Cherry-pick PR #50535 into release-4.8 (#50549)

Component commits: 7bd2a6e Only normalize intersections that include {} 698c3ab Accept new baselines Co-authored-by: Anders Hejlsberg <[email protected]>
microsoft · Sep 1, 2022 · ac0cc8c · ac0cc8c
1 parent 8b79b2f
commit ac0cc8c
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Showing 2 changed files with 4 additions and 3 deletions.
diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
@@ -18465,7 +18465,7 @@ namespace ts {
             if (reduced !== type) {
                 return reduced;
             }
-            if (type.flags & TypeFlags.Intersection) {
+            if (type.flags & TypeFlags.Intersection && some((type as IntersectionType).types, isEmptyAnonymousObjectType)) {
                 const normalizedTypes = sameMap(type.types, t => getNormalizedType(t, writing));
                 if (normalizedTypes !== type.types) {
                     return getIntersectionType(normalizedTypes);

diff --git a/tests/baselines/reference/conditionalTypes2.errors.txt b/tests/baselines/reference/conditionalTypes2.errors.txt
@@ -32,7 +32,7 @@ tests/cases/conformance/types/conditional/conditionalTypes2.ts(74,12): error TS2
   Property 'bat' is missing in type 'Foo & Bar' but required in type '{ foo: string; bat: string; }'.
 tests/cases/conformance/types/conditional/conditionalTypes2.ts(75,12): error TS2345: Argument of type 'Extract2<T, Foo, Bar>' is not assignable to parameter of type '{ foo: string; bat: string; }'.
   Type 'T extends Bar ? T : never' is not assignable to type '{ foo: string; bat: string; }'.
-    Type 'Bar & Foo & T' is not assignable to type '{ foo: string; bat: string; }'.
+    Property 'bat' is missing in type 'Bar & Foo' but required in type '{ foo: string; bat: string; }'.
 
 
 ==== tests/cases/conformance/types/conditional/conditionalTypes2.ts (7 errors) ====
@@ -159,7 +159,8 @@ tests/cases/conformance/types/conditional/conditionalTypes2.ts(75,12): error TS2
                ~
 !!! error TS2345: Argument of type 'Extract2<T, Foo, Bar>' is not assignable to parameter of type '{ foo: string; bat: string; }'.
 !!! error TS2345:   Type 'T extends Bar ? T : never' is not assignable to type '{ foo: string; bat: string; }'.
-!!! error TS2345:     Type 'Bar & Foo & T' is not assignable to type '{ foo: string; bat: string; }'.
+!!! error TS2345:     Property 'bat' is missing in type 'Bar & Foo' but required in type '{ foo: string; bat: string; }'.
+!!! related TS2728 tests/cases/conformance/types/conditional/conditionalTypes2.ts:62:43: 'bat' is declared here.
     }
 
     // Repros from #22860