Type Literal and Binding Name formatting

Author: Arthur Ozga

src/compiler/checker.ts

@@ -2602,7 +2602,8 @@ namespace ts {
                     context.inObjectTypeLiteral = true;
                     const members = createTypeNodesFromResolvedType(resolved);
                     context.inObjectTypeLiteral = saveInObjectTypeLiteral;
-                    return createTypeLiteralNode(members);
+                    const typeLiteralNode = createTypeLiteralNode(members);
+                    return setEmitFlags(typeLiteralNode, EmitFlags.ToStringFormatting);
                 }
 
                 function shouldAddParenthesisAroundFunctionType(callSignature: Signature, context: NodeBuilderContext) {
@@ -2811,8 +2812,14 @@ namespace ts {
                 const parameterDeclaration = <ParameterDeclaration>getDeclarationOfKind(parameterSymbol, SyntaxKind.Parameter);
                 const parameterType = getTypeOfSymbol(parameterSymbol);
                 const parameterTypeNode = typeToTypeNodeHelper(parameterType, context);
-                const name = getDeepSynthesizedClone(parameterDeclaration.name);
-
+                let name: BindingName;
+                if (parameterDeclaration.name.kind === SyntaxKind.Identifier) {
+                    name = getSynthesizedClone(parameterDeclaration.name);
+                }
+                else {
+                    Debug.assert(parameterDeclaration.name.kind === SyntaxKind.ArrayBindingPattern || parameterDeclaration.name.kind === SyntaxKind.ObjectBindingPattern);
+                    name = cloneBindingName(parameterDeclaration.name);
+                }
                 let questionToken: Token<SyntaxKind.QuestionToken> | undefined;
                 let initializer: Expression | undefined;
                 if (isOptionalParameter(parameterDeclaration)) {
@@ -2833,6 +2840,18 @@ namespace ts {
                     parameterTypeNode,
                     initializer);
                 return parameterNode;
+
+                function cloneBindingName(node: BindingName): BindingName {
+                    return <BindingName>elideInitializerAndSetEmitFlags(node);
+                    function elideInitializerAndSetEmitFlags(node: Node): Node {
+                        const visited = visitEachChild(node, elideInitializerAndSetEmitFlags, nullTransformationContext, /*nodesVisitor*/ undefined, elideInitializerAndSetEmitFlags);
+                        const clone = nodeIsSynthesized(visited) ? visited : getSynthesizedClone(visited);
+                        if (clone.kind === SyntaxKind.BindingElement) {
+                            (<BindingElement>clone).initializer = undefined;
+                        }
+                        return setEmitFlags(clone, EmitFlags.ToStringFormatting);
+                    }
+                }
             }
 
             // TODO: add meaning: SymbolFlags argument.

src/compiler/emitter.ts

@@ -956,7 +956,7 @@ namespace ts {
         function emitTypeLiteral(node: TypeLiteralNode) {
             write("{");
             if (node.members.length > 0) {
-                emitList(node, node.members, ListFormat.SingleLineTypeLiteralMembers);
+                emitList(node, node.members, getEmitFlags(node) & EmitFlags.ToStringFormatting ? ListFormat.SingleLineTypeLiteralMembers : ListFormat.MultiLineTypeLiteralMembers);
             }
             write("}");
         }
@@ -1037,7 +1037,7 @@ namespace ts {
             }
             else {
                 write("{");
-                emitList(node, elements, ListFormat.ObjectBindingPatternElements);
+                emitList(node, elements, getEmitFlags(node) & EmitFlags.ToStringFormatting ? ListFormat.ObjectBindingPatternElements : ListFormat.ObjectBindingPatternElementsWithSpaceBetweenBraces);
                 write("}");
             }
         }
@@ -2948,13 +2948,14 @@ namespace ts {
         // Precomputed Formats
         Modifiers = SingleLine | SpaceBetweenSiblings,
         HeritageClauses = SingleLine | SpaceBetweenSiblings,
-        SingleLineTypeLiteralMembers = SingleLine | SpaceBetweenBraces | SpaceBetweenSiblings | Indented, // MultiLine | Indented,
+        SingleLineTypeLiteralMembers = SingleLine | SpaceBetweenBraces | SpaceBetweenSiblings | Indented,
         MultiLineTypeLiteralMembers = MultiLine | Indented,
 
         TupleTypeElements = CommaDelimited | SpaceBetweenSiblings | SingleLine | Indented,
         UnionTypeConstituents = BarDelimited | SpaceBetweenSiblings | SingleLine,
         IntersectionTypeConstituents = AmpersandDelimited | SpaceBetweenSiblings | SingleLine,
-        ObjectBindingPatternElements = SingleLine | AllowTrailingComma | SpaceBetweenBraces | CommaDelimited | SpaceBetweenSiblings,
+        ObjectBindingPatternElements = SingleLine | AllowTrailingComma | CommaDelimited | SpaceBetweenSiblings,
+        ObjectBindingPatternElementsWithSpaceBetweenBraces = SingleLine | AllowTrailingComma | SpaceBetweenBraces | CommaDelimited | SpaceBetweenSiblings,
         ArrayBindingPatternElements = SingleLine | AllowTrailingComma | CommaDelimited | SpaceBetweenSiblings,
         ObjectLiteralExpressionProperties = PreserveLines | CommaDelimited | SpaceBetweenSiblings | SpaceBetweenBraces | Indented | Braces,
         ArrayLiteralExpressionElements = PreserveLines | CommaDelimited | SpaceBetweenSiblings | AllowTrailingComma | Indented | SquareBrackets,

src/compiler/types.ts

@@ -3943,6 +3943,7 @@ namespace ts {
     }
 
     export const enum EmitFlags {
+        None       = 0,
         SingleLine = 1 << 0,                     // The contents of this node should be emitted on a single line.
         AdviseOnEmitNode = 1 << 1,               // The printer should invoke the onEmitNode callback when printing this node.
         NoSubstitution = 1 << 2,                 // Disables further substitution of an expression.
@@ -3969,6 +3970,7 @@ namespace ts {
         NoHoisting = 1 << 20,                    // Do not hoist this declaration in --module system
         HasEndOfDeclarationMarker = 1 << 21,     // Declaration has an associated NotEmittedStatement to mark the end of the declaration
         Iterator = 1 << 22,                      // The expression to a `yield*` should be treated as an Iterator when down-leveling, not an Iterable.
+        ToStringFormatting = 1 << 23
     }
 
     export interface EmitHelper {