foo || wrap(function a() {}) } = obj;
-   ·         ┬                        ┬
-   ·         │                        ╰── 'a' is declared here
-   ·         ╰── shadowed declaration is here
-   ╰────
-  help: Consider renaming 'a' to avoid shadowing the variable from the outer scope.
-
   ⚠ eslint(no-shadow): 'a' is already declared in the upper scope.
    ╭─[no_shadow.tsx:1:9]
  1 │ const { a = foo, b = function a() {} } = {}
@@ -745,42 +700,6 @@ source: crates/oxc_linter/src/tester.rs
    ╰────
   help: Consider renaming 'a' to avoid shadowing the variable from the outer scope.
 
-  ⚠ eslint(no-shadow): 'A' is already declared in the upper scope.
-   ╭─[no_shadow.tsx:1:7]
- 1 │ const A = wrap(class A {});
-   ·       ┬              ┬
-   ·       │              ╰── 'A' is declared here
-   ·       ╰── shadowed declaration is here
-   ╰────
-  help: Consider renaming 'A' to avoid shadowing the variable from the outer scope.
-
-  ⚠ eslint(no-shadow): 'A' is already declared in the upper scope.
-   ╭─[no_shadow.tsx:1:7]
- 1 │ const A = foo || wrap(class A {});
-   ·       ┬                     ┬
-   ·       │                     ╰── 'A' is declared here
-   ·       ╰── shadowed declaration is here
-   ╰────
-  help: Consider renaming 'A' to avoid shadowing the variable from the outer scope.
-
-  ⚠ eslint(no-shadow): 'A' is already declared in the upper scope.
-   ╭─[no_shadow.tsx:1:9]
- 1 │ const { A = wrap(class A {}) } = obj;
-   ·         ┬              ┬
-   ·         │              ╰── 'A' is declared here
-   ·         ╰── shadowed declaration is here
-   ╰────
-  help: Consider renaming 'A' to avoid shadowing the variable from the outer scope.
-
-  ⚠ eslint(no-shadow): 'A' is already declared in the upper scope.
-   ╭─[no_shadow.tsx:1:9]
- 1 │ const { A = foo || wrap(class A {}) } = obj;
-   ·         ┬                     ┬
-   ·         │                     ╰── 'A' is declared here
-   ·         ╰── shadowed declaration is here
-   ╰────
-  help: Consider renaming 'A' to avoid shadowing the variable from the outer scope.
-
   ⚠ eslint(no-shadow): 'A' is already declared in the upper scope.
    ╭─[no_shadow.tsx:1:14]
  1 │ function foo(A = wrap(class A {})) {}
@@ -799,24 +718,6 @@ source: crates/oxc_linter/src/tester.rs
    ╰────
   help: Consider renaming 'A' to avoid shadowing the variable from the outer scope.
 
-  ⚠ eslint(no-shadow): 'a' is already declared in the upper scope.
-   ╭─[no_shadow.tsx:1:5]
- 1 │ var a = function a() {} ? foo : bar
-   ·     ┬            ┬
-   ·     │            ╰── 'a' is declared here
-   ·     ╰── shadowed declaration is here
-   ╰────
-  help: Consider renaming 'a' to avoid shadowing the variable from the outer scope.
-
-  ⚠ eslint(no-shadow): 'A' is already declared in the upper scope.
-   ╭─[no_shadow.tsx:1:5]
- 1 │ var A = class A {} ? foo : bar
-   ·     ┬         ┬
-   ·     │         ╰── 'A' is declared here
-   ·     ╰── shadowed declaration is here
-   ╰────
-  help: Consider renaming 'A' to avoid shadowing the variable from the outer scope.
-
   ⚠ eslint(no-shadow): 'Array' is already a global variable.
    ╭─[no_shadow.tsx:1:11]
  1 │ (function Array() {})