feat(linter): improve no_redeclare rule implementation (#2084)

crates/oxc_linter/src/rules/eslint/no_redeclare.rs

@@ -58,7 +58,7 @@ declare_oxc_lint!(
     /// var a = 10;
     /// ```
     NoRedeclare,
-    nursery // There are false positives within TypeScript files (e.g. redeclare on interface)
+    pedantic
 );
 
 impl Rule for NoRedeclare {
@@ -81,16 +81,20 @@ impl Rule for NoRedeclare {
             match ctx.nodes().kind(decl) {
                 AstKind::VariableDeclarator(var) => {
                     if let BindingPatternKind::BindingIdentifier(ident) = &var.id.kind {
+                        if *symbol_table.get_name(variable.symbol_id) == ident.name {
                             self.report_diagnostic(ctx, variable, ident);
                         }
                     }
+                }
                 AstKind::FormalParameters(params) => {
                     for item in &params.items {
                         if let BindingPatternKind::BindingIdentifier(ident) = &item.pattern.kind {
+                            if *symbol_table.get_name(variable.symbol_id) == ident.name {
                                 self.report_diagnostic(ctx, variable, ident);
                             }
                         }
                     }
+                }
                 _ => {}
             }
         }
@@ -106,7 +110,7 @@ impl NoRedeclare {
     ) {
         if self.built_in_globals && BUILTINS.get(&ident.name).is_some() {
             ctx.diagnostic(NoRedeclareAsBuiltiInDiagnostic(ident.name.clone(), ident.span));
-        } else if variable.name == ident.name && variable.span != ident.span {
+        } else if variable.span != ident.span {
             ctx.diagnostic(NoRedeclareDiagnostic(ident.name.clone(), ident.span, variable.span));
         }
     }
@@ -153,12 +157,10 @@ fn test() {
         ("var a = 3; var a = 10; var a = 15;", None),
         ("var a; var a;", None),
         ("export var a; var a;", None),
-        // `var` redeclaration in class static blocks. Redeclaration of functions is not allowed in class static blocks.
         ("class C { static { var a; var a; } }", None),
-        // Todo: Fix me
+        ("class C { static { var a; { var a; } } }", None),
-        // ("class C { static { var a; { var a; } } }", None),
+        ("class C { static { { var a; } var a; } }", None),
-        // ("class C { static { { var a; } var a; } }", None),
+        ("class C { static { { var a; } { var a; } } }", None),
-        // ("class C { static { { var a; } { var a; } } }", None),
         // ("var Object = 0;", Some(serde_json::json!([{ "builtinGlobals": true }]))),
         (
             "var a; var {a = 0, b: Object = 0} = {};",
@@ -171,7 +173,7 @@ fn test() {
         ),
         ("function f() { var a; var a; }", None),
         ("function f(a) { var a; }", None),
-        // ("function f() { var a; if (test) { var a; } }", None),
+        ("function f() { var a; if (test) { var a; } }", None),
         ("for (var a, a;;);", None),
     ];
 

crates/oxc_linter/src/snapshots/no_redeclare.snap

@@ -100,6 +100,30 @@ expression: no_redeclare
    ·                        ╰── 'a' is already defined.
    ╰────
 
+  ⚠ eslint(no-redeclare): 'a' is already defined.
+   ╭─[no_redeclare.tsx:1:1]
+ 1 │ class C { static { var a; { var a; } } }
+   ·                        ┬        ┬
+   ·                        │        ╰── It can not be redeclare here.
+   ·                        ╰── 'a' is already defined.
+   ╰────
+
+  ⚠ eslint(no-redeclare): 'a' is already defined.
+   ╭─[no_redeclare.tsx:1:1]
+ 1 │ class C { static { { var a; } var a; } }
+   ·                          ┬        ┬
+   ·                          │        ╰── It can not be redeclare here.
+   ·                          ╰── 'a' is already defined.
+   ╰────
+
+  ⚠ eslint(no-redeclare): 'a' is already defined.
+   ╭─[no_redeclare.tsx:1:1]
+ 1 │ class C { static { { var a; } { var a; } } }
+   ·                          ┬          ┬
+   ·                          │          ╰── It can not be redeclare here.
+   ·                          ╰── 'a' is already defined.
+   ╰────
+
   ⚠ eslint(no-redeclare): 'a' is already defined.
    ╭─[no_redeclare.tsx:1:1]
  1 │ var a; var {a = 0, b: Object = 0} = {};
@@ -132,6 +156,14 @@ expression: no_redeclare
    ·            ╰── 'a' is already defined.
    ╰────
 
+  ⚠ eslint(no-redeclare): 'a' is already defined.
+   ╭─[no_redeclare.tsx:1:1]
+ 1 │ function f() { var a; if (test) { var a; } }
+   ·                    ┬                  ┬
+   ·                    │                  ╰── It can not be redeclare here.
+   ·                    ╰── 'a' is already defined.
+   ╰────
+
   ⚠ eslint(no-redeclare): 'a' is already defined.
    ╭─[no_redeclare.tsx:1:1]
  1 │ for (var a, a;;);

crates/oxc_semantic/src/binder.rs

@@ -60,11 +60,10 @@ impl<'a> Binder for VariableDeclarator<'a> {
                     builder.check_redeclaration(*scope_id, span, name, excludes, true)
                 {
                     ident.symbol_id.set(Some(symbol_id));
-                    builder.add_redeclared_variables(VariableInfo {
+                    if self.kind.is_var() {
-                        name: ident.name.clone(),
+                        builder
-                        span: ident.span,
+                            .add_redeclared_variables(VariableInfo { span: ident.span, symbol_id });
-                        symbol_id,
+                    }
-                    });
                     return;
                 }
             }

crates/oxc_semantic/src/builder.rs

@@ -38,7 +38,6 @@ struct UnusedLabels<'a> {
 
 #[derive(Debug, Clone)]
 pub struct VariableInfo {
-    pub name: Atom,
     pub span: Span,
     pub symbol_id: SymbolId,
 }
@@ -253,7 +252,9 @@ impl<'a> SemanticBuilder<'a> {
     ) -> SymbolId {
         if let Some(symbol_id) = self.check_redeclaration(scope_id, span, name, excludes, true) {
             self.symbols.union_flag(symbol_id, includes);
-            self.add_redeclared_variables(VariableInfo { name: name.clone(), span, symbol_id });
+            if includes.is_function_scoped_declaration() {
+                self.add_redeclared_variables(VariableInfo { span, symbol_id });
+            }
             return symbol_id;
         }