fix(types): defer type parameters in MutuallyAssignable and boolean types

as of TS4.9, conditional types are only deferred for single-element tuples, not multi-element ones.
this should be fixed in microsoft/TypeScript#52091, slated for the TS5.0 milestone.
until then, however, the implementations of `MutuallyAssignable`, `And`, and `Xor` can be assumed to be bugged.
this commit fixes them to properly defer types.
`Or` was also like this but fixed in earlier commit 0cd75d4

Author: duanwilliam

packages/types/src/bool/and.d.ts

@@ -2,6 +2,14 @@
  * checks if both `A` and `B` extend true
  */
 export type And<A extends boolean, B extends boolean> =
-  [A, B] extends [true, true]
-    ? true
+  /* as of TS4.9, conditional types are only deferred for single-element tuples, not multi-element ones.
+   * this should be fixed in https://github.com/microsoft/TypeScript/pull/52091/, slated for the TS5.0 milestone.
+   */
+  // [A, B] extends [true, true]
+  //   ? true
+  //   : false
+  [A] extends [true]
+    ? [B] extends [true]
+      ? true
+      : false
     : false

packages/types/src/bool/xor.d.ts

@@ -2,6 +2,19 @@
  * checks if one of `A` and `B` is true and the other false
  */
 export type Xor<A extends boolean, B extends boolean> =
-  [A, B] extends [true, false] ? true
-  : [A, B] extends [false, true] ? true
+  /* as of TS4.9, conditional types are only deferred for single-element tuples, not multi-element ones.
+   * this should be fixed in https://github.com/microsoft/TypeScript/pull/52091/, slated for the TS5.0 milestone.
+   * also relevant: https://github.com/microsoft/TypeScript/issues/51145#issuecomment-1276804047
+   */
+  // [A, B] extends [true, false] ? true
+  // : [A, B] extends [false, true] ? true
+  // : false
+  [A] extends [true]
+    ? [B] extends [false]
+      ? true
+      : false
+  : [A] extends [false]
+    ? [B] extends [true]
+      ? true
+      : false
   : false

packages/types/src/type/mutually-assignable.d.ts

@@ -6,6 +6,15 @@
  * for example, `[string, any]` is not `[any, string]` but both _are_ assignable to each other
  */
 export type MutuallyAssignable<A, B> =
-  [A, B] extends [B, A]
-    ? true
+  /* as of TS4.9, conditional types are only deferred for single-element tuples, not multi-element ones.
+   * this should be fixed in https://github.com/microsoft/TypeScript/pull/52091/, slated for the TS5.0 milestone.
+   * also relevant: https://github.com/microsoft/TypeScript/issues/51145#issuecomment-1276804047
+   */
+  // [A, B] extends [B, A]
+  //   ? true
+  //   : false
+  [A] extends [B]
+    ? [B] extends [A]
+      ? true
+      : false
     : false