Add related info suggesting a fix

weswigham · weswigham · commit bc3d515370ee · 2020-10-22T16:13:08.000-07:00
diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
@@ -16918,6 +16918,9 @@ namespace ts {
                             return result;
                         }
                         reportRelationError(headMessage, source, target);
+                        if (source.flags & TypeFlags.TypeVariable && source.symbol?.declarations?.[0] && !getConstraintOfType(<TypeVariable>source) && isRelatedTo(emptyObjectType, extractTypesOfKind(target, ~TypeFlags.NonPrimitive))) {
+                            associateRelatedInfo(createDiagnosticForNode(source.symbol.declarations[0], Diagnostics.This_type_parameter_likely_needs_an_extends_object_constraint));
+                        }
                     }
                 }
             }
diff --git a/src/compiler/diagnosticMessages.json b/src/compiler/diagnosticMessages.json
@@ -3059,6 +3059,10 @@
         "category": "Error",
         "code": 2796
     },
+    "This type parameter likely needs an `extends object` constraint.": {
+        "category": "Error",
+        "code": 2797
+    },
 
     "Import declaration '{0}' is using private name '{1}'.": {
         "category": "Error",
diff --git a/tests/baselines/reference/bestCommonTypeOfConditionalExpressions.errors.txt b/tests/baselines/reference/bestCommonTypeOfConditionalExpressions.errors.txt
@@ -31,4 +31,5 @@ tests/cases/conformance/types/typeRelationships/bestCommonType/bestCommonTypeOfC
         ~~~~~~~~~~~~~~~~~~~~
 !!! error TS2322: Type 'T | U' is not assignable to type 'Object'.
 !!! error TS2322:   Type 'T' is not assignable to type 'Object'.
+!!! related TS2797 tests/cases/conformance/types/typeRelationships/bestCommonType/bestCommonTypeOfConditionalExpressions.ts:24:15: This type parameter likely needs an `extends object` constraint.
     }
diff --git a/tests/baselines/reference/complexRecursiveCollections.errors.txt b/tests/baselines/reference/complexRecursiveCollections.errors.txt
@@ -298,6 +298,7 @@ tests/cases/compiler/immutable.ts(391,22): error TS2430: Interface 'Set<T>' inco
       export function Record<T>(defaultValues: T, name?: string): Record.Class<T>;
                                                                                ~
 !!! error TS2344: Type 'T' does not satisfy the constraint 'Object'.
+!!! related TS2797 tests/cases/compiler/immutable.ts:261:26: This type parameter likely needs an `extends object` constraint.
       export module Seq {
         function isSeq(maybeSeq: any): maybeSeq is Seq.Indexed<any> | Seq.Keyed<any, any>;
         function of<T>(...values: Array<T>): Seq.Indexed<T>;
diff --git a/tests/baselines/reference/constructorReturningAPrimitive.errors.txt b/tests/baselines/reference/constructorReturningAPrimitive.errors.txt
@@ -20,6 +20,7 @@ tests/cases/compiler/constructorReturningAPrimitive.ts(15,9): error TS2409: Retu
             return x;
             ~~~~~~~~~
 !!! error TS2322: Type 'T' is not assignable to type 'B<T>'.
+!!! related TS2797 tests/cases/compiler/constructorReturningAPrimitive.ts:12:9: This type parameter likely needs an `extends object` constraint.
             ~~~~~~~~~
 !!! error TS2409: Return type of constructor signature must be assignable to the instance type of the class.
         }
diff --git a/tests/baselines/reference/keyofAndIndexedAccess.errors.txt b/tests/baselines/reference/keyofAndIndexedAccess.errors.txt
@@ -356,6 +356,7 @@ tests/cases/conformance/types/keyof/keyofAndIndexedAccess.ts(619,13): error TS23
         a = x;
         ~
 !!! error TS2322: Type 'T' is not assignable to type '{}'.
+!!! related TS2797 tests/cases/conformance/types/keyof/keyofAndIndexedAccess.ts:314:14: This type parameter likely needs an `extends object` constraint.
         a = y;
         ~
 !!! error TS2322: Type 'T[keyof T]' is not assignable to type '{}'.
@@ -373,6 +374,8 @@ tests/cases/conformance/types/keyof/keyofAndIndexedAccess.ts(619,13): error TS23
         ~
 !!! error TS2322: Type 'T' is not assignable to type '{} | null | undefined'.
 !!! error TS2322:   Type 'T' is not assignable to type '{}'.
+!!! related TS2797 tests/cases/conformance/types/keyof/keyofAndIndexedAccess.ts:321:14: This type parameter likely needs an `extends object` constraint.
+!!! related TS2797 tests/cases/conformance/types/keyof/keyofAndIndexedAccess.ts:321:14: This type parameter likely needs an `extends object` constraint.
         a = y;
         ~
 !!! error TS2322: Type 'T[keyof T]' is not assignable to type '{} | null | undefined'.
diff --git a/tests/baselines/reference/logicalOrOperatorWithTypeParameters.errors.txt b/tests/baselines/reference/logicalOrOperatorWithTypeParameters.errors.txt
@@ -13,6 +13,7 @@ tests/cases/conformance/expressions/binaryOperators/logicalOrOperator/logicalOrO
             ~~
 !!! error TS2322: Type 'T | U' is not assignable to type '{}'.
 !!! error TS2322:   Type 'T' is not assignable to type '{}'.
+!!! related TS2797 tests/cases/conformance/expressions/binaryOperators/logicalOrOperator/logicalOrOperatorWithTypeParameters.ts:1:14: This type parameter likely needs an `extends object` constraint.
     }
     
     function fn2<T, U/* extends T*/, V/* extends T*/>(t: T, u: U, v: V) {
@@ -25,6 +26,7 @@ tests/cases/conformance/expressions/binaryOperators/logicalOrOperator/logicalOrO
             ~~
 !!! error TS2322: Type 'U | V' is not assignable to type '{}'.
 !!! error TS2322:   Type 'U' is not assignable to type '{}'.
+!!! related TS2797 tests/cases/conformance/expressions/binaryOperators/logicalOrOperator/logicalOrOperatorWithTypeParameters.ts:8:17: This type parameter likely needs an `extends object` constraint.
         //var r7: T = u || v;
     }
     
diff --git a/tests/baselines/reference/mappedTypesAndObjects.errors.txt b/tests/baselines/reference/mappedTypesAndObjects.errors.txt
@@ -33,6 +33,7 @@ tests/cases/conformance/types/mapped/mappedTypesAndObjects.ts(25,11): error TS24
 !!! error TS2430: Interface 'E1<T>' incorrectly extends interface 'Base'.
 !!! error TS2430:   Types of property 'foo' are incompatible.
 !!! error TS2430:     Type 'T' is not assignable to type '{ [key: string]: any; }'.
+!!! related TS2797 tests/cases/conformance/types/mapped/mappedTypesAndObjects.ts:25:14: This type parameter likely needs an `extends object` constraint.
         foo: T;
     }
     
diff --git a/tests/baselines/reference/subclassThisTypeAssignable.errors.txt b/tests/baselines/reference/subclassThisTypeAssignable.errors.txt
@@ -8,6 +8,7 @@ tests/cases/compiler/tile1.ts(11,40): error TS2344: Type 'State' does not satisf
     	oninit?(vnode: Vnode<Attrs, State>): number;
     	                            ~~~~~
 !!! error TS2344: Type 'State' does not satisfy the constraint 'Lifecycle<Attrs, State>'.
+!!! related TS2797 tests/cases/compiler/tile1.ts:1:28: This type parameter likely needs an `extends object` constraint.
     	[_: number]: any;
     }
     
@@ -21,6 +22,7 @@ tests/cases/compiler/tile1.ts(11,40): error TS2344: Type 'State' does not satisf
     	view(this: State, vnode: Vnode<Attrs, State>): number;
     	                                      ~~~~~
 !!! error TS2344: Type 'State' does not satisfy the constraint 'Lifecycle<Attrs, State>'.
+!!! related TS2797 tests/cases/compiler/tile1.ts:10:28: This type parameter likely needs an `extends object` constraint.
     }
     
     interface ClassComponent<A> extends Lifecycle<A, ClassComponent<A>> {
diff --git a/tests/baselines/reference/subtypingWithOptionalProperties.errors.txt b/tests/baselines/reference/subtypingWithOptionalProperties.errors.txt
@@ -9,6 +9,7 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingW
         var b: { s?: number } = a;
             ~
 !!! error TS2322: Type 'T' is not assignable to type '{ s?: number; }'.
+!!! related TS2797 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithOptionalProperties.ts:4:12: This type parameter likely needs an `extends object` constraint.
         return b;
     }
     
diff --git a/tests/baselines/reference/tsxGenericAttributesType5.errors.txt b/tests/baselines/reference/tsxGenericAttributesType5.errors.txt
@@ -17,6 +17,7 @@ tests/cases/conformance/jsx/file.tsx(9,5): error TS2416: Property 'props' in typ
 !!! error TS2416: Property 'props' in type 'B<U>' is not assignable to the same property in base type 'Component<U, {}>'.
 !!! error TS2416:   Type 'U' is not assignable to type 'U & { children?: ReactNode; }'.
 !!! error TS2416:     Type 'U' is not assignable to type '{ children?: ReactNode; }'.
+!!! related TS2797 tests/cases/conformance/jsx/file.tsx:8:9: This type parameter likely needs an `extends object` constraint.
         render() {
             return <B1 {...this.props} x="hi" />;
         }
diff --git a/tests/baselines/reference/tsxGenericAttributesType6.errors.txt b/tests/baselines/reference/tsxGenericAttributesType6.errors.txt
@@ -17,6 +17,7 @@ tests/cases/conformance/jsx/file.tsx(9,5): error TS2416: Property 'props' in typ
 !!! error TS2416: Property 'props' in type 'B<U>' is not assignable to the same property in base type 'Component<U, {}>'.
 !!! error TS2416:   Type 'U' is not assignable to type 'U & { children?: ReactNode; }'.
 !!! error TS2416:     Type 'U' is not assignable to type '{ children?: ReactNode; }'.
+!!! related TS2797 tests/cases/conformance/jsx/file.tsx:8:9: This type parameter likely needs an `extends object` constraint.
         render() {
             return <B1 {...this.props} x="hi" />;
         }
diff --git a/tests/baselines/reference/tsxGenericAttributesType7.errors.txt b/tests/baselines/reference/tsxGenericAttributesType7.errors.txt
@@ -11,6 +11,7 @@ tests/cases/conformance/jsx/file.tsx(5,13): error TS2322: Type 'U' is not assign
                 ~~~~~~~~~
 !!! error TS2322: Type 'U' is not assignable to type 'IntrinsicAttributes & U'.
 !!! error TS2322:   Type 'U' is not assignable to type 'IntrinsicAttributes'.
+!!! related TS2797 tests/cases/conformance/jsx/file.tsx:4:29: This type parameter likely needs an `extends object` constraint.
     }
     
     const decorator1 = function <U extends {x: string}>(props: U) {
diff --git a/tests/baselines/reference/tsxGenericAttributesType8.errors.txt b/tests/baselines/reference/tsxGenericAttributesType8.errors.txt
@@ -11,6 +11,7 @@ tests/cases/conformance/jsx/file.tsx(5,13): error TS2322: Type 'U' is not assign
                 ~~~~~~~~~
 !!! error TS2322: Type 'U' is not assignable to type 'IntrinsicAttributes & U'.
 !!! error TS2322:   Type 'U' is not assignable to type 'IntrinsicAttributes'.
+!!! related TS2797 tests/cases/conformance/jsx/file.tsx:4:29: This type parameter likely needs an `extends object` constraint.
     }
     
     const decorator1 = function <U extends {x: string}>(props: U) {
diff --git a/tests/baselines/reference/tsxNotUsingApparentTypeOfSFC.errors.txt b/tests/baselines/reference/tsxNotUsingApparentTypeOfSFC.errors.txt
@@ -46,6 +46,7 @@ tests/cases/compiler/tsxNotUsingApparentTypeOfSFC.tsx(18,14): error TS2769: No o
                  ~~~~~
 !!! error TS2322: Type 'P' is not assignable to type 'IntrinsicAttributes & P'.
 !!! error TS2322:   Type 'P' is not assignable to type 'IntrinsicAttributes'.
+!!! related TS2797 tests/cases/compiler/tsxNotUsingApparentTypeOfSFC.tsx:5:15: This type parameter likely needs an `extends object` constraint.
         let q = <MyComponent {...wrappedProps} /> // should work
                  ~~~~~~~~~~~
 !!! error TS2769: No overload matches this call.
@@ -55,4 +56,6 @@ tests/cases/compiler/tsxNotUsingApparentTypeOfSFC.tsx(18,14): error TS2769: No o
 !!! error TS2769:   Overload 2 of 2, '(props: P, context?: any): MyComponent', gave the following error.
 !!! error TS2769:     Type 'P' is not assignable to type 'IntrinsicAttributes & IntrinsicClassAttributes<MyComponent> & Readonly<{ children?: ReactNode; }> & Readonly<P>'.
 !!! error TS2769:       Type 'P' is not assignable to type 'IntrinsicAttributes'.
+!!! related TS2797 tests/cases/compiler/tsxNotUsingApparentTypeOfSFC.tsx:5:15: This type parameter likely needs an `extends object` constraint.
+!!! related TS2797 tests/cases/compiler/tsxNotUsingApparentTypeOfSFC.tsx:5:15: This type parameter likely needs an `extends object` constraint.
     }
diff --git a/tests/baselines/reference/tsxStatelessFunctionComponentsWithTypeArguments2.errors.txt b/tests/baselines/reference/tsxStatelessFunctionComponentsWithTypeArguments2.errors.txt
@@ -27,6 +27,7 @@ tests/cases/conformance/jsx/file.tsx(31,52): error TS2322: Type '(val: string) =
                   ~~~~~~~~~~~~~~~~~~
 !!! error TS2322: Type 'T' is not assignable to type 'IntrinsicAttributes & { prop: unknown; "ignore-prop": string; }'.
 !!! error TS2322:   Type 'T' is not assignable to type 'IntrinsicAttributes'.
+!!! related TS2797 tests/cases/conformance/jsx/file.tsx:12:14: This type parameter likely needs an `extends object` constraint.
     }
     
     declare function Link<U>(l: {func: (arg: U)=>void}): JSX.Element;
diff --git a/tests/baselines/reference/typeParametersShouldNotBeEqual.errors.txt b/tests/baselines/reference/typeParametersShouldNotBeEqual.errors.txt
@@ -22,5 +22,6 @@ tests/cases/compiler/typeParametersShouldNotBeEqual.ts(6,5): error TS2322: Type
         z = x;  // Ok
         ~
 !!! error TS2322: Type 'T' is not assignable to type 'Object'.
+!!! related TS2797 tests/cases/compiler/typeParametersShouldNotBeEqual.ts:1:13: This type parameter likely needs an `extends object` constraint.
     }
     
diff --git a/tests/baselines/reference/unknownType1.errors.txt b/tests/baselines/reference/unknownType1.errors.txt
@@ -259,6 +259,7 @@ tests/cases/conformance/types/unknown/unknownType1.ts(181,5): error TS2322: Type
         let x: {} = t;
             ~
 !!! error TS2322: Type 'T' is not assignable to type '{}'.
+!!! related TS2797 tests/cases/conformance/types/unknown/unknownType1.ts:169:14: This type parameter likely needs an `extends object` constraint.
         let y: {} = u;
             ~
 !!! error TS2322: Type 'U' is not assignable to type '{}'.

Original file line number	Diff line number	Diff line change
`@@ -16918,6 +16918,9 @@ namespace ts {`
`16918`	`16918`	`return result;`
`16919`	`16919`	`}`
`16920`	`16920`	`reportRelationError(headMessage, source, target);`
	`16921`	`+ if (source.flags & TypeFlags.TypeVariable && source.symbol?.declarations?.[0] && !getConstraintOfType(<TypeVariable>source) && isRelatedTo(emptyObjectType, extractTypesOfKind(target, ~TypeFlags.NonPrimitive))) {`
	`16922`	`+ associateRelatedInfo(createDiagnosticForNode(source.symbol.declarations[0], Diagnostics.This_type_parameter_likely_needs_an_extends_object_constraint));`
	`16923`	`+ }`
`16921`	`16924`	`}`
`16922`	`16925`	`}`
`16923`	`16926`	`}`
Original file line number	Diff line number	Diff line change
`@@ -31,4 +31,5 @@ tests/cases/conformance/types/typeRelationships/bestCommonType/bestCommonTypeOfC`
`31`	`31`	`~~~~~~~~~~~~~~~~~~~~`
`32`	`32`	`!!! error TS2322: Type 'T \| U' is not assignable to type 'Object'.`
`33`	`33`	`!!! error TS2322: Type 'T' is not assignable to type 'Object'.`
	`34`	+!!! related TS2797 tests/cases/conformance/types/typeRelationships/bestCommonType/bestCommonTypeOfConditionalExpressions.ts:24:15: This type parameter likely needs an `extends object` constraint.
`34`	`35`	`}`
Original file line number	Diff line number	Diff line change
`@@ -298,6 +298,7 @@ tests/cases/compiler/immutable.ts(391,22): error TS2430: Interface 'Set<T>' inco`
`298`	`298`	`export function Record<T>(defaultValues: T, name?: string): Record.Class<T>;`
`299`	`299`	`~`
`300`	`300`	`!!! error TS2344: Type 'T' does not satisfy the constraint 'Object'.`
	`301`	+!!! related TS2797 tests/cases/compiler/immutable.ts:261:26: This type parameter likely needs an `extends object` constraint.
`301`	`302`	`export module Seq {`
`302`	`303`	`function isSeq(maybeSeq: any): maybeSeq is Seq.Indexed<any> \| Seq.Keyed<any, any>;`
`303`	`304`	`function of<T>(...values: Array<T>): Seq.Indexed<T>;`
Original file line number	Diff line number	Diff line change
`@@ -20,6 +20,7 @@ tests/cases/compiler/constructorReturningAPrimitive.ts(15,9): error TS2409: Retu`
`20`	`20`	`return x;`
`21`	`21`	`~~~~~~~~~`
`22`	`22`	`!!! error TS2322: Type 'T' is not assignable to type 'B<T>'.`
	`23`	+!!! related TS2797 tests/cases/compiler/constructorReturningAPrimitive.ts:12:9: This type parameter likely needs an `extends object` constraint.
`23`	`24`	`~~~~~~~~~`
`24`	`25`	`!!! error TS2409: Return type of constructor signature must be assignable to the instance type of the class.`
`25`	`26`	`}`
Original file line number	Diff line number	Diff line change
`@@ -356,6 +356,7 @@ tests/cases/conformance/types/keyof/keyofAndIndexedAccess.ts(619,13): error TS23`
`356`	`356`	`a = x;`
`357`	`357`	`~`
`358`	`358`	`!!! error TS2322: Type 'T' is not assignable to type '{}'.`
	`359`	+!!! related TS2797 tests/cases/conformance/types/keyof/keyofAndIndexedAccess.ts:314:14: This type parameter likely needs an `extends object` constraint.
`359`	`360`	`a = y;`
`360`	`361`	`~`
`361`	`362`	`!!! error TS2322: Type 'T[keyof T]' is not assignable to type '{}'.`
`@@ -373,6 +374,8 @@ tests/cases/conformance/types/keyof/keyofAndIndexedAccess.ts(619,13): error TS23`
`373`	`374`	`~`
`374`	`375`	`!!! error TS2322: Type 'T' is not assignable to type '{} \| null \| undefined'.`
`375`	`376`	`!!! error TS2322: Type 'T' is not assignable to type '{}'.`
	`377`	+!!! related TS2797 tests/cases/conformance/types/keyof/keyofAndIndexedAccess.ts:321:14: This type parameter likely needs an `extends object` constraint.
	`378`	+!!! related TS2797 tests/cases/conformance/types/keyof/keyofAndIndexedAccess.ts:321:14: This type parameter likely needs an `extends object` constraint.
`376`	`379`	`a = y;`
`377`	`380`	`~`
`378`	`381`	`!!! error TS2322: Type 'T[keyof T]' is not assignable to type '{} \| null \| undefined'.`
Original file line number	Diff line number	Diff line change
`@@ -13,6 +13,7 @@ tests/cases/conformance/expressions/binaryOperators/logicalOrOperator/logicalOrO`
`13`	`13`	`~~`
`14`	`14`	`!!! error TS2322: Type 'T \| U' is not assignable to type '{}'.`
`15`	`15`	`!!! error TS2322: Type 'T' is not assignable to type '{}'.`
	`16`	+!!! related TS2797 tests/cases/conformance/expressions/binaryOperators/logicalOrOperator/logicalOrOperatorWithTypeParameters.ts:1:14: This type parameter likely needs an `extends object` constraint.
`16`	`17`	`}`
`17`	`18`
`18`	`19`	`function fn2<T, U/* extends T/, V/ extends T*/>(t: T, u: U, v: V) {`
`@@ -25,6 +26,7 @@ tests/cases/conformance/expressions/binaryOperators/logicalOrOperator/logicalOrO`
`25`	`26`	`~~`
`26`	`27`	`!!! error TS2322: Type 'U \| V' is not assignable to type '{}'.`
`27`	`28`	`!!! error TS2322: Type 'U' is not assignable to type '{}'.`
	`29`	+!!! related TS2797 tests/cases/conformance/expressions/binaryOperators/logicalOrOperator/logicalOrOperatorWithTypeParameters.ts:8:17: This type parameter likely needs an `extends object` constraint.
`28`	`30`	`//var r7: T = u \|\| v;`
`29`	`31`	`}`
`30`	`32`
Original file line number	Diff line number	Diff line change
`@@ -33,6 +33,7 @@ tests/cases/conformance/types/mapped/mappedTypesAndObjects.ts(25,11): error TS24`
`33`	`33`	`!!! error TS2430: Interface 'E1<T>' incorrectly extends interface 'Base'.`
`34`	`34`	`!!! error TS2430: Types of property 'foo' are incompatible.`
`35`	`35`	`!!! error TS2430: Type 'T' is not assignable to type '{ [key: string]: any; }'.`
	`36`	+!!! related TS2797 tests/cases/conformance/types/mapped/mappedTypesAndObjects.ts:25:14: This type parameter likely needs an `extends object` constraint.
`36`	`37`	`foo: T;`
`37`	`38`	`}`
`38`	`39`
Original file line number	Diff line number	Diff line change
`@@ -8,6 +8,7 @@ tests/cases/compiler/tile1.ts(11,40): error TS2344: Type 'State' does not satisf`
`8`	`8`	`oninit?(vnode: Vnode<Attrs, State>): number;`
`9`	`9`	`~~~~~`
`10`	`10`	`!!! error TS2344: Type 'State' does not satisfy the constraint 'Lifecycle<Attrs, State>'.`
	`11`	+!!! related TS2797 tests/cases/compiler/tile1.ts:1:28: This type parameter likely needs an `extends object` constraint.
`11`	`12`	`[_: number]: any;`
`12`	`13`	`}`
`13`	`14`
`@@ -21,6 +22,7 @@ tests/cases/compiler/tile1.ts(11,40): error TS2344: Type 'State' does not satisf`
`21`	`22`	`view(this: State, vnode: Vnode<Attrs, State>): number;`
`22`	`23`	`~~~~~`
`23`	`24`	`!!! error TS2344: Type 'State' does not satisfy the constraint 'Lifecycle<Attrs, State>'.`
	`25`	+!!! related TS2797 tests/cases/compiler/tile1.ts:10:28: This type parameter likely needs an `extends object` constraint.
`24`	`26`	`}`
`25`	`27`
`26`	`28`	`interface ClassComponent<A> extends Lifecycle<A, ClassComponent<A>> {`
Original file line number	Diff line number	Diff line change
`@@ -9,6 +9,7 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingW`
`9`	`9`	`var b: { s?: number } = a;`
`10`	`10`	`~`
`11`	`11`	`!!! error TS2322: Type 'T' is not assignable to type '{ s?: number; }'.`
	`12`	+!!! related TS2797 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypingWithOptionalProperties.ts:4:12: This type parameter likely needs an `extends object` constraint.
`12`	`13`	`return b;`
`13`	`14`	`}`
`14`	`15`
Original file line number	Diff line number	Diff line change
`@@ -17,6 +17,7 @@ tests/cases/conformance/jsx/file.tsx(9,5): error TS2416: Property 'props' in typ`
`17`	`17`	`!!! error TS2416: Property 'props' in type 'B<U>' is not assignable to the same property in base type 'Component<U, {}>'.`
`18`	`18`	`!!! error TS2416: Type 'U' is not assignable to type 'U & { children?: ReactNode; }'.`
`19`	`19`	`!!! error TS2416: Type 'U' is not assignable to type '{ children?: ReactNode; }'.`
	`20`	+!!! related TS2797 tests/cases/conformance/jsx/file.tsx:8:9: This type parameter likely needs an `extends object` constraint.
`20`	`21`	`render() {`
`21`	`22`	`return <B1 {...this.props} x="hi" />;`
`22`	`23`	`}`