Add related info suggesting a fix

Author: weswigham

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));
+                        }
                     }
                 }
             }

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",

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.
     }

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>;

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.
         }

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;
     }
 

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;
     }
 

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>> {

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;
     }
 

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" />;
         }