From 897a5d50051fb2e13c482a18f4b189410f847475 Mon Sep 17 00:00:00 2001
From: Evgeniy Timokhov <timocov@gmail.com>
Date: Wed, 17 Apr 2024 23:29:36 +0100
Subject: [PATCH] Fixed incorrect caching of symbols usage values

Fixes #318
---
 src/types-usage-evaluator.ts                       | 6 +++++-
 tests/e2e/test-cases/recursive-types/config.ts     | 5 +++++
 tests/e2e/test-cases/recursive-types/index.spec.js | 1 +
 tests/e2e/test-cases/recursive-types/input.ts      | 3 +++
 tests/e2e/test-cases/recursive-types/output.d.ts   | 6 ++++++
 tests/e2e/test-cases/recursive-types/types.ts      | 5 +++++
 6 files changed, 25 insertions(+), 1 deletion(-)
 create mode 100644 tests/e2e/test-cases/recursive-types/config.ts
 create mode 100644 tests/e2e/test-cases/recursive-types/index.spec.js
 create mode 100644 tests/e2e/test-cases/recursive-types/input.ts
 create mode 100644 tests/e2e/test-cases/recursive-types/output.d.ts
 create mode 100644 tests/e2e/test-cases/recursive-types/types.ts

diff --git a/src/types-usage-evaluator.ts b/src/types-usage-evaluator.ts
index ee5603bf..a7004f29 100644
--- a/src/types-usage-evaluator.ts
+++ b/src/types-usage-evaluator.ts
@@ -57,7 +57,11 @@ export class TypesUsageEvaluator {
 
 		visitedSymbols.add(fromSymbol);
 
-		return this.setUsageCacheValue(fromSymbol, toSymbol, false);
+		// note that we can't save negative result here because it might be not a final one
+		// because we might ended up here because of `visitedSymbols.has(symbol)` check above
+		// while actually checking that `symbol` symbol and we will store all its "children" as `false`
+		// while in reality some of them might be `true` because of cross-references or using the same children symbols
+		return false;
 	}
 
 	private setUsageCacheValue(fromSymbol: ts.Symbol, toSymbol: ts.Symbol, value: boolean): boolean {
diff --git a/tests/e2e/test-cases/recursive-types/config.ts b/tests/e2e/test-cases/recursive-types/config.ts
new file mode 100644
index 00000000..f1fb1a8c
--- /dev/null
+++ b/tests/e2e/test-cases/recursive-types/config.ts
@@ -0,0 +1,5 @@
+import { TestCaseConfig } from '../../test-cases/test-case-config';
+
+const config: TestCaseConfig = {};
+
+export = config;
diff --git a/tests/e2e/test-cases/recursive-types/index.spec.js b/tests/e2e/test-cases/recursive-types/index.spec.js
new file mode 100644
index 00000000..c015c268
--- /dev/null
+++ b/tests/e2e/test-cases/recursive-types/index.spec.js
@@ -0,0 +1 @@
+require('../run-test-case').runTestCase(__dirname);
diff --git a/tests/e2e/test-cases/recursive-types/input.ts b/tests/e2e/test-cases/recursive-types/input.ts
new file mode 100644
index 00000000..4baea076
--- /dev/null
+++ b/tests/e2e/test-cases/recursive-types/input.ts
@@ -0,0 +1,3 @@
+import { FirstType } from './types';
+
+export type MyType = FirstType<string>;
diff --git a/tests/e2e/test-cases/recursive-types/output.d.ts b/tests/e2e/test-cases/recursive-types/output.d.ts
new file mode 100644
index 00000000..312db248
--- /dev/null
+++ b/tests/e2e/test-cases/recursive-types/output.d.ts
@@ -0,0 +1,6 @@
+export type ThirdType = number;
+export type SecondType<T, V> = T extends any ? V : FirstType<T>;
+export type FirstType<T> = SecondType<ThirdType, T>;
+export type MyType = FirstType<string>;
+
+export {};
diff --git a/tests/e2e/test-cases/recursive-types/types.ts b/tests/e2e/test-cases/recursive-types/types.ts
new file mode 100644
index 00000000..70c62f3b
--- /dev/null
+++ b/tests/e2e/test-cases/recursive-types/types.ts
@@ -0,0 +1,5 @@
+type ThirdType = number;
+
+type SecondType<T, V> = T extends any ? V : FirstType<T>;
+
+export type FirstType<T> = SecondType<ThirdType, T>;