refactor(semantic): always use SymbolFlags::Function for function id

crates/oxc_ast/src/ast_impl/js.rs

@@ -968,11 +968,7 @@ impl<'a> Function<'a> {
 
     /// `true` for overload signatures and `declare function` statements.
     pub fn is_typescript_syntax(&self) -> bool {
-        matches!(
-            self.r#type,
-            FunctionType::TSDeclareFunction | FunctionType::TSEmptyBodyFunctionExpression
-        ) || self.body.is_none()
-            || self.declare
+        self.r#type.is_typescript_syntax() || self.body.is_none() || self.declare
     }
 
     /// `true` for function expressions
@@ -1001,6 +997,13 @@ impl<'a> Function<'a> {
     }
 }
 
+impl FunctionType {
+    /// Returns `true` if it is a [`FunctionType::TSDeclareFunction`] or [`FunctionType::TSEmptyBodyFunctionExpression`].
+    pub fn is_typescript_syntax(&self) -> bool {
+        matches!(self, Self::TSDeclareFunction | Self::TSEmptyBodyFunctionExpression)
+    }
+}
+
 impl<'a> FormalParameters<'a> {
     /// Number of parameters bound in this parameter list.
     pub fn parameters_count(&self) -> usize {

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

@@ -1,6 +1,7 @@
 use oxc_ast::AstKind;
 use oxc_diagnostics::OxcDiagnostic;
 use oxc_macros::declare_oxc_lint;
+use oxc_semantic::ScopeFlags;
 use oxc_span::Span;
 
 use crate::{context::LintContext, rule::Rule, AstNode};
@@ -41,7 +42,16 @@ impl Rule for NoSetterReturn {
         let AstKind::ReturnStatement(stmt) = node.kind() else {
             return;
         };
-        if stmt.argument.is_some() && ctx.scopes().get_flags(node.scope_id()).is_set_accessor() {
+
+        if stmt.argument.is_some() {
+            for scope_id in ctx.scopes().ancestors(node.scope_id()) {
+                let flags = ctx.scopes().get_flags(scope_id);
+                if flags.is_set_accessor() {
+                    break;
+                } else if flags.intersects(ScopeFlags::Function | ScopeFlags::Top) {
+                    return;
+                }
+            }
             ctx.diagnostic(no_setter_return_diagnostic(stmt.span));
         }
     }

crates/oxc_linter/src/rules/eslint/no_unused_vars/usage.rs

@@ -614,9 +614,6 @@ impl<'s, 'a> Symbol<'s, 'a> {
         let Some(ref_node) = self.get_ref_relevant_node(reference) else {
             return false;
         };
-        if !matches!(ref_node.kind(), AstKind::CallExpression(_) | AstKind::NewExpression(_)) {
-            return false;
-        }
 
         // Do the easy/fast path if possible. If we know its a class/fn from
         // flags, that means it's declared within this file in an understandable

crates/oxc_linter/src/snapshots/eslint_no_shadow_restricted_names.snap

@@ -1,6 +1,5 @@
 ---
 source: crates/oxc_linter/src/tester.rs
-snapshot_kind: text
 ---
   ⚠ eslint(no-shadow-restricted-names): Shadowing of global properties such as 'undefined' is not allowed.
    ╭─[no_shadow_restricted_names.tsx:1:10]
@@ -24,16 +23,16 @@ snapshot_kind: text
   help: Shadowing of global properties 'NaN'.
 
   ⚠ eslint(no-shadow-restricted-names): Shadowing of global properties such as 'undefined' is not allowed.
-   ╭─[no_shadow_restricted_names.tsx:1:40]
+   ╭─[no_shadow_restricted_names.tsx:1:44]
  1 │ function NaN(NaN) { var NaN; !function NaN(NaN) { try {} catch(NaN) {} }; }
-   ·                                        ───
+   ·                                            ───
    ╰────
   help: Shadowing of global properties 'NaN'.
 
   ⚠ eslint(no-shadow-restricted-names): Shadowing of global properties such as 'undefined' is not allowed.
-   ╭─[no_shadow_restricted_names.tsx:1:44]
+   ╭─[no_shadow_restricted_names.tsx:1:40]
  1 │ function NaN(NaN) { var NaN; !function NaN(NaN) { try {} catch(NaN) {} }; }
-   ·                                            ───
+   ·                                        ───
    ╰────
   help: Shadowing of global properties 'NaN'.
 
@@ -59,16 +58,16 @@ snapshot_kind: text
   help: Shadowing of global properties 'undefined'.
 
   ⚠ eslint(no-shadow-restricted-names): Shadowing of global properties such as 'undefined' is not allowed.
-   ╭─[no_shadow_restricted_names.tsx:1:43]
+   ╭─[no_shadow_restricted_names.tsx:1:53]
  1 │ function undefined(undefined) { !function undefined(undefined) { try {} catch(undefined) {} }; }
-   ·                                           ─────────
+   ·                                                     ─────────
    ╰────
   help: Shadowing of global properties 'undefined'.
 
   ⚠ eslint(no-shadow-restricted-names): Shadowing of global properties such as 'undefined' is not allowed.
-   ╭─[no_shadow_restricted_names.tsx:1:53]
+   ╭─[no_shadow_restricted_names.tsx:1:43]
  1 │ function undefined(undefined) { !function undefined(undefined) { try {} catch(undefined) {} }; }
-   ·                                                     ─────────
+   ·                                           ─────────
    ╰────
   help: Shadowing of global properties 'undefined'.
 
@@ -101,16 +100,16 @@ snapshot_kind: text
   help: Shadowing of global properties 'Infinity'.
 
   ⚠ eslint(no-shadow-restricted-names): Shadowing of global properties such as 'undefined' is not allowed.
-   ╭─[no_shadow_restricted_names.tsx:1:55]
+   ╭─[no_shadow_restricted_names.tsx:1:64]
  1 │ function Infinity(Infinity) { var Infinity; !function Infinity(Infinity) { try {} catch(Infinity) {} }; }
-   ·                                                       ────────
+   ·                                                                ────────
    ╰────
   help: Shadowing of global properties 'Infinity'.
 
   ⚠ eslint(no-shadow-restricted-names): Shadowing of global properties such as 'undefined' is not allowed.
-   ╭─[no_shadow_restricted_names.tsx:1:64]
+   ╭─[no_shadow_restricted_names.tsx:1:55]
  1 │ function Infinity(Infinity) { var Infinity; !function Infinity(Infinity) { try {} catch(Infinity) {} }; }
-   ·                                                                ────────
+   ·                                                       ────────
    ╰────
   help: Shadowing of global properties 'Infinity'.
 
@@ -143,16 +142,16 @@ snapshot_kind: text
   help: Shadowing of global properties 'arguments'.
 
   ⚠ eslint(no-shadow-restricted-names): Shadowing of global properties such as 'undefined' is not allowed.
-   ╭─[no_shadow_restricted_names.tsx:1:58]
+   ╭─[no_shadow_restricted_names.tsx:1:68]
  1 │ function arguments(arguments) { var arguments; !function arguments(arguments) { try {} catch(arguments) {} }; }
-   ·                                                          ─────────
+   ·                                                                    ─────────
    ╰────
   help: Shadowing of global properties 'arguments'.
 
   ⚠ eslint(no-shadow-restricted-names): Shadowing of global properties such as 'undefined' is not allowed.
-   ╭─[no_shadow_restricted_names.tsx:1:68]
+   ╭─[no_shadow_restricted_names.tsx:1:58]
  1 │ function arguments(arguments) { var arguments; !function arguments(arguments) { try {} catch(arguments) {} }; }
-   ·                                                                    ─────────
+   ·                                                          ─────────
    ╰────
   help: Shadowing of global properties 'arguments'.
 
@@ -185,16 +184,16 @@ snapshot_kind: text
   help: Shadowing of global properties 'eval'.
 
   ⚠ eslint(no-shadow-restricted-names): Shadowing of global properties such as 'undefined' is not allowed.
-   ╭─[no_shadow_restricted_names.tsx:1:43]
+   ╭─[no_shadow_restricted_names.tsx:1:48]
  1 │ function eval(eval) { var eval; !function eval(eval) { try {} catch(eval) {} }; }
-   ·                                           ────
+   ·                                                ────
    ╰────
   help: Shadowing of global properties 'eval'.
 
   ⚠ eslint(no-shadow-restricted-names): Shadowing of global properties such as 'undefined' is not allowed.
-   ╭─[no_shadow_restricted_names.tsx:1:48]
+   ╭─[no_shadow_restricted_names.tsx:1:43]
  1 │ function eval(eval) { var eval; !function eval(eval) { try {} catch(eval) {} }; }
-   ·                                                ────
+   ·                                           ────
    ╰────
   help: Shadowing of global properties 'eval'.
 
@@ -227,16 +226,16 @@ snapshot_kind: text
   help: Shadowing of global properties 'eval'.
 
   ⚠ eslint(no-shadow-restricted-names): Shadowing of global properties such as 'undefined' is not allowed.
-   ╭─[no_shadow_restricted_names.tsx:1:44]
+   ╭─[no_shadow_restricted_names.tsx:1:49]
  1 │ var eval = (eval) => { var eval; !function eval(eval) { try {} catch(eval) {} }; }
-   ·                                            ────
+   ·                                                 ────
    ╰────
   help: Shadowing of global properties 'eval'.
 
   ⚠ eslint(no-shadow-restricted-names): Shadowing of global properties such as 'undefined' is not allowed.
-   ╭─[no_shadow_restricted_names.tsx:1:49]
+   ╭─[no_shadow_restricted_names.tsx:1:44]
  1 │ var eval = (eval) => { var eval; !function eval(eval) { try {} catch(eval) {} }; }
-   ·                                                 ────
+   ·                                            ────
    ╰────
   help: Shadowing of global properties 'eval'.
 

crates/oxc_linter/src/snapshots/eslint_no_unused_vars@eslint.snap

@@ -132,15 +132,15 @@ source: crates/oxc_linter/src/tester.rs
    ╰────
   help: Consider removing this declaration.
 
-  ⚠ eslint(no-unused-vars): Variable 'a' is declared but never used.
+  ⚠ eslint(no-unused-vars): Function 'a' is declared but never used.
    ╭─[no_unused_vars.tsx:1:29]
  1 │ function f(){var x;function a(){x=42;}function b(){alert(x);}}
    ·                             ┬
    ·                             ╰── 'a' is declared here
    ╰────
   help: Consider removing this declaration.
 
-  ⚠ eslint(no-unused-vars): Variable 'b' is declared but never used.
+  ⚠ eslint(no-unused-vars): Function 'b' is declared but never used.
    ╭─[no_unused_vars.tsx:1:48]
  1 │ function f(){var x;function a(){x=42;}function b(){alert(x);}}
    ·                                                ┬

crates/oxc_linter/src/snapshots/eslint_no_unused_vars@oxc-functions.snap

@@ -1,6 +1,5 @@
 ---
 source: crates/oxc_linter/src/tester.rs
-snapshot_kind: text
 ---
   ⚠ eslint(no-unused-vars): Function 'foo' is declared but never used.
    ╭─[no_unused_vars.tsx:1:10]
@@ -18,7 +17,7 @@ snapshot_kind: text
    ╰────
   help: Consider removing this declaration.
 
-  ⚠ eslint(no-unused-vars): Variable 'bar' is declared but never used.
+  ⚠ eslint(no-unused-vars): Function 'bar' is declared but never used.
    ╭─[no_unused_vars.tsx:1:30]
  1 │ const foo = () => { function bar() { } }
    ·                              ─┬─

crates/oxc_semantic/src/binder.rs

@@ -126,6 +126,16 @@ fn function_as_var(flags: ScopeFlags, source_type: SourceType) -> bool {
     flags.is_function() || (source_type.is_script() && flags.is_top())
 }
 
+/// Check if the function is not allowed to be redeclared.
+pub fn is_function_redeclared_not_allowed(
+    func: &Function<'_>,
+    builder: &SemanticBuilder<'_>,
+) -> bool {
+    let current_scope_flags = builder.current_scope_flags();
+    (current_scope_flags.is_strict_mode() || func.r#async || func.generator)
+        && !function_as_var(current_scope_flags, builder.source_type)
+}
+
 /// Check for Annex B `if (foo) function a() {} else function b() {}`
 fn is_function_part_of_if_statement(function: &Function, builder: &SemanticBuilder) -> bool {
     if builder.current_scope_flags().is_strict_mode() {
@@ -150,8 +160,9 @@ fn is_function_part_of_if_statement(function: &Function, builder: &SemanticBuild
 
 impl<'a> Binder<'a> for Function<'a> {
     fn bind(&self, builder: &mut SemanticBuilder) {
-        let current_scope_id = builder.current_scope_id;
-        let scope_flags = builder.current_scope_flags();
+        if self.r#type.is_typescript_syntax() {
+            return;
+        }
         if let Some(ident) = &self.id {
             if is_function_part_of_if_statement(self, builder) {
                 let symbol_id = builder.symbols.create_symbol(
@@ -162,35 +173,30 @@ impl<'a> Binder<'a> for Function<'a> {
                     builder.current_node_id,
                 );
                 ident.symbol_id.set(Some(symbol_id));
-            } else if self.r#type == FunctionType::FunctionDeclaration {
-                // The visitor is already inside the function scope,
-                // retrieve the parent scope for the function id to bind to.
-
-                let (includes, excludes) =
-                    if (scope_flags.is_strict_mode() || self.r#async || self.generator)
-                        && !function_as_var(scope_flags, builder.source_type)
-                    {
-                        (
-                            SymbolFlags::Function | SymbolFlags::BlockScopedVariable,
-                            SymbolFlags::BlockScopedVariableExcludes,
-                        )
+            } else {
+                let excludes = if self.is_declaration() {
+                    // The visitor is already inside the function scope,
+                    // retrieve the parent scope for the function id to bind to.
+                    if is_function_redeclared_not_allowed(self, builder) {
+                        SymbolFlags::BlockScopedVariableExcludes
                     } else {
-                        (
-                            SymbolFlags::FunctionScopedVariable,
-                            SymbolFlags::FunctionScopedVariableExcludes,
-                        )
-                    };
+                        SymbolFlags::FunctionScopedVariableExcludes
+                    }
+                } else if self.is_expression() {
+                    // https://tc39.es/ecma262/#sec-runtime-semantics-instantiateordinaryfunctionexpression
+                    // 5. Perform ! funcEnv.CreateImmutableBinding(name, false).
+                    SymbolFlags::empty()
+                } else {
+                    unreachable!(
+                        "Currently we haven't create a symbol for typescript syntax function"
+                    );
+                };
 
-                let symbol_id = builder.declare_symbol(ident.span, &ident.name, includes, excludes);
-                ident.symbol_id.set(Some(symbol_id));
-            } else if self.r#type == FunctionType::FunctionExpression {
-                // https://tc39.es/ecma262/#sec-runtime-semantics-instantiateordinaryfunctionexpression
-                // 5. Perform ! funcEnv.CreateImmutableBinding(name, false).
                 let symbol_id = builder.declare_symbol(
                     ident.span,
                     &ident.name,
                     SymbolFlags::Function,
-                    SymbolFlags::empty(),
+                    excludes,
                 );
                 ident.symbol_id.set(Some(symbol_id));
             }
@@ -200,7 +206,7 @@ impl<'a> Binder<'a> for Function<'a> {
         if let Some(AstKind::ObjectProperty(prop)) =
             builder.nodes.parent_kind(builder.current_node_id)
         {
-            let flags = builder.scope.get_flags_mut(current_scope_id);
+            let flags = builder.scope.get_flags_mut(builder.current_scope_id);
             match prop.kind {
                 PropertyKind::Get => *flags |= ScopeFlags::GetAccessor,
                 PropertyKind::Set => *flags |= ScopeFlags::SetAccessor,

crates/oxc_semantic/src/builder.rs

@@ -18,7 +18,7 @@ use oxc_span::{Atom, CompactStr, SourceType, Span};
 use oxc_syntax::module_record::ModuleRecord;
 
 use crate::{
-    binder::Binder,
+    binder::{is_function_redeclared_not_allowed, Binder},
     checker,
     class::ClassTableBuilder,
     diagnostics::redeclaration,
@@ -461,9 +461,23 @@ impl<'a> SemanticBuilder<'a> {
         let symbol_id = self.scope.get_binding(scope_id, name).or_else(|| {
             self.hoisting_variables.get(&scope_id).and_then(|symbols| symbols.get(name).copied())
         })?;
-        if report_error && self.symbols.get_flags(symbol_id).intersects(excludes) {
-            let symbol_span = self.symbols.get_span(symbol_id);
-            self.error(redeclaration(name, symbol_span, span));
+        if report_error {
+            let flags = self.symbols.get_flags(symbol_id);
+            if flags.intersects(excludes)
+                // Needs to further check if the previous declaration is a function and the function
+                // is not allowed to be redeclared.
+                // For example: `async function goo() var goo;`
+                //                                        ^^^ Redeclare
+                || (excludes == SymbolFlags::FunctionScopedVariableExcludes
+                    && flags.is_function() // The previous declaration is a function
+                    && matches!( // Check the previous function whether it is allowed to be redeclared
+                        self.nodes.kind(self.symbols.get_declaration(symbol_id)),
+                        AstKind::Function(func) if is_function_redeclared_not_allowed(func, self)
+                    ))
+            {
+                let symbol_span = self.symbols.get_span(symbol_id);
+                self.error(redeclaration(name, symbol_span, span));
+            }
         }
         Some(symbol_id)
     }
@@ -1628,11 +1642,6 @@ impl<'a> Visit<'a> for SemanticBuilder<'a> {
             &func.scope_id,
         );
 
-        if func.is_expression() {
-            // We need to bind function expression in the function scope
-            func.bind(self);
-        }
-
         if let Some(id) = &func.id {
             self.visit_binding_identifier(id);
         }
@@ -1691,6 +1700,14 @@ impl<'a> Visit<'a> for SemanticBuilder<'a> {
         });
         /* cfg */
 
+        if func.is_expression() {
+            // We need to bind the function expression in the function scope and place
+            // it at the end of the function body in order to prevent redeclaration errors,
+            // as the function body may contain variables with the same name as the function.
+            // For example: `function foo() { let foo = 1; }` is valid.
+            func.bind(self);
+        }
+
         self.leave_scope();
         self.leave_node(kind);
     }