oxc-project · graphite-app · Mar 24, 2025 · Mar 24, 2025
diff --git a/crates/oxc_ast/src/ast_impl/js.rs b/crates/oxc_ast/src/ast_impl/js.rs
@@ -1316,11 +1316,7 @@ impl<'a> Function<'a> {
 
     /// Returns `true` if this function uses overload signatures or `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
@@ -1349,6 +1345,13 @@ 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 {

@@ -616,9 +616,6 @@ impl<'a> Symbol<'_, '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

@@ -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);}}
    ·                                                ┬

@@ -17,7 +17,7 @@ source: crates/oxc_linter/src/tester.rs
    ╰────
   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() { } }
    ·                              ─┬─

@@ -141,6 +141,16 @@ 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() {
@@ -165,8 +175,9 @@ 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.scoping.create_symbol(
@@ -177,35 +188,30 @@ 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));
             }
@@ -215,7 +221,7 @@ impl<'a> Binder<'a> for Function<'a> {
         if let Some(AstKind::ObjectProperty(prop)) =
             builder.nodes.parent_kind(builder.current_node_id)
         {
-            let flags = builder.scoping.scope_flags_mut(current_scope_id);
+            let flags = builder.scoping.scope_flags_mut(builder.current_scope_id);
             match prop.kind {
                 PropertyKind::Get => *flags |= ScopeFlags::GetAccessor,
                 PropertyKind::Set => *flags |= ScopeFlags::SetAccessor,

@@ -25,7 +25,7 @@ use oxc_syntax::{
 
 use crate::{
     JSDocFinder, Semantic,
-    binder::Binder,
+    binder::{Binder, is_function_redeclared_not_allowed},
     checker,
     class::ClassTableBuilder,
     diagnostics::redeclaration,
@@ -425,11 +425,43 @@ impl<'a> SemanticBuilder<'a> {
         let symbol_id = self.scoping.get_binding(scope_id, name).or_else(|| {
             self.hoisting_variables.get(&scope_id).and_then(|symbols| symbols.get(name).copied())
         })?;
-        if report_error && self.scoping.symbol_flags(symbol_id).intersects(excludes) {
+        if report_error {
+            self.check_and_report_redeclaration(name, span, symbol_id, excludes);
+        }
+        Some(symbol_id)
+    }
+
+    /// Check if a symbol with the same name has already been declared but
+    /// it actually is not allowed to be redeclared.
+    fn check_and_report_redeclaration(
+        &self,
+        name: &str,
+        span: Span,
+        symbol_id: SymbolId,
+        excludes: SymbolFlags,
+    ) {
+        let flags = self.scoping.symbol_flags(symbol_id);
+        let function_kind = if flags.is_function() {
+            self.nodes.kind(self.scoping.symbol_declaration(symbol_id)).as_function()
+        } else {
+            None
+        };
+
+        if (
+            flags.intersects(excludes)
+            // `function n() { let n; }`
+            //                     ^ is not a redeclaration
+            && !function_kind.is_some_and(Function::is_expression))
+            // 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 &&
+                 function_kind.is_some_and(|func| is_function_redeclared_not_allowed(func, self)))
+        {
             let symbol_span = self.scoping.symbol_span(symbol_id);
             self.error(redeclaration(name, symbol_span, span));
         }
-        Some(symbol_id)
     }
 
     /// Declare an unresolved reference in the current scope.

@@ -1,6 +1,7 @@
 ---
 source: crates/oxc_semantic/tests/main.rs
 input_file: crates/oxc_semantic/tests/fixtures/oxc/ts/functions/return-type.ts
+snapshot_kind: text
 ---
 [
   {
@@ -84,7 +85,7 @@ input_file: crates/oxc_semantic/tests/fixtures/oxc/ts/functions/return-type.ts
         ]
       },
       {
-        "flags": "SymbolFlags(BlockScopedVariable | Function)",
+        "flags": "SymbolFlags(Function)",
         "id": 1,
         "name": "Foo",
         "node": "Function(Foo)",

@@ -33,7 +33,7 @@ input_file: crates/oxc_semantic/tests/fixtures/typescript-eslint/class/declarati
     "node": "Program",
     "symbols": [
       {
-        "flags": "SymbolFlags(BlockScopedVariable | Function)",
+        "flags": "SymbolFlags(Function)",
         "id": 0,
         "name": "f",
         "node": "Function(f)",

@@ -40,7 +40,7 @@ input_file: crates/oxc_semantic/tests/fixtures/typescript-eslint/class/declarati
     "node": "Program",
     "symbols": [
       {
-        "flags": "SymbolFlags(BlockScopedVariable | Function)",
+        "flags": "SymbolFlags(Function)",
         "id": 0,
         "name": "f",
         "node": "Function(f)",

@@ -48,7 +48,7 @@ input_file: crates/oxc_semantic/tests/fixtures/typescript-eslint/decorators/acce
     "node": "Program",
     "symbols": [
       {
-        "flags": "SymbolFlags(BlockScopedVariable | Function)",
+        "flags": "SymbolFlags(Function)",
         "id": 0,
         "name": "decorator",
         "node": "Function(decorator)",

@@ -25,7 +25,7 @@ input_file: crates/oxc_semantic/tests/fixtures/typescript-eslint/decorators/clas
     "node": "Program",
     "symbols": [
       {
-        "flags": "SymbolFlags(BlockScopedVariable | Function)",
+        "flags": "SymbolFlags(Function)",
         "id": 0,
         "name": "decorator",
         "node": "Function(decorator)",

@@ -25,7 +25,7 @@ input_file: crates/oxc_semantic/tests/fixtures/typescript-eslint/decorators/clas
     "node": "Program",
     "symbols": [
       {
-        "flags": "SymbolFlags(BlockScopedVariable | Function)",
+        "flags": "SymbolFlags(Function)",
         "id": 0,
         "name": "decorator",
         "node": "Function(decorator)",

@@ -33,7 +33,7 @@ input_file: crates/oxc_semantic/tests/fixtures/typescript-eslint/decorators/meth
     "node": "Program",
     "symbols": [
       {
-        "flags": "SymbolFlags(BlockScopedVariable | Function)",
+        "flags": "SymbolFlags(Function)",
         "id": 0,
         "name": "decorator",
         "node": "Function(decorator)",

@@ -48,7 +48,7 @@ input_file: crates/oxc_semantic/tests/fixtures/typescript-eslint/decorators/para
     "node": "Program",
     "symbols": [
       {
-        "flags": "SymbolFlags(BlockScopedVariable | Function)",
+        "flags": "SymbolFlags(Function)",
         "id": 0,
         "name": "decorator",
         "node": "Function(decorator)",

@@ -62,7 +62,7 @@ input_file: crates/oxc_semantic/tests/fixtures/typescript-eslint/decorators/para
     "node": "Program",
     "symbols": [
       {
-        "flags": "SymbolFlags(BlockScopedVariable | Function)",
+        "flags": "SymbolFlags(Function)",
         "id": 0,
         "name": "decorator",
         "node": "Function(decorator)",

@@ -41,7 +41,7 @@ input_file: crates/oxc_semantic/tests/fixtures/typescript-eslint/decorators/type
     "node": "Program",
     "symbols": [
       {
-        "flags": "SymbolFlags(BlockScopedVariable | Function)",
+        "flags": "SymbolFlags(Function)",
         "id": 0,
         "name": "decorator",
         "node": "Function(decorator)",

@@ -18,7 +18,7 @@ input_file: crates/oxc_semantic/tests/fixtures/typescript-eslint/export/default1
     "node": "Program",
     "symbols": [
       {
-        "flags": "SymbolFlags(BlockScopedVariable | Function)",
+        "flags": "SymbolFlags(Function)",
         "id": 0,
         "name": "f",
         "node": "Function(f)",

@@ -47,7 +47,7 @@ input_file: crates/oxc_semantic/tests/fixtures/typescript-eslint/functions/funct
         ]
       },
       {
-        "flags": "SymbolFlags(BlockScopedVariable | Function)",
+        "flags": "SymbolFlags(Function)",
         "id": 1,
         "name": "foo",
         "node": "Function(foo)",

@@ -40,7 +40,7 @@ input_file: crates/oxc_semantic/tests/fixtures/typescript-eslint/functions/funct
         ]
       },
       {
-        "flags": "SymbolFlags(BlockScopedVariable | Function)",
+        "flags": "SymbolFlags(Function)",
         "id": 1,
         "name": "foo",
         "node": "Function(foo)",

@@ -40,7 +40,7 @@ input_file: crates/oxc_semantic/tests/fixtures/typescript-eslint/functions/funct
         ]
       },
       {
-        "flags": "SymbolFlags(BlockScopedVariable | Function)",
+        "flags": "SymbolFlags(Function)",
         "id": 1,
         "name": "foo",
         "node": "Function(foo)",

@@ -55,7 +55,7 @@ input_file: crates/oxc_semantic/tests/fixtures/typescript-eslint/functions/funct
         ]
       },
       {
-        "flags": "SymbolFlags(BlockScopedVariable | Function)",
+        "flags": "SymbolFlags(Function)",
         "id": 1,
         "name": "foo",
         "node": "Function(foo)",

@@ -48,7 +48,7 @@ input_file: crates/oxc_semantic/tests/fixtures/typescript-eslint/functions/funct
         ]
       },
       {
-        "flags": "SymbolFlags(BlockScopedVariable | Function)",
+        "flags": "SymbolFlags(Function)",
         "id": 1,
         "name": "foo",
         "node": "Function(foo)",

@@ -47,7 +47,7 @@ input_file: crates/oxc_semantic/tests/fixtures/typescript-eslint/functions/funct
         "references": []
       },
       {
-        "flags": "SymbolFlags(BlockScopedVariable | Function)",
+        "flags": "SymbolFlags(Function)",
         "id": 1,
         "name": "foo",
         "node": "Function(foo)",

@@ -40,7 +40,7 @@ input_file: crates/oxc_semantic/tests/fixtures/typescript-eslint/functions/funct
         ]
       },
       {
-        "flags": "SymbolFlags(BlockScopedVariable | Function)",
+        "flags": "SymbolFlags(Function)",
         "id": 1,
         "name": "foo",
         "node": "Function(foo)",

@@ -33,7 +33,7 @@ input_file: crates/oxc_semantic/tests/fixtures/typescript-eslint/functions/funct
     "node": "Program",
     "symbols": [
       {
-        "flags": "SymbolFlags(BlockScopedVariable | Function)",
+        "flags": "SymbolFlags(Function)",
         "id": 0,
         "name": "foo",
         "node": "Function(foo)",

@@ -32,7 +32,7 @@ input_file: crates/oxc_semantic/tests/fixtures/typescript-eslint/functions/funct
         ]
       },
       {
-        "flags": "SymbolFlags(BlockScopedVariable | Function)",
+        "flags": "SymbolFlags(Function)",
         "id": 1,
         "name": "foo",
         "node": "Function(foo)",