fix(semantic): panics when function is the part of IfStatement

crates/oxc_semantic/src/binder.rs

@@ -1,18 +1,13 @@
 //! Declare symbol for `BindingIdentifier`s
 
-use std::ptr;
-
 use oxc_allocator::{Address, GetAddress};
 use oxc_ast::{AstKind, ast::*};
 use oxc_ecmascript::{BoundNames, IsSimpleParameterList};
 use oxc_span::GetSpan;
-use oxc_syntax::{
-    node::NodeId,
-    scope::{ScopeFlags, ScopeId},
-    symbol::SymbolFlags,
-};
+use oxc_syntax::{node::NodeId, scope::ScopeFlags, symbol::SymbolFlags};
 
 use crate::SemanticBuilder;
+use crate::checker::is_function_part_of_if_statement;
 
 pub trait Binder<'a> {
     #[expect(unused_variables)]
@@ -138,27 +133,6 @@ impl<'a> Binder<'a> for Class<'a> {
     }
 }
 
-/// 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() {
-        return false;
-    }
-    let AstKind::IfStatement(stmt) = builder.nodes.parent_kind(builder.current_node_id) else {
-        return false;
-    };
-    if let Statement::FunctionDeclaration(func) = &stmt.consequent {
-        if ptr::eq(func.as_ref(), function) {
-            return true;
-        }
-    }
-    if let Some(Statement::FunctionDeclaration(func)) = &stmt.alternate {
-        if ptr::eq(func.as_ref(), function) {
-            return true;
-        }
-    }
-    false
-}
-
 impl<'a> Binder<'a> for Function<'a> {
     fn bind(&self, builder: &mut SemanticBuilder) {
         let includes = if self.declare {
@@ -168,27 +142,19 @@ impl<'a> Binder<'a> for Function<'a> {
         };
 
         if let Some(ident) = &self.id {
-            if is_function_part_of_if_statement(self, builder) {
-                let symbol_id = builder.scoping.create_symbol(
-                    ident.span,
-                    ident.name.into(),
-                    includes,
-                    ScopeId::new(u32::MAX - 1), // Not bound to any scope.
-                    builder.current_node_id,
-                );
-                ident.symbol_id.set(Some(symbol_id));
+            let excludes = if builder.source_type.is_typescript() {
+                SymbolFlags::FunctionExcludes
+            } else if is_function_part_of_if_statement(self, builder) {
+                SymbolFlags::empty()
             } else {
-                let excludes = if builder.source_type.is_typescript() {
-                    SymbolFlags::FunctionExcludes
-                } else {
-                    // `var x; function x() {}` is valid in non-strict mode, but `TypeScript`
-                    // doesn't care about non-strict mode, so we need to exclude this,
-                    // and further check in checker.
-                    SymbolFlags::FunctionExcludes - SymbolFlags::FunctionScopedVariable
-                };
-                let symbol_id = builder.declare_symbol(ident.span, &ident.name, includes, excludes);
-                ident.symbol_id.set(Some(symbol_id));
-            }
+                // `var x; function x() {}` is valid in non-strict mode, but `TypeScript`
+                // doesn't care about non-strict mode, so we need to exclude this,
+                // and further check in checker.
+                SymbolFlags::FunctionExcludes - SymbolFlags::FunctionScopedVariable
+            };
+
+            let symbol_id = builder.declare_symbol(ident.span, &ident.name, includes, excludes);
+            ident.symbol_id.set(Some(symbol_id));
         }
 
         // Bind scope flags: GetAccessor | SetAccessor

crates/oxc_semantic/src/checker/javascript.rs

@@ -1,3 +1,5 @@
+use std::ptr;
+
 use phf::{Set, phf_set};
 use rustc_hash::FxHashMap;
 
@@ -475,12 +477,38 @@ pub fn check_variable_declarator_redeclaration(
     });
 }
 
+/// Check for Annex B `if (foo) function a() {} else function b() {}`
+pub fn is_function_part_of_if_statement(function: &Function, builder: &SemanticBuilder) -> bool {
+    if builder.current_scope_flags().is_strict_mode() {
+        return false;
+    }
+    let AstKind::IfStatement(stmt) = builder.nodes.parent_kind(builder.current_node_id) else {
+        return false;
+    };
+    if let Statement::FunctionDeclaration(func) = &stmt.consequent {
+        if ptr::eq(func.as_ref(), function) {
+            return true;
+        }
+    }
+    if let Some(Statement::FunctionDeclaration(func)) = &stmt.alternate {
+        if ptr::eq(func.as_ref(), function) {
+            return true;
+        }
+    }
+    false
+}
+
 // It is a Syntax Error if the LexicallyDeclaredNames of StatementList contains any duplicate entries,
 // unless the source text matched by this production is not strict mode code
 // and the duplicate entries are only bound by FunctionDeclarations.
 // https://tc39.es/ecma262/#sec-block-level-function-declarations-web-legacy-compatibility-semantics
 pub fn check_function_redeclaration(func: &Function, ctx: &SemanticBuilder<'_>) {
     let Some(id) = &func.id else { return };
+
+    if is_function_part_of_if_statement(func, ctx) {
+        return;
+    }
+
     let symbol_id = id.symbol_id();
 
     let redeclarations = ctx.scoping.symbol_redeclarations(symbol_id);

crates/oxc_semantic/src/checker/mod.rs

@@ -12,6 +12,7 @@ use javascript as js;
 use typescript as ts;
 
 use crate::builder::SemanticBuilder;
+pub use javascript::is_function_part_of_if_statement;
 
 pub fn check<'a>(kind: AstKind<'a>, ctx: &SemanticBuilder<'a>) {
     match kind {

tasks/coverage/snapshots/semantic_babel.snap

@@ -2,15 +2,7 @@ commit: 1d4546bc
 
 semantic_babel Summary:
 AST Parsed     : 2362/2362 (100.00%)
-Positive Passed: 1945/2362 (82.35%)
-semantic Error: tasks/coverage/babel/packages/babel-parser/test/fixtures/annex-b/enabled/3.3-function-in-if-body/input.js
-Symbol scope ID mismatch for "f":
-after transform: SymbolId(0): ScopeId(4294967294)
-rebuilt        : SymbolId(0): ScopeId(4294967294)
-Symbol scope ID mismatch for "g":
-after transform: SymbolId(1): ScopeId(4294967294)
-rebuilt        : SymbolId(1): ScopeId(4294967294)
-
+Positive Passed: 1948/2362 (82.47%)
 semantic Error: tasks/coverage/babel/packages/babel-parser/test/fixtures/comments/decorators/decorators-after-export/input.js
 Symbol span mismatch for "C":
 after transform: SymbolId(0): Span { start: 65, end: 66 }
@@ -37,11 +29,6 @@ semantic Error: tasks/coverage/babel/packages/babel-parser/test/fixtures/core/op
 Unexpected new.target expression
 Unexpected new.target expression
 
-semantic Error: tasks/coverage/babel/packages/babel-parser/test/fixtures/core/scope/dupl-bind-catch-hang-func/input.js
-Symbol scope ID mismatch for "foo":
-after transform: SymbolId(1): ScopeId(4294967294)
-rebuilt        : SymbolId(1): ScopeId(4294967294)
-
 semantic Error: tasks/coverage/babel/packages/babel-parser/test/fixtures/core/sourcetype-unambiguous/typescript-type-only/input.ts
 Bindings mismatch:
 after transform: ScopeId(0): ["Foo"]
@@ -118,11 +105,6 @@ Identifier `x` has already been declared
 semantic Error: tasks/coverage/babel/packages/babel-parser/test/fixtures/es2022/top-level-await-unambiguous/module/input.js
 `await` is only allowed within async functions and at the top levels of modules
 
-semantic Error: tasks/coverage/babel/packages/babel-parser/test/fixtures/esprima/statement-if/migrated_0003/input.js
-Symbol scope ID mismatch for "a":
-after transform: SymbolId(0): ScopeId(4294967294)
-rebuilt        : SymbolId(0): ScopeId(4294967294)
-
 semantic Error: tasks/coverage/babel/packages/babel-parser/test/fixtures/estree/class-method/typescript/input.ts
 Scope children mismatch:
 after transform: ScopeId(1): [ScopeId(2)]