Merge pull request #4112 from Microsoft/nonObjectTypeConstraints

Support non-object type constraints

src/compiler/checker.ts

@@ -4668,19 +4668,21 @@ namespace ts {
                 let result: Ternary;
                 // both types are the same - covers 'they are the same primitive type or both are Any' or the same type parameter cases
                 if (source === target) return Ternary.True;
-                if (relation !== identityRelation) {
+                if (relation === identityRelation) {
-                    if (isTypeAny(target)) return Ternary.True;
+                    return isIdenticalTo(source, target);
-                    if (source === undefinedType) return Ternary.True;
-                    if (source === nullType && target !== undefinedType) return Ternary.True;
-                    if (source.flags & TypeFlags.Enum && target === numberType) return Ternary.True;
-                    if (source.flags & TypeFlags.StringLiteral && target === stringType) return Ternary.True;
-                    if (relation === assignableRelation) {
-                        if (isTypeAny(source)) return Ternary.True;
-                        if (source === numberType && target.flags & TypeFlags.Enum) return Ternary.True;
-                    }
                 }
 
-                if (relation !== identityRelation && source.flags & TypeFlags.FreshObjectLiteral) {
+                if (isTypeAny(target)) return Ternary.True;
+                if (source === undefinedType) return Ternary.True;
+                if (source === nullType && target !== undefinedType) return Ternary.True;
+                if (source.flags & TypeFlags.Enum && target === numberType) return Ternary.True;
+                if (source.flags & TypeFlags.StringLiteral && target === stringType) return Ternary.True;
+                if (relation === assignableRelation) {
+                    if (isTypeAny(source)) return Ternary.True;
+                    if (source === numberType && target.flags & TypeFlags.Enum) return Ternary.True;
+                }
+
+                if (source.flags & TypeFlags.FreshObjectLiteral) {
                     if (hasExcessProperties(<FreshObjectLiteralType>source, target, reportErrors)) {
                         if (reportErrors) {
                             reportRelationError(headMessage, source, target);
@@ -4696,78 +4698,66 @@ namespace ts {
 
                 let saveErrorInfo = errorInfo;
 
-                if (source.flags & TypeFlags.Reference && target.flags & TypeFlags.Reference && (<TypeReference>source).target === (<TypeReference>target).target) {
+                // Note that the "each" checks must precede the "some" checks to produce the correct results
-                    // We have type references to same target type, see if relationship holds for all type arguments
+                if (source.flags & TypeFlags.Union) {
-                    if (result = typesRelatedTo((<TypeReference>source).typeArguments, (<TypeReference>target).typeArguments, reportErrors)) {
+                    if (result = eachTypeRelatedToType(<UnionType>source, target, reportErrors)) {
                         return result;
                     }
                 }
-                else if (source.flags & TypeFlags.TypeParameter && target.flags & TypeFlags.TypeParameter) {
+                else if (target.flags & TypeFlags.Intersection) {
-                    if (result = typeParameterRelatedTo(<TypeParameter>source, <TypeParameter>target, reportErrors)) {
+                    if (result = typeRelatedToEachType(source, <IntersectionType>target, reportErrors)) {
                         return result;
                     }
                 }
-                else if (relation !== identityRelation) {
-                    // Note that the "each" checks must precede the "some" checks to produce the correct results
-                    if (source.flags & TypeFlags.Union) {
-                        if (result = eachTypeRelatedToType(<UnionType>source, target, reportErrors)) {
-                            return result;
-                        }
-                    }
-                    else if (target.flags & TypeFlags.Intersection) {
-                        if (result = typeRelatedToEachType(source, <IntersectionType>target, reportErrors)) {
-                            return result;
-                        }
-                    }
-                    else {
-                        // It is necessary to try "each" checks on both sides because there may be nested "some" checks
-                        // on either side that need to be prioritized. For example, A | B = (A | B) & (C | D) or
-                        // A & B = (A & B) | (C & D).
-                        if (source.flags & TypeFlags.Intersection) {
-                            // If target is a union type the following check will report errors so we suppress them here
-                            if (result = someTypeRelatedToType(<IntersectionType>source, target, reportErrors && !(target.flags & TypeFlags.Union))) {
-                                return result;
-                            }
-                        }
-                        if (target.flags & TypeFlags.Union) {
-                            if (result = typeRelatedToSomeType(source, <UnionType>target, reportErrors)) {
-                                return result;
-                            }
-                        }
-                    }
-                }
                 else {
-                    if (source.flags & TypeFlags.Union && target.flags & TypeFlags.Union ||
+                    // It is necessary to try "some" checks on both sides because there may be nested "each" checks
-                        source.flags & TypeFlags.Intersection && target.flags & TypeFlags.Intersection) {
+                    // on either side that need to be prioritized. For example, A | B = (A | B) & (C | D) or
-                        if (result = eachTypeRelatedToSomeType(<UnionOrIntersectionType>source, <UnionOrIntersectionType>target)) {
+                    // A & B = (A & B) | (C & D).
-                            if (result &= eachTypeRelatedToSomeType(<UnionOrIntersectionType>target, <UnionOrIntersectionType>source)) {
+                    if (source.flags & TypeFlags.Intersection) {
-                                return result;
+                        // If target is a union type the following check will report errors so we suppress them here
-                            }
+                        if (result = someTypeRelatedToType(<IntersectionType>source, target, reportErrors && !(target.flags & TypeFlags.Union))) {
+                            return result;
+                        }
+                    }
+                    if (target.flags & TypeFlags.Union) {
+                        if (result = typeRelatedToSomeType(source, <UnionType>target, reportErrors)) {
+                            return result;
                         }
                     }
                 }
 
-                // Even if relationship doesn't hold for unions, type parameters, or generic type references,
+                if (source.flags & TypeFlags.TypeParameter) {
-                // it may hold in a structural comparison.
+                    let constraint = getConstraintOfTypeParameter(<TypeParameter>source);
-                // Report structural errors only if we haven't reported any errors yet
+                    if (!constraint || constraint.flags & TypeFlags.Any) {
-                let reportStructuralErrors = reportErrors && errorInfo === saveErrorInfo;
+                        constraint = emptyObjectType;
-                // Identity relation does not use apparent type
+                    }
-                let sourceOrApparentType = relation === identityRelation ? source : getApparentType(source);
+                    // Report constraint errors only if the constraint is not the empty object type
-                // In a check of the form X = A & B, we will have previously checked if A relates to X or B relates
+                    let reportConstraintErrors = reportErrors && constraint !== emptyObjectType;
-                // to X. Failing both of those we want to check if the aggregation of A and B's members structurally
+                    if (result = isRelatedTo(constraint, target, reportConstraintErrors)) {
-                // relates to X. Thus, we include intersection types on the source side here.
-                if (sourceOrApparentType.flags & (TypeFlags.ObjectType | TypeFlags.Intersection) && target.flags & TypeFlags.ObjectType) {
-                    if (result = objectTypeRelatedTo(sourceOrApparentType, <ObjectType>target, reportStructuralErrors)) {
                         errorInfo = saveErrorInfo;
                         return result;
                     }
                 }
-                else if (source.flags & TypeFlags.TypeParameter && sourceOrApparentType.flags & TypeFlags.UnionOrIntersection) {
+                else {
-                    // We clear the errors first because the following check often gives a better error than
+                    if (source.flags & TypeFlags.Reference && target.flags & TypeFlags.Reference && (<TypeReference>source).target === (<TypeReference>target).target) {
-                    // the union or intersection comparison above if it is applicable.
+                        // We have type references to same target type, see if relationship holds for all type arguments
-                    errorInfo = saveErrorInfo;
+                        if (result = typesRelatedTo((<TypeReference>source).typeArguments, (<TypeReference>target).typeArguments, reportErrors)) {
-                    if (result = isRelatedTo(sourceOrApparentType, target, reportErrors)) {
+                            return result;
-                        return result;
+                        }
+                    }
+                    // Even if relationship doesn't hold for unions, intersections, or generic type references,
+                    // it may hold in a structural comparison.
+                    let apparentType = getApparentType(source);
+                    // In a check of the form X = A & B, we will have previously checked if A relates to X or B relates
+                    // to X. Failing both of those we want to check if the aggregation of A and B's members structurally
+                    // relates to X. Thus, we include intersection types on the source side here.
+                    if (apparentType.flags & (TypeFlags.ObjectType | TypeFlags.Intersection) && target.flags & TypeFlags.ObjectType) {
+                        // Report structural errors only if we haven't reported any errors yet
+                        let reportStructuralErrors = reportErrors && errorInfo === saveErrorInfo;
+                        if (result = objectTypeRelatedTo(apparentType, <ObjectType>target, reportStructuralErrors)) {
+                            errorInfo = saveErrorInfo;
+                            return result;
+                        }
                     }
                 }
 
@@ -4777,6 +4767,31 @@ namespace ts {
                 return Ternary.False;
             }
 
+            function isIdenticalTo(source: Type, target: Type): Ternary {
+                let result: Ternary;
+                if (source.flags & TypeFlags.ObjectType && target.flags & TypeFlags.ObjectType) {
+                    if (source.flags & TypeFlags.Reference && target.flags & TypeFlags.Reference && (<TypeReference>source).target === (<TypeReference>target).target) {
+                        // We have type references to same target type, see if all type arguments are identical
+                        if (result = typesRelatedTo((<TypeReference>source).typeArguments, (<TypeReference>target).typeArguments, /*reportErrors*/ false)) {
+                            return result;
+                        }
+                    }
+                    return objectTypeRelatedTo(<ObjectType>source, <ObjectType>target, /*reportErrors*/ false);
+                }
+                if (source.flags & TypeFlags.TypeParameter && target.flags & TypeFlags.TypeParameter) {
+                    return typeParameterIdenticalTo(<TypeParameter>source, <TypeParameter>target);
+                }
+                if (source.flags & TypeFlags.Union && target.flags & TypeFlags.Union ||
+                    source.flags & TypeFlags.Intersection && target.flags & TypeFlags.Intersection) {
+                    if (result = eachTypeRelatedToSomeType(<UnionOrIntersectionType>source, <UnionOrIntersectionType>target)) {
+                        if (result &= eachTypeRelatedToSomeType(<UnionOrIntersectionType>target, <UnionOrIntersectionType>source)) {
+                            return result;
+                        }
+                    }
+                }
+                return Ternary.False;
+            }
+
             function hasExcessProperties(source: FreshObjectLiteralType, target: Type, reportErrors: boolean): boolean {
                 for (let prop of getPropertiesOfObjectType(source)) {
                     if (!isKnownProperty(target, prop.name)) {
@@ -4861,29 +4876,18 @@ namespace ts {
                 return result;
             }
 
-            function typeParameterRelatedTo(source: TypeParameter, target: TypeParameter, reportErrors: boolean): Ternary {
+            function typeParameterIdenticalTo(source: TypeParameter, target: TypeParameter): Ternary {
-                if (relation === identityRelation) {
+                if (source.symbol.name !== target.symbol.name) {
-                    if (source.symbol.name !== target.symbol.name) {
-                        return Ternary.False;
-                    }
-                    // covers case when both type parameters does not have constraint (both equal to noConstraintType)
-                    if (source.constraint === target.constraint) {
-                        return Ternary.True;
-                    }
-                    if (source.constraint === noConstraintType || target.constraint === noConstraintType) {
-                        return Ternary.False;
-                    }
-                    return isRelatedTo(source.constraint, target.constraint, reportErrors);
-                }
-                else {
-                    while (true) {
-                        let constraint = getConstraintOfTypeParameter(source);
-                        if (constraint === target) return Ternary.True;
-                        if (!(constraint && constraint.flags & TypeFlags.TypeParameter)) break;
-                        source = <TypeParameter>constraint;
-                    }
                     return Ternary.False;
                 }
+                // covers case when both type parameters does not have constraint (both equal to noConstraintType)
+                if (source.constraint === target.constraint) {
+                    return Ternary.True;
+                }
+                if (source.constraint === noConstraintType || target.constraint === noConstraintType) {
+                    return Ternary.False;
+                }
+                return isIdenticalTo(source.constraint, target.constraint);
             }
 
             // Determine if two object types are related by structure. First, check if the result is already available in the global cache.

tests/baselines/reference/apparentTypeSupertype.errors.txt

@@ -1,6 +1,7 @@
 tests/cases/conformance/types/typeRelationships/apparentType/apparentTypeSupertype.ts(9,7): error TS2415: Class 'Derived<U>' incorrectly extends base class 'Base'.
   Types of property 'x' are incompatible.
     Type 'U' is not assignable to type 'string'.
+      Type 'String' is not assignable to type 'string'.
 
 
 ==== tests/cases/conformance/types/typeRelationships/apparentType/apparentTypeSupertype.ts (1 errors) ====
@@ -17,5 +18,6 @@ tests/cases/conformance/types/typeRelationships/apparentType/apparentTypeSuperty
 !!! error TS2415: Class 'Derived<U>' incorrectly extends base class 'Base'.
 !!! error TS2415:   Types of property 'x' are incompatible.
 !!! error TS2415:     Type 'U' is not assignable to type 'string'.
+!!! error TS2415:       Type 'String' is not assignable to type 'string'.
         x: U;
     }

tests/baselines/reference/assignmentCompatWithNumericIndexer.errors.txt

@@ -12,12 +12,14 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithNumericIndexer.ts(33,9): error TS2322: Type 'A<T>' is not assignable to type '{ [x: number]: Derived; }'.
   Index signatures are incompatible.
     Type 'T' is not assignable to type 'Derived'.
+      Type 'Base' is not assignable to type 'Derived'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithNumericIndexer.ts(36,9): error TS2322: Type '{ [x: number]: Derived2; }' is not assignable to type 'A<T>'.
   Index signatures are incompatible.
     Type 'Derived2' is not assignable to type 'T'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithNumericIndexer.ts(37,9): error TS2322: Type 'A<T>' is not assignable to type '{ [x: number]: Derived2; }'.
   Index signatures are incompatible.
     Type 'T' is not assignable to type 'Derived2'.
+      Type 'Base' is not assignable to type 'Derived2'.
 
 
 ==== tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithNumericIndexer.ts (6 errors) ====
@@ -72,6 +74,7 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
 !!! error TS2322: Type 'A<T>' is not assignable to type '{ [x: number]: Derived; }'.
 !!! error TS2322:   Index signatures are incompatible.
 !!! error TS2322:     Type 'T' is not assignable to type 'Derived'.
+!!! error TS2322:       Type 'Base' is not assignable to type 'Derived'.
     
             var b2: { [x: number]: Derived2; }
             a = b2; // error
@@ -84,6 +87,7 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
 !!! error TS2322: Type 'A<T>' is not assignable to type '{ [x: number]: Derived2; }'.
 !!! error TS2322:   Index signatures are incompatible.
 !!! error TS2322:     Type 'T' is not assignable to type 'Derived2'.
+!!! error TS2322:       Type 'Base' is not assignable to type 'Derived2'.
     
             var b3: { [x: number]: T; }
             a = b3; // ok

tests/baselines/reference/assignmentCompatWithNumericIndexer2.errors.txt

@@ -12,12 +12,14 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithNumericIndexer2.ts(33,9): error TS2322: Type 'A<T>' is not assignable to type '{ [x: number]: Derived; }'.
   Index signatures are incompatible.
     Type 'T' is not assignable to type 'Derived'.
+      Type 'Base' is not assignable to type 'Derived'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithNumericIndexer2.ts(36,9): error TS2322: Type '{ [x: number]: Derived2; }' is not assignable to type 'A<T>'.
   Index signatures are incompatible.
     Type 'Derived2' is not assignable to type 'T'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithNumericIndexer2.ts(37,9): error TS2322: Type 'A<T>' is not assignable to type '{ [x: number]: Derived2; }'.
   Index signatures are incompatible.
     Type 'T' is not assignable to type 'Derived2'.
+      Type 'Base' is not assignable to type 'Derived2'.
 
 
 ==== tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithNumericIndexer2.ts (6 errors) ====
@@ -72,6 +74,7 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
 !!! error TS2322: Type 'A<T>' is not assignable to type '{ [x: number]: Derived; }'.
 !!! error TS2322:   Index signatures are incompatible.
 !!! error TS2322:     Type 'T' is not assignable to type 'Derived'.
+!!! error TS2322:       Type 'Base' is not assignable to type 'Derived'.
     
             var b2: { [x: number]: Derived2; }
             a = b2; // error
@@ -84,6 +87,7 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
 !!! error TS2322: Type 'A<T>' is not assignable to type '{ [x: number]: Derived2; }'.
 !!! error TS2322:   Index signatures are incompatible.
 !!! error TS2322:     Type 'T' is not assignable to type 'Derived2'.
+!!! error TS2322:       Type 'Base' is not assignable to type 'Derived2'.
     
             var b3: { [x: number]: T; }
             a = b3; // ok

tests/baselines/reference/assignmentCompatWithStringIndexer.errors.txt

@@ -18,12 +18,14 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithStringIndexer.ts(47,9): error TS2322: Type 'A<T>' is not assignable to type '{ [x: string]: Derived; }'.
   Index signatures are incompatible.
     Type 'T' is not assignable to type 'Derived'.
+      Type 'Base' is not assignable to type 'Derived'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithStringIndexer.ts(50,9): error TS2322: Type '{ [x: string]: Derived2; }' is not assignable to type 'A<T>'.
   Index signatures are incompatible.
     Type 'Derived2' is not assignable to type 'T'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithStringIndexer.ts(51,9): error TS2322: Type 'A<T>' is not assignable to type '{ [x: string]: Derived2; }'.
   Index signatures are incompatible.
     Type 'T' is not assignable to type 'Derived2'.
+      Type 'Base' is not assignable to type 'Derived2'.
 
 
 ==== tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithStringIndexer.ts (8 errors) ====
@@ -100,6 +102,7 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
 !!! error TS2322: Type 'A<T>' is not assignable to type '{ [x: string]: Derived; }'.
 !!! error TS2322:   Index signatures are incompatible.
 !!! error TS2322:     Type 'T' is not assignable to type 'Derived'.
+!!! error TS2322:       Type 'Base' is not assignable to type 'Derived'.
     
             var b4: { [x: string]: Derived2; };
             a3 = b4; // error
@@ -112,5 +115,6 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
 !!! error TS2322: Type 'A<T>' is not assignable to type '{ [x: string]: Derived2; }'.
 !!! error TS2322:   Index signatures are incompatible.
 !!! error TS2322:     Type 'T' is not assignable to type 'Derived2'.
+!!! error TS2322:       Type 'Base' is not assignable to type 'Derived2'.
         }
     }

tests/baselines/reference/assignmentCompatWithStringIndexer2.errors.txt

@@ -18,12 +18,14 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithStringIndexer2.ts(47,9): error TS2322: Type 'A<T>' is not assignable to type '{ [x: string]: Derived; }'.
   Index signatures are incompatible.
     Type 'T' is not assignable to type 'Derived'.
+      Type 'Base' is not assignable to type 'Derived'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithStringIndexer2.ts(50,9): error TS2322: Type '{ [x: string]: Derived2; }' is not assignable to type 'A<T>'.
   Index signatures are incompatible.
     Type 'Derived2' is not assignable to type 'T'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithStringIndexer2.ts(51,9): error TS2322: Type 'A<T>' is not assignable to type '{ [x: string]: Derived2; }'.
   Index signatures are incompatible.
     Type 'T' is not assignable to type 'Derived2'.
+      Type 'Base' is not assignable to type 'Derived2'.
 
 
 ==== tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithStringIndexer2.ts (8 errors) ====
@@ -100,6 +102,7 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
 !!! error TS2322: Type 'A<T>' is not assignable to type '{ [x: string]: Derived; }'.
 !!! error TS2322:   Index signatures are incompatible.
 !!! error TS2322:     Type 'T' is not assignable to type 'Derived'.
+!!! error TS2322:       Type 'Base' is not assignable to type 'Derived'.
     
             var b4: { [x: string]: Derived2; };
             a3 = b4; // error
@@ -112,5 +115,6 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
 !!! error TS2322: Type 'A<T>' is not assignable to type '{ [x: string]: Derived2; }'.
 !!! error TS2322:   Index signatures are incompatible.
 !!! error TS2322:     Type 'T' is not assignable to type 'Derived2'.
+!!! error TS2322:       Type 'Base' is not assignable to type 'Derived2'.
         }
     }

tests/baselines/reference/assignmentCompatWithStringIndexer3.errors.txt

@@ -5,6 +5,7 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithStringIndexer3.ts(21,9): error TS2322: Type 'A<T>' is not assignable to type '{ [x: string]: string; }'.
   Index signatures are incompatible.
     Type 'T' is not assignable to type 'string'.
+      Type 'Derived' is not assignable to type 'string'.
 
 
 ==== tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignmentCompatWithStringIndexer3.ts (3 errors) ====
@@ -39,5 +40,6 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/assignme
 !!! error TS2322: Type 'A<T>' is not assignable to type '{ [x: string]: string; }'.
 !!! error TS2322:   Index signatures are incompatible.
 !!! error TS2322:     Type 'T' is not assignable to type 'string'.
+!!! error TS2322:       Type 'Derived' is not assignable to type 'string'.
         }
     }

tests/baselines/reference/assignmentNonObjectTypeConstraints.js

@@ -0,0 +1,42 @@
+//// [assignmentNonObjectTypeConstraints.ts]
+const enum E { A, B, C }
+
+function foo<T extends number>(x: T) {
+    var y: number = x;  // Ok
+}
+
+foo(5);
+foo(E.A);
+
+class A { a }
+class B { b }
+
+function bar<T extends A | B>(x: T) {
+    var y: A | B = x;  // Ok
+}
+
+bar(new A);
+bar(new B);
+
+
+//// [assignmentNonObjectTypeConstraints.js]
+function foo(x) {
+    var y = x; // Ok
+}
+foo(5);
+foo(0 /* A */);
+var A = (function () {
+    function A() {
+    }
+    return A;
+})();
+var B = (function () {
+    function B() {
+    }
+    return B;
+})();
+function bar(x) {
+    var y = x; // Ok
+}
+bar(new A);
+bar(new B);

tests/baselines/reference/assignmentNonObjectTypeConstraints.symbols

@@ -0,0 +1,58 @@
+=== tests/cases/compiler/assignmentNonObjectTypeConstraints.ts ===
+const enum E { A, B, C }
+>E : Symbol(E, Decl(assignmentNonObjectTypeConstraints.ts, 0, 0))
+>A : Symbol(E.A, Decl(assignmentNonObjectTypeConstraints.ts, 0, 14))
+>B : Symbol(E.B, Decl(assignmentNonObjectTypeConstraints.ts, 0, 17))
+>C : Symbol(E.C, Decl(assignmentNonObjectTypeConstraints.ts, 0, 20))
+
+function foo<T extends number>(x: T) {
+>foo : Symbol(foo, Decl(assignmentNonObjectTypeConstraints.ts, 0, 24))
+>T : Symbol(T, Decl(assignmentNonObjectTypeConstraints.ts, 2, 13))
+>x : Symbol(x, Decl(assignmentNonObjectTypeConstraints.ts, 2, 31))
+>T : Symbol(T, Decl(assignmentNonObjectTypeConstraints.ts, 2, 13))
+
+    var y: number = x;  // Ok
+>y : Symbol(y, Decl(assignmentNonObjectTypeConstraints.ts, 3, 7))
+>x : Symbol(x, Decl(assignmentNonObjectTypeConstraints.ts, 2, 31))
+}
+
+foo(5);
+>foo : Symbol(foo, Decl(assignmentNonObjectTypeConstraints.ts, 0, 24))
+
+foo(E.A);
+>foo : Symbol(foo, Decl(assignmentNonObjectTypeConstraints.ts, 0, 24))
+>E.A : Symbol(E.A, Decl(assignmentNonObjectTypeConstraints.ts, 0, 14))
+>E : Symbol(E, Decl(assignmentNonObjectTypeConstraints.ts, 0, 0))
+>A : Symbol(E.A, Decl(assignmentNonObjectTypeConstraints.ts, 0, 14))
+
+class A { a }
+>A : Symbol(A, Decl(assignmentNonObjectTypeConstraints.ts, 7, 9))
+>a : Symbol(a, Decl(assignmentNonObjectTypeConstraints.ts, 9, 9))
+
+class B { b }
+>B : Symbol(B, Decl(assignmentNonObjectTypeConstraints.ts, 9, 13))
+>b : Symbol(b, Decl(assignmentNonObjectTypeConstraints.ts, 10, 9))
+
+function bar<T extends A | B>(x: T) {
+>bar : Symbol(bar, Decl(assignmentNonObjectTypeConstraints.ts, 10, 13))
+>T : Symbol(T, Decl(assignmentNonObjectTypeConstraints.ts, 12, 13))
+>A : Symbol(A, Decl(assignmentNonObjectTypeConstraints.ts, 7, 9))
+>B : Symbol(B, Decl(assignmentNonObjectTypeConstraints.ts, 9, 13))
+>x : Symbol(x, Decl(assignmentNonObjectTypeConstraints.ts, 12, 30))
+>T : Symbol(T, Decl(assignmentNonObjectTypeConstraints.ts, 12, 13))
+
+    var y: A | B = x;  // Ok
+>y : Symbol(y, Decl(assignmentNonObjectTypeConstraints.ts, 13, 7))
+>A : Symbol(A, Decl(assignmentNonObjectTypeConstraints.ts, 7, 9))
+>B : Symbol(B, Decl(assignmentNonObjectTypeConstraints.ts, 9, 13))
+>x : Symbol(x, Decl(assignmentNonObjectTypeConstraints.ts, 12, 30))
+}
+
+bar(new A);
+>bar : Symbol(bar, Decl(assignmentNonObjectTypeConstraints.ts, 10, 13))
+>A : Symbol(A, Decl(assignmentNonObjectTypeConstraints.ts, 7, 9))
+
+bar(new B);
+>bar : Symbol(bar, Decl(assignmentNonObjectTypeConstraints.ts, 10, 13))
+>B : Symbol(B, Decl(assignmentNonObjectTypeConstraints.ts, 9, 13))
+

tests/baselines/reference/assignmentNonObjectTypeConstraints.types

@@ -0,0 +1,65 @@
+=== tests/cases/compiler/assignmentNonObjectTypeConstraints.ts ===
+const enum E { A, B, C }
+>E : E
+>A : E
+>B : E
+>C : E
+
+function foo<T extends number>(x: T) {
+>foo : <T extends number>(x: T) => void
+>T : T
+>x : T
+>T : T
+
+    var y: number = x;  // Ok
+>y : number
+>x : T
+}
+
+foo(5);
+>foo(5) : void
+>foo : <T extends number>(x: T) => void
+>5 : number
+
+foo(E.A);
+>foo(E.A) : void
+>foo : <T extends number>(x: T) => void
+>E.A : E
+>E : typeof E
+>A : E
+
+class A { a }
+>A : A
+>a : any
+
+class B { b }
+>B : B
+>b : any
+
+function bar<T extends A | B>(x: T) {
+>bar : <T extends A | B>(x: T) => void
+>T : T
+>A : A
+>B : B
+>x : T
+>T : T
+
+    var y: A | B = x;  // Ok
+>y : A | B
+>A : A
+>B : B
+>x : T
+}
+
+bar(new A);
+>bar(new A) : void
+>bar : <T extends A | B>(x: T) => void
+>new A : A
+>A : typeof A
+
+bar(new B);
+>bar(new B) : void
+>bar : <T extends A | B>(x: T) => void
+>new B : B
+>B : typeof B
+

tests/baselines/reference/functionConstraintSatisfaction2.errors.txt

@@ -14,7 +14,7 @@ tests/cases/conformance/types/typeParameters/typeArgumentLists/functionConstrain
 tests/cases/conformance/types/typeParameters/typeArgumentLists/functionConstraintSatisfaction2.ts(34,16): error TS2345: Argument of type 'F2' is not assignable to parameter of type '(x: string) => string'.
 tests/cases/conformance/types/typeParameters/typeArgumentLists/functionConstraintSatisfaction2.ts(36,38): error TS2313: Constraint of a type parameter cannot reference any type parameter from the same type parameter list.
 tests/cases/conformance/types/typeParameters/typeArgumentLists/functionConstraintSatisfaction2.ts(37,10): error TS2345: Argument of type 'T' is not assignable to parameter of type '(x: string) => string'.
-  Type 'void' is not assignable to type 'string'.
+  Type '() => void' is not assignable to type '(x: string) => string'.
 tests/cases/conformance/types/typeParameters/typeArgumentLists/functionConstraintSatisfaction2.ts(38,10): error TS2345: Argument of type 'U' is not assignable to parameter of type '(x: string) => string'.
 
 
@@ -85,7 +85,7 @@ tests/cases/conformance/types/typeParameters/typeArgumentLists/functionConstrain
         foo2(x);
              ~
 !!! error TS2345: Argument of type 'T' is not assignable to parameter of type '(x: string) => string'.
-!!! error TS2345:   Type 'void' is not assignable to type 'string'.
+!!! error TS2345:   Type '() => void' is not assignable to type '(x: string) => string'.
         foo2(y);
              ~
 !!! error TS2345: Argument of type 'U' is not assignable to parameter of type '(x: string) => string'.

tests/baselines/reference/genericCallWithGenericSignatureArguments2.errors.txt

@@ -5,7 +5,8 @@ tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithGen
 tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithGenericSignatureArguments2.ts(25,23): error TS2345: Argument of type '(a: T) => T' is not assignable to parameter of type '(x: Date) => Date'.
   Types of parameters 'a' and 'x' are incompatible.
     Type 'T' is not assignable to type 'Date'.
-      Property 'toDateString' is missing in type 'RegExp'.
+      Type 'RegExp' is not assignable to type 'Date'.
+        Property 'toDateString' is missing in type 'RegExp'.
 tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithGenericSignatureArguments2.ts(37,36): error TS2345: Argument of type '(x: E) => F' is not assignable to parameter of type '(x: E) => E'.
   Type 'F' is not assignable to type 'E'.
 tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithGenericSignatureArguments2.ts(50,21): error TS2345: Argument of type 'Date' is not assignable to parameter of type 'T'.
@@ -13,6 +14,7 @@ tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithGen
 tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithGenericSignatureArguments2.ts(60,23): error TS2345: Argument of type '(a: T) => T' is not assignable to parameter of type '(x: Date) => Date'.
   Types of parameters 'a' and 'x' are incompatible.
     Type 'T' is not assignable to type 'Date'.
+      Type 'RegExp' is not assignable to type 'Date'.
 tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithGenericSignatureArguments2.ts(67,51): error TS2304: Cannot find name 'U'.
 tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithGenericSignatureArguments2.ts(67,57): error TS2304: Cannot find name 'U'.
 
@@ -54,7 +56,8 @@ tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithGen
 !!! error TS2345: Argument of type '(a: T) => T' is not assignable to parameter of type '(x: Date) => Date'.
 !!! error TS2345:   Types of parameters 'a' and 'x' are incompatible.
 !!! error TS2345:     Type 'T' is not assignable to type 'Date'.
-!!! error TS2345:       Property 'toDateString' is missing in type 'RegExp'.
+!!! error TS2345:       Type 'RegExp' is not assignable to type 'Date'.
+!!! error TS2345:         Property 'toDateString' is missing in type 'RegExp'.
             var r7b = foo2((a) => a, (b) => b); // valid, T is inferred to be Date
         }
     
@@ -101,6 +104,7 @@ tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithGen
 !!! error TS2345: Argument of type '(a: T) => T' is not assignable to parameter of type '(x: Date) => Date'.
 !!! error TS2345:   Types of parameters 'a' and 'x' are incompatible.
 !!! error TS2345:     Type 'T' is not assignable to type 'Date'.
+!!! error TS2345:       Type 'RegExp' is not assignable to type 'Date'.
             var r7b = foo2((a) => a, (b) => b); 
         }
     

tests/baselines/reference/genericCallWithObjectTypeArgsAndIndexersErrors.errors.txt

@@ -1,9 +1,8 @@
 tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithObjectTypeArgsAndIndexersErrors.ts(15,17): error TS2313: Constraint of a type parameter cannot reference any type parameter from the same type parameter list.
-tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithObjectTypeArgsAndIndexersErrors.ts(18,9): error TS2413: Numeric index type 'T' is not assignable to string index type 'Object'.
 tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithObjectTypeArgsAndIndexersErrors.ts(23,9): error TS2322: Type 'T' is not assignable to type 'U'.
 
 
-==== tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithObjectTypeArgsAndIndexersErrors.ts (3 errors) ====
+==== tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithObjectTypeArgsAndIndexersErrors.ts (2 errors) ====
     // Type inference infers from indexers in target type, error cases
     
     function foo<T>(x: T) {
@@ -24,8 +23,6 @@ tests/cases/conformance/types/typeRelationships/typeInference/genericCallWithObj
         var b: {
             [x: string]: Object;
             [x: number]: T;
-            ~~~~~~~~~~~~~~~
-!!! error TS2413: Numeric index type 'T' is not assignable to string index type 'Object'.
         };
         var r2 = foo(b);
         var d = r2[1];

tests/baselines/reference/genericTypeAssertions6.errors.txt

@@ -1,6 +1,7 @@
 tests/cases/compiler/genericTypeAssertions6.ts(8,13): error TS2352: Neither type 'U' nor type 'T' is assignable to the other.
 tests/cases/compiler/genericTypeAssertions6.ts(9,13): error TS2352: Neither type 'T' nor type 'U' is assignable to the other.
 tests/cases/compiler/genericTypeAssertions6.ts(19,17): error TS2352: Neither type 'U' nor type 'T' is assignable to the other.
+  Type 'Date' is not assignable to type 'T'.
 
 
 ==== tests/cases/compiler/genericTypeAssertions6.ts (3 errors) ====
@@ -29,6 +30,7 @@ tests/cases/compiler/genericTypeAssertions6.ts(19,17): error TS2352: Neither typ
             var e = <T><U>new Date();
                     ~~~~~~~~~~~~~~~~
 !!! error TS2352: Neither type 'U' nor type 'T' is assignable to the other.
+!!! error TS2352:   Type 'Date' is not assignable to type 'T'.
         }
     }
     

tests/baselines/reference/genericTypeWithNonGenericBaseMisMatch.errors.txt

@@ -3,8 +3,9 @@ tests/cases/compiler/genericTypeWithNonGenericBaseMisMatch.ts(4,7): error TS2420
     Type '(a: T) => void' is not assignable to type '(a: { a: number; }) => void'.
       Types of parameters 'a' and 'a' are incompatible.
         Type 'T' is not assignable to type '{ a: number; }'.
-          Types of property 'a' are incompatible.
+          Type '{ a: string; }' is not assignable to type '{ a: number; }'.
-            Type 'string' is not assignable to type 'number'.
+            Types of property 'a' are incompatible.
+              Type 'string' is not assignable to type 'number'.
 tests/cases/compiler/genericTypeWithNonGenericBaseMisMatch.ts(8,5): error TS2322: Type 'X<{ a: string; }>' is not assignable to type 'I'.
   Types of property 'f' are incompatible.
     Type '(a: { a: string; }) => void' is not assignable to type '(a: { a: number; }) => void'.
@@ -25,8 +26,9 @@ tests/cases/compiler/genericTypeWithNonGenericBaseMisMatch.ts(8,5): error TS2322
 !!! error TS2420:     Type '(a: T) => void' is not assignable to type '(a: { a: number; }) => void'.
 !!! error TS2420:       Types of parameters 'a' and 'a' are incompatible.
 !!! error TS2420:         Type 'T' is not assignable to type '{ a: number; }'.
-!!! error TS2420:           Types of property 'a' are incompatible.
+!!! error TS2420:           Type '{ a: string; }' is not assignable to type '{ a: number; }'.
-!!! error TS2420:             Type 'string' is not assignable to type 'number'.
+!!! error TS2420:             Types of property 'a' are incompatible.
+!!! error TS2420:               Type 'string' is not assignable to type 'number'.
     	f(a: T): void { }
     }
     var x = new X<{ a: string }>();

tests/baselines/reference/interfaceWithMultipleBaseTypes.errors.txt

@@ -18,11 +18,9 @@ tests/cases/conformance/interfaces/interfaceDeclarations/interfaceWithMultipleBa
 tests/cases/conformance/interfaces/interfaceDeclarations/interfaceWithMultipleBaseTypes.ts(60,15): error TS2430: Interface 'Derived5<T>' incorrectly extends interface 'Base1<T>'.
   Types of property 'x' are incompatible.
     Type 'T' is not assignable to type '{ a: T; }'.
-      Property 'a' is missing in type '{}'.
 tests/cases/conformance/interfaces/interfaceDeclarations/interfaceWithMultipleBaseTypes.ts(60,15): error TS2430: Interface 'Derived5<T>' incorrectly extends interface 'Base2<T>'.
   Types of property 'x' are incompatible.
     Type 'T' is not assignable to type '{ b: T; }'.
-      Property 'b' is missing in type '{}'.
 
 
 ==== tests/cases/conformance/interfaces/interfaceDeclarations/interfaceWithMultipleBaseTypes.ts (6 errors) ====
@@ -111,12 +109,10 @@ tests/cases/conformance/interfaces/interfaceDeclarations/interfaceWithMultipleBa
 !!! error TS2430: Interface 'Derived5<T>' incorrectly extends interface 'Base1<T>'.
 !!! error TS2430:   Types of property 'x' are incompatible.
 !!! error TS2430:     Type 'T' is not assignable to type '{ a: T; }'.
-!!! error TS2430:       Property 'a' is missing in type '{}'.
                   ~~~~~~~~
 !!! error TS2430: Interface 'Derived5<T>' incorrectly extends interface 'Base2<T>'.
 !!! error TS2430:   Types of property 'x' are incompatible.
 !!! error TS2430:     Type 'T' is not assignable to type '{ b: T; }'.
-!!! error TS2430:       Property 'b' is missing in type '{}'.
             x: T;
         }
     }

tests/baselines/reference/objectTypeWithRecursiveWrappedPropertyCheckedNominally.errors.txt

@@ -5,9 +5,12 @@ tests/cases/conformance/types/typeRelationships/recursiveTypes/objectTypeWithRec
   Types of property 'data' are incompatible.
     Type 'number' is not assignable to type 'string'.
 tests/cases/conformance/types/typeRelationships/recursiveTypes/objectTypeWithRecursiveWrappedPropertyCheckedNominally.ts(30,5): error TS2322: Type 'U' is not assignable to type 'T'.
+  Type 'MyList<number>' is not assignable to type 'T'.
 tests/cases/conformance/types/typeRelationships/recursiveTypes/objectTypeWithRecursiveWrappedPropertyCheckedNominally.ts(31,5): error TS2322: Type 'T' is not assignable to type 'U'.
+  Type 'List<number>' is not assignable to type 'U'.
 tests/cases/conformance/types/typeRelationships/recursiveTypes/objectTypeWithRecursiveWrappedPropertyCheckedNominally.ts(41,15): error TS2313: Constraint of a type parameter cannot reference any type parameter from the same type parameter list.
 tests/cases/conformance/types/typeRelationships/recursiveTypes/objectTypeWithRecursiveWrappedPropertyCheckedNominally.ts(42,5): error TS2322: Type 'U' is not assignable to type 'T'.
+  Type 'MyList<number>' is not assignable to type 'T'.
 tests/cases/conformance/types/typeRelationships/recursiveTypes/objectTypeWithRecursiveWrappedPropertyCheckedNominally.ts(43,5): error TS2322: Type 'T' is not assignable to type 'U'.
 tests/cases/conformance/types/typeRelationships/recursiveTypes/objectTypeWithRecursiveWrappedPropertyCheckedNominally.ts(48,5): error TS2322: Type 'T' is not assignable to type 'List<number>'.
 tests/cases/conformance/types/typeRelationships/recursiveTypes/objectTypeWithRecursiveWrappedPropertyCheckedNominally.ts(50,5): error TS2322: Type 'T' is not assignable to type 'MyList<number>'.
@@ -54,9 +57,11 @@ tests/cases/conformance/types/typeRelationships/recursiveTypes/objectTypeWithRec
         t = u; // error
         ~
 !!! error TS2322: Type 'U' is not assignable to type 'T'.
+!!! error TS2322:   Type 'MyList<number>' is not assignable to type 'T'.
         u = t; // error
         ~
 !!! error TS2322: Type 'T' is not assignable to type 'U'.
+!!! error TS2322:   Type 'List<number>' is not assignable to type 'U'.
     
         var a: List<number>;
         var b: MyList<number>;
@@ -72,6 +77,7 @@ tests/cases/conformance/types/typeRelationships/recursiveTypes/objectTypeWithRec
         t = u; // error
         ~
 !!! error TS2322: Type 'U' is not assignable to type 'T'.
+!!! error TS2322:   Type 'MyList<number>' is not assignable to type 'T'.
         u = t; // was error, ok after constraint made illegal, doesn't matter
         ~
 !!! error TS2322: Type 'T' is not assignable to type 'U'.

tests/baselines/reference/subtypesOfTypeParameterWithConstraints.errors.txt

@@ -101,12 +101,14 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOf
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOfTypeParameterWithConstraints.ts(132,7): error TS2415: Class 'D23<T, U, V>' incorrectly extends base class 'C3<T>'.
   Types of property 'foo' are incompatible.
     Type 'V' is not assignable to type 'T'.
+      Type 'Date' is not assignable to type 'T'.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOfTypeParameterWithConstraints.ts(132,11): error TS2313: Constraint of a type parameter cannot reference any type parameter from the same type parameter list.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOfTypeParameterWithConstraints.ts(132,24): error TS2313: Constraint of a type parameter cannot reference any type parameter from the same type parameter list.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOfTypeParameterWithConstraints.ts(134,5): error TS2411: Property 'foo' of type 'V' is not assignable to string index type 'T'.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOfTypeParameterWithConstraints.ts(137,7): error TS2415: Class 'D24<T, U, V>' incorrectly extends base class 'C3<U>'.
   Types of property 'foo' are incompatible.
     Type 'V' is not assignable to type 'U'.
+      Type 'Date' is not assignable to type 'U'.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOfTypeParameterWithConstraints.ts(137,11): error TS2313: Constraint of a type parameter cannot reference any type parameter from the same type parameter list.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOfTypeParameterWithConstraints.ts(137,24): error TS2313: Constraint of a type parameter cannot reference any type parameter from the same type parameter list.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOfTypeParameterWithConstraints.ts(139,5): error TS2411: Property 'foo' of type 'V' is not assignable to string index type 'U'.
@@ -441,6 +443,7 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOf
 !!! error TS2415: Class 'D23<T, U, V>' incorrectly extends base class 'C3<T>'.
 !!! error TS2415:   Types of property 'foo' are incompatible.
 !!! error TS2415:     Type 'V' is not assignable to type 'T'.
+!!! error TS2415:       Type 'Date' is not assignable to type 'T'.
               ~~~~~~~~~~~
 !!! error TS2313: Constraint of a type parameter cannot reference any type parameter from the same type parameter list.
                            ~~~~~~~~~~~
@@ -456,6 +459,7 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOf
 !!! error TS2415: Class 'D24<T, U, V>' incorrectly extends base class 'C3<U>'.
 !!! error TS2415:   Types of property 'foo' are incompatible.
 !!! error TS2415:     Type 'V' is not assignable to type 'U'.
+!!! error TS2415:       Type 'Date' is not assignable to type 'U'.
               ~~~~~~~~~~~
 !!! error TS2313: Constraint of a type parameter cannot reference any type parameter from the same type parameter list.
                            ~~~~~~~~~~~

tests/baselines/reference/subtypesOfTypeParameterWithConstraints4.errors.txt

@@ -1,11 +1,11 @@
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOfTypeParameterWithConstraints4.ts(45,7): error TS2415: Class 'D3<T, U, V>' incorrectly extends base class 'B1<Foo>'.
   Types of property 'foo' are incompatible.
     Type 'V' is not assignable to type 'Foo'.
-      Property 'foo' is missing in type '{}'.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOfTypeParameterWithConstraints4.ts(47,5): error TS2411: Property 'foo' of type 'V' is not assignable to string index type 'Foo'.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOfTypeParameterWithConstraints4.ts(55,7): error TS2415: Class 'D5<T, U, V>' incorrectly extends base class 'B1<T>'.
   Types of property 'foo' are incompatible.
     Type 'U' is not assignable to type 'T'.
+      Type 'Foo' is not assignable to type 'T'.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOfTypeParameterWithConstraints4.ts(57,5): error TS2411: Property 'foo' of type 'U' is not assignable to string index type 'T'.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOfTypeParameterWithConstraints4.ts(60,7): error TS2415: Class 'D6<T, U, V>' incorrectly extends base class 'B1<T>'.
   Types of property 'foo' are incompatible.
@@ -14,6 +14,7 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOf
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOfTypeParameterWithConstraints4.ts(65,7): error TS2415: Class 'D7<T, U, V>' incorrectly extends base class 'B1<U>'.
   Types of property 'foo' are incompatible.
     Type 'T' is not assignable to type 'U'.
+      Type 'Foo' is not assignable to type 'U'.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOfTypeParameterWithConstraints4.ts(67,5): error TS2411: Property 'foo' of type 'T' is not assignable to string index type 'U'.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOfTypeParameterWithConstraints4.ts(75,7): error TS2415: Class 'D9<T, U, V>' incorrectly extends base class 'B1<U>'.
   Types of property 'foo' are incompatible.
@@ -71,7 +72,6 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOf
 !!! error TS2415: Class 'D3<T, U, V>' incorrectly extends base class 'B1<Foo>'.
 !!! error TS2415:   Types of property 'foo' are incompatible.
 !!! error TS2415:     Type 'V' is not assignable to type 'Foo'.
-!!! error TS2415:       Property 'foo' is missing in type '{}'.
         [x: string]: Foo;
         foo: V; // error
         ~~~~~~~
@@ -88,6 +88,7 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOf
 !!! error TS2415: Class 'D5<T, U, V>' incorrectly extends base class 'B1<T>'.
 !!! error TS2415:   Types of property 'foo' are incompatible.
 !!! error TS2415:     Type 'U' is not assignable to type 'T'.
+!!! error TS2415:       Type 'Foo' is not assignable to type 'T'.
         [x: string]: T;
         foo: U; // error
         ~~~~~~~
@@ -110,6 +111,7 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOf
 !!! error TS2415: Class 'D7<T, U, V>' incorrectly extends base class 'B1<U>'.
 !!! error TS2415:   Types of property 'foo' are incompatible.
 !!! error TS2415:     Type 'T' is not assignable to type 'U'.
+!!! error TS2415:       Type 'Foo' is not assignable to type 'U'.
         [x: string]: U;
         foo: T; // error
         ~~~~~~~

tests/baselines/reference/subtypesOfTypeParameterWithRecursiveConstraints.errors.txt

@@ -7,6 +7,7 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOf
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOfTypeParameterWithRecursiveConstraints.ts(66,11): error TS2415: Class 'D2<T, U, V>' incorrectly extends base class 'Base<T>'.
   Types of property 'foo' are incompatible.
     Type 'U' is not assignable to type 'T'.
+      Type 'Foo<any>' is not assignable to type 'T'.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOfTypeParameterWithRecursiveConstraints.ts(66,14): error TS2313: Constraint of a type parameter cannot reference any type parameter from the same type parameter list.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOfTypeParameterWithRecursiveConstraints.ts(66,32): error TS2313: Constraint of a type parameter cannot reference any type parameter from the same type parameter list.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOfTypeParameterWithRecursiveConstraints.ts(66,50): error TS2313: Constraint of a type parameter cannot reference any type parameter from the same type parameter list.
@@ -14,6 +15,7 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOf
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOfTypeParameterWithRecursiveConstraints.ts(71,11): error TS2415: Class 'D3<T, U, V>' incorrectly extends base class 'Base<T>'.
   Types of property 'foo' are incompatible.
     Type 'V' is not assignable to type 'T'.
+      Type 'Foo<any>' is not assignable to type 'T'.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOfTypeParameterWithRecursiveConstraints.ts(71,14): error TS2313: Constraint of a type parameter cannot reference any type parameter from the same type parameter list.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOfTypeParameterWithRecursiveConstraints.ts(71,32): error TS2313: Constraint of a type parameter cannot reference any type parameter from the same type parameter list.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOfTypeParameterWithRecursiveConstraints.ts(71,50): error TS2313: Constraint of a type parameter cannot reference any type parameter from the same type parameter list.
@@ -21,6 +23,7 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOf
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOfTypeParameterWithRecursiveConstraints.ts(76,11): error TS2415: Class 'D4<T, U, V>' incorrectly extends base class 'Base<U>'.
   Types of property 'foo' are incompatible.
     Type 'T' is not assignable to type 'U'.
+      Type 'Foo<any>' is not assignable to type 'U'.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOfTypeParameterWithRecursiveConstraints.ts(76,14): error TS2313: Constraint of a type parameter cannot reference any type parameter from the same type parameter list.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOfTypeParameterWithRecursiveConstraints.ts(76,32): error TS2313: Constraint of a type parameter cannot reference any type parameter from the same type parameter list.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOfTypeParameterWithRecursiveConstraints.ts(76,50): error TS2313: Constraint of a type parameter cannot reference any type parameter from the same type parameter list.
@@ -31,6 +34,7 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOf
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOfTypeParameterWithRecursiveConstraints.ts(86,11): error TS2415: Class 'D6<T, U, V>' incorrectly extends base class 'Base<U>'.
   Types of property 'foo' are incompatible.
     Type 'V' is not assignable to type 'U'.
+      Type 'Foo<any>' is not assignable to type 'U'.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOfTypeParameterWithRecursiveConstraints.ts(86,14): error TS2313: Constraint of a type parameter cannot reference any type parameter from the same type parameter list.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOfTypeParameterWithRecursiveConstraints.ts(86,32): error TS2313: Constraint of a type parameter cannot reference any type parameter from the same type parameter list.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOfTypeParameterWithRecursiveConstraints.ts(86,50): error TS2313: Constraint of a type parameter cannot reference any type parameter from the same type parameter list.
@@ -38,6 +42,7 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOf
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOfTypeParameterWithRecursiveConstraints.ts(91,11): error TS2415: Class 'D7<T, U, V>' incorrectly extends base class 'Base<V>'.
   Types of property 'foo' are incompatible.
     Type 'T' is not assignable to type 'V'.
+      Type 'Foo<any>' is not assignable to type 'V'.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOfTypeParameterWithRecursiveConstraints.ts(91,14): error TS2313: Constraint of a type parameter cannot reference any type parameter from the same type parameter list.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOfTypeParameterWithRecursiveConstraints.ts(91,32): error TS2313: Constraint of a type parameter cannot reference any type parameter from the same type parameter list.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOfTypeParameterWithRecursiveConstraints.ts(91,50): error TS2313: Constraint of a type parameter cannot reference any type parameter from the same type parameter list.
@@ -45,6 +50,7 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOf
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOfTypeParameterWithRecursiveConstraints.ts(96,11): error TS2415: Class 'D8<T, U, V>' incorrectly extends base class 'Base<V>'.
   Types of property 'foo' are incompatible.
     Type 'U' is not assignable to type 'V'.
+      Type 'Foo<any>' is not assignable to type 'V'.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOfTypeParameterWithRecursiveConstraints.ts(96,14): error TS2313: Constraint of a type parameter cannot reference any type parameter from the same type parameter list.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOfTypeParameterWithRecursiveConstraints.ts(96,32): error TS2313: Constraint of a type parameter cannot reference any type parameter from the same type parameter list.
 tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOfTypeParameterWithRecursiveConstraints.ts(96,50): error TS2313: Constraint of a type parameter cannot reference any type parameter from the same type parameter list.
@@ -170,6 +176,7 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOf
 !!! error TS2415: Class 'D2<T, U, V>' incorrectly extends base class 'Base<T>'.
 !!! error TS2415:   Types of property 'foo' are incompatible.
 !!! error TS2415:     Type 'U' is not assignable to type 'T'.
+!!! error TS2415:       Type 'Foo<any>' is not assignable to type 'T'.
                  ~~~~~~~~~~~~~~~~
 !!! error TS2313: Constraint of a type parameter cannot reference any type parameter from the same type parameter list.
                                    ~~~~~~~~~~~~~~~~
@@ -187,6 +194,7 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOf
 !!! error TS2415: Class 'D3<T, U, V>' incorrectly extends base class 'Base<T>'.
 !!! error TS2415:   Types of property 'foo' are incompatible.
 !!! error TS2415:     Type 'V' is not assignable to type 'T'.
+!!! error TS2415:       Type 'Foo<any>' is not assignable to type 'T'.
                  ~~~~~~~~~~~~~~~~
 !!! error TS2313: Constraint of a type parameter cannot reference any type parameter from the same type parameter list.
                                    ~~~~~~~~~~~~~~~~
@@ -204,6 +212,7 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOf
 !!! error TS2415: Class 'D4<T, U, V>' incorrectly extends base class 'Base<U>'.
 !!! error TS2415:   Types of property 'foo' are incompatible.
 !!! error TS2415:     Type 'T' is not assignable to type 'U'.
+!!! error TS2415:       Type 'Foo<any>' is not assignable to type 'U'.
                  ~~~~~~~~~~~~~~~~
 !!! error TS2313: Constraint of a type parameter cannot reference any type parameter from the same type parameter list.
                                    ~~~~~~~~~~~~~~~~
@@ -232,6 +241,7 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOf
 !!! error TS2415: Class 'D6<T, U, V>' incorrectly extends base class 'Base<U>'.
 !!! error TS2415:   Types of property 'foo' are incompatible.
 !!! error TS2415:     Type 'V' is not assignable to type 'U'.
+!!! error TS2415:       Type 'Foo<any>' is not assignable to type 'U'.
                  ~~~~~~~~~~~~~~~~
 !!! error TS2313: Constraint of a type parameter cannot reference any type parameter from the same type parameter list.
                                    ~~~~~~~~~~~~~~~~
@@ -249,6 +259,7 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOf
 !!! error TS2415: Class 'D7<T, U, V>' incorrectly extends base class 'Base<V>'.
 !!! error TS2415:   Types of property 'foo' are incompatible.
 !!! error TS2415:     Type 'T' is not assignable to type 'V'.
+!!! error TS2415:       Type 'Foo<any>' is not assignable to type 'V'.
                  ~~~~~~~~~~~~~~~~
 !!! error TS2313: Constraint of a type parameter cannot reference any type parameter from the same type parameter list.
                                    ~~~~~~~~~~~~~~~~
@@ -266,6 +277,7 @@ tests/cases/conformance/types/typeRelationships/subtypesAndSuperTypes/subtypesOf
 !!! error TS2415: Class 'D8<T, U, V>' incorrectly extends base class 'Base<V>'.
 !!! error TS2415:   Types of property 'foo' are incompatible.
 !!! error TS2415:     Type 'U' is not assignable to type 'V'.
+!!! error TS2415:       Type 'Foo<any>' is not assignable to type 'V'.
                  ~~~~~~~~~~~~~~~~
 !!! error TS2313: Constraint of a type parameter cannot reference any type parameter from the same type parameter list.
                                    ~~~~~~~~~~~~~~~~

tests/baselines/reference/typeParameterAssignability2.errors.txt

@@ -16,9 +16,11 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/typePara
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/typeParameterAssignability2.ts(24,28): error TS2313: Constraint of a type parameter cannot reference any type parameter from the same type parameter list.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/typeParameterAssignability2.ts(25,5): error TS2322: Type 'U' is not assignable to type 'T'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/typeParameterAssignability2.ts(26,5): error TS2322: Type 'V' is not assignable to type 'T'.
+  Type 'Date' is not assignable to type 'T'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/typeParameterAssignability2.ts(27,5): error TS2322: Type 'Date' is not assignable to type 'T'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/typeParameterAssignability2.ts(29,5): error TS2322: Type 'T' is not assignable to type 'U'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/typeParameterAssignability2.ts(30,5): error TS2322: Type 'V' is not assignable to type 'U'.
+  Type 'Date' is not assignable to type 'U'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/typeParameterAssignability2.ts(31,5): error TS2322: Type 'Date' is not assignable to type 'U'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/typeParameterAssignability2.ts(33,5): error TS2322: Type 'T' is not assignable to type 'V'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/typeParameterAssignability2.ts(34,5): error TS2322: Type 'U' is not assignable to type 'V'.
@@ -29,9 +31,11 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/typePara
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/typeParameterAssignability2.ts(44,44): error TS2313: Constraint of a type parameter cannot reference any type parameter from the same type parameter list.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/typeParameterAssignability2.ts(45,5): error TS2322: Type 'U' is not assignable to type 'T'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/typeParameterAssignability2.ts(46,5): error TS2322: Type 'V' is not assignable to type 'T'.
+  Type 'Date' is not assignable to type 'T'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/typeParameterAssignability2.ts(47,5): error TS2322: Type 'Date' is not assignable to type 'T'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/typeParameterAssignability2.ts(49,5): error TS2322: Type 'T' is not assignable to type 'U'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/typeParameterAssignability2.ts(50,5): error TS2322: Type 'V' is not assignable to type 'U'.
+  Type 'Date' is not assignable to type 'U'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/typeParameterAssignability2.ts(51,5): error TS2322: Type 'Date' is not assignable to type 'U'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/typeParameterAssignability2.ts(53,5): error TS2322: Type 'T' is not assignable to type 'V'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/typeParameterAssignability2.ts(54,5): error TS2322: Type 'U' is not assignable to type 'V'.
@@ -110,6 +114,7 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/typePara
         t = v; // error
         ~
 !!! error TS2322: Type 'V' is not assignable to type 'T'.
+!!! error TS2322:   Type 'Date' is not assignable to type 'T'.
         t = new Date(); // error
         ~
 !!! error TS2322: Type 'Date' is not assignable to type 'T'.
@@ -120,6 +125,7 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/typePara
         u = v; // error
         ~
 !!! error TS2322: Type 'V' is not assignable to type 'U'.
+!!! error TS2322:   Type 'Date' is not assignable to type 'U'.
         u = new Date(); // error
         ~
 !!! error TS2322: Type 'Date' is not assignable to type 'U'.
@@ -156,6 +162,7 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/typePara
         t = v; // error
         ~
 !!! error TS2322: Type 'V' is not assignable to type 'T'.
+!!! error TS2322:   Type 'Date' is not assignable to type 'T'.
         t = new Date(); // error
         ~
 !!! error TS2322: Type 'Date' is not assignable to type 'T'.
@@ -166,6 +173,7 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/typePara
         u = v; // error
         ~
 !!! error TS2322: Type 'V' is not assignable to type 'U'.
+!!! error TS2322:   Type 'Date' is not assignable to type 'U'.
         u = new Date(); // error
         ~
 !!! error TS2322: Type 'Date' is not assignable to type 'U'.

tests/baselines/reference/typeParameterAssignability3.errors.txt

@@ -1,7 +1,11 @@
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/typeParameterAssignability3.ts(14,5): error TS2322: Type 'U' is not assignable to type 'T'.
+  Type 'Foo' is not assignable to type 'T'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/typeParameterAssignability3.ts(15,5): error TS2322: Type 'T' is not assignable to type 'U'.
+  Type 'Foo' is not assignable to type 'U'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/typeParameterAssignability3.ts(22,9): error TS2322: Type 'U' is not assignable to type 'T'.
+  Type 'Foo' is not assignable to type 'T'.
 tests/cases/conformance/types/typeRelationships/assignmentCompatibility/typeParameterAssignability3.ts(23,9): error TS2322: Type 'T' is not assignable to type 'U'.
+  Type 'Foo' is not assignable to type 'U'.
 
 
 ==== tests/cases/conformance/types/typeRelationships/assignmentCompatibility/typeParameterAssignability3.ts (4 errors) ====
@@ -21,9 +25,11 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/typePara
         t = u; // error
         ~
 !!! error TS2322: Type 'U' is not assignable to type 'T'.
+!!! error TS2322:   Type 'Foo' is not assignable to type 'T'.
         u = t; // error
         ~
 !!! error TS2322: Type 'T' is not assignable to type 'U'.
+!!! error TS2322:   Type 'Foo' is not assignable to type 'U'.
     }
     
     class C<T extends Foo, U extends Foo> {
@@ -33,8 +39,10 @@ tests/cases/conformance/types/typeRelationships/assignmentCompatibility/typePara
             this.t = this.u; // error
             ~~~~~~
 !!! error TS2322: Type 'U' is not assignable to type 'T'.
+!!! error TS2322:   Type 'Foo' is not assignable to type 'T'.
             this.u = this.t; // error
             ~~~~~~
 !!! error TS2322: Type 'T' is not assignable to type 'U'.
+!!! error TS2322:   Type 'Foo' is not assignable to type 'U'.
         }
     }

tests/baselines/reference/typeParameterDiamond3.errors.txt

@@ -4,6 +4,9 @@ tests/cases/compiler/typeParameterDiamond3.ts(9,13): error TS2322: Type 'Bottom'
   Type 'Top | T | U' is not assignable to type 'T | U'.
     Type 'Top' is not assignable to type 'T | U'.
       Type 'Top' is not assignable to type 'U'.
+        Type 'Bottom' is not assignable to type 'U'.
+          Type 'Top | T | U' is not assignable to type 'U'.
+            Type 'Top' is not assignable to type 'U'.
 tests/cases/compiler/typeParameterDiamond3.ts(10,13): error TS2322: Type 'Bottom' is not assignable to type 'Top'.
   Type 'Top | T | U' is not assignable to type 'Top'.
     Type 'T' is not assignable to type 'Top'.
@@ -27,6 +30,9 @@ tests/cases/compiler/typeParameterDiamond3.ts(10,13): error TS2322: Type 'Bottom
 !!! error TS2322:   Type 'Top | T | U' is not assignable to type 'T | U'.
 !!! error TS2322:     Type 'Top' is not assignable to type 'T | U'.
 !!! error TS2322:       Type 'Top' is not assignable to type 'U'.
+!!! error TS2322:         Type 'Bottom' is not assignable to type 'U'.
+!!! error TS2322:           Type 'Top | T | U' is not assignable to type 'U'.
+!!! error TS2322:             Type 'Top' is not assignable to type 'U'.
                 top = bottom;
                 ~~~
 !!! error TS2322: Type 'Bottom' is not assignable to type 'Top'.

tests/baselines/reference/typeParameterUsedAsTypeParameterConstraint4.errors.txt

@@ -2,6 +2,7 @@ tests/cases/conformance/types/objectTypeLiteral/callSignatures/typeParameterUsed
 tests/cases/conformance/types/objectTypeLiteral/callSignatures/typeParameterUsedAsTypeParameterConstraint4.ts(4,25): error TS2313: Constraint of a type parameter cannot reference any type parameter from the same type parameter list.
 tests/cases/conformance/types/objectTypeLiteral/callSignatures/typeParameterUsedAsTypeParameterConstraint4.ts(5,8): error TS2304: Cannot find name 'W'.
 tests/cases/conformance/types/objectTypeLiteral/callSignatures/typeParameterUsedAsTypeParameterConstraint4.ts(8,16): error TS2322: Type 'W' is not assignable to type 'T'.
+  Type 'V' is not assignable to type 'T'.
 tests/cases/conformance/types/objectTypeLiteral/callSignatures/typeParameterUsedAsTypeParameterConstraint4.ts(12,16): error TS2313: Constraint of a type parameter cannot reference any type parameter from the same type parameter list.
 tests/cases/conformance/types/objectTypeLiteral/callSignatures/typeParameterUsedAsTypeParameterConstraint4.ts(12,29): error TS2313: Constraint of a type parameter cannot reference any type parameter from the same type parameter list.
 tests/cases/conformance/types/objectTypeLiteral/callSignatures/typeParameterUsedAsTypeParameterConstraint4.ts(15,8): error TS2304: Cannot find name 'W'.
@@ -42,6 +43,7 @@ tests/cases/conformance/types/objectTypeLiteral/callSignatures/typeParameterUsed
             return x;
                    ~
 !!! error TS2322: Type 'W' is not assignable to type 'T'.
+!!! error TS2322:   Type 'V' is not assignable to type 'T'.
         }
     }
     

tests/baselines/reference/typeParametersShouldNotBeEqual2.errors.txt

@@ -1,8 +1,11 @@
 tests/cases/compiler/typeParametersShouldNotBeEqual2.ts(4,5): error TS2322: Type 'U' is not assignable to type 'T'.
+  Type 'Date' is not assignable to type 'T'.
 tests/cases/compiler/typeParametersShouldNotBeEqual2.ts(5,5): error TS2322: Type 'V' is not assignable to type 'T'.
 tests/cases/compiler/typeParametersShouldNotBeEqual2.ts(6,5): error TS2322: Type 'T' is not assignable to type 'V'.
+  Type 'Date' is not assignable to type 'V'.
 tests/cases/compiler/typeParametersShouldNotBeEqual2.ts(7,5): error TS2322: Type 'V' is not assignable to type 'U'.
 tests/cases/compiler/typeParametersShouldNotBeEqual2.ts(8,5): error TS2322: Type 'U' is not assignable to type 'V'.
+  Type 'Date' is not assignable to type 'V'.
 tests/cases/compiler/typeParametersShouldNotBeEqual2.ts(9,5): error TS2322: Type 'Object' is not assignable to type 'T'.
 
 
@@ -13,18 +16,21 @@ tests/cases/compiler/typeParametersShouldNotBeEqual2.ts(9,5): error TS2322: Type
         x = y;  // Ok
         ~
 !!! error TS2322: Type 'U' is not assignable to type 'T'.
+!!! error TS2322:   Type 'Date' is not assignable to type 'T'.
         x = z;  // Error
         ~
 !!! error TS2322: Type 'V' is not assignable to type 'T'.
         z = x;  // Error
         ~
 !!! error TS2322: Type 'T' is not assignable to type 'V'.
+!!! error TS2322:   Type 'Date' is not assignable to type 'V'.
         y = z;  // Error
         ~
 !!! error TS2322: Type 'V' is not assignable to type 'U'.
         z = y;  // Error
         ~
 !!! error TS2322: Type 'U' is not assignable to type 'V'.
+!!! error TS2322:   Type 'Date' is not assignable to type 'V'.
         x = zz;  // Error
         ~
 !!! error TS2322: Type 'Object' is not assignable to type 'T'.

tests/baselines/reference/typeParametersShouldNotBeEqual3.errors.txt

@@ -1,4 +1,5 @@
 tests/cases/compiler/typeParametersShouldNotBeEqual3.ts(4,5): error TS2322: Type 'U' is not assignable to type 'T'.
+  Type 'Object' is not assignable to type 'T'.
 tests/cases/compiler/typeParametersShouldNotBeEqual3.ts(5,5): error TS2322: Type 'Object' is not assignable to type 'T'.
 
 
@@ -9,6 +10,7 @@ tests/cases/compiler/typeParametersShouldNotBeEqual3.ts(5,5): error TS2322: Type
         x = y;  // Ok
         ~
 !!! error TS2322: Type 'U' is not assignable to type 'T'.
+!!! error TS2322:   Type 'Object' is not assignable to type 'T'.
         x = z;  // Ok
         ~
 !!! error TS2322: Type 'Object' is not assignable to type 'T'.

tests/cases/compiler/assignmentNonObjectTypeConstraints.ts

@@ -0,0 +1,18 @@
+const enum E { A, B, C }
+
+function foo<T extends number>(x: T) {
+    var y: number = x;  // Ok
+}
+
+foo(5);
+foo(E.A);
+
+class A { a }
+class B { b }
+
+function bar<T extends A | B>(x: T) {
+    var y: A | B = x;  // Ok
+}
+
+bar(new A);
+bar(new B);