From 644e9876332f04ea4427ba7b24f199deef5fd8a4 Mon Sep 17 00:00:00 2001
From: Anders Hejlsberg <andersh@microsoft.com>
Date: Fri, 29 Apr 2016 16:20:32 -0700
Subject: [PATCH] Adding regression test

---
 .../reference/narrowingOfDottedNames.js       |  80 ++++++++++++
 .../reference/narrowingOfDottedNames.symbols  | 105 ++++++++++++++++
 .../reference/narrowingOfDottedNames.types    | 115 ++++++++++++++++++
 .../cases/compiler/narrowingOfDottedNames.ts  |  39 ++++++
 4 files changed, 339 insertions(+)
 create mode 100644 tests/baselines/reference/narrowingOfDottedNames.js
 create mode 100644 tests/baselines/reference/narrowingOfDottedNames.symbols
 create mode 100644 tests/baselines/reference/narrowingOfDottedNames.types
 create mode 100644 tests/cases/compiler/narrowingOfDottedNames.ts

diff --git a/tests/baselines/reference/narrowingOfDottedNames.js b/tests/baselines/reference/narrowingOfDottedNames.js
new file mode 100644
index 00000000000..5a159f38220
--- /dev/null
+++ b/tests/baselines/reference/narrowingOfDottedNames.js
@@ -0,0 +1,80 @@
+//// [narrowingOfDottedNames.ts]
+// Repro from #8383
+
+class A {
+    prop: { a: string; };
+}
+
+class B {
+    prop: { b: string; }
+}
+
+function isA(x: any): x is A {
+    return x instanceof A;
+}
+
+function isB(x: any): x is B {
+    return x instanceof B;
+}
+
+function f1(x: A | B) {
+    while (true) {
+        if (x instanceof A) {
+            x.prop.a;
+        }
+        else if (x instanceof B) {
+            x.prop.b; // error: property 'b' doesn't exist on type { a: string }
+        }
+    }
+}
+
+function f2(x: A | B) {
+    while (true) {
+        if (isA(x)) {
+            x.prop.a;
+        }
+        else if (isB(x)) {
+            x.prop.b; // error: property 'b' doesn't exist on type { a: string }
+        }
+    }
+}
+
+
+//// [narrowingOfDottedNames.js]
+// Repro from #8383
+var A = (function () {
+    function A() {
+    }
+    return A;
+}());
+var B = (function () {
+    function B() {
+    }
+    return B;
+}());
+function isA(x) {
+    return x instanceof A;
+}
+function isB(x) {
+    return x instanceof B;
+}
+function f1(x) {
+    while (true) {
+        if (x instanceof A) {
+            x.prop.a;
+        }
+        else if (x instanceof B) {
+            x.prop.b; // error: property 'b' doesn't exist on type { a: string }
+        }
+    }
+}
+function f2(x) {
+    while (true) {
+        if (isA(x)) {
+            x.prop.a;
+        }
+        else if (isB(x)) {
+            x.prop.b; // error: property 'b' doesn't exist on type { a: string }
+        }
+    }
+}
diff --git a/tests/baselines/reference/narrowingOfDottedNames.symbols b/tests/baselines/reference/narrowingOfDottedNames.symbols
new file mode 100644
index 00000000000..474b8c0b655
--- /dev/null
+++ b/tests/baselines/reference/narrowingOfDottedNames.symbols
@@ -0,0 +1,105 @@
+=== tests/cases/compiler/narrowingOfDottedNames.ts ===
+// Repro from #8383
+
+class A {
+>A : Symbol(A, Decl(narrowingOfDottedNames.ts, 0, 0))
+
+    prop: { a: string; };
+>prop : Symbol(A.prop, Decl(narrowingOfDottedNames.ts, 2, 9))
+>a : Symbol(a, Decl(narrowingOfDottedNames.ts, 3, 11))
+}
+
+class B {
+>B : Symbol(B, Decl(narrowingOfDottedNames.ts, 4, 1))
+
+    prop: { b: string; }
+>prop : Symbol(B.prop, Decl(narrowingOfDottedNames.ts, 6, 9))
+>b : Symbol(b, Decl(narrowingOfDottedNames.ts, 7, 11))
+}
+
+function isA(x: any): x is A {
+>isA : Symbol(isA, Decl(narrowingOfDottedNames.ts, 8, 1))
+>x : Symbol(x, Decl(narrowingOfDottedNames.ts, 10, 13))
+>x : Symbol(x, Decl(narrowingOfDottedNames.ts, 10, 13))
+>A : Symbol(A, Decl(narrowingOfDottedNames.ts, 0, 0))
+
+    return x instanceof A;
+>x : Symbol(x, Decl(narrowingOfDottedNames.ts, 10, 13))
+>A : Symbol(A, Decl(narrowingOfDottedNames.ts, 0, 0))
+}
+
+function isB(x: any): x is B {
+>isB : Symbol(isB, Decl(narrowingOfDottedNames.ts, 12, 1))
+>x : Symbol(x, Decl(narrowingOfDottedNames.ts, 14, 13))
+>x : Symbol(x, Decl(narrowingOfDottedNames.ts, 14, 13))
+>B : Symbol(B, Decl(narrowingOfDottedNames.ts, 4, 1))
+
+    return x instanceof B;
+>x : Symbol(x, Decl(narrowingOfDottedNames.ts, 14, 13))
+>B : Symbol(B, Decl(narrowingOfDottedNames.ts, 4, 1))
+}
+
+function f1(x: A | B) {
+>f1 : Symbol(f1, Decl(narrowingOfDottedNames.ts, 16, 1))
+>x : Symbol(x, Decl(narrowingOfDottedNames.ts, 18, 12))
+>A : Symbol(A, Decl(narrowingOfDottedNames.ts, 0, 0))
+>B : Symbol(B, Decl(narrowingOfDottedNames.ts, 4, 1))
+
+    while (true) {
+        if (x instanceof A) {
+>x : Symbol(x, Decl(narrowingOfDottedNames.ts, 18, 12))
+>A : Symbol(A, Decl(narrowingOfDottedNames.ts, 0, 0))
+
+            x.prop.a;
+>x.prop.a : Symbol(a, Decl(narrowingOfDottedNames.ts, 3, 11))
+>x.prop : Symbol(A.prop, Decl(narrowingOfDottedNames.ts, 2, 9))
+>x : Symbol(x, Decl(narrowingOfDottedNames.ts, 18, 12))
+>prop : Symbol(A.prop, Decl(narrowingOfDottedNames.ts, 2, 9))
+>a : Symbol(a, Decl(narrowingOfDottedNames.ts, 3, 11))
+        }
+        else if (x instanceof B) {
+>x : Symbol(x, Decl(narrowingOfDottedNames.ts, 18, 12))
+>B : Symbol(B, Decl(narrowingOfDottedNames.ts, 4, 1))
+
+            x.prop.b; // error: property 'b' doesn't exist on type { a: string }
+>x.prop.b : Symbol(b, Decl(narrowingOfDottedNames.ts, 7, 11))
+>x.prop : Symbol(B.prop, Decl(narrowingOfDottedNames.ts, 6, 9))
+>x : Symbol(x, Decl(narrowingOfDottedNames.ts, 18, 12))
+>prop : Symbol(B.prop, Decl(narrowingOfDottedNames.ts, 6, 9))
+>b : Symbol(b, Decl(narrowingOfDottedNames.ts, 7, 11))
+        }
+    }
+}
+
+function f2(x: A | B) {
+>f2 : Symbol(f2, Decl(narrowingOfDottedNames.ts, 27, 1))
+>x : Symbol(x, Decl(narrowingOfDottedNames.ts, 29, 12))
+>A : Symbol(A, Decl(narrowingOfDottedNames.ts, 0, 0))
+>B : Symbol(B, Decl(narrowingOfDottedNames.ts, 4, 1))
+
+    while (true) {
+        if (isA(x)) {
+>isA : Symbol(isA, Decl(narrowingOfDottedNames.ts, 8, 1))
+>x : Symbol(x, Decl(narrowingOfDottedNames.ts, 29, 12))
+
+            x.prop.a;
+>x.prop.a : Symbol(a, Decl(narrowingOfDottedNames.ts, 3, 11))
+>x.prop : Symbol(A.prop, Decl(narrowingOfDottedNames.ts, 2, 9))
+>x : Symbol(x, Decl(narrowingOfDottedNames.ts, 29, 12))
+>prop : Symbol(A.prop, Decl(narrowingOfDottedNames.ts, 2, 9))
+>a : Symbol(a, Decl(narrowingOfDottedNames.ts, 3, 11))
+        }
+        else if (isB(x)) {
+>isB : Symbol(isB, Decl(narrowingOfDottedNames.ts, 12, 1))
+>x : Symbol(x, Decl(narrowingOfDottedNames.ts, 29, 12))
+
+            x.prop.b; // error: property 'b' doesn't exist on type { a: string }
+>x.prop.b : Symbol(b, Decl(narrowingOfDottedNames.ts, 7, 11))
+>x.prop : Symbol(B.prop, Decl(narrowingOfDottedNames.ts, 6, 9))
+>x : Symbol(x, Decl(narrowingOfDottedNames.ts, 29, 12))
+>prop : Symbol(B.prop, Decl(narrowingOfDottedNames.ts, 6, 9))
+>b : Symbol(b, Decl(narrowingOfDottedNames.ts, 7, 11))
+        }
+    }
+}
+
diff --git a/tests/baselines/reference/narrowingOfDottedNames.types b/tests/baselines/reference/narrowingOfDottedNames.types
new file mode 100644
index 00000000000..f9d640dccab
--- /dev/null
+++ b/tests/baselines/reference/narrowingOfDottedNames.types
@@ -0,0 +1,115 @@
+=== tests/cases/compiler/narrowingOfDottedNames.ts ===
+// Repro from #8383
+
+class A {
+>A : A
+
+    prop: { a: string; };
+>prop : { a: string; }
+>a : string
+}
+
+class B {
+>B : B
+
+    prop: { b: string; }
+>prop : { b: string; }
+>b : string
+}
+
+function isA(x: any): x is A {
+>isA : (x: any) => x is A
+>x : any
+>x : any
+>A : A
+
+    return x instanceof A;
+>x instanceof A : boolean
+>x : any
+>A : typeof A
+}
+
+function isB(x: any): x is B {
+>isB : (x: any) => x is B
+>x : any
+>x : any
+>B : B
+
+    return x instanceof B;
+>x instanceof B : boolean
+>x : any
+>B : typeof B
+}
+
+function f1(x: A | B) {
+>f1 : (x: A | B) => void
+>x : A | B
+>A : A
+>B : B
+
+    while (true) {
+>true : boolean
+
+        if (x instanceof A) {
+>x instanceof A : boolean
+>x : A | B
+>A : typeof A
+
+            x.prop.a;
+>x.prop.a : string
+>x.prop : { a: string; }
+>x : A
+>prop : { a: string; }
+>a : string
+        }
+        else if (x instanceof B) {
+>x instanceof B : boolean
+>x : B
+>B : typeof B
+
+            x.prop.b; // error: property 'b' doesn't exist on type { a: string }
+>x.prop.b : string
+>x.prop : { b: string; }
+>x : B
+>prop : { b: string; }
+>b : string
+        }
+    }
+}
+
+function f2(x: A | B) {
+>f2 : (x: A | B) => void
+>x : A | B
+>A : A
+>B : B
+
+    while (true) {
+>true : boolean
+
+        if (isA(x)) {
+>isA(x) : boolean
+>isA : (x: any) => x is A
+>x : A | B
+
+            x.prop.a;
+>x.prop.a : string
+>x.prop : { a: string; }
+>x : A
+>prop : { a: string; }
+>a : string
+        }
+        else if (isB(x)) {
+>isB(x) : boolean
+>isB : (x: any) => x is B
+>x : B
+
+            x.prop.b; // error: property 'b' doesn't exist on type { a: string }
+>x.prop.b : string
+>x.prop : { b: string; }
+>x : B
+>prop : { b: string; }
+>b : string
+        }
+    }
+}
+
diff --git a/tests/cases/compiler/narrowingOfDottedNames.ts b/tests/cases/compiler/narrowingOfDottedNames.ts
new file mode 100644
index 00000000000..fd64d6d8874
--- /dev/null
+++ b/tests/cases/compiler/narrowingOfDottedNames.ts
@@ -0,0 +1,39 @@
+// Repro from #8383
+
+class A {
+    prop: { a: string; };
+}
+
+class B {
+    prop: { b: string; }
+}
+
+function isA(x: any): x is A {
+    return x instanceof A;
+}
+
+function isB(x: any): x is B {
+    return x instanceof B;
+}
+
+function f1(x: A | B) {
+    while (true) {
+        if (x instanceof A) {
+            x.prop.a;
+        }
+        else if (x instanceof B) {
+            x.prop.b; // error: property 'b' doesn't exist on type { a: string }
+        }
+    }
+}
+
+function f2(x: A | B) {
+    while (true) {
+        if (isA(x)) {
+            x.prop.a;
+        }
+        else if (isB(x)) {
+            x.prop.b; // error: property 'b' doesn't exist on type { a: string }
+        }
+    }
+}