Addressing CR feedback

unknown · unknown · commit 9a2846ef72e7 · 2015-04-14T14:51:08.000-07:00
diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
@@ -3584,7 +3584,8 @@ module ts {
 
         // The noSubtypeReduction flag is there because it isn't possible to always do subtype reduction. The flag
         // is true when creating a union type from a type node and when instantiating a union type. In both of those
-        // cases subtype reduction has to be deferred to properly support recursive union types.
+        // cases subtype reduction has to be deferred to properly support recursive union types. For example, a
+        // type alias of the form "type Item = string | (() => Item)" cannot be reduced during its declaration.
         function getUnionType(types: Type[], noSubtypeReduction?: boolean): Type {
             if (types.length === 0) {
                 return emptyObjectType;
@@ -3615,8 +3616,9 @@ module ts {
         }
 
         function getReducedTypeOfUnionType(type: UnionType): Type {
+            // If union type was created without subtype reduction, perform the deferred reduction now
             if (!type.reducedType) {
-                type.reducedType = getUnionType(type.types);
+                type.reducedType = getUnionType(type.types, /*noSubtypeReduction*/ false);
             }
             return type.reducedType;
         }

Original file line number	Diff line number	Diff line change
`@@ -3584,7 +3584,8 @@ module ts {`
`3584`	`3584`
`3585`	`3585`	`// The noSubtypeReduction flag is there because it isn't possible to always do subtype reduction. The flag`
`3586`	`3586`	`// is true when creating a union type from a type node and when instantiating a union type. In both of those`
`3587`		`- // cases subtype reduction has to be deferred to properly support recursive union types.`
	`3587`	`+ // cases subtype reduction has to be deferred to properly support recursive union types. For example, a`
	`3588`	`+ // type alias of the form "type Item = string \| (() => Item)" cannot be reduced during its declaration.`
`3588`	`3589`	`function getUnionType(types: Type[], noSubtypeReduction?: boolean): Type {`
`3589`	`3590`	`if (types.length === 0) {`
`3590`	`3591`	`return emptyObjectType;`
`@@ -3615,8 +3616,9 @@ module ts {`
`3615`	`3616`	`}`
`3616`	`3617`
`3617`	`3618`	`function getReducedTypeOfUnionType(type: UnionType): Type {`
	`3619`	`+ // If union type was created without subtype reduction, perform the deferred reduction now`
`3618`	`3620`	`if (!type.reducedType) {`
`3619`		`- type.reducedType = getUnionType(type.types);`
	`3621`	`+ type.reducedType = getUnionType(type.types, /noSubtypeReduction/ false);`
`3620`	`3622`	`}`
`3621`	`3623`	`return type.reducedType;`
`3622`	`3624`	`}`