Fix unions

Author: jakebailey

src/compiler/checker.ts

@@ -22978,6 +22978,11 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
             type;
     }
 
+    function getBaseTypeOfLiteralTypeUnion(type: UnionType) {
+        const key = `B${getTypeId(type)}`;
+        return getCachedType(key) ?? setCachedType(key, mapType(type, getBaseTypeOfLiteralType));
+    }
+
     // This is the same as getBaseTypeOfLiteralType, but checks EnumLiteral last so we get
     // a specific literal's base type rather than the enum's base type.
     function getBaseTypeOfLiteralTypeForComparison(type: Type): Type {
@@ -22986,13 +22991,13 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
             type.flags & TypeFlags.BigIntLiteral ? bigintType :
             type.flags & TypeFlags.BooleanLiteral ? booleanType :
             type.flags & TypeFlags.EnumLiteral ? getBaseTypeOfEnumLiteralType(type as LiteralType) :
-            type.flags & TypeFlags.Union ? getBaseTypeOfLiteralTypeUnion(type as UnionType) :
+            type.flags & TypeFlags.Union ? getBaseTypeOfLiteralTypeUnionForComparison(type as UnionType) :
             type;
     }
 
-    function getBaseTypeOfLiteralTypeUnion(type: UnionType) {
-        const key = `B${getTypeId(type)}`;
-        return getCachedType(key) ?? setCachedType(key, mapType(type, getBaseTypeOfLiteralType));
+    function getBaseTypeOfLiteralTypeUnionForComparison(type: UnionType) {
+        const key = `BC${getTypeId(type)}`;
+        return getCachedType(key) ?? setCachedType(key, mapType(type, getBaseTypeOfLiteralTypeForComparison));
     }
 
     function getWidenedLiteralType(type: Type): Type {

tests/baselines/reference/mixedTypeEnumComparison.errors.txt

@@ -13,6 +13,12 @@ if (someNumber > E.N2) {
     someNumber = E.N2;
 }
 
+declare const unionOfEnum: E.N1 | E.N2;
+
+if (someNumber > unionOfEnum) {
+    someNumber = E.N2;
+}
+
 declare var someString: string
 
 if (someString > E.S1) {
@@ -26,6 +32,9 @@ if (someString > E.S1) {
 if (someNumber > 25 /* E.N2 */) {
     someNumber = 25 /* E.N2 */;
 }
+if (someNumber > unionOfEnum) {
+    someNumber = 25 /* E.N2 */;
+}
 if (someString > "foo" /* E.S1 */) {
     someString = "bar" /* E.S2 */;
 }

tests/baselines/reference/mixedTypeEnumComparison.js

@@ -31,17 +31,35 @@ if (someNumber > E.N2) {
 >N2 : Symbol(E.N2, Decl(mixedTypeEnumComparison.ts, 4, 14))
 }
 
+declare const unionOfEnum: E.N1 | E.N2;
+>unionOfEnum : Symbol(unionOfEnum, Decl(mixedTypeEnumComparison.ts, 14, 13))
+>E : Symbol(E, Decl(mixedTypeEnumComparison.ts, 0, 0))
+>N1 : Symbol(E.N1, Decl(mixedTypeEnumComparison.ts, 2, 15))
+>E : Symbol(E, Decl(mixedTypeEnumComparison.ts, 0, 0))
+>N2 : Symbol(E.N2, Decl(mixedTypeEnumComparison.ts, 4, 14))
+
+if (someNumber > unionOfEnum) {
+>someNumber : Symbol(someNumber, Decl(mixedTypeEnumComparison.ts, 8, 11))
+>unionOfEnum : Symbol(unionOfEnum, Decl(mixedTypeEnumComparison.ts, 14, 13))
+
+    someNumber = E.N2;
+>someNumber : Symbol(someNumber, Decl(mixedTypeEnumComparison.ts, 8, 11))
+>E.N2 : Symbol(E.N2, Decl(mixedTypeEnumComparison.ts, 4, 14))
+>E : Symbol(E, Decl(mixedTypeEnumComparison.ts, 0, 0))
+>N2 : Symbol(E.N2, Decl(mixedTypeEnumComparison.ts, 4, 14))
+}
+
 declare var someString: string
->someString : Symbol(someString, Decl(mixedTypeEnumComparison.ts, 14, 11))
+>someString : Symbol(someString, Decl(mixedTypeEnumComparison.ts, 20, 11))
 
 if (someString > E.S1) {
->someString : Symbol(someString, Decl(mixedTypeEnumComparison.ts, 14, 11))
+>someString : Symbol(someString, Decl(mixedTypeEnumComparison.ts, 20, 11))
 >E.S1 : Symbol(E.S1, Decl(mixedTypeEnumComparison.ts, 0, 14))
 >E : Symbol(E, Decl(mixedTypeEnumComparison.ts, 0, 0))
 >S1 : Symbol(E.S1, Decl(mixedTypeEnumComparison.ts, 0, 14))
 
     someString = E.S2;
->someString : Symbol(someString, Decl(mixedTypeEnumComparison.ts, 14, 11))
+>someString : Symbol(someString, Decl(mixedTypeEnumComparison.ts, 20, 11))
 >E.S2 : Symbol(E.S2, Decl(mixedTypeEnumComparison.ts, 1, 15))
 >E : Symbol(E, Decl(mixedTypeEnumComparison.ts, 0, 0))
 >S2 : Symbol(E.S2, Decl(mixedTypeEnumComparison.ts, 1, 15))

tests/baselines/reference/mixedTypeEnumComparison.symbols

@@ -37,6 +37,24 @@ if (someNumber > E.N2) {
 >N2 : E.N2
 }
 
+declare const unionOfEnum: E.N1 | E.N2;
+>unionOfEnum : E.N1 | E.N2
+>E : any
+>E : any
+
+if (someNumber > unionOfEnum) {
+>someNumber > unionOfEnum : boolean
+>someNumber : number
+>unionOfEnum : E.N1 | E.N2
+
+    someNumber = E.N2;
+>someNumber = E.N2 : E.N2
+>someNumber : number
+>E.N2 : E.N2
+>E : typeof E
+>N2 : E.N2
+}
+
 declare var someString: string
 >someString : string
 

tests/baselines/reference/mixedTypeEnumComparison.types

@@ -14,6 +14,12 @@ if (someNumber > E.N2) {
     someNumber = E.N2;
 }
 
+declare const unionOfEnum: E.N1 | E.N2;
+
+if (someNumber > unionOfEnum) {
+    someNumber = E.N2;
+}
+
 declare var someString: string
 
 if (someString > E.S1) {