[React] change createElement declaration (#19858)

* fix https://github.com/Microsoft/TypeScript/issues/15019

* change the stable v15 declaration too

* catch-all case also take string

* add string for test

types/react/index.d.ts

@@ -216,7 +216,7 @@ declare namespace React {
         props?: ClassAttributes<T> & P,
         ...children: ReactNode[]): CElement<P, T>;
     function createElement<P>(
-        type: ComponentClass<P>,
+        type: SFC<P> | ComponentClass<P> | string,
         props?: Attributes & P,
         ...children: ReactNode[]): ReactElement<P>;
 

types/react/test/index.ts

@@ -193,6 +193,12 @@ const customProps: React.HTMLProps<HTMLElement> = props;
 const customDomElement = "my-element";
 const nonLiteralElement = React.createElement(customDomElement, customProps);
 
+// https://github.com/Microsoft/TypeScript/issues/15019
+
+function foo3(child: React.ComponentClass<{ name: string }> | React.StatelessComponent<{ name: string }> | string) {
+    React.createElement(child, { name: "bar" });
+}
+
 // React.cloneElement
 const clonedElement: React.CElement<Props, ModernComponent> = React.cloneElement(element, { foo: 43 });
 

types/react/v15/index.d.ts

@@ -223,7 +223,7 @@ declare namespace React {
         props?: ClassAttributes<T> & P,
         ...children: ReactNode[]): CElement<P, T>;
     function createElement<P>(
-        type: ComponentClass<P>,
+        type: SFC<P> | ComponentClass<P> | string,
         props?: Attributes & P,
         ...children: ReactNode[]): ReactElement<P>;
 

types/react/v15/test/index.ts

@@ -193,6 +193,12 @@ const customProps: React.HTMLProps<HTMLElement> = props;
 const customDomElement = "my-element";
 const nonLiteralElement = React.createElement(customDomElement, customProps);
 
+// https://github.com/Microsoft/TypeScript/issues/15019
+
+function foo3(child: React.ComponentClass<{ name: string }> | React.StatelessComponent<{ name: string }> | string) {
+    React.createElement(child, { name: "bar" });
+}
+
 // React.cloneElement
 const clonedElement: React.CElement<Props, ModernComponent> = React.cloneElement(element, { foo: 43 });