From c5a81edfb1515c694ffd1fcc2639c288d5f71695 Mon Sep 17 00:00:00 2001
From: Mohamed Hegazy <mhegazy@microsoft.com>
Date: Tue, 3 May 2016 14:51:30 -0700
Subject: [PATCH] Fix #8423: Remove undefined while getting the type of the
 first argument of then signature

---
 src/compiler/checker.ts                       |   2 +-
 .../asyncFunctionsAndStrictNullChecks.js      |  33 ++++++
 .../asyncFunctionsAndStrictNullChecks.symbols | 102 +++++++++++++++++
 .../asyncFunctionsAndStrictNullChecks.types   | 103 ++++++++++++++++++
 .../asyncFunctionsAndStrictNullChecks.ts      |  18 +++
 5 files changed, 257 insertions(+), 1 deletion(-)
 create mode 100644 tests/baselines/reference/asyncFunctionsAndStrictNullChecks.js
 create mode 100644 tests/baselines/reference/asyncFunctionsAndStrictNullChecks.symbols
 create mode 100644 tests/baselines/reference/asyncFunctionsAndStrictNullChecks.types
 create mode 100644 tests/cases/compiler/asyncFunctionsAndStrictNullChecks.ts

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index bf0ba6beb25..68a0c23a301 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -13443,7 +13443,7 @@ namespace ts {
         }
 
         function getTypeOfFirstParameterOfSignature(signature: Signature) {
-            return getTypeAtPosition(signature, 0);
+            return getTypeWithFacts(getTypeAtPosition(signature, 0), TypeFacts.NEUndefined);
         }
 
         /**
diff --git a/tests/baselines/reference/asyncFunctionsAndStrictNullChecks.js b/tests/baselines/reference/asyncFunctionsAndStrictNullChecks.js
new file mode 100644
index 00000000000..32fc769e4f3
--- /dev/null
+++ b/tests/baselines/reference/asyncFunctionsAndStrictNullChecks.js
@@ -0,0 +1,33 @@
+//// [asyncFunctionsAndStrictNullChecks.ts]
+
+declare namespace Windows.Foundation {
+    interface IPromise<TResult> {
+        then<U>(success?: (value: TResult) => IPromise<U>, error?: (error: any) => IPromise<U>, progress?: (progress: any) => void): IPromise<U>;
+        then<U>(success?: (value: TResult) => IPromise<U>, error?: (error: any) => U, progress?: (progress: any) => void): IPromise<U>;
+        then<U>(success?: (value: TResult) => U, error?: (error: any) => IPromise<U>, progress?: (progress: any) => void): IPromise<U>;
+        then<U>(success?: (value: TResult) => U, error?: (error: any) => U, progress?: (progress: any) => void): IPromise<U>;
+        done<U>(success?: (value: TResult) => any, error?: (error: any) => any, progress?: (progress: any) => void): void;
+
+        cancel(): void;
+    }
+}
+
+async function sample(promise: Windows.Foundation.IPromise<number>) {
+    var number = await promise;
+}
+
+
+//// [asyncFunctionsAndStrictNullChecks.js]
+var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, generator) {
+    return new (P || (P = Promise))(function (resolve, reject) {
+        function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
+        function rejected(value) { try { step(generator.throw(value)); } catch (e) { reject(e); } }
+        function step(result) { result.done ? resolve(result.value) : new P(function (resolve) { resolve(result.value); }).then(fulfilled, rejected); }
+        step((generator = generator.apply(thisArg, _arguments)).next());
+    });
+};
+function sample(promise) {
+    return __awaiter(this, void 0, void 0, function* () {
+        var number = yield promise;
+    });
+}
diff --git a/tests/baselines/reference/asyncFunctionsAndStrictNullChecks.symbols b/tests/baselines/reference/asyncFunctionsAndStrictNullChecks.symbols
new file mode 100644
index 00000000000..593702a35fd
--- /dev/null
+++ b/tests/baselines/reference/asyncFunctionsAndStrictNullChecks.symbols
@@ -0,0 +1,102 @@
+=== tests/cases/compiler/asyncFunctionsAndStrictNullChecks.ts ===
+
+declare namespace Windows.Foundation {
+>Windows : Symbol(Windows, Decl(asyncFunctionsAndStrictNullChecks.ts, 0, 0))
+>Foundation : Symbol(Foundation, Decl(asyncFunctionsAndStrictNullChecks.ts, 1, 26))
+
+    interface IPromise<TResult> {
+>IPromise : Symbol(IPromise, Decl(asyncFunctionsAndStrictNullChecks.ts, 1, 38))
+>TResult : Symbol(TResult, Decl(asyncFunctionsAndStrictNullChecks.ts, 2, 23))
+
+        then<U>(success?: (value: TResult) => IPromise<U>, error?: (error: any) => IPromise<U>, progress?: (progress: any) => void): IPromise<U>;
+>then : Symbol(IPromise.then, Decl(asyncFunctionsAndStrictNullChecks.ts, 2, 33), Decl(asyncFunctionsAndStrictNullChecks.ts, 3, 145), Decl(asyncFunctionsAndStrictNullChecks.ts, 4, 135), Decl(asyncFunctionsAndStrictNullChecks.ts, 5, 135))
+>U : Symbol(U, Decl(asyncFunctionsAndStrictNullChecks.ts, 3, 13))
+>success : Symbol(success, Decl(asyncFunctionsAndStrictNullChecks.ts, 3, 16))
+>value : Symbol(value, Decl(asyncFunctionsAndStrictNullChecks.ts, 3, 27))
+>TResult : Symbol(TResult, Decl(asyncFunctionsAndStrictNullChecks.ts, 2, 23))
+>IPromise : Symbol(IPromise, Decl(asyncFunctionsAndStrictNullChecks.ts, 1, 38))
+>U : Symbol(U, Decl(asyncFunctionsAndStrictNullChecks.ts, 3, 13))
+>error : Symbol(error, Decl(asyncFunctionsAndStrictNullChecks.ts, 3, 58))
+>error : Symbol(error, Decl(asyncFunctionsAndStrictNullChecks.ts, 3, 68))
+>IPromise : Symbol(IPromise, Decl(asyncFunctionsAndStrictNullChecks.ts, 1, 38))
+>U : Symbol(U, Decl(asyncFunctionsAndStrictNullChecks.ts, 3, 13))
+>progress : Symbol(progress, Decl(asyncFunctionsAndStrictNullChecks.ts, 3, 95))
+>progress : Symbol(progress, Decl(asyncFunctionsAndStrictNullChecks.ts, 3, 108))
+>IPromise : Symbol(IPromise, Decl(asyncFunctionsAndStrictNullChecks.ts, 1, 38))
+>U : Symbol(U, Decl(asyncFunctionsAndStrictNullChecks.ts, 3, 13))
+
+        then<U>(success?: (value: TResult) => IPromise<U>, error?: (error: any) => U, progress?: (progress: any) => void): IPromise<U>;
+>then : Symbol(IPromise.then, Decl(asyncFunctionsAndStrictNullChecks.ts, 2, 33), Decl(asyncFunctionsAndStrictNullChecks.ts, 3, 145), Decl(asyncFunctionsAndStrictNullChecks.ts, 4, 135), Decl(asyncFunctionsAndStrictNullChecks.ts, 5, 135))
+>U : Symbol(U, Decl(asyncFunctionsAndStrictNullChecks.ts, 4, 13))
+>success : Symbol(success, Decl(asyncFunctionsAndStrictNullChecks.ts, 4, 16))
+>value : Symbol(value, Decl(asyncFunctionsAndStrictNullChecks.ts, 4, 27))
+>TResult : Symbol(TResult, Decl(asyncFunctionsAndStrictNullChecks.ts, 2, 23))
+>IPromise : Symbol(IPromise, Decl(asyncFunctionsAndStrictNullChecks.ts, 1, 38))
+>U : Symbol(U, Decl(asyncFunctionsAndStrictNullChecks.ts, 4, 13))
+>error : Symbol(error, Decl(asyncFunctionsAndStrictNullChecks.ts, 4, 58))
+>error : Symbol(error, Decl(asyncFunctionsAndStrictNullChecks.ts, 4, 68))
+>U : Symbol(U, Decl(asyncFunctionsAndStrictNullChecks.ts, 4, 13))
+>progress : Symbol(progress, Decl(asyncFunctionsAndStrictNullChecks.ts, 4, 85))
+>progress : Symbol(progress, Decl(asyncFunctionsAndStrictNullChecks.ts, 4, 98))
+>IPromise : Symbol(IPromise, Decl(asyncFunctionsAndStrictNullChecks.ts, 1, 38))
+>U : Symbol(U, Decl(asyncFunctionsAndStrictNullChecks.ts, 4, 13))
+
+        then<U>(success?: (value: TResult) => U, error?: (error: any) => IPromise<U>, progress?: (progress: any) => void): IPromise<U>;
+>then : Symbol(IPromise.then, Decl(asyncFunctionsAndStrictNullChecks.ts, 2, 33), Decl(asyncFunctionsAndStrictNullChecks.ts, 3, 145), Decl(asyncFunctionsAndStrictNullChecks.ts, 4, 135), Decl(asyncFunctionsAndStrictNullChecks.ts, 5, 135))
+>U : Symbol(U, Decl(asyncFunctionsAndStrictNullChecks.ts, 5, 13))
+>success : Symbol(success, Decl(asyncFunctionsAndStrictNullChecks.ts, 5, 16))
+>value : Symbol(value, Decl(asyncFunctionsAndStrictNullChecks.ts, 5, 27))
+>TResult : Symbol(TResult, Decl(asyncFunctionsAndStrictNullChecks.ts, 2, 23))
+>U : Symbol(U, Decl(asyncFunctionsAndStrictNullChecks.ts, 5, 13))
+>error : Symbol(error, Decl(asyncFunctionsAndStrictNullChecks.ts, 5, 48))
+>error : Symbol(error, Decl(asyncFunctionsAndStrictNullChecks.ts, 5, 58))
+>IPromise : Symbol(IPromise, Decl(asyncFunctionsAndStrictNullChecks.ts, 1, 38))
+>U : Symbol(U, Decl(asyncFunctionsAndStrictNullChecks.ts, 5, 13))
+>progress : Symbol(progress, Decl(asyncFunctionsAndStrictNullChecks.ts, 5, 85))
+>progress : Symbol(progress, Decl(asyncFunctionsAndStrictNullChecks.ts, 5, 98))
+>IPromise : Symbol(IPromise, Decl(asyncFunctionsAndStrictNullChecks.ts, 1, 38))
+>U : Symbol(U, Decl(asyncFunctionsAndStrictNullChecks.ts, 5, 13))
+
+        then<U>(success?: (value: TResult) => U, error?: (error: any) => U, progress?: (progress: any) => void): IPromise<U>;
+>then : Symbol(IPromise.then, Decl(asyncFunctionsAndStrictNullChecks.ts, 2, 33), Decl(asyncFunctionsAndStrictNullChecks.ts, 3, 145), Decl(asyncFunctionsAndStrictNullChecks.ts, 4, 135), Decl(asyncFunctionsAndStrictNullChecks.ts, 5, 135))
+>U : Symbol(U, Decl(asyncFunctionsAndStrictNullChecks.ts, 6, 13))
+>success : Symbol(success, Decl(asyncFunctionsAndStrictNullChecks.ts, 6, 16))
+>value : Symbol(value, Decl(asyncFunctionsAndStrictNullChecks.ts, 6, 27))
+>TResult : Symbol(TResult, Decl(asyncFunctionsAndStrictNullChecks.ts, 2, 23))
+>U : Symbol(U, Decl(asyncFunctionsAndStrictNullChecks.ts, 6, 13))
+>error : Symbol(error, Decl(asyncFunctionsAndStrictNullChecks.ts, 6, 48))
+>error : Symbol(error, Decl(asyncFunctionsAndStrictNullChecks.ts, 6, 58))
+>U : Symbol(U, Decl(asyncFunctionsAndStrictNullChecks.ts, 6, 13))
+>progress : Symbol(progress, Decl(asyncFunctionsAndStrictNullChecks.ts, 6, 75))
+>progress : Symbol(progress, Decl(asyncFunctionsAndStrictNullChecks.ts, 6, 88))
+>IPromise : Symbol(IPromise, Decl(asyncFunctionsAndStrictNullChecks.ts, 1, 38))
+>U : Symbol(U, Decl(asyncFunctionsAndStrictNullChecks.ts, 6, 13))
+
+        done<U>(success?: (value: TResult) => any, error?: (error: any) => any, progress?: (progress: any) => void): void;
+>done : Symbol(IPromise.done, Decl(asyncFunctionsAndStrictNullChecks.ts, 6, 125))
+>U : Symbol(U, Decl(asyncFunctionsAndStrictNullChecks.ts, 7, 13))
+>success : Symbol(success, Decl(asyncFunctionsAndStrictNullChecks.ts, 7, 16))
+>value : Symbol(value, Decl(asyncFunctionsAndStrictNullChecks.ts, 7, 27))
+>TResult : Symbol(TResult, Decl(asyncFunctionsAndStrictNullChecks.ts, 2, 23))
+>error : Symbol(error, Decl(asyncFunctionsAndStrictNullChecks.ts, 7, 50))
+>error : Symbol(error, Decl(asyncFunctionsAndStrictNullChecks.ts, 7, 60))
+>progress : Symbol(progress, Decl(asyncFunctionsAndStrictNullChecks.ts, 7, 79))
+>progress : Symbol(progress, Decl(asyncFunctionsAndStrictNullChecks.ts, 7, 92))
+
+        cancel(): void;
+>cancel : Symbol(IPromise.cancel, Decl(asyncFunctionsAndStrictNullChecks.ts, 7, 122))
+    }
+}
+
+async function sample(promise: Windows.Foundation.IPromise<number>) {
+>sample : Symbol(sample, Decl(asyncFunctionsAndStrictNullChecks.ts, 11, 1))
+>promise : Symbol(promise, Decl(asyncFunctionsAndStrictNullChecks.ts, 13, 22))
+>Windows : Symbol(Windows, Decl(asyncFunctionsAndStrictNullChecks.ts, 0, 0))
+>Foundation : Symbol(Windows.Foundation, Decl(asyncFunctionsAndStrictNullChecks.ts, 1, 26))
+>IPromise : Symbol(Windows.Foundation.IPromise, Decl(asyncFunctionsAndStrictNullChecks.ts, 1, 38))
+
+    var number = await promise;
+>number : Symbol(number, Decl(asyncFunctionsAndStrictNullChecks.ts, 14, 7))
+>promise : Symbol(promise, Decl(asyncFunctionsAndStrictNullChecks.ts, 13, 22))
+}
+
diff --git a/tests/baselines/reference/asyncFunctionsAndStrictNullChecks.types b/tests/baselines/reference/asyncFunctionsAndStrictNullChecks.types
new file mode 100644
index 00000000000..4d3424b730c
--- /dev/null
+++ b/tests/baselines/reference/asyncFunctionsAndStrictNullChecks.types
@@ -0,0 +1,103 @@
+=== tests/cases/compiler/asyncFunctionsAndStrictNullChecks.ts ===
+
+declare namespace Windows.Foundation {
+>Windows : any
+>Foundation : any
+
+    interface IPromise<TResult> {
+>IPromise : IPromise<TResult>
+>TResult : TResult
+
+        then<U>(success?: (value: TResult) => IPromise<U>, error?: (error: any) => IPromise<U>, progress?: (progress: any) => void): IPromise<U>;
+>then : { <U>(success?: ((value: TResult) => IPromise<U>) | undefined, error?: ((error: any) => IPromise<U>) | undefined, progress?: ((progress: any) => void) | undefined): IPromise<U>; <U>(success?: ((value: TResult) => IPromise<U>) | undefined, error?: ((error: any) => U) | undefined, progress?: ((progress: any) => void) | undefined): IPromise<U>; <U>(success?: ((value: TResult) => U) | undefined, error?: ((error: any) => IPromise<U>) | undefined, progress?: ((progress: any) => void) | undefined): IPromise<U>; <U>(success?: ((value: TResult) => U) | undefined, error?: ((error: any) => U) | undefined, progress?: ((progress: any) => void) | undefined): IPromise<U>; }
+>U : U
+>success : ((value: TResult) => IPromise<U>) | undefined
+>value : TResult
+>TResult : TResult
+>IPromise : IPromise<TResult>
+>U : U
+>error : ((error: any) => IPromise<U>) | undefined
+>error : any
+>IPromise : IPromise<TResult>
+>U : U
+>progress : ((progress: any) => void) | undefined
+>progress : any
+>IPromise : IPromise<TResult>
+>U : U
+
+        then<U>(success?: (value: TResult) => IPromise<U>, error?: (error: any) => U, progress?: (progress: any) => void): IPromise<U>;
+>then : { <U>(success?: ((value: TResult) => IPromise<U>) | undefined, error?: ((error: any) => IPromise<U>) | undefined, progress?: ((progress: any) => void) | undefined): IPromise<U>; <U>(success?: ((value: TResult) => IPromise<U>) | undefined, error?: ((error: any) => U) | undefined, progress?: ((progress: any) => void) | undefined): IPromise<U>; <U>(success?: ((value: TResult) => U) | undefined, error?: ((error: any) => IPromise<U>) | undefined, progress?: ((progress: any) => void) | undefined): IPromise<U>; <U>(success?: ((value: TResult) => U) | undefined, error?: ((error: any) => U) | undefined, progress?: ((progress: any) => void) | undefined): IPromise<U>; }
+>U : U
+>success : ((value: TResult) => IPromise<U>) | undefined
+>value : TResult
+>TResult : TResult
+>IPromise : IPromise<TResult>
+>U : U
+>error : ((error: any) => U) | undefined
+>error : any
+>U : U
+>progress : ((progress: any) => void) | undefined
+>progress : any
+>IPromise : IPromise<TResult>
+>U : U
+
+        then<U>(success?: (value: TResult) => U, error?: (error: any) => IPromise<U>, progress?: (progress: any) => void): IPromise<U>;
+>then : { <U>(success?: ((value: TResult) => IPromise<U>) | undefined, error?: ((error: any) => IPromise<U>) | undefined, progress?: ((progress: any) => void) | undefined): IPromise<U>; <U>(success?: ((value: TResult) => IPromise<U>) | undefined, error?: ((error: any) => U) | undefined, progress?: ((progress: any) => void) | undefined): IPromise<U>; <U>(success?: ((value: TResult) => U) | undefined, error?: ((error: any) => IPromise<U>) | undefined, progress?: ((progress: any) => void) | undefined): IPromise<U>; <U>(success?: ((value: TResult) => U) | undefined, error?: ((error: any) => U) | undefined, progress?: ((progress: any) => void) | undefined): IPromise<U>; }
+>U : U
+>success : ((value: TResult) => U) | undefined
+>value : TResult
+>TResult : TResult
+>U : U
+>error : ((error: any) => IPromise<U>) | undefined
+>error : any
+>IPromise : IPromise<TResult>
+>U : U
+>progress : ((progress: any) => void) | undefined
+>progress : any
+>IPromise : IPromise<TResult>
+>U : U
+
+        then<U>(success?: (value: TResult) => U, error?: (error: any) => U, progress?: (progress: any) => void): IPromise<U>;
+>then : { <U>(success?: ((value: TResult) => IPromise<U>) | undefined, error?: ((error: any) => IPromise<U>) | undefined, progress?: ((progress: any) => void) | undefined): IPromise<U>; <U>(success?: ((value: TResult) => IPromise<U>) | undefined, error?: ((error: any) => U) | undefined, progress?: ((progress: any) => void) | undefined): IPromise<U>; <U>(success?: ((value: TResult) => U) | undefined, error?: ((error: any) => IPromise<U>) | undefined, progress?: ((progress: any) => void) | undefined): IPromise<U>; <U>(success?: ((value: TResult) => U) | undefined, error?: ((error: any) => U) | undefined, progress?: ((progress: any) => void) | undefined): IPromise<U>; }
+>U : U
+>success : ((value: TResult) => U) | undefined
+>value : TResult
+>TResult : TResult
+>U : U
+>error : ((error: any) => U) | undefined
+>error : any
+>U : U
+>progress : ((progress: any) => void) | undefined
+>progress : any
+>IPromise : IPromise<TResult>
+>U : U
+
+        done<U>(success?: (value: TResult) => any, error?: (error: any) => any, progress?: (progress: any) => void): void;
+>done : <U>(success?: ((value: TResult) => any) | undefined, error?: ((error: any) => any) | undefined, progress?: ((progress: any) => void) | undefined) => void
+>U : U
+>success : ((value: TResult) => any) | undefined
+>value : TResult
+>TResult : TResult
+>error : ((error: any) => any) | undefined
+>error : any
+>progress : ((progress: any) => void) | undefined
+>progress : any
+
+        cancel(): void;
+>cancel : () => void
+    }
+}
+
+async function sample(promise: Windows.Foundation.IPromise<number>) {
+>sample : (promise: Windows.Foundation.IPromise<number>) => Promise<void>
+>promise : Windows.Foundation.IPromise<number>
+>Windows : any
+>Foundation : any
+>IPromise : Windows.Foundation.IPromise<TResult>
+
+    var number = await promise;
+>number : number
+>await promise : number
+>promise : Windows.Foundation.IPromise<number>
+}
+
diff --git a/tests/cases/compiler/asyncFunctionsAndStrictNullChecks.ts b/tests/cases/compiler/asyncFunctionsAndStrictNullChecks.ts
new file mode 100644
index 00000000000..f9a751314e9
--- /dev/null
+++ b/tests/cases/compiler/asyncFunctionsAndStrictNullChecks.ts
@@ -0,0 +1,18 @@
+// @target: es6
+// @strictNullChecks: true
+
+declare namespace Windows.Foundation {
+    interface IPromise<TResult> {
+        then<U>(success?: (value: TResult) => IPromise<U>, error?: (error: any) => IPromise<U>, progress?: (progress: any) => void): IPromise<U>;
+        then<U>(success?: (value: TResult) => IPromise<U>, error?: (error: any) => U, progress?: (progress: any) => void): IPromise<U>;
+        then<U>(success?: (value: TResult) => U, error?: (error: any) => IPromise<U>, progress?: (progress: any) => void): IPromise<U>;
+        then<U>(success?: (value: TResult) => U, error?: (error: any) => U, progress?: (progress: any) => void): IPromise<U>;
+        done<U>(success?: (value: TResult) => any, error?: (error: any) => any, progress?: (progress: any) => void): void;
+
+        cancel(): void;
+    }
+}
+
+async function sample(promise: Windows.Foundation.IPromise<number>) {
+    var number = await promise;
+}