From 67b3fe58fa9b0761da93d9ea6ab2e8019b6a4b22 Mon Sep 17 00:00:00 2001
From: Anders Hejlsberg <andersh@microsoft.com>
Date: Sun, 7 Aug 2016 08:53:36 -0700
Subject: [PATCH] Add regression test

---
 .../reference/controlFlowInstanceof.js        | 156 +++++++++++++
 .../reference/controlFlowInstanceof.symbols   | 194 ++++++++++++++++
 .../reference/controlFlowInstanceof.types     | 217 ++++++++++++++++++
 tests/cases/compiler/controlFlowInstanceof.ts |  80 +++++++
 4 files changed, 647 insertions(+)
 create mode 100644 tests/baselines/reference/controlFlowInstanceof.js
 create mode 100644 tests/baselines/reference/controlFlowInstanceof.symbols
 create mode 100644 tests/baselines/reference/controlFlowInstanceof.types
 create mode 100644 tests/cases/compiler/controlFlowInstanceof.ts

diff --git a/tests/baselines/reference/controlFlowInstanceof.js b/tests/baselines/reference/controlFlowInstanceof.js
new file mode 100644
index 00000000000..7c7833927ca
--- /dev/null
+++ b/tests/baselines/reference/controlFlowInstanceof.js
@@ -0,0 +1,156 @@
+//// [controlFlowInstanceof.ts]
+
+// Repros from #10167
+
+function f1(s: Set<string> | Set<number>) {
+    s = new Set<number>();
+    s;  // Set<number>
+    if (s instanceof Set) {
+        s;  // Set<number>
+    }
+    s;  // Set<number>
+    s.add(42);
+}
+
+function f2(s: Set<string> | Set<number>) {
+    s = new Set<number>();
+    s;  // Set<number>
+    if (s instanceof Promise) {
+        s;  // Set<number> & Promise<any>
+    }
+    s;  // Set<number>
+    s.add(42);
+}
+
+function f3(s: Set<string> | Set<number>) {
+    s;  // Set<string> | Set<number>
+    if (s instanceof Set) {
+        s;  // Set<string> | Set<number>
+    }
+    else {
+        s;  // never
+    }
+}
+
+function f4(s: Set<string> | Set<number>) {
+    s = new Set<number>();
+    s;  // Set<number>
+    if (s instanceof Set) {
+        s;  // Set<number>
+    }
+    else {
+        s;  // never
+    }
+}
+
+// More tests
+
+class A { a: string }
+class B extends A { b: string }
+class C extends A { c: string }
+
+function foo(x: A | undefined) {
+    x;  // A | undefined
+    if (x instanceof B || x instanceof C) {
+        x;  // B | C
+    }
+    x;  // A | undefined
+    if (x instanceof B && x instanceof C) {
+        x;  // B & C
+    }
+    x;  // A | undefined
+    if (!x) {
+        return;
+    }
+    x;  // A
+    if (x instanceof B) {
+        x;  // B
+        if (x instanceof C) {
+            x;  // B & C
+        }
+        else {
+            x;  // B
+        }
+        x;  // B
+    }
+    else {
+        x;  // A
+    }
+    x;  // A
+}
+
+//// [controlFlowInstanceof.js]
+// Repros from #10167
+function f1(s) {
+    s = new Set();
+    s; // Set<number>
+    if (s instanceof Set) {
+        s; // Set<number>
+    }
+    s; // Set<number>
+    s.add(42);
+}
+function f2(s) {
+    s = new Set();
+    s; // Set<number>
+    if (s instanceof Promise) {
+        s; // Set<number> & Promise<any>
+    }
+    s; // Set<number>
+    s.add(42);
+}
+function f3(s) {
+    s; // Set<string> | Set<number>
+    if (s instanceof Set) {
+        s; // Set<string> | Set<number>
+    }
+    else {
+        s; // never
+    }
+}
+function f4(s) {
+    s = new Set();
+    s; // Set<number>
+    if (s instanceof Set) {
+        s; // Set<number>
+    }
+    else {
+        s; // never
+    }
+}
+// More tests
+class A {
+}
+class B extends A {
+}
+class C extends A {
+}
+function foo(x) {
+    x; // A | undefined
+    if (x instanceof B || x instanceof C) {
+        x; // B | C
+    }
+    x; // A | undefined
+    if (x instanceof B && x instanceof C) {
+        x; // B & C
+    }
+    x; // A | undefined
+    if (!x) {
+        return;
+    }
+    x; // A
+    if (x instanceof B) {
+        x; // B
+        if (x instanceof C) {
+            x; // B & C
+        }
+        else {
+            x; // B
+        }
+        x; // B
+    }
+    else {
+        x; // A
+    }
+    x; // A
+}
diff --git a/tests/baselines/reference/controlFlowInstanceof.symbols b/tests/baselines/reference/controlFlowInstanceof.symbols
new file mode 100644
index 00000000000..64b567c1548
--- /dev/null
+++ b/tests/baselines/reference/controlFlowInstanceof.symbols
@@ -0,0 +1,194 @@
+=== tests/cases/compiler/controlFlowInstanceof.ts ===
+
+// Repros from #10167
+
+function f1(s: Set<string> | Set<number>) {
+>f1 : Symbol(f1, Decl(controlFlowInstanceof.ts, 0, 0))
+>s : Symbol(s, Decl(controlFlowInstanceof.ts, 3, 12))
+>Set : Symbol(Set, Decl(lib.es2015.symbol.wellknown.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.collection.d.ts, --, --), Decl(lib.es2015.collection.d.ts, --, --))
+>Set : Symbol(Set, Decl(lib.es2015.symbol.wellknown.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.collection.d.ts, --, --), Decl(lib.es2015.collection.d.ts, --, --))
+
+    s = new Set<number>();
+>s : Symbol(s, Decl(controlFlowInstanceof.ts, 3, 12))
+>Set : Symbol(Set, Decl(lib.es2015.symbol.wellknown.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.collection.d.ts, --, --), Decl(lib.es2015.collection.d.ts, --, --))
+
+    s;  // Set<number>
+>s : Symbol(s, Decl(controlFlowInstanceof.ts, 3, 12))
+
+    if (s instanceof Set) {
+>s : Symbol(s, Decl(controlFlowInstanceof.ts, 3, 12))
+>Set : Symbol(Set, Decl(lib.es2015.symbol.wellknown.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.collection.d.ts, --, --), Decl(lib.es2015.collection.d.ts, --, --))
+
+        s;  // Set<number>
+>s : Symbol(s, Decl(controlFlowInstanceof.ts, 3, 12))
+    }
+    s;  // Set<number>
+>s : Symbol(s, Decl(controlFlowInstanceof.ts, 3, 12))
+
+    s.add(42);
+>s.add : Symbol(Set.add, Decl(lib.es2015.collection.d.ts, --, --))
+>s : Symbol(s, Decl(controlFlowInstanceof.ts, 3, 12))
+>add : Symbol(Set.add, Decl(lib.es2015.collection.d.ts, --, --))
+}
+
+function f2(s: Set<string> | Set<number>) {
+>f2 : Symbol(f2, Decl(controlFlowInstanceof.ts, 11, 1))
+>s : Symbol(s, Decl(controlFlowInstanceof.ts, 13, 12))
+>Set : Symbol(Set, Decl(lib.es2015.symbol.wellknown.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.collection.d.ts, --, --), Decl(lib.es2015.collection.d.ts, --, --))
+>Set : Symbol(Set, Decl(lib.es2015.symbol.wellknown.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.collection.d.ts, --, --), Decl(lib.es2015.collection.d.ts, --, --))
+
+    s = new Set<number>();
+>s : Symbol(s, Decl(controlFlowInstanceof.ts, 13, 12))
+>Set : Symbol(Set, Decl(lib.es2015.symbol.wellknown.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.collection.d.ts, --, --), Decl(lib.es2015.collection.d.ts, --, --))
+
+    s;  // Set<number>
+>s : Symbol(s, Decl(controlFlowInstanceof.ts, 13, 12))
+
+    if (s instanceof Promise) {
+>s : Symbol(s, Decl(controlFlowInstanceof.ts, 13, 12))
+>Promise : Symbol(Promise, Decl(lib.es2015.symbol.wellknown.d.ts, --, --), Decl(lib.es2015.promise.d.ts, --, --), Decl(lib.es2015.promise.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --))
+
+        s;  // Set<number> & Promise<any>
+>s : Symbol(s, Decl(controlFlowInstanceof.ts, 13, 12))
+    }
+    s;  // Set<number>
+>s : Symbol(s, Decl(controlFlowInstanceof.ts, 13, 12))
+
+    s.add(42);
+>s.add : Symbol(Set.add, Decl(lib.es2015.collection.d.ts, --, --))
+>s : Symbol(s, Decl(controlFlowInstanceof.ts, 13, 12))
+>add : Symbol(Set.add, Decl(lib.es2015.collection.d.ts, --, --))
+}
+
+function f3(s: Set<string> | Set<number>) {
+>f3 : Symbol(f3, Decl(controlFlowInstanceof.ts, 21, 1))
+>s : Symbol(s, Decl(controlFlowInstanceof.ts, 23, 12))
+>Set : Symbol(Set, Decl(lib.es2015.symbol.wellknown.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.collection.d.ts, --, --), Decl(lib.es2015.collection.d.ts, --, --))
+>Set : Symbol(Set, Decl(lib.es2015.symbol.wellknown.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.collection.d.ts, --, --), Decl(lib.es2015.collection.d.ts, --, --))
+
+    s;  // Set<string> | Set<number>
+>s : Symbol(s, Decl(controlFlowInstanceof.ts, 23, 12))
+
+    if (s instanceof Set) {
+>s : Symbol(s, Decl(controlFlowInstanceof.ts, 23, 12))
+>Set : Symbol(Set, Decl(lib.es2015.symbol.wellknown.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.collection.d.ts, --, --), Decl(lib.es2015.collection.d.ts, --, --))
+
+        s;  // Set<string> | Set<number>
+>s : Symbol(s, Decl(controlFlowInstanceof.ts, 23, 12))
+    }
+    else {
+        s;  // never
+>s : Symbol(s, Decl(controlFlowInstanceof.ts, 23, 12))
+    }
+}
+
+function f4(s: Set<string> | Set<number>) {
+>f4 : Symbol(f4, Decl(controlFlowInstanceof.ts, 31, 1))
+>s : Symbol(s, Decl(controlFlowInstanceof.ts, 33, 12))
+>Set : Symbol(Set, Decl(lib.es2015.symbol.wellknown.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.collection.d.ts, --, --), Decl(lib.es2015.collection.d.ts, --, --))
+>Set : Symbol(Set, Decl(lib.es2015.symbol.wellknown.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.collection.d.ts, --, --), Decl(lib.es2015.collection.d.ts, --, --))
+
+    s = new Set<number>();
+>s : Symbol(s, Decl(controlFlowInstanceof.ts, 33, 12))
+>Set : Symbol(Set, Decl(lib.es2015.symbol.wellknown.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.collection.d.ts, --, --), Decl(lib.es2015.collection.d.ts, --, --))
+
+    s;  // Set<number>
+>s : Symbol(s, Decl(controlFlowInstanceof.ts, 33, 12))
+
+    if (s instanceof Set) {
+>s : Symbol(s, Decl(controlFlowInstanceof.ts, 33, 12))
+>Set : Symbol(Set, Decl(lib.es2015.symbol.wellknown.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.collection.d.ts, --, --), Decl(lib.es2015.collection.d.ts, --, --))
+
+        s;  // Set<number>
+>s : Symbol(s, Decl(controlFlowInstanceof.ts, 33, 12))
+    }
+    else {
+        s;  // never
+>s : Symbol(s, Decl(controlFlowInstanceof.ts, 33, 12))
+    }
+}
+
+// More tests
+
+class A { a: string }
+>A : Symbol(A, Decl(controlFlowInstanceof.ts, 42, 1))
+>a : Symbol(A.a, Decl(controlFlowInstanceof.ts, 46, 9))
+
+class B extends A { b: string }
+>B : Symbol(B, Decl(controlFlowInstanceof.ts, 46, 21))
+>A : Symbol(A, Decl(controlFlowInstanceof.ts, 42, 1))
+>b : Symbol(B.b, Decl(controlFlowInstanceof.ts, 47, 19))
+
+class C extends A { c: string }
+>C : Symbol(C, Decl(controlFlowInstanceof.ts, 47, 31))
+>A : Symbol(A, Decl(controlFlowInstanceof.ts, 42, 1))
+>c : Symbol(C.c, Decl(controlFlowInstanceof.ts, 48, 19))
+
+function foo(x: A | undefined) {
+>foo : Symbol(foo, Decl(controlFlowInstanceof.ts, 48, 31))
+>x : Symbol(x, Decl(controlFlowInstanceof.ts, 50, 13))
+>A : Symbol(A, Decl(controlFlowInstanceof.ts, 42, 1))
+
+    x;  // A | undefined
+>x : Symbol(x, Decl(controlFlowInstanceof.ts, 50, 13))
+
+    if (x instanceof B || x instanceof C) {
+>x : Symbol(x, Decl(controlFlowInstanceof.ts, 50, 13))
+>B : Symbol(B, Decl(controlFlowInstanceof.ts, 46, 21))
+>x : Symbol(x, Decl(controlFlowInstanceof.ts, 50, 13))
+>C : Symbol(C, Decl(controlFlowInstanceof.ts, 47, 31))
+
+        x;  // B | C
+>x : Symbol(x, Decl(controlFlowInstanceof.ts, 50, 13))
+    }
+    x;  // A | undefined
+>x : Symbol(x, Decl(controlFlowInstanceof.ts, 50, 13))
+
+    if (x instanceof B && x instanceof C) {
+>x : Symbol(x, Decl(controlFlowInstanceof.ts, 50, 13))
+>B : Symbol(B, Decl(controlFlowInstanceof.ts, 46, 21))
+>x : Symbol(x, Decl(controlFlowInstanceof.ts, 50, 13))
+>C : Symbol(C, Decl(controlFlowInstanceof.ts, 47, 31))
+
+        x;  // B & C
+>x : Symbol(x, Decl(controlFlowInstanceof.ts, 50, 13))
+    }
+    x;  // A | undefined
+>x : Symbol(x, Decl(controlFlowInstanceof.ts, 50, 13))
+
+    if (!x) {
+>x : Symbol(x, Decl(controlFlowInstanceof.ts, 50, 13))
+
+        return;
+    }
+    x;  // A
+>x : Symbol(x, Decl(controlFlowInstanceof.ts, 50, 13))
+
+    if (x instanceof B) {
+>x : Symbol(x, Decl(controlFlowInstanceof.ts, 50, 13))
+>B : Symbol(B, Decl(controlFlowInstanceof.ts, 46, 21))
+
+        x;  // B
+>x : Symbol(x, Decl(controlFlowInstanceof.ts, 50, 13))
+
+        if (x instanceof C) {
+>x : Symbol(x, Decl(controlFlowInstanceof.ts, 50, 13))
+>C : Symbol(C, Decl(controlFlowInstanceof.ts, 47, 31))
+
+            x;  // B & C
+>x : Symbol(x, Decl(controlFlowInstanceof.ts, 50, 13))
+        }
+        else {
+            x;  // B
+>x : Symbol(x, Decl(controlFlowInstanceof.ts, 50, 13))
+        }
+        x;  // B
+>x : Symbol(x, Decl(controlFlowInstanceof.ts, 50, 13))
+    }
+    else {
+        x;  // A
+>x : Symbol(x, Decl(controlFlowInstanceof.ts, 50, 13))
+    }
+    x;  // A
+>x : Symbol(x, Decl(controlFlowInstanceof.ts, 50, 13))
+}
diff --git a/tests/baselines/reference/controlFlowInstanceof.types b/tests/baselines/reference/controlFlowInstanceof.types
new file mode 100644
index 00000000000..362715914f9
--- /dev/null
+++ b/tests/baselines/reference/controlFlowInstanceof.types
@@ -0,0 +1,217 @@
+=== tests/cases/compiler/controlFlowInstanceof.ts ===
+
+// Repros from #10167
+
+function f1(s: Set<string> | Set<number>) {
+>f1 : (s: Set<string> | Set<number>) => void
+>s : Set<string> | Set<number>
+>Set : Set<T>
+>Set : Set<T>
+
+    s = new Set<number>();
+>s = new Set<number>() : Set<number>
+>s : Set<string> | Set<number>
+>new Set<number>() : Set<number>
+>Set : SetConstructor
+
+    s;  // Set<number>
+>s : Set<number>
+
+    if (s instanceof Set) {
+>s instanceof Set : boolean
+>s : Set<number>
+>Set : SetConstructor
+
+        s;  // Set<number>
+>s : Set<number>
+    }
+    s;  // Set<number>
+>s : Set<number>
+
+    s.add(42);
+>s.add(42) : Set<number>
+>s.add : (value: number) => Set<number>
+>s : Set<number>
+>add : (value: number) => Set<number>
+>42 : number
+}
+
+function f2(s: Set<string> | Set<number>) {
+>f2 : (s: Set<string> | Set<number>) => void
+>s : Set<string> | Set<number>
+>Set : Set<T>
+>Set : Set<T>
+
+    s = new Set<number>();
+>s = new Set<number>() : Set<number>
+>s : Set<string> | Set<number>
+>new Set<number>() : Set<number>
+>Set : SetConstructor
+
+    s;  // Set<number>
+>s : Set<number>
+
+    if (s instanceof Promise) {
+>s instanceof Promise : boolean
+>s : Set<number>
+>Promise : PromiseConstructor
+
+        s;  // Set<number> & Promise<any>
+>s : Set<number> & Promise<any>
+    }
+    s;  // Set<number>
+>s : Set<number>
+
+    s.add(42);
+>s.add(42) : Set<number>
+>s.add : (value: number) => Set<number>
+>s : Set<number>
+>add : (value: number) => Set<number>
+>42 : number
+}
+
+function f3(s: Set<string> | Set<number>) {
+>f3 : (s: Set<string> | Set<number>) => void
+>s : Set<string> | Set<number>
+>Set : Set<T>
+>Set : Set<T>
+
+    s;  // Set<string> | Set<number>
+>s : Set<string> | Set<number>
+
+    if (s instanceof Set) {
+>s instanceof Set : boolean
+>s : Set<string> | Set<number>
+>Set : SetConstructor
+
+        s;  // Set<string> | Set<number>
+>s : Set<string> | Set<number>
+    }
+    else {
+        s;  // never
+>s : never
+    }
+}
+
+function f4(s: Set<string> | Set<number>) {
+>f4 : (s: Set<string> | Set<number>) => void
+>s : Set<string> | Set<number>
+>Set : Set<T>
+>Set : Set<T>
+
+    s = new Set<number>();
+>s = new Set<number>() : Set<number>
+>s : Set<string> | Set<number>
+>new Set<number>() : Set<number>
+>Set : SetConstructor
+
+    s;  // Set<number>
+>s : Set<number>
+
+    if (s instanceof Set) {
+>s instanceof Set : boolean
+>s : Set<number>
+>Set : SetConstructor
+
+        s;  // Set<number>
+>s : Set<number>
+    }
+    else {
+        s;  // never
+>s : never
+    }
+}
+
+// More tests
+
+class A { a: string }
+>A : A
+>a : string
+
+class B extends A { b: string }
+>B : B
+>A : A
+>b : string
+
+class C extends A { c: string }
+>C : C
+>A : A
+>c : string
+
+function foo(x: A | undefined) {
+>foo : (x: A) => void
+>x : A
+>A : A
+
+    x;  // A | undefined
+>x : A
+
+    if (x instanceof B || x instanceof C) {
+>x instanceof B || x instanceof C : boolean
+>x instanceof B : boolean
+>x : A
+>B : typeof B
+>x instanceof C : boolean
+>x : A
+>C : typeof C
+
+        x;  // B | C
+>x : B | C
+    }
+    x;  // A | undefined
+>x : A
+
+    if (x instanceof B && x instanceof C) {
+>x instanceof B && x instanceof C : boolean
+>x instanceof B : boolean
+>x : A
+>B : typeof B
+>x instanceof C : boolean
+>x : B
+>C : typeof C
+
+        x;  // B & C
+>x : B & C
+    }
+    x;  // A | undefined
+>x : A
+
+    if (!x) {
+>!x : boolean
+>x : A
+
+        return;
+    }
+    x;  // A
+>x : A
+
+    if (x instanceof B) {
+>x instanceof B : boolean
+>x : A
+>B : typeof B
+
+        x;  // B
+>x : B
+
+        if (x instanceof C) {
+>x instanceof C : boolean
+>x : B
+>C : typeof C
+
+            x;  // B & C
+>x : B & C
+        }
+        else {
+            x;  // B
+>x : B
+        }
+        x;  // B
+>x : B
+    }
+    else {
+        x;  // A
+>x : A
+    }
+    x;  // A
+>x : A
+}
diff --git a/tests/cases/compiler/controlFlowInstanceof.ts b/tests/cases/compiler/controlFlowInstanceof.ts
new file mode 100644
index 00000000000..229a00236ba
--- /dev/null
+++ b/tests/cases/compiler/controlFlowInstanceof.ts
@@ -0,0 +1,80 @@
+// @target: es6
+
+// Repros from #10167
+
+function f1(s: Set<string> | Set<number>) {
+    s = new Set<number>();
+    s;  // Set<number>
+    if (s instanceof Set) {
+        s;  // Set<number>
+    }
+    s;  // Set<number>
+    s.add(42);
+}
+
+function f2(s: Set<string> | Set<number>) {
+    s = new Set<number>();
+    s;  // Set<number>
+    if (s instanceof Promise) {
+        s;  // Set<number> & Promise<any>
+    }
+    s;  // Set<number>
+    s.add(42);
+}
+
+function f3(s: Set<string> | Set<number>) {
+    s;  // Set<string> | Set<number>
+    if (s instanceof Set) {
+        s;  // Set<string> | Set<number>
+    }
+    else {
+        s;  // never
+    }
+}
+
+function f4(s: Set<string> | Set<number>) {
+    s = new Set<number>();
+    s;  // Set<number>
+    if (s instanceof Set) {
+        s;  // Set<number>
+    }
+    else {
+        s;  // never
+    }
+}
+
+// More tests
+
+class A { a: string }
+class B extends A { b: string }
+class C extends A { c: string }
+
+function foo(x: A | undefined) {
+    x;  // A | undefined
+    if (x instanceof B || x instanceof C) {
+        x;  // B | C
+    }
+    x;  // A | undefined
+    if (x instanceof B && x instanceof C) {
+        x;  // B & C
+    }
+    x;  // A | undefined
+    if (!x) {
+        return;
+    }
+    x;  // A
+    if (x instanceof B) {
+        x;  // B
+        if (x instanceof C) {
+            x;  // B & C
+        }
+        else {
+            x;  // B
+        }
+        x;  // B
+    }
+    else {
+        x;  // A
+    }
+    x;  // A
+}
\ No newline at end of file