Prevent ObjectFlags.IdenticalBaseTypeExists and ObjectFlags.IsConstrainedTypeVariable confusion (#56711)

2026-02-04 21:53:42 -06:00 · 2023-12-11 19:24:32 +01:00 · 2023-12-11 19:24:32 +01:00 · 5b10466b63
commit 5b10466b63
parent 769453003c
4 changed files with 559 additions and 3 deletions
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@ -17006,7 +17006,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
        const typeVariables: TypeVariable[] = [];
        // First collect a list of the type variables occurring in constraining intersections.
        for (const type of types) {
-            if (getObjectFlags(type) & ObjectFlags.IsConstrainedTypeVariable) {
+            if (type.flags & TypeFlags.Intersection && getObjectFlags(type) & ObjectFlags.IsConstrainedTypeVariable) {
                const index = (type as IntersectionType).types[0].flags & TypeFlags.TypeVariable ? 0 : 1;
                pushIfUnique(typeVariables, (type as IntersectionType).types[index]);
            }
@ -17018,7 +17018,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
            const primitives: Type[] = [];
            // First collect the primitive types from the constraining intersections.
            for (const type of types) {
-                if (getObjectFlags(type) & ObjectFlags.IsConstrainedTypeVariable) {
+                if (type.flags & TypeFlags.Intersection && getObjectFlags(type) & ObjectFlags.IsConstrainedTypeVariable) {
                    const index = (type as IntersectionType).types[0].flags & TypeFlags.TypeVariable ? 0 : 1;
                    if ((type as IntersectionType).types[index] === typeVariable) {
                        insertType(primitives, (type as IntersectionType).types[1 - index]);
@ -17033,7 +17033,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
                while (i > 0) {
                    i--;
                    const type = types[i];
-                    if (getObjectFlags(type) & ObjectFlags.IsConstrainedTypeVariable) {
+                    if (type.flags & TypeFlags.Intersection && getObjectFlags(type) & ObjectFlags.IsConstrainedTypeVariable) {
                        const index = (type as IntersectionType).types[0].flags & TypeFlags.TypeVariable ? 0 : 1;
                        if ((type as IntersectionType).types[index] === typeVariable && containsType(primitives, (type as IntersectionType).types[1 - index])) {
                            orderedRemoveItemAt(types, i);
--- a/tests/baselines/reference/unionReductionWithStringMappingAndIdenticalBaseTypeExistsNoCrash.symbols
+++ b/tests/baselines/reference/unionReductionWithStringMappingAndIdenticalBaseTypeExistsNoCrash.symbols
@ -0,0 +1,275 @@
+//// [tests/cases/compiler/unionReductionWithStringMappingAndIdenticalBaseTypeExistsNoCrash.tsx] ////
+
+=== node_modules/@types/react/index.d.ts ===
+// https://github.com/microsoft/TypeScript/issues/56688
+
+
+export = React;
+>React : Symbol(React, Decl(index.d.ts, 4, 26))
+
+export as namespace React;
+>React : Symbol(React, Decl(index.d.ts, 3, 15))
+
+declare namespace React {
+>React : Symbol(React, Decl(index.d.ts, 4, 26))
+
+  type ReactNode =
+>ReactNode : Symbol(ReactNode, Decl(index.d.ts, 6, 25))
+
+    | ReactElement
+>ReactElement : Symbol(ReactElement, Decl(index.d.ts, 15, 58))
+
+    | string
+    | number
+    | Iterable<ReactNode>
+>Iterable : Symbol(Iterable, Decl(lib.es2015.iterable.d.ts, --, --))
+>ReactNode : Symbol(ReactNode, Decl(index.d.ts, 6, 25))
+
+    | boolean
+    | null
+    | undefined;
+  type JSXElementConstructor<P> = (props: P) => ReactNode;
+>JSXElementConstructor : Symbol(JSXElementConstructor, Decl(index.d.ts, 14, 16))
+>P : Symbol(P, Decl(index.d.ts, 15, 29))
+>props : Symbol(props, Decl(index.d.ts, 15, 35))
+>P : Symbol(P, Decl(index.d.ts, 15, 29))
+>ReactNode : Symbol(ReactNode, Decl(index.d.ts, 6, 25))
+
+  interface ReactElement<
+>ReactElement : Symbol(ReactElement, Decl(index.d.ts, 15, 58))
+
+    P = any,
+>P : Symbol(P, Decl(index.d.ts, 16, 25))
+
+    T extends string | JSXElementConstructor<any> =
+>T : Symbol(T, Decl(index.d.ts, 17, 12))
+>JSXElementConstructor : Symbol(JSXElementConstructor, Decl(index.d.ts, 14, 16))
+
+      | string
+      | JSXElementConstructor<any>,
+>JSXElementConstructor : Symbol(JSXElementConstructor, Decl(index.d.ts, 14, 16))
+
+  > {
+    type: T;
+>type : Symbol(ReactElement.type, Decl(index.d.ts, 21, 5))
+>T : Symbol(T, Decl(index.d.ts, 17, 12))
+
+    props: P;
+>props : Symbol(ReactElement.props, Decl(index.d.ts, 22, 12))
+>P : Symbol(P, Decl(index.d.ts, 16, 25))
+
+    key: string | null;
+>key : Symbol(ReactElement.key, Decl(index.d.ts, 23, 13))
+  }
+
+  type ComponentProps<T extends JSXElementConstructor<any>> =
+>ComponentProps : Symbol(ComponentProps, Decl(index.d.ts, 25, 3))
+>T : Symbol(T, Decl(index.d.ts, 27, 22))
+>JSXElementConstructor : Symbol(JSXElementConstructor, Decl(index.d.ts, 14, 16))
+
+    T extends JSXElementConstructor<infer P> ? P : never;
+>T : Symbol(T, Decl(index.d.ts, 27, 22))
+>JSXElementConstructor : Symbol(JSXElementConstructor, Decl(index.d.ts, 14, 16))
+>P : Symbol(P, Decl(index.d.ts, 28, 41))
+>P : Symbol(P, Decl(index.d.ts, 28, 41))
+
+  interface ExoticComponent<P = {}> {
+>ExoticComponent : Symbol(ExoticComponent, Decl(index.d.ts, 28, 57))
+>P : Symbol(P, Decl(index.d.ts, 30, 28))
+
+    (props: P): ReactNode;
+>props : Symbol(props, Decl(index.d.ts, 31, 5))
+>P : Symbol(P, Decl(index.d.ts, 30, 28))
+>ReactNode : Symbol(ReactNode, Decl(index.d.ts, 6, 25))
+
+    readonly $$typeof: symbol;
+>$$typeof : Symbol(ExoticComponent.$$typeof, Decl(index.d.ts, 31, 26))
+  }
+
+  type LazyExoticComponent<T extends JSXElementConstructor<any>> =
+>LazyExoticComponent : Symbol(LazyExoticComponent, Decl(index.d.ts, 33, 3))
+>T : Symbol(T, Decl(index.d.ts, 35, 27))
+>JSXElementConstructor : Symbol(JSXElementConstructor, Decl(index.d.ts, 14, 16))
+
+    ExoticComponent<ComponentProps<T>> & {
+>ExoticComponent : Symbol(ExoticComponent, Decl(index.d.ts, 28, 57))
+>ComponentProps : Symbol(ComponentProps, Decl(index.d.ts, 25, 3))
+>T : Symbol(T, Decl(index.d.ts, 35, 27))
+
+      readonly _result: T;
+>_result : Symbol(_result, Decl(index.d.ts, 36, 42))
+>T : Symbol(T, Decl(index.d.ts, 35, 27))
+
+    };
+
+  function createElement(): void;
+>createElement : Symbol(createElement, Decl(index.d.ts, 38, 6))
+
+  namespace JSX {
+>JSX : Symbol(JSX, Decl(index.d.ts, 40, 33))
+
+    interface Element extends GlobalJSXElement {}
+>Element : Symbol(Element, Decl(index.d.ts, 42, 17))
+>GlobalJSXElement : Symbol(GlobalJSXElement, Decl(index.d.ts, 74, 1))
+
+    interface ElementChildrenAttribute
+>ElementChildrenAttribute : Symbol(ElementChildrenAttribute, Decl(index.d.ts, 43, 49))
+
+      extends GlobalJSXElementChildrenAttribute {}
+>GlobalJSXElementChildrenAttribute : Symbol(GlobalJSXElementChildrenAttribute, Decl(index.d.ts, 76, 49))
+
+    type LibraryManagedAttributes<C, P> = GlobalJSXLibraryManagedAttributes<
+>LibraryManagedAttributes : Symbol(LibraryManagedAttributes, Decl(index.d.ts, 45, 50))
+>C : Symbol(C, Decl(index.d.ts, 46, 34))
+>P : Symbol(P, Decl(index.d.ts, 46, 36))
+>GlobalJSXLibraryManagedAttributes : Symbol(GlobalJSXLibraryManagedAttributes, Decl(index.d.ts, 78, 41))
+
+      C,
+>C : Symbol(C, Decl(index.d.ts, 46, 34))
+
+      P
+>P : Symbol(P, Decl(index.d.ts, 46, 36))
+
+    >;
+    interface IntrinsicElements extends GlobalJSXIntrinsicElements {}
+>IntrinsicElements : Symbol(IntrinsicElements, Decl(index.d.ts, 49, 6))
+>GlobalJSXIntrinsicElements : Symbol(GlobalJSXIntrinsicElements, Decl(index.d.ts, 82, 2))
+  }
+}
+
+type ReactManagedAttributes<C, P> = C extends { defaultProps: infer D }
+>ReactManagedAttributes : Symbol(ReactManagedAttributes, Decl(index.d.ts, 52, 1))
+>C : Symbol(C, Decl(index.d.ts, 54, 28))
+>P : Symbol(P, Decl(index.d.ts, 54, 30))
+>C : Symbol(C, Decl(index.d.ts, 54, 28))
+>defaultProps : Symbol(defaultProps, Decl(index.d.ts, 54, 47))
+>D : Symbol(D, Decl(index.d.ts, 54, 67))
+
+  ? P & D
+>P : Symbol(P, Decl(index.d.ts, 54, 30))
+>D : Symbol(D, Decl(index.d.ts, 54, 67))
+
+  : P;
+>P : Symbol(P, Decl(index.d.ts, 54, 30))
+
+declare global {
+>global : Symbol(global, Decl(index.d.ts, 56, 6))
+
+  namespace JSX {
+>JSX : Symbol(JSX, Decl(index.d.ts, 58, 16))
+
+    interface Element extends React.ReactElement<any, any> {}
+>Element : Symbol(Element, Decl(index.d.ts, 59, 17))
+>React.ReactElement : Symbol(React.ReactElement, Decl(index.d.ts, 15, 58))
+>React : Symbol(React, Decl(index.d.ts, 4, 26))
+>ReactElement : Symbol(React.ReactElement, Decl(index.d.ts, 15, 58))
+
+    interface ElementChildrenAttribute {
+>ElementChildrenAttribute : Symbol(ElementChildrenAttribute, Decl(index.d.ts, 60, 61))
+
+      children: {};
+>children : Symbol(ElementChildrenAttribute.children, Decl(index.d.ts, 61, 40))
+    }
+    type LibraryManagedAttributes<C, P> = C extends React.LazyExoticComponent<
+>LibraryManagedAttributes : Symbol(LibraryManagedAttributes, Decl(index.d.ts, 63, 5))
+>C : Symbol(C, Decl(index.d.ts, 64, 34))
+>P : Symbol(P, Decl(index.d.ts, 64, 36))
+>C : Symbol(C, Decl(index.d.ts, 64, 34))
+>React : Symbol(React, Decl(index.d.ts, 4, 26))
+>LazyExoticComponent : Symbol(React.LazyExoticComponent, Decl(index.d.ts, 33, 3))
+
+      infer T
+>T : Symbol(T, Decl(index.d.ts, 65, 11))
+
+    >
+      ? ReactManagedAttributes<T, P>
+>ReactManagedAttributes : Symbol(ReactManagedAttributes, Decl(index.d.ts, 52, 1))
+>T : Symbol(T, Decl(index.d.ts, 65, 11))
+>P : Symbol(P, Decl(index.d.ts, 64, 36))
+
+      : ReactManagedAttributes<C, P>;
+>ReactManagedAttributes : Symbol(ReactManagedAttributes, Decl(index.d.ts, 52, 1))
+>C : Symbol(C, Decl(index.d.ts, 64, 34))
+>P : Symbol(P, Decl(index.d.ts, 64, 36))
+
+    interface IntrinsicElements {
+>IntrinsicElements : Symbol(IntrinsicElements, Decl(index.d.ts, 68, 37))
+
+      div: {};
+>div : Symbol(IntrinsicElements.div, Decl(index.d.ts, 69, 33))
+
+      span: {};
+>span : Symbol(IntrinsicElements.span, Decl(index.d.ts, 70, 14))
+    }
+  }
+}
+
+interface GlobalJSXElement extends JSX.Element {}
+>GlobalJSXElement : Symbol(GlobalJSXElement, Decl(index.d.ts, 74, 1))
+>JSX.Element : Symbol(JSX.Element, Decl(index.d.ts, 59, 17))
+>JSX : Symbol(JSX, Decl(index.d.ts, 58, 16))
+>Element : Symbol(JSX.Element, Decl(index.d.ts, 59, 17))
+
+interface GlobalJSXElementChildrenAttribute
+>GlobalJSXElementChildrenAttribute : Symbol(GlobalJSXElementChildrenAttribute, Decl(index.d.ts, 76, 49))
+
+  extends JSX.ElementChildrenAttribute {}
+>JSX.ElementChildrenAttribute : Symbol(JSX.ElementChildrenAttribute, Decl(index.d.ts, 60, 61))
+>JSX : Symbol(JSX, Decl(index.d.ts, 58, 16))
+>ElementChildrenAttribute : Symbol(JSX.ElementChildrenAttribute, Decl(index.d.ts, 60, 61))
+
+type GlobalJSXLibraryManagedAttributes<C, P> = JSX.LibraryManagedAttributes<
+>GlobalJSXLibraryManagedAttributes : Symbol(GlobalJSXLibraryManagedAttributes, Decl(index.d.ts, 78, 41))
+>C : Symbol(C, Decl(index.d.ts, 79, 39))
+>P : Symbol(P, Decl(index.d.ts, 79, 41))
+>JSX : Symbol(JSX, Decl(index.d.ts, 58, 16))
+>LibraryManagedAttributes : Symbol(JSX.LibraryManagedAttributes, Decl(index.d.ts, 63, 5))
+
+  C,
+>C : Symbol(C, Decl(index.d.ts, 79, 39))
+
+  P
+>P : Symbol(P, Decl(index.d.ts, 79, 41))
+
+>;
+interface GlobalJSXIntrinsicElements extends JSX.IntrinsicElements {}
+>GlobalJSXIntrinsicElements : Symbol(GlobalJSXIntrinsicElements, Decl(index.d.ts, 82, 2))
+>JSX.IntrinsicElements : Symbol(JSX.IntrinsicElements, Decl(index.d.ts, 68, 37))
+>JSX : Symbol(JSX, Decl(index.d.ts, 58, 16))
+>IntrinsicElements : Symbol(JSX.IntrinsicElements, Decl(index.d.ts, 68, 37))
+
+=== src/index.tsx ===
+import React from 'react'
+>React : Symbol(React, Decl(index.tsx, 0, 6))
+
+declare function upperFirst<T extends string>(str: T): Capitalize<T>
+>upperFirst : Symbol(upperFirst, Decl(index.tsx, 0, 25))
+>T : Symbol(T, Decl(index.tsx, 2, 28))
+>str : Symbol(str, Decl(index.tsx, 2, 46))
+>T : Symbol(T, Decl(index.tsx, 2, 28))
+>Capitalize : Symbol(Capitalize, Decl(lib.es5.d.ts, --, --))
+>T : Symbol(T, Decl(index.tsx, 2, 28))
+
+const displayEnum = (value: string) => upperFirst(value.toLowerCase())
+>displayEnum : Symbol(displayEnum, Decl(index.tsx, 4, 5))
+>value : Symbol(value, Decl(index.tsx, 4, 21))
+>upperFirst : Symbol(upperFirst, Decl(index.tsx, 0, 25))
+>value.toLowerCase : Symbol(String.toLowerCase, Decl(lib.es5.d.ts, --, --))
+>value : Symbol(value, Decl(index.tsx, 4, 21))
+>toLowerCase : Symbol(String.toLowerCase, Decl(lib.es5.d.ts, --, --))
+
+function Comp() {
+>Comp : Symbol(Comp, Decl(index.tsx, 4, 70))
+
+  return <div>
+>div : Symbol(JSX.IntrinsicElements.div, Decl(index.d.ts, 69, 33))
+
+    <span>Scope:</span> {displayEnum("VALUE")}
+>span : Symbol(JSX.IntrinsicElements.span, Decl(index.d.ts, 70, 14))
+>span : Symbol(JSX.IntrinsicElements.span, Decl(index.d.ts, 70, 14))
+>displayEnum : Symbol(displayEnum, Decl(index.tsx, 4, 5))
+
+  </div>
+>div : Symbol(JSX.IntrinsicElements.div, Decl(index.d.ts, 69, 33))
+}
+
--- a/tests/baselines/reference/unionReductionWithStringMappingAndIdenticalBaseTypeExistsNoCrash.types
+++ b/tests/baselines/reference/unionReductionWithStringMappingAndIdenticalBaseTypeExistsNoCrash.types
@ -0,0 +1,175 @@
+//// [tests/cases/compiler/unionReductionWithStringMappingAndIdenticalBaseTypeExistsNoCrash.tsx] ////
+
+=== node_modules/@types/react/index.d.ts ===
+// https://github.com/microsoft/TypeScript/issues/56688
+
+
+export = React;
+>React : typeof React
+
+export as namespace React;
+>React : typeof React
+
+declare namespace React {
+>React : typeof React
+
+  type ReactNode =
+>ReactNode : string | number | boolean | ReactElement<any, string | JSXElementConstructor<any>> | Iterable<ReactNode> | null | undefined
+
+    | ReactElement
+    | string
+    | number
+    | Iterable<ReactNode>
+    | boolean
+    | null
+    | undefined;
+  type JSXElementConstructor<P> = (props: P) => ReactNode;
+>JSXElementConstructor : JSXElementConstructor<P>
+>props : P
+
+  interface ReactElement<
+    P = any,
+    T extends string | JSXElementConstructor<any> =
+      | string
+      | JSXElementConstructor<any>,
+  > {
+    type: T;
+>type : T
+
+    props: P;
+>props : P
+
+    key: string | null;
+>key : string | null
+  }
+
+  type ComponentProps<T extends JSXElementConstructor<any>> =
+>ComponentProps : ComponentProps<T>
+
+    T extends JSXElementConstructor<infer P> ? P : never;
+
+  interface ExoticComponent<P = {}> {
+    (props: P): ReactNode;
+>props : P
+
+    readonly $$typeof: symbol;
+>$$typeof : symbol
+  }
+
+  type LazyExoticComponent<T extends JSXElementConstructor<any>> =
+>LazyExoticComponent : LazyExoticComponent<T>
+
+    ExoticComponent<ComponentProps<T>> & {
+      readonly _result: T;
+>_result : T
+
+    };
+
+  function createElement(): void;
+>createElement : () => void
+
+  namespace JSX {
+    interface Element extends GlobalJSXElement {}
+    interface ElementChildrenAttribute
+      extends GlobalJSXElementChildrenAttribute {}
+    type LibraryManagedAttributes<C, P> = GlobalJSXLibraryManagedAttributes<
+>LibraryManagedAttributes : LibraryManagedAttributes<C, P>
+
+      C,
+      P
+    >;
+    interface IntrinsicElements extends GlobalJSXIntrinsicElements {}
+  }
+}
+
+type ReactManagedAttributes<C, P> = C extends { defaultProps: infer D }
+>ReactManagedAttributes : ReactManagedAttributes<C, P>
+>defaultProps : D
+
+  ? P & D
+  : P;
+
+declare global {
+>global : any
+
+  namespace JSX {
+    interface Element extends React.ReactElement<any, any> {}
+>React : typeof React
+
+    interface ElementChildrenAttribute {
+      children: {};
+>children : {}
+    }
+    type LibraryManagedAttributes<C, P> = C extends React.LazyExoticComponent<
+>LibraryManagedAttributes : LibraryManagedAttributes<C, P>
+>React : any
+
+      infer T
+    >
+      ? ReactManagedAttributes<T, P>
+      : ReactManagedAttributes<C, P>;
+    interface IntrinsicElements {
+      div: {};
+>div : {}
+
+      span: {};
+>span : {}
+    }
+  }
+}
+
+interface GlobalJSXElement extends JSX.Element {}
+>JSX : any
+
+interface GlobalJSXElementChildrenAttribute
+  extends JSX.ElementChildrenAttribute {}
+>JSX : any
+
+type GlobalJSXLibraryManagedAttributes<C, P> = JSX.LibraryManagedAttributes<
+>GlobalJSXLibraryManagedAttributes : GlobalJSXLibraryManagedAttributes<C, P>
+>JSX : any
+
+  C,
+  P
+>;
+interface GlobalJSXIntrinsicElements extends JSX.IntrinsicElements {}
+>JSX : any
+
+=== src/index.tsx ===
+import React from 'react'
+>React : typeof React
+
+declare function upperFirst<T extends string>(str: T): Capitalize<T>
+>upperFirst : <T extends string>(str: T) => Capitalize<T>
+>str : T
+
+const displayEnum = (value: string) => upperFirst(value.toLowerCase())
+>displayEnum : (value: string) => Capitalize<string>
+>(value: string) => upperFirst(value.toLowerCase()) : (value: string) => Capitalize<string>
+>value : string
+>upperFirst(value.toLowerCase()) : Capitalize<string>
+>upperFirst : <T extends string>(str: T) => Capitalize<T>
+>value.toLowerCase() : string
+>value.toLowerCase : () => string
+>value : string
+>toLowerCase : () => string
+
+function Comp() {
+>Comp : () => React.JSX.Element
+
+  return <div>
+><div>    <span>Scope:</span> {displayEnum("VALUE")}  </div> : React.JSX.Element
+>div : any
+
+    <span>Scope:</span> {displayEnum("VALUE")}
+><span>Scope:</span> : React.JSX.Element
+>span : any
+>span : any
+>displayEnum("VALUE") : Capitalize<string>
+>displayEnum : (value: string) => Capitalize<string>
+>"VALUE" : "VALUE"
+
+  </div>
+>div : any
+}
+
--- a/tests/cases/compiler/unionReductionWithStringMappingAndIdenticalBaseTypeExistsNoCrash.tsx
+++ b/tests/cases/compiler/unionReductionWithStringMappingAndIdenticalBaseTypeExistsNoCrash.tsx
@ -0,0 +1,106 @@
+// @strict: true
+// @noEmit: true
+// @target: esnext
+// @lib: dom, esnext
+// @jsx: react
+// @esModuleInterop: true
+// @moduleResolution: node
+
+// https://github.com/microsoft/TypeScript/issues/56688
+
+// @filename: node_modules/@types/react/index.d.ts
+
+export = React;
+export as namespace React;
+
+declare namespace React {
+  type ReactNode =
+    | ReactElement
+    | string
+    | number
+    | Iterable<ReactNode>
+    | boolean
+    | null
+    | undefined;
+  type JSXElementConstructor<P> = (props: P) => ReactNode;
+  interface ReactElement<
+    P = any,
+    T extends string | JSXElementConstructor<any> =
+      | string
+      | JSXElementConstructor<any>,
+  > {
+    type: T;
+    props: P;
+    key: string | null;
+  }
+
+  type ComponentProps<T extends JSXElementConstructor<any>> =
+    T extends JSXElementConstructor<infer P> ? P : never;
+
+  interface ExoticComponent<P = {}> {
+    (props: P): ReactNode;
+    readonly $$typeof: symbol;
+  }
+
+  type LazyExoticComponent<T extends JSXElementConstructor<any>> =
+    ExoticComponent<ComponentProps<T>> & {
+      readonly _result: T;
+    };
+
+  function createElement(): void;
+
+  namespace JSX {
+    interface Element extends GlobalJSXElement {}
+    interface ElementChildrenAttribute
+      extends GlobalJSXElementChildrenAttribute {}
+    type LibraryManagedAttributes<C, P> = GlobalJSXLibraryManagedAttributes<
+      C,
+      P
+    >;
+    interface IntrinsicElements extends GlobalJSXIntrinsicElements {}
+  }
+}
+
+type ReactManagedAttributes<C, P> = C extends { defaultProps: infer D }
+  ? P & D
+  : P;
+
+declare global {
+  namespace JSX {
+    interface Element extends React.ReactElement<any, any> {}
+    interface ElementChildrenAttribute {
+      children: {};
+    }
+    type LibraryManagedAttributes<C, P> = C extends React.LazyExoticComponent<
+      infer T
+    >
+      ? ReactManagedAttributes<T, P>
+      : ReactManagedAttributes<C, P>;
+    interface IntrinsicElements {
+      div: {};
+      span: {};
+    }
+  }
+}
+
+interface GlobalJSXElement extends JSX.Element {}
+interface GlobalJSXElementChildrenAttribute
+  extends JSX.ElementChildrenAttribute {}
+type GlobalJSXLibraryManagedAttributes<C, P> = JSX.LibraryManagedAttributes<
+  C,
+  P
+>;
+interface GlobalJSXIntrinsicElements extends JSX.IntrinsicElements {}
+
+// @filename: src/index.tsx
+import React from 'react'
+
+declare function upperFirst<T extends string>(str: T): Capitalize<T>
+
+const displayEnum = (value: string) => upperFirst(value.toLowerCase())
+
+function Comp() {
+  return <div>
+    <span>Scope:</span> {displayEnum("VALUE")}
+  </div>
+}