JS: mark for initializers to distinguish between declaration in body

js/ast.go

@@ -113,6 +113,7 @@ type Scope struct {
 	Declared       VarArray // Link in Var are always nil
 	Undeclared     VarArray
 	NumVarDecls    uint16 // number of variable declaration statements in a function scope
+	NumForInit     uint16 // offset into Declared to mark variables used in for initializer
 	NumArguments   uint16 // offset into Undeclared to mark variables used in arguments
 	IsGlobalOrFunc bool
 	HasWith        bool
@@ -213,6 +214,11 @@ func (s *Scope) findUndeclared(name []byte) *Var {
 	return nil
 }
 
+func (s *Scope) MarkForInit() {
+	// set the offset for variables declared in for initializer to distinguish from declarations in body
+	s.NumForInit = uint16(len(s.Declared))
+}
+
 func (s *Scope) MarkArguments() {
 	// set the offset for variables used for arguments, to ensure different b's for: function f(a=b){var b}
 	s.NumArguments = uint16(len(s.Undeclared))

js/parse.go

@@ -333,6 +333,7 @@ func (p *Parser) parseStmt(allowDeclaration bool) (stmt IStmt) {
 			if !p.consume("for statement", CloseParenToken) {
 				return
 			}
+			p.scope.MarkForInit()
 			if p.tt == OpenBraceToken {
 				body.List = p.parseStmtList("")
 			} else if p.tt != SemicolonToken {
@@ -352,6 +353,7 @@ func (p *Parser) parseStmt(allowDeclaration bool) (stmt IStmt) {
 			if !p.consume("for statement", CloseParenToken) {
 				return
 			}
+			p.scope.MarkForInit()
 			if p.tt == OpenBraceToken {
 				body.List = p.parseStmtList("")
 			} else if p.tt != SemicolonToken {
@@ -368,6 +370,7 @@ func (p *Parser) parseStmt(allowDeclaration bool) (stmt IStmt) {
 			if !p.consume("for statement", CloseParenToken) {
 				return
 			}
+			p.scope.MarkForInit()
 			if p.tt == OpenBraceToken {
 				body.List = p.parseStmtList("")
 			} else if p.tt != SemicolonToken {