Add tests

Author: ahejlsberg

tests/cases/conformance/types/keyof/keyofAndIndexedAccess.ts

@@ -567,3 +567,21 @@ function f3<T, K extends Extract<keyof T, string>>(t: T, k: K, tk: T[K]): void {
 type Predicates<TaggedRecord> = {
   [T in keyof TaggedRecord]: (variant: TaggedRecord[keyof TaggedRecord]) => variant is TaggedRecord[T]
 }
+
+// Repro from #23618
+
+type DBBoolTable<K extends string> = { [k in K]: 0 | 1 } 
+enum Flag {
+    FLAG_1 = "flag_1",
+    FLAG_2 = "flag_2"
+}
+
+type SimpleDBRecord<Flag extends string> = { staticField: number } & DBBoolTable<Flag>
+function getFlagsFromSimpleRecord<Flag extends string>(record: SimpleDBRecord<Flag>, flags: Flag[]) {
+    return record[flags[0]];
+}
+
+type DynamicDBRecord<Flag extends string> = ({ dynamicField: number } | { dynamicField: string }) & DBBoolTable<Flag>
+function getFlagsFromDynamicRecord<Flag extends string>(record: DynamicDBRecord<Flag>, flags: Flag[]) {
+    return record[flags[0]];
+}

tests/cases/conformance/types/keyof/keyofAndIndexedAccessErrors.ts

@@ -67,15 +67,32 @@ function f10(shape: Shape) {
     setProperty(shape, cond ? "name" : "size", 10);  // Error
 }
 
-function f20<T, U>(k1: keyof (T | U), k2: keyof (T & U), o1: T | U, o2: T & U) {
-    o1[k1];
-    o1[k2];   // Error
-    o2[k1];
-    o2[k2];
-    o1 = o2;
-    o2 = o1;  // Error
-    k1 = k2;  // Error
+function f20<T, U>(x: T | U, y: T & U, k1: keyof (T | U), k2: keyof T & keyof U, k3: keyof (T & U), k4: keyof T | keyof U) {
+    x[k1];
+    x[k2];
+    x[k3];  // Error
+    x[k4];  // Error
+
+    y[k1];
+    y[k2];
+    y[k3];
+    y[k4];
+
+    k1 = k2;
+    k1 = k3;  // Error
+    k1 = k4;  // Error
+
     k2 = k1;
+    k2 = k3;  // Error
+    k2 = k4;  // Error
+
+    k3 = k1;
+    k3 = k2;
+    k3 = k4;
+
+    k4 = k1;
+    k4 = k2;
+    k4 = k3;
 }
 
 // Repro from #17166