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avoid var declaration overwritten #2085

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avoid var declaration overwritten #2085

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3f45816
avoid var declaration overwritten
magic-akari Mar 5, 2022
eb4425a
fix merge hoist
magic-akari Mar 13, 2022
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9 changes: 5 additions & 4 deletions internal/js_ast/js_ast.go
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Expand Up @@ -1482,10 +1482,11 @@ type Scope struct {
// This will be non-nil if this is a TypeScript "namespace" or "enum"
TSNamespace *TSNamespaceScope

Parent *Scope
Children []*Scope
Members map[string]ScopeMember
Generated []Ref
Parent *Scope
Children []*Scope
Members map[string]ScopeMember
HoistFnRef map[string]*Ref
Generated []Ref

// The location of the "use strict" directive for ExplicitStrictMode
UseStrictLoc logger.Loc
Expand Down
52 changes: 41 additions & 11 deletions internal/js_parser/js_parser.go
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Expand Up @@ -910,10 +910,11 @@ func (p *parser) selectLocalKind(kind js_ast.LocalKind) js_ast.LocalKind {
func (p *parser) pushScopeForParsePass(kind js_ast.ScopeKind, loc logger.Loc) int {
parent := p.currentScope
scope := &js_ast.Scope{
Kind: kind,
Parent: parent,
Members: make(map[string]js_ast.ScopeMember),
Label: js_ast.LocRef{Ref: js_ast.InvalidRef},
Kind: kind,
Parent: parent,
Members: make(map[string]js_ast.ScopeMember),
HoistFnRef: make(map[string]*js_ast.Ref),
Label: js_ast.LocRef{Ref: js_ast.InvalidRef},
}
if parent != nil {
parent.Children = append(parent.Children, scope)
Expand Down Expand Up @@ -1107,6 +1108,7 @@ const (
mergeForbidden = iota
mergeReplaceWithNew
mergeOverwriteWithNew
mergeHoist
mergeKeepExisting
mergeBecomePrivateGetSetPair
mergeBecomePrivateStaticGetSetPair
Expand Down Expand Up @@ -1147,14 +1149,12 @@ func (p *parser) canMergeSymbols(scope *js_ast.Scope, existing js_ast.SymbolKind
}
}

// "var foo; var foo;"
// "var foo; function foo() {}"
// "function foo() {} var foo;"
// only top level function can be overwritten
// "function *foo() {} function *foo() {}" but not "{ function *foo() {} function *foo() {} }"
if new.IsHoistedOrFunction() && existing.IsHoistedOrFunction() &&
(scope.Kind == js_ast.ScopeEntry || scope.Kind == js_ast.ScopeFunctionBody ||
(new.IsHoisted() && existing.IsHoisted())) {
return mergeReplaceWithNew
return mergeHoist
}

// "get #foo() {} set #foo() {}"
Expand Down Expand Up @@ -1219,11 +1219,41 @@ func (p *parser) declareSymbol(kind js_ast.SymbolKind, loc logger.Loc, name stri
case mergeReplaceWithNew:
symbol.Link = ref

// If these are both functions, remove the overwritten declaration
if p.options.minifySyntax && kind.IsFunction() && symbol.Kind.IsFunction() {
symbol.Flags |= js_ast.RemoveOverwrittenFunctionDeclaration
case mergeHoist:
if !kind.IsFunction() && !symbol.Kind.IsFunction() {
ref = existing.Ref
break
}

fnRef := p.currentScope.HoistFnRef[name]
if fnRef == nil && symbol.Kind.IsFunction() {
p.currentScope.HoistFnRef[name] = &existing.Ref
fnRef = &existing.Ref
}

if p.options.minifySyntax && fnRef != nil && kind.IsFunction() {
fnSymbol := &p.symbols[fnRef.InnerIndex]
fnSymbol.Flags |= js_ast.RemoveOverwrittenFunctionDeclaration
}

if kind.IsFunction() && symbol.Kind.IsFunction() {
symbol.Link = ref
p.currentScope.HoistFnRef[name] = &ref
break
}

if kind.IsFunction() {
// The past are variables, we encountered the first function
p.currentScope.HoistFnRef[name] = &ref
p.symbols[existing.Ref.InnerIndex].Link = ref

// do not update currentScope.Members
return ref
}

// The past are functions, we encountered the first variable
p.symbols[existing.Ref.InnerIndex].Link = ref

case mergeBecomePrivateGetSetPair:
ref = existing.Ref
symbol.Kind = js_ast.SymbolPrivateGetSetPair
Expand Down
4 changes: 3 additions & 1 deletion internal/js_parser/js_parser_test.go
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Expand Up @@ -1357,8 +1357,10 @@ func TestFunction(t *testing.T) {
expectPrintedMangle(t, "function f() {} var f", "function f() {\n}\nvar f;\n")
expectPrintedMangle(t, "var f; function f() { x() } function f() { y() }", "var f;\nfunction f() {\n y();\n}\n")
expectPrintedMangle(t, "function f() { x() } function f() { y() } var f", "function f() {\n y();\n}\nvar f;\n")
expectPrintedMangle(t, "function f() { x() } var f; function f() { y() }", "function f() {\n x();\n}\nvar f;\nfunction f() {\n y();\n}\n")
expectPrintedMangle(t, "function f() { x() } var f; function f() { y() }", "var f;\nfunction f() {\n y();\n}\n")
expectPrintedMangle(t, "export function f() { x() } function f() { y() }", "export function f() {\n x();\n}\nfunction f() {\n y();\n}\n")

expectPrintedMangle(t, "var x = x || {}; console.log(x); var x = x || {};", "var x = x || {};\nconsole.log(x);\nvar x = x || {};\n")
}

func TestClass(t *testing.T) {
Expand Down