From a56b254ad3c52b598bc5d44f83f3d0a1cf806068 Mon Sep 17 00:00:00 2001
From: Ron Buckton <ron.buckton@microsoft.com>
Date: Fri, 21 Oct 2022 08:00:24 -0400
Subject: [PATCH] Include 'this' type parameter in isRelatedTo fast path
 (#51230)

---
 src/compiler/checker.ts                               |  4 ++--
 .../baselines/reference/asyncFunctionReturnType.2.js  | 11 +++++++++++
 .../reference/asyncFunctionReturnType.2.symbols       | 10 ++++++++++
 .../reference/asyncFunctionReturnType.2.types         | 10 ++++++++++
 tests/cases/compiler/asyncFunctionReturnType.2.ts     |  6 ++++++
 5 files changed, 39 insertions(+), 2 deletions(-)
 create mode 100644 tests/baselines/reference/asyncFunctionReturnType.2.js
 create mode 100644 tests/baselines/reference/asyncFunctionReturnType.2.symbols
 create mode 100644 tests/baselines/reference/asyncFunctionReturnType.2.types
 create mode 100644 tests/cases/compiler/asyncFunctionReturnType.2.ts

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 5b30941b5ccb3..76b9a21d73f0f 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -36994,7 +36994,7 @@ namespace ts {
             }
 
             // primitives with a `{ then() }` won't be unwrapped/adopted.
-            if (allTypesAssignableToKind(type, TypeFlags.Primitive | TypeFlags.Never)) {
+            if (allTypesAssignableToKind(getBaseConstraintOrType(type), TypeFlags.Primitive | TypeFlags.Never)) {
                 return undefined;
             }
 
@@ -37069,7 +37069,7 @@ namespace ts {
          * Determines whether a type is an object with a callable `then` member.
          */
         function isThenableType(type: Type): boolean {
-            if (allTypesAssignableToKind(type, TypeFlags.Primitive | TypeFlags.Never)) {
+            if (allTypesAssignableToKind(getBaseConstraintOrType(type), TypeFlags.Primitive | TypeFlags.Never)) {
                 // primitive types cannot be considered "thenable" since they are not objects.
                 return false;
             }
diff --git a/tests/baselines/reference/asyncFunctionReturnType.2.js b/tests/baselines/reference/asyncFunctionReturnType.2.js
new file mode 100644
index 0000000000000..9405b3f2bb5b6
--- /dev/null
+++ b/tests/baselines/reference/asyncFunctionReturnType.2.js
@@ -0,0 +1,11 @@
+//// [asyncFunctionReturnType.2.ts]
+// https://github.com/microsoft/TypeScript/issues/47291
+class X {
+    f = async (): Promise<this> => this;
+}
+
+//// [asyncFunctionReturnType.2.js]
+// https://github.com/microsoft/TypeScript/issues/47291
+class X {
+    f = async () => this;
+}
diff --git a/tests/baselines/reference/asyncFunctionReturnType.2.symbols b/tests/baselines/reference/asyncFunctionReturnType.2.symbols
new file mode 100644
index 0000000000000..2e9988be963d3
--- /dev/null
+++ b/tests/baselines/reference/asyncFunctionReturnType.2.symbols
@@ -0,0 +1,10 @@
+=== tests/cases/compiler/asyncFunctionReturnType.2.ts ===
+// https://github.com/microsoft/TypeScript/issues/47291
+class X {
+>X : Symbol(X, Decl(asyncFunctionReturnType.2.ts, 0, 0))
+
+    f = async (): Promise<this> => this;
+>f : Symbol(X.f, Decl(asyncFunctionReturnType.2.ts, 1, 9))
+>Promise : Symbol(Promise, Decl(lib.es5.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.promise.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --), Decl(lib.es2018.promise.d.ts, --, --))
+>this : Symbol(X, Decl(asyncFunctionReturnType.2.ts, 0, 0))
+}
diff --git a/tests/baselines/reference/asyncFunctionReturnType.2.types b/tests/baselines/reference/asyncFunctionReturnType.2.types
new file mode 100644
index 0000000000000..1559dda5bf47f
--- /dev/null
+++ b/tests/baselines/reference/asyncFunctionReturnType.2.types
@@ -0,0 +1,10 @@
+=== tests/cases/compiler/asyncFunctionReturnType.2.ts ===
+// https://github.com/microsoft/TypeScript/issues/47291
+class X {
+>X : X
+
+    f = async (): Promise<this> => this;
+>f : () => Promise<this>
+>async (): Promise<this> => this : () => Promise<this>
+>this : this
+}
diff --git a/tests/cases/compiler/asyncFunctionReturnType.2.ts b/tests/cases/compiler/asyncFunctionReturnType.2.ts
new file mode 100644
index 0000000000000..628ecf915ef46
--- /dev/null
+++ b/tests/cases/compiler/asyncFunctionReturnType.2.ts
@@ -0,0 +1,6 @@
+// @target: esnext
+
+// https://github.com/microsoft/TypeScript/issues/47291
+class X {
+    f = async (): Promise<this> => this;
+}
\ No newline at end of file