Optimize deferred type references (#36607)

ahejlsberg · web-flow · commit de37c87252fb · 2020-02-05T16:03:42.000-08:00
* Improve reasoning about when to create deferred type references

* Accept new baselines

* Fix minor issues

* Handle default type arguments case in isDeferredTypeReferenceNode
diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
@@ -11090,7 +11090,7 @@ namespace ts {
                         return errorType;
                     }
                 }
-                if (node.kind === SyntaxKind.TypeReference && isAliasedType(node)) {
+                if (node.kind === SyntaxKind.TypeReference && isDeferredTypeReferenceNode(<TypeReferenceNode>node, length(node.typeArguments) !== typeParameters.length)) {
                     return createDeferredTypeReference(<GenericType>type, <TypeReferenceNode>node, /*mapper*/ undefined);
                 }
                 // In a type reference, the outer type parameters of the referenced class or interface are automatically
@@ -11552,10 +11552,19 @@ namespace ts {
             return getTupleTypeOfArity(node.elementTypes.length, minLength, !!restElement, readonly, /*associatedNames*/ undefined);
         }
 
+        // Return true if the given type reference node is directly aliased or if it needs to be deferred
+        // because it is possibly contained in a circular chain of eagerly resolved types.
+        function isDeferredTypeReferenceNode(node: TypeReferenceNode | ArrayTypeNode | TupleTypeNode, hasDefaultTypeArguments?: boolean) {
+            return !!getAliasSymbolForTypeNode(node) || isResolvedByTypeAlias(node) && (
+                node.kind === SyntaxKind.ArrayType ? mayResolveTypeAlias(node.elementType) :
+                node.kind === SyntaxKind.TupleType ? some(node.elementTypes, mayResolveTypeAlias) :
+                hasDefaultTypeArguments || some(node.typeArguments, mayResolveTypeAlias));
+        }
+
         // Return true when the given node is transitively contained in type constructs that eagerly
         // resolve their constituent types. We include SyntaxKind.TypeReference because type arguments
         // of type aliases are eagerly resolved.
-        function isAliasedType(node: Node): boolean {
+        function isResolvedByTypeAlias(node: Node): boolean {
             const parent = node.parent;
             switch (parent.kind) {
                 case SyntaxKind.ParenthesizedType:
@@ -11565,21 +11574,52 @@ namespace ts {
                 case SyntaxKind.IndexedAccessType:
                 case SyntaxKind.ConditionalType:
                 case SyntaxKind.TypeOperator:
-                    return isAliasedType(parent);
+                    return isResolvedByTypeAlias(parent);
                 case SyntaxKind.TypeAliasDeclaration:
                     return true;
             }
             return false;
         }
 
+        // Return true if resolving the given node (i.e. getTypeFromTypeNode) possibly causes resolution
+        // of a type alias.
+        function mayResolveTypeAlias(node: Node): boolean {
+            switch (node.kind) {
+                case SyntaxKind.TypeReference:
+                    return isJSDocTypeReference(node) || !!(resolveTypeReferenceName((<TypeReferenceNode>node).typeName, SymbolFlags.Type).flags & SymbolFlags.TypeAlias);
+                case SyntaxKind.TypeQuery:
+                    return true;
+                case SyntaxKind.TypeOperator:
+                    return (<TypeOperatorNode>node).operator !== SyntaxKind.UniqueKeyword && mayResolveTypeAlias((<TypeOperatorNode>node).type);
+                case SyntaxKind.ParenthesizedType:
+                case SyntaxKind.OptionalType:
+                case SyntaxKind.JSDocOptionalType:
+                case SyntaxKind.JSDocNullableType:
+                case SyntaxKind.JSDocNonNullableType:
+                case SyntaxKind.JSDocTypeExpression:
+                    return mayResolveTypeAlias((<ParenthesizedTypeNode | OptionalTypeNode | JSDocTypeReferencingNode>node).type);
+                case SyntaxKind.RestType:
+                    return (<RestTypeNode>node).type.kind !== SyntaxKind.ArrayType || mayResolveTypeAlias((<ArrayTypeNode>(<RestTypeNode>node).type).elementType);
+                case SyntaxKind.UnionType:
+                case SyntaxKind.IntersectionType:
+                    return some((<UnionOrIntersectionTypeNode>node).types, mayResolveTypeAlias);
+                case SyntaxKind.IndexedAccessType:
+                    return mayResolveTypeAlias((<IndexedAccessTypeNode>node).objectType) || mayResolveTypeAlias((<IndexedAccessTypeNode>node).indexType);
+                case SyntaxKind.ConditionalType:
+                    return mayResolveTypeAlias((<ConditionalTypeNode>node).checkType) || mayResolveTypeAlias((<ConditionalTypeNode>node).extendsType) ||
+                        mayResolveTypeAlias((<ConditionalTypeNode>node).trueType) || mayResolveTypeAlias((<ConditionalTypeNode>node).falseType);
+            }
+            return false;
+        }
+
         function getTypeFromArrayOrTupleTypeNode(node: ArrayTypeNode | TupleTypeNode): Type {
             const links = getNodeLinks(node);
             if (!links.resolvedType) {
                 const target = getArrayOrTupleTargetType(node);
                 if (target === emptyGenericType) {
                     links.resolvedType = emptyObjectType;
                 }
-                else if (isAliasedType(node)) {
+                else if (isDeferredTypeReferenceNode(node)) {
                     links.resolvedType = node.kind === SyntaxKind.TupleType && node.elementTypes.length === 0 ? target :
                         createDeferredTypeReference(target, node, /*mapper*/ undefined);
                 }
@@ -12902,7 +12942,7 @@ namespace ts {
             return links.resolvedType;
         }
 
-        function getAliasSymbolForTypeNode(node: TypeNode) {
+        function getAliasSymbolForTypeNode(node: Node) {
             let host = node.parent;
             while (isParenthesizedTypeNode(host) || isTypeOperatorNode(host) && host.operator === SyntaxKind.ReadonlyKeyword) {
                 host = host.parent;
diff --git a/tests/baselines/reference/checkJsxChildrenProperty3.types b/tests/baselines/reference/checkJsxChildrenProperty3.types
@@ -31,11 +31,11 @@ class FetchUser extends React.Component<IFetchUserProps, any> {
 
             ? this.props.children(this.state.result)
 >this.props.children(this.state.result) : JSX.Element
->this.props.children : ((user: IUser) => JSX.Element) | (((user: IUser) => JSX.Element) & string) | (((user: IUser) => JSX.Element) & number) | (((user: IUser) => JSX.Element) & false) | (((user: IUser) => JSX.Element) & true) | (((user: IUser) => JSX.Element) & React.ReactElement<any>) | (((user: IUser) => JSX.Element) & (string | number | boolean | React.ReactElement<any> | any[])[])
+>this.props.children : ((user: IUser) => JSX.Element) | (((user: IUser) => JSX.Element) & string) | (((user: IUser) => JSX.Element) & number) | (((user: IUser) => JSX.Element) & false) | (((user: IUser) => JSX.Element) & true) | (((user: IUser) => JSX.Element) & React.ReactElement<any>) | (((user: IUser) => JSX.Element) & (string | number | boolean | any[] | React.ReactElement<any>)[])
 >this.props : IFetchUserProps & { children?: React.ReactNode; }
 >this : this
 >props : IFetchUserProps & { children?: React.ReactNode; }
->children : ((user: IUser) => JSX.Element) | (((user: IUser) => JSX.Element) & string) | (((user: IUser) => JSX.Element) & number) | (((user: IUser) => JSX.Element) & false) | (((user: IUser) => JSX.Element) & true) | (((user: IUser) => JSX.Element) & React.ReactElement<any>) | (((user: IUser) => JSX.Element) & (string | number | boolean | React.ReactElement<any> | any[])[])
+>children : ((user: IUser) => JSX.Element) | (((user: IUser) => JSX.Element) & string) | (((user: IUser) => JSX.Element) & number) | (((user: IUser) => JSX.Element) & false) | (((user: IUser) => JSX.Element) & true) | (((user: IUser) => JSX.Element) & React.ReactElement<any>) | (((user: IUser) => JSX.Element) & (string | number | boolean | any[] | React.ReactElement<any>)[])
 >this.state.result : any
 >this.state : any
 >this : this
diff --git a/tests/baselines/reference/checkJsxChildrenProperty4.errors.txt b/tests/baselines/reference/checkJsxChildrenProperty4.errors.txt
@@ -1,8 +1,8 @@
 tests/cases/conformance/jsx/file.tsx(24,28): error TS2551: Property 'NAme' does not exist on type 'IUser'. Did you mean 'Name'?
-tests/cases/conformance/jsx/file.tsx(36,15): error TS2322: Type '(user: IUser) => Element' is not assignable to type 'string | number | boolean | ReactElement<any> | any[]'.
-  Type '(user: IUser) => Element' is missing the following properties from type 'any[]': push, pop, concat, join, and 15 more.
-tests/cases/conformance/jsx/file.tsx(39,15): error TS2322: Type '(user: IUser) => Element' is not assignable to type 'string | number | boolean | ReactElement<any> | any[]'.
-  Type '(user: IUser) => Element' is missing the following properties from type 'any[]': push, pop, concat, join, and 15 more.
+tests/cases/conformance/jsx/file.tsx(36,15): error TS2322: Type '(user: IUser) => Element' is not assignable to type 'string | number | boolean | any[] | ReactElement<any>'.
+  Type '(user: IUser) => Element' is missing the following properties from type 'ReactElement<any>': type, props
+tests/cases/conformance/jsx/file.tsx(39,15): error TS2322: Type '(user: IUser) => Element' is not assignable to type 'string | number | boolean | any[] | ReactElement<any>'.
+  Type '(user: IUser) => Element' is missing the following properties from type 'ReactElement<any>': type, props
 
 
 ==== tests/cases/conformance/jsx/file.tsx (3 errors) ====
@@ -50,17 +50,17 @@ tests/cases/conformance/jsx/file.tsx(39,15): error TS2322: Type '(user: IUser) =
     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                 ) }
     ~~~~~~~~~~~~~
-!!! error TS2322: Type '(user: IUser) => Element' is not assignable to type 'string | number | boolean | ReactElement<any> | any[]'.
-!!! error TS2322:   Type '(user: IUser) => Element' is missing the following properties from type 'any[]': push, pop, concat, join, and 15 more.
+!!! error TS2322: Type '(user: IUser) => Element' is not assignable to type 'string | number | boolean | any[] | ReactElement<any>'.
+!!! error TS2322:   Type '(user: IUser) => Element' is missing the following properties from type 'ReactElement<any>': type, props
 !!! related TS6212 tests/cases/conformance/jsx/file.tsx:36:15: Did you mean to call this expression?
                 { user => (
                   ~~~~~~~~~
                     <h1>{ user.Name }</h1>
     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                 ) }
     ~~~~~~~~~~~~~
-!!! error TS2322: Type '(user: IUser) => Element' is not assignable to type 'string | number | boolean | ReactElement<any> | any[]'.
-!!! error TS2322:   Type '(user: IUser) => Element' is missing the following properties from type 'any[]': push, pop, concat, join, and 15 more.
+!!! error TS2322: Type '(user: IUser) => Element' is not assignable to type 'string | number | boolean | any[] | ReactElement<any>'.
+!!! error TS2322:   Type '(user: IUser) => Element' is missing the following properties from type 'ReactElement<any>': type, props
 !!! related TS6212 tests/cases/conformance/jsx/file.tsx:39:15: Did you mean to call this expression?
             </FetchUser>
         );
diff --git a/tests/baselines/reference/checkJsxChildrenProperty4.types b/tests/baselines/reference/checkJsxChildrenProperty4.types
@@ -31,11 +31,11 @@ class FetchUser extends React.Component<IFetchUserProps, any> {
 
             ? this.props.children(this.state.result)
 >this.props.children(this.state.result) : JSX.Element
->this.props.children : ((user: IUser) => JSX.Element) | (((user: IUser) => JSX.Element) & string) | (((user: IUser) => JSX.Element) & number) | (((user: IUser) => JSX.Element) & false) | (((user: IUser) => JSX.Element) & true) | (((user: IUser) => JSX.Element) & React.ReactElement<any>) | (((user: IUser) => JSX.Element) & (string | number | boolean | React.ReactElement<any> | any[])[])
+>this.props.children : ((user: IUser) => JSX.Element) | (((user: IUser) => JSX.Element) & string) | (((user: IUser) => JSX.Element) & number) | (((user: IUser) => JSX.Element) & false) | (((user: IUser) => JSX.Element) & true) | (((user: IUser) => JSX.Element) & React.ReactElement<any>) | (((user: IUser) => JSX.Element) & (string | number | boolean | any[] | React.ReactElement<any>)[])
 >this.props : IFetchUserProps & { children?: React.ReactNode; }
 >this : this
 >props : IFetchUserProps & { children?: React.ReactNode; }
->children : ((user: IUser) => JSX.Element) | (((user: IUser) => JSX.Element) & string) | (((user: IUser) => JSX.Element) & number) | (((user: IUser) => JSX.Element) & false) | (((user: IUser) => JSX.Element) & true) | (((user: IUser) => JSX.Element) & React.ReactElement<any>) | (((user: IUser) => JSX.Element) & (string | number | boolean | React.ReactElement<any> | any[])[])
+>children : ((user: IUser) => JSX.Element) | (((user: IUser) => JSX.Element) & string) | (((user: IUser) => JSX.Element) & number) | (((user: IUser) => JSX.Element) & false) | (((user: IUser) => JSX.Element) & true) | (((user: IUser) => JSX.Element) & React.ReactElement<any>) | (((user: IUser) => JSX.Element) & (string | number | boolean | any[] | React.ReactElement<any>)[])
 >this.state.result : any
 >this.state : any
 >this : this
