fix: remove .value field from type declarations for boolean literal types (#535)

## PR Checklist

- [x] Addresses an existing open issue: fixes #528 
- [x] That issue was marked as [`status: accepting
prs`](https://github.com/JoshuaKGoldberg/ts-api-utils/issues?q=is%3Aopen+is%3Aissue+label%3A%22status%3A+accepting+prs%22)
- [x] Steps in
[CONTRIBUTING.md](https://github.com/JoshuaKGoldberg/ts-api-utils/blob/main/.github/CONTRIBUTING.md)
were taken

## Overview

Ostensibly, this is the code change, but it looks pretty intentional
that it was written this way in the first place, so.... maybe needs some
more investigation in order to understand why it was written this way.

<s>I'm not really sure how to test for this, either. I've written a test
that proves the bug's existence, but wouldn't prevent it from
regressing. Open to suggestions 🤔</s> I've written a test that proves
the bug's existence at runtime, _and_ will cause a type-checking error
if the `value` field is added back, due to its use of `@ts-expect-error`

---------

Co-authored-by: Rebecca Stevens <rebecca.stevens@outlook.co.nz>

Author: kirkwaiblinger

src/types/typeGuards/literal.test.ts

@@ -3,7 +3,9 @@ import { describe, expect, it } from "vitest";
 
 import { createSourceFileAndTypeChecker } from "../../test/utils";
 import {
+	BooleanLiteralType,
 	isBigIntLiteralType,
+	isBooleanLiteralType,
 	isFalseLiteralType,
 	isLiteralType,
 	isNumberLiteralType,
@@ -40,3 +42,24 @@ describe.each([
 		});
 	});
 });
+
+describe("booleans don't have .value", () => {
+	for (const trueOrFalse of ["true", "false"]) {
+		it(`should show that ${trueOrFalse} is a boolean literal type but doesn't have a .value field`, () => {
+			const { sourceFile, typeChecker } = createSourceFileAndTypeChecker(`
+				declare const x: ${trueOrFalse};
+			`);
+
+			const node = (sourceFile.statements[0] as ts.VariableStatement)
+				.declarationList.declarations[0].name;
+
+			const type = typeChecker.getTypeAtLocation(node);
+
+			expect(isBooleanLiteralType(type)).toBe(true);
+			const booleanLiteralType = type as BooleanLiteralType;
+			expect(booleanLiteralType.intrinsicName).toEqual(trueOrFalse);
+
+			expect(booleanLiteralType).not.toHaveProperty("value");
+		});
+	}
+});

src/types/typeGuards/literal.ts

@@ -8,9 +8,8 @@ import { type FreshableIntrinsicType } from "./compound";
  * i.e. Either a "true" or "false" literal.
  * @category Type Types
  */
-export interface BooleanLiteralType extends UnknownLiteralType {
+export interface BooleanLiteralType extends FreshableIntrinsicType {
 	intrinsicName: "false" | "true";
-	value: boolean;
 }
 
 /**
@@ -55,7 +54,6 @@ export function isBigIntLiteralType(
  */
 export interface FalseLiteralType extends BooleanLiteralType {
 	intrinsicName: "false";
-	value: false;
 }
 
 /**
@@ -150,7 +148,6 @@ export function isTemplateLiteralType(
  */
 export interface TrueLiteralType extends BooleanLiteralType {
 	intrinsicName: "true";
-	value: true;
 }
 
 /**
@@ -171,14 +168,16 @@ export function isTrueLiteralType(type: ts.Type): type is TrueLiteralType {
 
 /**
  * `LiteralType` from typescript except that it allows for it to work on arbitrary types.
+ * @deprecated Use {@link FreshableIntrinsicType} instead.
  * @category Type Types
  */
 export interface UnknownLiteralType extends FreshableIntrinsicType {
-	value: unknown;
+	value?: unknown;
 }
 
 /**
  * Test if a type is a {@link UnknownLiteralType}.
+ * @deprecated Use {@link isFreshableIntrinsicType} instead.
  * @category Types - Type Guards
  * @example
  * ```ts
@@ -191,6 +190,7 @@ export interface UnknownLiteralType extends FreshableIntrinsicType {
  */
 export function isUnknownLiteralType(
 	type: ts.Type,
+	// eslint-disable-next-line deprecation/deprecation
 ): type is UnknownLiteralType {
 	return isTypeFlagSet(type, ts.TypeFlags.Literal);
 }