From fbebbcaa7e663d6d2c8070190cc92d7b564f3237 Mon Sep 17 00:00:00 2001
From: Anders Hejlsberg <andersh@microsoft.com>
Date: Sat, 10 Sep 2016 07:20:05 -0700
Subject: [PATCH] Add regression test

---
 .../narrowingConstrainedTypeParameter.js      | 32 ++++++++++++
 .../narrowingConstrainedTypeParameter.symbols | 42 +++++++++++++++
 .../narrowingConstrainedTypeParameter.types   | 52 +++++++++++++++++++
 .../narrowingConstrainedTypeParameter.ts      | 18 +++++++
 4 files changed, 144 insertions(+)
 create mode 100644 tests/baselines/reference/narrowingConstrainedTypeParameter.js
 create mode 100644 tests/baselines/reference/narrowingConstrainedTypeParameter.symbols
 create mode 100644 tests/baselines/reference/narrowingConstrainedTypeParameter.types
 create mode 100644 tests/cases/compiler/narrowingConstrainedTypeParameter.ts

diff --git a/tests/baselines/reference/narrowingConstrainedTypeParameter.js b/tests/baselines/reference/narrowingConstrainedTypeParameter.js
new file mode 100644
index 0000000000..3107585d94
--- /dev/null
+++ b/tests/baselines/reference/narrowingConstrainedTypeParameter.js
@@ -0,0 +1,32 @@
+//// [narrowingConstrainedTypeParameter.ts]
+
+// Repro from #10811
+
+interface Pet {
+    name: string;
+}
+
+function isPet(pet: any): pet is Pet {
+    return typeof pet.name === "string";
+}
+
+export function speak<TPet extends Pet>(pet: TPet, voice: (pet: TPet) => string): string {
+    if (!isPet(pet)) {
+        throw new Error("Expected \"pet\" to be a Pet");
+    }
+    return voice(pet);
+}
+
+//// [narrowingConstrainedTypeParameter.js]
+// Repro from #10811
+"use strict";
+function isPet(pet) {
+    return typeof pet.name === "string";
+}
+function speak(pet, voice) {
+    if (!isPet(pet)) {
+        throw new Error("Expected \"pet\" to be a Pet");
+    }
+    return voice(pet);
+}
+exports.speak = speak;
diff --git a/tests/baselines/reference/narrowingConstrainedTypeParameter.symbols b/tests/baselines/reference/narrowingConstrainedTypeParameter.symbols
new file mode 100644
index 0000000000..89ca39e98a
--- /dev/null
+++ b/tests/baselines/reference/narrowingConstrainedTypeParameter.symbols
@@ -0,0 +1,42 @@
+=== tests/cases/compiler/narrowingConstrainedTypeParameter.ts ===
+
+// Repro from #10811
+
+interface Pet {
+>Pet : Symbol(Pet, Decl(narrowingConstrainedTypeParameter.ts, 0, 0))
+
+    name: string;
+>name : Symbol(Pet.name, Decl(narrowingConstrainedTypeParameter.ts, 3, 15))
+}
+
+function isPet(pet: any): pet is Pet {
+>isPet : Symbol(isPet, Decl(narrowingConstrainedTypeParameter.ts, 5, 1))
+>pet : Symbol(pet, Decl(narrowingConstrainedTypeParameter.ts, 7, 15))
+>pet : Symbol(pet, Decl(narrowingConstrainedTypeParameter.ts, 7, 15))
+>Pet : Symbol(Pet, Decl(narrowingConstrainedTypeParameter.ts, 0, 0))
+
+    return typeof pet.name === "string";
+>pet : Symbol(pet, Decl(narrowingConstrainedTypeParameter.ts, 7, 15))
+}
+
+export function speak<TPet extends Pet>(pet: TPet, voice: (pet: TPet) => string): string {
+>speak : Symbol(speak, Decl(narrowingConstrainedTypeParameter.ts, 9, 1))
+>TPet : Symbol(TPet, Decl(narrowingConstrainedTypeParameter.ts, 11, 22))
+>Pet : Symbol(Pet, Decl(narrowingConstrainedTypeParameter.ts, 0, 0))
+>pet : Symbol(pet, Decl(narrowingConstrainedTypeParameter.ts, 11, 40))
+>TPet : Symbol(TPet, Decl(narrowingConstrainedTypeParameter.ts, 11, 22))
+>voice : Symbol(voice, Decl(narrowingConstrainedTypeParameter.ts, 11, 50))
+>pet : Symbol(pet, Decl(narrowingConstrainedTypeParameter.ts, 11, 59))
+>TPet : Symbol(TPet, Decl(narrowingConstrainedTypeParameter.ts, 11, 22))
+
+    if (!isPet(pet)) {
+>isPet : Symbol(isPet, Decl(narrowingConstrainedTypeParameter.ts, 5, 1))
+>pet : Symbol(pet, Decl(narrowingConstrainedTypeParameter.ts, 11, 40))
+
+        throw new Error("Expected \"pet\" to be a Pet");
+>Error : Symbol(Error, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
+    }
+    return voice(pet);
+>voice : Symbol(voice, Decl(narrowingConstrainedTypeParameter.ts, 11, 50))
+>pet : Symbol(pet, Decl(narrowingConstrainedTypeParameter.ts, 11, 40))
+}
diff --git a/tests/baselines/reference/narrowingConstrainedTypeParameter.types b/tests/baselines/reference/narrowingConstrainedTypeParameter.types
new file mode 100644
index 0000000000..adefb63ab8
--- /dev/null
+++ b/tests/baselines/reference/narrowingConstrainedTypeParameter.types
@@ -0,0 +1,52 @@
+=== tests/cases/compiler/narrowingConstrainedTypeParameter.ts ===
+
+// Repro from #10811
+
+interface Pet {
+>Pet : Pet
+
+    name: string;
+>name : string
+}
+
+function isPet(pet: any): pet is Pet {
+>isPet : (pet: any) => pet is Pet
+>pet : any
+>pet : any
+>Pet : Pet
+
+    return typeof pet.name === "string";
+>typeof pet.name === "string" : boolean
+>typeof pet.name : string
+>pet.name : any
+>pet : any
+>name : any
+>"string" : "string"
+}
+
+export function speak<TPet extends Pet>(pet: TPet, voice: (pet: TPet) => string): string {
+>speak : <TPet extends Pet>(pet: TPet, voice: (pet: TPet) => string) => string
+>TPet : TPet
+>Pet : Pet
+>pet : TPet
+>TPet : TPet
+>voice : (pet: TPet) => string
+>pet : TPet
+>TPet : TPet
+
+    if (!isPet(pet)) {
+>!isPet(pet) : boolean
+>isPet(pet) : boolean
+>isPet : (pet: any) => pet is Pet
+>pet : TPet
+
+        throw new Error("Expected \"pet\" to be a Pet");
+>new Error("Expected \"pet\" to be a Pet") : Error
+>Error : ErrorConstructor
+>"Expected \"pet\" to be a Pet" : string
+    }
+    return voice(pet);
+>voice(pet) : string
+>voice : (pet: TPet) => string
+>pet : TPet
+}
diff --git a/tests/cases/compiler/narrowingConstrainedTypeParameter.ts b/tests/cases/compiler/narrowingConstrainedTypeParameter.ts
new file mode 100644
index 0000000000..8eacbca011
--- /dev/null
+++ b/tests/cases/compiler/narrowingConstrainedTypeParameter.ts
@@ -0,0 +1,18 @@
+// @strictNullChecks: true
+
+// Repro from #10811
+
+interface Pet {
+    name: string;
+}
+
+function isPet(pet: any): pet is Pet {
+    return typeof pet.name === "string";
+}
+
+export function speak<TPet extends Pet>(pet: TPet, voice: (pet: TPet) => string): string {
+    if (!isPet(pet)) {
+        throw new Error("Expected \"pet\" to be a Pet");
+    }
+    return voice(pet);
+}
\ No newline at end of file