fix(1374): support declaration emit for expando functions

internal/ast/utilities.go

@@ -1348,7 +1348,7 @@ func IsBindableStaticElementAccessExpression(node *Node, excludeThisKeyword bool
 	return IsLiteralLikeElementAccess(node) &&
 		((!excludeThisKeyword && node.Expression().Kind == KindThisKeyword) ||
 			IsEntityNameExpression(node.Expression()) ||
-			IsBindableStaticAccessExpression(node.Expression() /*excludeThisKeyword*/, true))
+			IsBindableStaticAccessExpression(node.Expression(), true /*excludeThisKeyword*/))
 }
 
 func IsLiteralLikeElementAccess(node *Node) bool {
@@ -2817,10 +2817,6 @@ func IsModuleExportsAccessExpression(node *Node) bool {
 	return false
 }
 
-func isLiteralLikeElementAccess(node *Node) bool {
-	return node.Kind == KindElementAccessExpression && IsStringOrNumericLiteralLike(node.AsElementAccessExpression().ArgumentExpression)
-}
-
 func IsCheckJSEnabledForFile(sourceFile *SourceFile, compilerOptions *core.CompilerOptions) bool {
 	if sourceFile.CheckJsDirective != nil {
 		return sourceFile.CheckJsDirective.Enabled
@@ -2924,6 +2920,14 @@ func IsContextualKeyword(token Kind) bool {
 	return KindFirstContextualKeyword <= token && token <= KindLastContextualKeyword
 }
 
+func IsKeyword(token Kind) bool {
+	return KindFirstKeyword <= token && token <= KindLastKeyword
+}
+
+func IsNonContextualKeyword(token Kind) bool {
+	return IsKeyword(token) && !IsContextualKeyword(token)
+}
+
 func IsThisInTypeQuery(node *Node) bool {
 	if !IsThisIdentifier(node) {
 		return false
@@ -3633,3 +3637,79 @@ func GetSemanticJsxChildren(children []*JsxChild) []*JsxChild {
 		}
 	})
 }
+
+func IsExpandoPropertyDeclaration(node *Node) bool {
+	if node == nil {
+		return false
+	}
+	return IsPropertyAccessExpression(node) || IsElementAccessExpression(node) || IsBinaryExpression(node)
+}
+
+func GetExpandoInitializer(initializer *Node, isPrototypeAssignment bool) *Node {
+	if initializer.Kind == KindCallExpression {
+		expr := SkipParentheses(initializer.Expression())
+		if expr.Kind == KindFunctionExpression || expr.Kind == KindArrowFunction {
+			return initializer
+		}
+		return nil
+	}
+
+	if initializer.Kind == KindFunctionExpression || initializer.Kind == KindCallExpression || initializer.Kind == KindArrowFunction {
+		return initializer
+	}
+
+	if initializer.Kind == KindObjectLiteralExpression && (len(initializer.Properties()) == 0 || isPrototypeAssignment) {
+		return initializer
+	}
+
+	return nil
+}
+
+func GetEffectiveInitializer(node *Node) *Expression {
+	if IsInJSFile(node) && node.Initializer() != nil && IsBinaryExpression(node.Initializer()) {
+		initializer := node.Initializer().AsBinaryExpression()
+		if initializer.OperatorToken.Kind == KindBarBarToken || initializer.OperatorToken.Kind == KindQuestionQuestionToken {
+			if node.Name() != nil && IsEntityNameExpressionEx(node.Name(), IsInJSFile(node)) && IsSameEntityName(node.Name(), initializer.Left) {
+				return initializer.Right
+			}
+		}
+	}
+	return node.Initializer()
+}
+
+func GetDeclaredExpandoInitializer(node *Node) *Expression {
+	initializer := GetEffectiveInitializer(node)
+	if initializer == nil {
+		return nil
+	}
+	return GetExpandoInitializer(initializer, IsPrototypeAccess(node.Name()))
+}
+
+func IsPrototypeAccess(node *Node) bool {
+	return IsBindableStaticAccessExpression(node, false /*excludeThisKeyword*/)
+}
+
+func IsLiteralLikeAccess(node *Node) bool {
+	return IsPropertyAccessExpression(node) || IsLiteralLikeElementAccess(node)
+}
+
+func GetNameOrArgument(node *Expression) *Expression {
+	if IsPropertyAccessExpression(node) {
+		return node.Name()
+	}
+	return node.AsElementAccessExpression().ArgumentExpression
+}
+
+func IsSameEntityName(name *Expression, initializer *Expression) bool {
+	if IsPropertyNameLiteral(name) && IsPropertyNameLiteral(initializer) {
+		return name.Text() == initializer.Text()
+	}
+	if IsMemberName(name) && IsLiteralLikeAccess(initializer) && (initializer.Expression().Kind == KindThisKeyword || IsIdentifier(initializer.Expression()) &&
+		(initializer.Expression().Text() == "window" || initializer.Expression().Text() == "self" || initializer.Expression().Text() == "global")) {
+		return IsSameEntityName(name, GetNameOrArgument(initializer))
+	}
+	if IsLiteralLikeAccess(name) && IsLiteralLikeAccess(initializer) {
+		return GetElementOrPropertyAccessName(name) == GetElementOrPropertyAccessName(initializer) && IsSameEntityName(name.Expression(), initializer.Expression())
+	}
+	return false
+}

internal/checker/emitresolver.go

@@ -605,8 +605,43 @@ func (r *emitResolver) IsLiteralConstDeclaration(node *ast.Node) bool {
 }
 
 func (r *emitResolver) IsExpandoFunctionDeclaration(node *ast.Node) bool {
-	// node = r.emitContext.ParseNode(node)
-	// !!! TODO: expando function support
+	if !ast.IsParseTreeNode(node) {
+		return false
+	}
+
+	r.checkerMu.Lock()
+	defer r.checkerMu.Unlock()
+
+	var symbol *ast.Symbol
+	if ast.IsVariableDeclaration(node) {
+		if node.Type() != nil || (!ast.IsInJSFile(node) && !ast.IsVarConstLike(node)) {
+			return false
+		}
+		initializer := ast.GetDeclaredExpandoInitializer(node)
+		if initializer == nil || !ast.CanHaveSymbol(initializer) {
+			return false
+		}
+		symbol = r.checker.getSymbolOfDeclaration(initializer)
+	} else if ast.IsFunctionDeclaration(node) {
+		symbol = r.checker.getSymbolOfDeclaration(node)
+	}
+
+	if symbol == nil || (symbol.Flags&(ast.SymbolFlagsFunction|ast.SymbolFlagsVariable)) == 0 {
+		return false
+	}
+
+	exports := r.checker.getExportsOfSymbol(symbol)
+	for _, p := range exports {
+		if p.Flags&ast.SymbolFlagsValue == 0 {
+			continue
+		}
+		if p.ValueDeclaration == nil {
+			continue
+		}
+		if ast.IsExpandoPropertyDeclaration(p.ValueDeclaration) {
+			return true
+		}
+	}
 	return false
 }
 
@@ -847,6 +882,26 @@ func (r *emitResolver) GetReferencedValueDeclarations(node *ast.IdentifierNode)
 	return r.getReferenceResolver().GetReferencedValueDeclarations(node)
 }
 
+func (r *emitResolver) GetPropertiesOfContainerFunction(node *ast.Node) []*ast.Symbol {
+	props := []*ast.Symbol{}
+
+	if !ast.IsParseTreeNode(node) {
+		return props
+	}
+
+	if ast.IsFunctionDeclaration(node) {
+		r.checkerMu.Lock()
+		defer r.checkerMu.Unlock()
+
+		symbol := r.checker.getSymbolOfDeclaration(node)
+		if symbol == nil {
+			return props
+		}
+		props = r.checker.getPropertiesOfType(r.checker.getTypeOfSymbol(symbol))
+	}
+	return props
+}
+
 // TODO: the emit resolver being responsible for some amount of node construction is a very leaky abstraction,
 // and requires giving it access to a lot of context it's otherwise not required to have, which also further complicates the API
 // and likely reduces performance. There's probably some refactoring that could be done here to simplify this.

internal/parser/parser.go

@@ -293,7 +293,7 @@ func (p *Parser) lookAhead(callback func(p *Parser) bool) bool {
 
 func (p *Parser) nextToken() ast.Kind {
 	// if the keyword had an escape
-	if isKeyword(p.token) && (p.scanner.HasUnicodeEscape() || p.scanner.HasExtendedUnicodeEscape()) {
+	if ast.IsKeyword(p.token) && (p.scanner.HasUnicodeEscape() || p.scanner.HasExtendedUnicodeEscape()) {
 		// issue a parse error for the escape
 		p.parseErrorAtCurrentToken(diagnostics.Keywords_cannot_contain_escape_characters)
 	}
@@ -641,7 +641,7 @@ func (p *Parser) parsingContextErrors(context ParsingContext) {
 	case PCHeritageClauseElement:
 		p.parseErrorAtCurrentToken(diagnostics.Expression_expected)
 	case PCVariableDeclarations:
-		if isKeyword(p.token) {
+		if ast.IsKeyword(p.token) {
 			p.parseErrorAtCurrentToken(diagnostics.X_0_is_not_allowed_as_a_variable_declaration_name, scanner.TokenToString(p.token))
 		} else {
 			p.parseErrorAtCurrentToken(diagnostics.Variable_declaration_expected)
@@ -659,7 +659,7 @@ func (p *Parser) parsingContextErrors(context ParsingContext) {
 	case PCJSDocParameters:
 		p.parseErrorAtCurrentToken(diagnostics.Parameter_declaration_expected)
 	case PCParameters:
-		if isKeyword(p.token) {
+		if ast.IsKeyword(p.token) {
 			p.parseErrorAtCurrentToken(diagnostics.X_0_is_not_allowed_as_a_parameter_name, scanner.TokenToString(p.token))
 		} else {
 			p.parseErrorAtCurrentToken(diagnostics.Parameter_declaration_expected)
@@ -2376,7 +2376,7 @@ func (p *Parser) parseModuleExportName(disallowKeywords bool) (node *ast.Node, n
 	if p.token == ast.KindStringLiteral {
 		return p.parseLiteralExpression(false /*intern*/), nameOk
 	}
-	if disallowKeywords && isKeyword(p.token) && !p.isIdentifier() {
+	if disallowKeywords && ast.IsKeyword(p.token) && !p.isIdentifier() {
 		nameOk = false
 	}
 	return p.parseIdentifierName(), nameOk
@@ -6011,7 +6011,7 @@ func (p *Parser) scanClassMemberStart() bool {
 	// If we were able to get any potential identifier...
 	if idToken != ast.KindUnknown {
 		// If we have a non-keyword identifier, or if we have an accessor, then it's safe to parse.
-		if !isKeyword(idToken) || idToken == ast.KindSetKeyword || idToken == ast.KindGetKeyword {
+		if !ast.IsKeyword(idToken) || idToken == ast.KindSetKeyword || idToken == ast.KindGetKeyword {
 			return true
 		}
 		// If it *is* a keyword, but not an accessor, check a little farther along
@@ -6411,10 +6411,6 @@ func (p *Parser) skipRangeTrivia(textRange core.TextRange) core.TextRange {
 	return core.NewTextRange(scanner.SkipTrivia(p.sourceText, textRange.Pos()), textRange.End())
 }
 
-func isKeyword(token ast.Kind) bool {
-	return ast.KindFirstKeyword <= token && token <= ast.KindLastKeyword
-}
-
 func isReservedWord(token ast.Kind) bool {
 	return ast.KindFirstReservedWord <= token && token <= ast.KindLastReservedWord
 }

internal/printer/emitresolver.go

@@ -34,6 +34,7 @@ type EmitResolver interface {
 	GetExternalModuleFileFromDeclaration(node *ast.Node) *ast.SourceFile
 	GetEffectiveDeclarationFlags(node *ast.Node, flags ast.ModifierFlags) ast.ModifierFlags
 	GetResolutionModeOverride(node *ast.Node) core.ResolutionMode
+	GetPropertiesOfContainerFunction(node *ast.Node) []*ast.Symbol
 
 	// JSX Emit
 	GetJsxFactoryEntity(location *ast.Node) *ast.Node