Revert "Allow variance annotations on generic references (#56418)" (#59793)

2025-12-11 17:41:26 -06:00 · 2024-09-04 01:08:13 +02:00 · 2024-09-04 01:08:13 +02:00 · 29d92edd1c
commit 29d92edd1c
parent fe2cb8ebaa
6 changed files with 348 additions and 85 deletions
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@ -41147,7 +41147,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
            const modifiers = getTypeParameterModifiers(typeParameter) & (ModifierFlags.In | ModifierFlags.Out);
            if (modifiers) {
                const symbol = getSymbolOfDeclaration(node.parent);
-                if (isTypeAliasDeclaration(node.parent) && !(getObjectFlags(getDeclaredTypeOfSymbol(symbol)) & (ObjectFlags.Reference | ObjectFlags.Anonymous | ObjectFlags.Mapped))) {
+                if (isTypeAliasDeclaration(node.parent) && !(getObjectFlags(getDeclaredTypeOfSymbol(symbol)) & (ObjectFlags.Anonymous | ObjectFlags.Mapped))) {
                    error(node, Diagnostics.Variance_annotations_are_only_supported_in_type_aliases_for_object_function_constructor_and_mapped_types);
                }
                else if (modifiers === ModifierFlags.In || modifiers === ModifierFlags.Out) {
--- a/tests/baselines/reference/varianceReferences.errors.txt
+++ b/tests/baselines/reference/varianceReferences.errors.txt
@ -1,9 +1,23 @@
 varianceReferences.ts(3,32): error TS2637: Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.
-varianceReferences.ts(8,28): error TS2637: Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.
-varianceReferences.ts(14,32): error TS2637: Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.
+varianceReferences.ts(9,1): error TS2322: Type '1 | 2' is not assignable to type '1'.
+  Type '2' is not assignable to type '1'.
+varianceReferences.ts(14,28): error TS2637: Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.
+varianceReferences.ts(19,1): error TS2322: Type '1 | 2' is not assignable to type '1'.
+  Type '2' is not assignable to type '1'.
+varianceReferences.ts(26,32): error TS2637: Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.
+varianceReferences.ts(31,1): error TS2322: Type '1 | 2' is not assignable to type '1'.
+  Type '2' is not assignable to type '1'.
+varianceReferences.ts(38,20): error TS2637: Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.
+varianceReferences.ts(43,1): error TS2322: Type 'VarianceShape<1 | 2>' is not assignable to type 'VarianceShape<1>'.
+  Type '1 | 2' is not assignable to type '1'.
+    Type '2' is not assignable to type '1'.
+varianceReferences.ts(53,24): error TS2637: Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.
+varianceReferences.ts(58,1): error TS2322: Type 'VarianceDeepShape<1 | 2>' is not assignable to type 'VarianceDeepShape<1>'.
+  Type '1 | 2' is not assignable to type '1'.
+    Type '2' is not assignable to type '1'.


-==== varianceReferences.ts (3 errors) ====
+==== varianceReferences.ts (10 errors) ====
    type NumericConstraint<Value extends number> = Value;
    
    type VarianceConstrainedNumber<in out Value extends number> =
@ -11,12 +25,30 @@ varianceReferences.ts(14,32): error TS2637: Variance annotations are only suppor
 !!! error TS2637: Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.
      NumericConstraint<Value>;
    
+    declare let vcn1: VarianceConstrainedNumber<1>;
+    declare let vcn12: VarianceConstrainedNumber<1 | 2>;
+    
+    vcn1 = vcn12;
+    ~~~~
+!!! error TS2322: Type '1 | 2' is not assignable to type '1'.
+!!! error TS2322:   Type '2' is not assignable to type '1'.
+    vcn12 = vcn1;
+    
    type Unconstrained<Value> = Value;
    
    type VarianceUnconstrained<in out Value> = Unconstrained<Value>;
                               ~~~~~~~~~~~~
 !!! error TS2637: Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.
    
+    declare let vu1: VarianceUnconstrained<1>;
+    declare let vu12: VarianceUnconstrained<1 | 2>;
+    
+    vu1 = vu12;
+    ~~~
+!!! error TS2322: Type '1 | 2' is not assignable to type '1'.
+!!! error TS2322:   Type '2' is not assignable to type '1'.
+    vu12 = vu1;
+    
    type Level3of3Unconstrained<Value> = Value;
    type Level2of3Unconstrained<Value> = Level3of3Unconstrained<Value>;
    type Level1of3Unconstrained<Value> = Level2of3Unconstrained<Value>;
@ -25,11 +57,32 @@ varianceReferences.ts(14,32): error TS2637: Variance annotations are only suppor
                                   ~~~~~~~~~~~~
 !!! error TS2637: Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.
    
+    declare let vdu1: VarianceDeepUnconstrained<1>;
+    declare let vdu12: VarianceDeepUnconstrained<1 | 2>;
+    
+    vdu1 = vdu12;
+    ~~~~
+!!! error TS2322: Type '1 | 2' is not assignable to type '1'.
+!!! error TS2322:   Type '2' is not assignable to type '1'.
+    vdu12 = vdu1;
+    
    interface Shape<Value> {
      value: Value;
    }
    
    type VarianceShape<in out Value> = Shape<Value>;
+                       ~~~~~~~~~~~~
+!!! error TS2637: Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.
+    
+    declare let vs1: VarianceShape<1>;
+    declare let vs12: VarianceShape<1 | 2>;
+    
+    vs1 = vs12;
+    ~~~
+!!! error TS2322: Type 'VarianceShape<1 | 2>' is not assignable to type 'VarianceShape<1>'.
+!!! error TS2322:   Type '1 | 2' is not assignable to type '1'.
+!!! error TS2322:     Type '2' is not assignable to type '1'.
+    vs12 = vs1;
    
    interface Level3of3Shape<Value> {
      value: Value;
@ -39,4 +92,16 @@ varianceReferences.ts(14,32): error TS2637: Variance annotations are only suppor
    type Level1of3Shape<Value> = Level2of3Shape<Value>;
    
    type VarianceDeepShape<in out Value> = Level1of3Shape<Value>;
+                           ~~~~~~~~~~~~
+!!! error TS2637: Variance annotations are only supported in type aliases for object, function, constructor, and mapped types.
+    
+    declare let vds1: VarianceDeepShape<1>;
+    declare let vds12: VarianceDeepShape<1 | 2>;
+    
+    vds1 = vds12;
+    ~~~~
+!!! error TS2322: Type 'VarianceDeepShape<1 | 2>' is not assignable to type 'VarianceDeepShape<1>'.
+!!! error TS2322:   Type '1 | 2' is not assignable to type '1'.
+!!! error TS2322:     Type '2' is not assignable to type '1'.
+    vds12 = vds1;
    
--- a/tests/baselines/reference/varianceReferences.js
+++ b/tests/baselines/reference/varianceReferences.js
@ -1,35 +0,0 @@
-//// [tests/cases/compiler/varianceReferences.ts] ////
-
-//// [varianceReferences.ts]
-type NumericConstraint<Value extends number> = Value;
-
-type VarianceConstrainedNumber<in out Value extends number> =
-  NumericConstraint<Value>;
-
-type Unconstrained<Value> = Value;
-
-type VarianceUnconstrained<in out Value> = Unconstrained<Value>;
-
-type Level3of3Unconstrained<Value> = Value;
-type Level2of3Unconstrained<Value> = Level3of3Unconstrained<Value>;
-type Level1of3Unconstrained<Value> = Level2of3Unconstrained<Value>;
-
-type VarianceDeepUnconstrained<in out Value> = Level1of3Unconstrained<Value>;
-
-interface Shape<Value> {
-  value: Value;
-}
-
-type VarianceShape<in out Value> = Shape<Value>;
-
-interface Level3of3Shape<Value> {
-  value: Value;
-}
-
-type Level2of3Shape<Value> = Level3of3Shape<Value>;
-type Level1of3Shape<Value> = Level2of3Shape<Value>;
-
-type VarianceDeepShape<in out Value> = Level1of3Shape<Value>;
-
-
-//// [varianceReferences.js]
--- a/tests/baselines/reference/varianceReferences.symbols
+++ b/tests/baselines/reference/varianceReferences.symbols
@ -14,79 +14,159 @@ type VarianceConstrainedNumber<in out Value extends number> =
 >NumericConstraint : Symbol(NumericConstraint, Decl(varianceReferences.ts, 0, 0))
 >Value : Symbol(Value, Decl(varianceReferences.ts, 2, 31))

+declare let vcn1: VarianceConstrainedNumber<1>;
+>vcn1 : Symbol(vcn1, Decl(varianceReferences.ts, 5, 11))
+>VarianceConstrainedNumber : Symbol(VarianceConstrainedNumber, Decl(varianceReferences.ts, 0, 53))
+
+declare let vcn12: VarianceConstrainedNumber<1 | 2>;
+>vcn12 : Symbol(vcn12, Decl(varianceReferences.ts, 6, 11))
+>VarianceConstrainedNumber : Symbol(VarianceConstrainedNumber, Decl(varianceReferences.ts, 0, 53))
+
+vcn1 = vcn12;
+>vcn1 : Symbol(vcn1, Decl(varianceReferences.ts, 5, 11))
+>vcn12 : Symbol(vcn12, Decl(varianceReferences.ts, 6, 11))
+
+vcn12 = vcn1;
+>vcn12 : Symbol(vcn12, Decl(varianceReferences.ts, 6, 11))
+>vcn1 : Symbol(vcn1, Decl(varianceReferences.ts, 5, 11))
+
 type Unconstrained<Value> = Value;
->Unconstrained : Symbol(Unconstrained, Decl(varianceReferences.ts, 3, 27))
->Value : Symbol(Value, Decl(varianceReferences.ts, 5, 19))
->Value : Symbol(Value, Decl(varianceReferences.ts, 5, 19))
+>Unconstrained : Symbol(Unconstrained, Decl(varianceReferences.ts, 9, 13))
+>Value : Symbol(Value, Decl(varianceReferences.ts, 11, 19))
+>Value : Symbol(Value, Decl(varianceReferences.ts, 11, 19))

 type VarianceUnconstrained<in out Value> = Unconstrained<Value>;
->VarianceUnconstrained : Symbol(VarianceUnconstrained, Decl(varianceReferences.ts, 5, 34))
->Value : Symbol(Value, Decl(varianceReferences.ts, 7, 27))
->Unconstrained : Symbol(Unconstrained, Decl(varianceReferences.ts, 3, 27))
->Value : Symbol(Value, Decl(varianceReferences.ts, 7, 27))
+>VarianceUnconstrained : Symbol(VarianceUnconstrained, Decl(varianceReferences.ts, 11, 34))
+>Value : Symbol(Value, Decl(varianceReferences.ts, 13, 27))
+>Unconstrained : Symbol(Unconstrained, Decl(varianceReferences.ts, 9, 13))
+>Value : Symbol(Value, Decl(varianceReferences.ts, 13, 27))
+
+declare let vu1: VarianceUnconstrained<1>;
+>vu1 : Symbol(vu1, Decl(varianceReferences.ts, 15, 11))
+>VarianceUnconstrained : Symbol(VarianceUnconstrained, Decl(varianceReferences.ts, 11, 34))
+
+declare let vu12: VarianceUnconstrained<1 | 2>;
+>vu12 : Symbol(vu12, Decl(varianceReferences.ts, 16, 11))
+>VarianceUnconstrained : Symbol(VarianceUnconstrained, Decl(varianceReferences.ts, 11, 34))
+
+vu1 = vu12;
+>vu1 : Symbol(vu1, Decl(varianceReferences.ts, 15, 11))
+>vu12 : Symbol(vu12, Decl(varianceReferences.ts, 16, 11))
+
+vu12 = vu1;
+>vu12 : Symbol(vu12, Decl(varianceReferences.ts, 16, 11))
+>vu1 : Symbol(vu1, Decl(varianceReferences.ts, 15, 11))

 type Level3of3Unconstrained<Value> = Value;
->Level3of3Unconstrained : Symbol(Level3of3Unconstrained, Decl(varianceReferences.ts, 7, 64))
->Value : Symbol(Value, Decl(varianceReferences.ts, 9, 28))
->Value : Symbol(Value, Decl(varianceReferences.ts, 9, 28))
+>Level3of3Unconstrained : Symbol(Level3of3Unconstrained, Decl(varianceReferences.ts, 19, 11))
+>Value : Symbol(Value, Decl(varianceReferences.ts, 21, 28))
+>Value : Symbol(Value, Decl(varianceReferences.ts, 21, 28))

 type Level2of3Unconstrained<Value> = Level3of3Unconstrained<Value>;
->Level2of3Unconstrained : Symbol(Level2of3Unconstrained, Decl(varianceReferences.ts, 9, 43))
->Value : Symbol(Value, Decl(varianceReferences.ts, 10, 28))
->Level3of3Unconstrained : Symbol(Level3of3Unconstrained, Decl(varianceReferences.ts, 7, 64))
->Value : Symbol(Value, Decl(varianceReferences.ts, 10, 28))
+>Level2of3Unconstrained : Symbol(Level2of3Unconstrained, Decl(varianceReferences.ts, 21, 43))
+>Value : Symbol(Value, Decl(varianceReferences.ts, 22, 28))
+>Level3of3Unconstrained : Symbol(Level3of3Unconstrained, Decl(varianceReferences.ts, 19, 11))
+>Value : Symbol(Value, Decl(varianceReferences.ts, 22, 28))

 type Level1of3Unconstrained<Value> = Level2of3Unconstrained<Value>;
->Level1of3Unconstrained : Symbol(Level1of3Unconstrained, Decl(varianceReferences.ts, 10, 67))
->Value : Symbol(Value, Decl(varianceReferences.ts, 11, 28))
->Level2of3Unconstrained : Symbol(Level2of3Unconstrained, Decl(varianceReferences.ts, 9, 43))
->Value : Symbol(Value, Decl(varianceReferences.ts, 11, 28))
+>Level1of3Unconstrained : Symbol(Level1of3Unconstrained, Decl(varianceReferences.ts, 22, 67))
+>Value : Symbol(Value, Decl(varianceReferences.ts, 23, 28))
+>Level2of3Unconstrained : Symbol(Level2of3Unconstrained, Decl(varianceReferences.ts, 21, 43))
+>Value : Symbol(Value, Decl(varianceReferences.ts, 23, 28))

 type VarianceDeepUnconstrained<in out Value> = Level1of3Unconstrained<Value>;
->VarianceDeepUnconstrained : Symbol(VarianceDeepUnconstrained, Decl(varianceReferences.ts, 11, 67))
->Value : Symbol(Value, Decl(varianceReferences.ts, 13, 31))
->Level1of3Unconstrained : Symbol(Level1of3Unconstrained, Decl(varianceReferences.ts, 10, 67))
->Value : Symbol(Value, Decl(varianceReferences.ts, 13, 31))
+>VarianceDeepUnconstrained : Symbol(VarianceDeepUnconstrained, Decl(varianceReferences.ts, 23, 67))
+>Value : Symbol(Value, Decl(varianceReferences.ts, 25, 31))
+>Level1of3Unconstrained : Symbol(Level1of3Unconstrained, Decl(varianceReferences.ts, 22, 67))
+>Value : Symbol(Value, Decl(varianceReferences.ts, 25, 31))
+
+declare let vdu1: VarianceDeepUnconstrained<1>;
+>vdu1 : Symbol(vdu1, Decl(varianceReferences.ts, 27, 11))
+>VarianceDeepUnconstrained : Symbol(VarianceDeepUnconstrained, Decl(varianceReferences.ts, 23, 67))
+
+declare let vdu12: VarianceDeepUnconstrained<1 | 2>;
+>vdu12 : Symbol(vdu12, Decl(varianceReferences.ts, 28, 11))
+>VarianceDeepUnconstrained : Symbol(VarianceDeepUnconstrained, Decl(varianceReferences.ts, 23, 67))
+
+vdu1 = vdu12;
+>vdu1 : Symbol(vdu1, Decl(varianceReferences.ts, 27, 11))
+>vdu12 : Symbol(vdu12, Decl(varianceReferences.ts, 28, 11))
+
+vdu12 = vdu1;
+>vdu12 : Symbol(vdu12, Decl(varianceReferences.ts, 28, 11))
+>vdu1 : Symbol(vdu1, Decl(varianceReferences.ts, 27, 11))

 interface Shape<Value> {
->Shape : Symbol(Shape, Decl(varianceReferences.ts, 13, 77))
->Value : Symbol(Value, Decl(varianceReferences.ts, 15, 16))
+>Shape : Symbol(Shape, Decl(varianceReferences.ts, 31, 13))
+>Value : Symbol(Value, Decl(varianceReferences.ts, 33, 16))

  value: Value;
->value : Symbol(Shape.value, Decl(varianceReferences.ts, 15, 24))
->Value : Symbol(Value, Decl(varianceReferences.ts, 15, 16))
+>value : Symbol(Shape.value, Decl(varianceReferences.ts, 33, 24))
+>Value : Symbol(Value, Decl(varianceReferences.ts, 33, 16))
 }

 type VarianceShape<in out Value> = Shape<Value>;
->VarianceShape : Symbol(VarianceShape, Decl(varianceReferences.ts, 17, 1))
->Value : Symbol(Value, Decl(varianceReferences.ts, 19, 19))
->Shape : Symbol(Shape, Decl(varianceReferences.ts, 13, 77))
->Value : Symbol(Value, Decl(varianceReferences.ts, 19, 19))
+>VarianceShape : Symbol(VarianceShape, Decl(varianceReferences.ts, 35, 1))
+>Value : Symbol(Value, Decl(varianceReferences.ts, 37, 19))
+>Shape : Symbol(Shape, Decl(varianceReferences.ts, 31, 13))
+>Value : Symbol(Value, Decl(varianceReferences.ts, 37, 19))
+
+declare let vs1: VarianceShape<1>;
+>vs1 : Symbol(vs1, Decl(varianceReferences.ts, 39, 11))
+>VarianceShape : Symbol(VarianceShape, Decl(varianceReferences.ts, 35, 1))
+
+declare let vs12: VarianceShape<1 | 2>;
+>vs12 : Symbol(vs12, Decl(varianceReferences.ts, 40, 11))
+>VarianceShape : Symbol(VarianceShape, Decl(varianceReferences.ts, 35, 1))
+
+vs1 = vs12;
+>vs1 : Symbol(vs1, Decl(varianceReferences.ts, 39, 11))
+>vs12 : Symbol(vs12, Decl(varianceReferences.ts, 40, 11))
+
+vs12 = vs1;
+>vs12 : Symbol(vs12, Decl(varianceReferences.ts, 40, 11))
+>vs1 : Symbol(vs1, Decl(varianceReferences.ts, 39, 11))

 interface Level3of3Shape<Value> {
->Level3of3Shape : Symbol(Level3of3Shape, Decl(varianceReferences.ts, 19, 48))
->Value : Symbol(Value, Decl(varianceReferences.ts, 21, 25))
+>Level3of3Shape : Symbol(Level3of3Shape, Decl(varianceReferences.ts, 43, 11))
+>Value : Symbol(Value, Decl(varianceReferences.ts, 45, 25))

  value: Value;
->value : Symbol(Level3of3Shape.value, Decl(varianceReferences.ts, 21, 33))
->Value : Symbol(Value, Decl(varianceReferences.ts, 21, 25))
+>value : Symbol(Level3of3Shape.value, Decl(varianceReferences.ts, 45, 33))
+>Value : Symbol(Value, Decl(varianceReferences.ts, 45, 25))
 }

 type Level2of3Shape<Value> = Level3of3Shape<Value>;
->Level2of3Shape : Symbol(Level2of3Shape, Decl(varianceReferences.ts, 23, 1))
->Value : Symbol(Value, Decl(varianceReferences.ts, 25, 20))
->Level3of3Shape : Symbol(Level3of3Shape, Decl(varianceReferences.ts, 19, 48))
->Value : Symbol(Value, Decl(varianceReferences.ts, 25, 20))
+>Level2of3Shape : Symbol(Level2of3Shape, Decl(varianceReferences.ts, 47, 1))
+>Value : Symbol(Value, Decl(varianceReferences.ts, 49, 20))
+>Level3of3Shape : Symbol(Level3of3Shape, Decl(varianceReferences.ts, 43, 11))
+>Value : Symbol(Value, Decl(varianceReferences.ts, 49, 20))

 type Level1of3Shape<Value> = Level2of3Shape<Value>;
->Level1of3Shape : Symbol(Level1of3Shape, Decl(varianceReferences.ts, 25, 51))
->Value : Symbol(Value, Decl(varianceReferences.ts, 26, 20))
->Level2of3Shape : Symbol(Level2of3Shape, Decl(varianceReferences.ts, 23, 1))
->Value : Symbol(Value, Decl(varianceReferences.ts, 26, 20))
+>Level1of3Shape : Symbol(Level1of3Shape, Decl(varianceReferences.ts, 49, 51))
+>Value : Symbol(Value, Decl(varianceReferences.ts, 50, 20))
+>Level2of3Shape : Symbol(Level2of3Shape, Decl(varianceReferences.ts, 47, 1))
+>Value : Symbol(Value, Decl(varianceReferences.ts, 50, 20))

 type VarianceDeepShape<in out Value> = Level1of3Shape<Value>;
->VarianceDeepShape : Symbol(VarianceDeepShape, Decl(varianceReferences.ts, 26, 51))
->Value : Symbol(Value, Decl(varianceReferences.ts, 28, 23))
->Level1of3Shape : Symbol(Level1of3Shape, Decl(varianceReferences.ts, 25, 51))
->Value : Symbol(Value, Decl(varianceReferences.ts, 28, 23))
+>VarianceDeepShape : Symbol(VarianceDeepShape, Decl(varianceReferences.ts, 50, 51))
+>Value : Symbol(Value, Decl(varianceReferences.ts, 52, 23))
+>Level1of3Shape : Symbol(Level1of3Shape, Decl(varianceReferences.ts, 49, 51))
+>Value : Symbol(Value, Decl(varianceReferences.ts, 52, 23))
+
+declare let vds1: VarianceDeepShape<1>;
+>vds1 : Symbol(vds1, Decl(varianceReferences.ts, 54, 11))
+>VarianceDeepShape : Symbol(VarianceDeepShape, Decl(varianceReferences.ts, 50, 51))
+
+declare let vds12: VarianceDeepShape<1 | 2>;
+>vds12 : Symbol(vds12, Decl(varianceReferences.ts, 55, 11))
+>VarianceDeepShape : Symbol(VarianceDeepShape, Decl(varianceReferences.ts, 50, 51))
+
+vds1 = vds12;
+>vds1 : Symbol(vds1, Decl(varianceReferences.ts, 54, 11))
+>vds12 : Symbol(vds12, Decl(varianceReferences.ts, 55, 11))
+
+vds12 = vds1;
+>vds12 : Symbol(vds12, Decl(varianceReferences.ts, 55, 11))
+>vds1 : Symbol(vds1, Decl(varianceReferences.ts, 54, 11))

--- a/tests/baselines/reference/varianceReferences.types
+++ b/tests/baselines/reference/varianceReferences.types
@ -11,6 +11,30 @@ type VarianceConstrainedNumber<in out Value extends number> =

  NumericConstraint<Value>;

+declare let vcn1: VarianceConstrainedNumber<1>;
+>vcn1 : 1
+>     : ^
+
+declare let vcn12: VarianceConstrainedNumber<1 | 2>;
+>vcn12 : 1 | 2
+>      : ^^^^^
+
+vcn1 = vcn12;
+>vcn1 = vcn12 : 1 | 2
+>             : ^^^^^
+>vcn1 : 1
+>     : ^
+>vcn12 : 1 | 2
+>      : ^^^^^
+
+vcn12 = vcn1;
+>vcn12 = vcn1 : 1
+>             : ^
+>vcn12 : 1 | 2
+>      : ^^^^^
+>vcn1 : 1
+>     : ^
+
 type Unconstrained<Value> = Value;
 >Unconstrained : Value
 >              : ^^^^^
@ -19,6 +43,30 @@ type VarianceUnconstrained<in out Value> = Unconstrained<Value>;
 >VarianceUnconstrained : Value
 >                      : ^^^^^

+declare let vu1: VarianceUnconstrained<1>;
+>vu1 : 1
+>    : ^
+
+declare let vu12: VarianceUnconstrained<1 | 2>;
+>vu12 : 1 | 2
+>     : ^^^^^
+
+vu1 = vu12;
+>vu1 = vu12 : 1 | 2
+>           : ^^^^^
+>vu1 : 1
+>    : ^
+>vu12 : 1 | 2
+>     : ^^^^^
+
+vu12 = vu1;
+>vu12 = vu1 : 1
+>           : ^
+>vu12 : 1 | 2
+>     : ^^^^^
+>vu1 : 1
+>    : ^
+
 type Level3of3Unconstrained<Value> = Value;
 >Level3of3Unconstrained : Value
 >                       : ^^^^^
@ -35,6 +83,30 @@ type VarianceDeepUnconstrained<in out Value> = Level1of3Unconstrained<Value>;
 >VarianceDeepUnconstrained : Value
 >                          : ^^^^^

+declare let vdu1: VarianceDeepUnconstrained<1>;
+>vdu1 : 1
+>     : ^
+
+declare let vdu12: VarianceDeepUnconstrained<1 | 2>;
+>vdu12 : 1 | 2
+>      : ^^^^^
+
+vdu1 = vdu12;
+>vdu1 = vdu12 : 1 | 2
+>             : ^^^^^
+>vdu1 : 1
+>     : ^
+>vdu12 : 1 | 2
+>      : ^^^^^
+
+vdu12 = vdu1;
+>vdu12 = vdu1 : 1
+>             : ^
+>vdu12 : 1 | 2
+>      : ^^^^^
+>vdu1 : 1
+>     : ^
+
 interface Shape<Value> {
  value: Value;
 >value : Value
@ -45,6 +117,30 @@ type VarianceShape<in out Value> = Shape<Value>;
 >VarianceShape : VarianceShape<Value>
 >              : ^^^^^^^^^^^^^^^^^^^^

+declare let vs1: VarianceShape<1>;
+>vs1 : VarianceShape<1>
+>    : ^^^^^^^^^^^^^^^^
+
+declare let vs12: VarianceShape<1 | 2>;
+>vs12 : VarianceShape<1 | 2>
+>     : ^^^^^^^^^^^^^^^^^^^^
+
+vs1 = vs12;
+>vs1 = vs12 : VarianceShape<1 | 2>
+>           : ^^^^^^^^^^^^^^^^^^^^
+>vs1 : VarianceShape<1>
+>    : ^^^^^^^^^^^^^^^^
+>vs12 : VarianceShape<1 | 2>
+>     : ^^^^^^^^^^^^^^^^^^^^
+
+vs12 = vs1;
+>vs12 = vs1 : VarianceShape<1>
+>           : ^^^^^^^^^^^^^^^^
+>vs12 : VarianceShape<1 | 2>
+>     : ^^^^^^^^^^^^^^^^^^^^
+>vs1 : VarianceShape<1>
+>    : ^^^^^^^^^^^^^^^^
+
 interface Level3of3Shape<Value> {
  value: Value;
 >value : Value
@ -63,3 +159,27 @@ type VarianceDeepShape<in out Value> = Level1of3Shape<Value>;
 >VarianceDeepShape : VarianceDeepShape<Value>
 >                  : ^^^^^^^^^^^^^^^^^^^^^^^^

+declare let vds1: VarianceDeepShape<1>;
+>vds1 : VarianceDeepShape<1>
+>     : ^^^^^^^^^^^^^^^^^^^^
+
+declare let vds12: VarianceDeepShape<1 | 2>;
+>vds12 : VarianceDeepShape<1 | 2>
+>      : ^^^^^^^^^^^^^^^^^^^^^^^^
+
+vds1 = vds12;
+>vds1 = vds12 : VarianceDeepShape<1 | 2>
+>             : ^^^^^^^^^^^^^^^^^^^^^^^^
+>vds1 : VarianceDeepShape<1>
+>     : ^^^^^^^^^^^^^^^^^^^^
+>vds12 : VarianceDeepShape<1 | 2>
+>      : ^^^^^^^^^^^^^^^^^^^^^^^^
+
+vds12 = vds1;
+>vds12 = vds1 : VarianceDeepShape<1>
+>             : ^^^^^^^^^^^^^^^^^^^^
+>vds12 : VarianceDeepShape<1 | 2>
+>      : ^^^^^^^^^^^^^^^^^^^^^^^^
+>vds1 : VarianceDeepShape<1>
+>     : ^^^^^^^^^^^^^^^^^^^^
+
--- a/tests/cases/compiler/varianceReferences.ts
+++ b/tests/cases/compiler/varianceReferences.ts
@ -1,24 +1,51 @@
+// @strict: true
+// @noEmit: true
+
 type NumericConstraint<Value extends number> = Value;

 type VarianceConstrainedNumber<in out Value extends number> =
  NumericConstraint<Value>;

+declare let vcn1: VarianceConstrainedNumber<1>;
+declare let vcn12: VarianceConstrainedNumber<1 | 2>;
+
+vcn1 = vcn12;
+vcn12 = vcn1;
+
 type Unconstrained<Value> = Value;

 type VarianceUnconstrained<in out Value> = Unconstrained<Value>;

+declare let vu1: VarianceUnconstrained<1>;
+declare let vu12: VarianceUnconstrained<1 | 2>;
+
+vu1 = vu12;
+vu12 = vu1;
+
 type Level3of3Unconstrained<Value> = Value;
 type Level2of3Unconstrained<Value> = Level3of3Unconstrained<Value>;
 type Level1of3Unconstrained<Value> = Level2of3Unconstrained<Value>;

 type VarianceDeepUnconstrained<in out Value> = Level1of3Unconstrained<Value>;

+declare let vdu1: VarianceDeepUnconstrained<1>;
+declare let vdu12: VarianceDeepUnconstrained<1 | 2>;
+
+vdu1 = vdu12;
+vdu12 = vdu1;
+
 interface Shape<Value> {
  value: Value;
 }

 type VarianceShape<in out Value> = Shape<Value>;

+declare let vs1: VarianceShape<1>;
+declare let vs12: VarianceShape<1 | 2>;
+
+vs1 = vs12;
+vs12 = vs1;
+
 interface Level3of3Shape<Value> {
  value: Value;
 }
@ -27,3 +54,9 @@ type Level2of3Shape<Value> = Level3of3Shape<Value>;
 type Level1of3Shape<Value> = Level2of3Shape<Value>;

 type VarianceDeepShape<in out Value> = Level1of3Shape<Value>;
+
+declare let vds1: VarianceDeepShape<1>;
+declare let vds12: VarianceDeepShape<1 | 2>;
+
+vds1 = vds12;
+vds12 = vds1;