From 60e7b5d17e9fc7ebfc7c55154cc000db0d773721 Mon Sep 17 00:00:00 2001
From: Daniel Rosenwasser <Daniel.Rosenwasser@microsoft.com>
Date: Wed, 24 Apr 2019 16:43:17 -0700
Subject: [PATCH 1/4] Added tests.

---
 tests/cases/compiler/omitTypeTestErrors01.ts | 19 +++++++++++++++++++
 tests/cases/compiler/omitTypeTests01.ts      | 19 +++++++++++++++++++
 2 files changed, 38 insertions(+)
 create mode 100644 tests/cases/compiler/omitTypeTestErrors01.ts
 create mode 100644 tests/cases/compiler/omitTypeTests01.ts

diff --git a/tests/cases/compiler/omitTypeTestErrors01.ts b/tests/cases/compiler/omitTypeTestErrors01.ts
new file mode 100644
index 0000000000000..fd3f5fc1e5d2a
--- /dev/null
+++ b/tests/cases/compiler/omitTypeTestErrors01.ts
@@ -0,0 +1,19 @@
+// @declaration: true
+
+interface Foo {
+    a: string;
+    b: number;
+    c: boolean;
+}
+
+export type Bar = Omit<Foo, "c">;
+export type Baz = Omit<Foo, "b" | "c">;
+
+export function getBarC(bar: Bar) {
+    return bar.c;
+}
+
+export function getBazB(baz: Baz) {
+    return baz.b;
+}
+
diff --git a/tests/cases/compiler/omitTypeTests01.ts b/tests/cases/compiler/omitTypeTests01.ts
new file mode 100644
index 0000000000000..d3b2ce26e1ec4
--- /dev/null
+++ b/tests/cases/compiler/omitTypeTests01.ts
@@ -0,0 +1,19 @@
+// @declaration: true
+
+interface Foo {
+    a: string;
+    b: number;
+    c: boolean;
+}
+
+export type Bar = Omit<Foo, "c">;
+export type Baz = Omit<Foo, "b" | "c">;
+
+export function getBarA(bar: Bar) {
+    return bar.a;
+}
+
+export function getBazA(baz: Baz) {
+    return baz.a;
+}
+

From 622cb421373e47cac3672795b64748723734570f Mon Sep 17 00:00:00 2001
From: Daniel Rosenwasser <Daniel.Rosenwasser@microsoft.com>
Date: Wed, 24 Apr 2019 16:45:30 -0700
Subject: [PATCH 2/4] Accepted baselines.

---
 .../reference/omitTypeTestErrors01.errors.txt | 27 +++++++++++
 .../reference/omitTypeTestErrors01.js         | 44 +++++++++++++++++
 .../reference/omitTypeTestErrors01.symbols    | 43 +++++++++++++++++
 .../reference/omitTypeTestErrors01.types      | 39 +++++++++++++++
 tests/baselines/reference/omitTypeTests01.js  | 44 +++++++++++++++++
 .../reference/omitTypeTests01.symbols         | 47 +++++++++++++++++++
 .../baselines/reference/omitTypeTests01.types | 39 +++++++++++++++
 7 files changed, 283 insertions(+)
 create mode 100644 tests/baselines/reference/omitTypeTestErrors01.errors.txt
 create mode 100644 tests/baselines/reference/omitTypeTestErrors01.js
 create mode 100644 tests/baselines/reference/omitTypeTestErrors01.symbols
 create mode 100644 tests/baselines/reference/omitTypeTestErrors01.types
 create mode 100644 tests/baselines/reference/omitTypeTests01.js
 create mode 100644 tests/baselines/reference/omitTypeTests01.symbols
 create mode 100644 tests/baselines/reference/omitTypeTests01.types

diff --git a/tests/baselines/reference/omitTypeTestErrors01.errors.txt b/tests/baselines/reference/omitTypeTestErrors01.errors.txt
new file mode 100644
index 0000000000000..a66ab384b8935
--- /dev/null
+++ b/tests/baselines/reference/omitTypeTestErrors01.errors.txt
@@ -0,0 +1,27 @@
+tests/cases/compiler/omitTypeTestErrors01.ts(11,16): error TS2339: Property 'c' does not exist on type 'Pick<Foo, "a" | "b">'.
+tests/cases/compiler/omitTypeTestErrors01.ts(15,16): error TS2339: Property 'b' does not exist on type 'Pick<Foo, "a">'.
+
+
+==== tests/cases/compiler/omitTypeTestErrors01.ts (2 errors) ====
+    interface Foo {
+        a: string;
+        b: number;
+        c: boolean;
+    }
+    
+    export type Bar = Omit<Foo, "c">;
+    export type Baz = Omit<Foo, "b" | "c">;
+    
+    export function getBarC(bar: Bar) {
+        return bar.c;
+                   ~
+!!! error TS2339: Property 'c' does not exist on type 'Pick<Foo, "a" | "b">'.
+    }
+    
+    export function getBazB(baz: Baz) {
+        return baz.b;
+                   ~
+!!! error TS2339: Property 'b' does not exist on type 'Pick<Foo, "a">'.
+    }
+    
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/omitTypeTestErrors01.js b/tests/baselines/reference/omitTypeTestErrors01.js
new file mode 100644
index 0000000000000..03f1f5cc6b7b6
--- /dev/null
+++ b/tests/baselines/reference/omitTypeTestErrors01.js
@@ -0,0 +1,44 @@
+//// [omitTypeTestErrors01.ts]
+interface Foo {
+    a: string;
+    b: number;
+    c: boolean;
+}
+
+export type Bar = Omit<Foo, "c">;
+export type Baz = Omit<Foo, "b" | "c">;
+
+export function getBarC(bar: Bar) {
+    return bar.c;
+}
+
+export function getBazB(baz: Baz) {
+    return baz.b;
+}
+
+
+
+//// [omitTypeTestErrors01.js]
+"use strict";
+exports.__esModule = true;
+function getBarC(bar) {
+    return bar.c;
+}
+exports.getBarC = getBarC;
+function getBazB(baz) {
+    return baz.b;
+}
+exports.getBazB = getBazB;
+
+
+//// [omitTypeTestErrors01.d.ts]
+interface Foo {
+    a: string;
+    b: number;
+    c: boolean;
+}
+export declare type Bar = Omit<Foo, "c">;
+export declare type Baz = Omit<Foo, "b" | "c">;
+export declare function getBarC(bar: Bar): any;
+export declare function getBazB(baz: Baz): any;
+export {};
diff --git a/tests/baselines/reference/omitTypeTestErrors01.symbols b/tests/baselines/reference/omitTypeTestErrors01.symbols
new file mode 100644
index 0000000000000..b913e20de4f93
--- /dev/null
+++ b/tests/baselines/reference/omitTypeTestErrors01.symbols
@@ -0,0 +1,43 @@
+=== tests/cases/compiler/omitTypeTestErrors01.ts ===
+interface Foo {
+>Foo : Symbol(Foo, Decl(omitTypeTestErrors01.ts, 0, 0))
+
+    a: string;
+>a : Symbol(Foo.a, Decl(omitTypeTestErrors01.ts, 0, 15))
+
+    b: number;
+>b : Symbol(Foo.b, Decl(omitTypeTestErrors01.ts, 1, 14))
+
+    c: boolean;
+>c : Symbol(Foo.c, Decl(omitTypeTestErrors01.ts, 2, 14))
+}
+
+export type Bar = Omit<Foo, "c">;
+>Bar : Symbol(Bar, Decl(omitTypeTestErrors01.ts, 4, 1))
+>Omit : Symbol(Omit, Decl(lib.es5.d.ts, --, --))
+>Foo : Symbol(Foo, Decl(omitTypeTestErrors01.ts, 0, 0))
+
+export type Baz = Omit<Foo, "b" | "c">;
+>Baz : Symbol(Baz, Decl(omitTypeTestErrors01.ts, 6, 33))
+>Omit : Symbol(Omit, Decl(lib.es5.d.ts, --, --))
+>Foo : Symbol(Foo, Decl(omitTypeTestErrors01.ts, 0, 0))
+
+export function getBarC(bar: Bar) {
+>getBarC : Symbol(getBarC, Decl(omitTypeTestErrors01.ts, 7, 39))
+>bar : Symbol(bar, Decl(omitTypeTestErrors01.ts, 9, 24))
+>Bar : Symbol(Bar, Decl(omitTypeTestErrors01.ts, 4, 1))
+
+    return bar.c;
+>bar : Symbol(bar, Decl(omitTypeTestErrors01.ts, 9, 24))
+}
+
+export function getBazB(baz: Baz) {
+>getBazB : Symbol(getBazB, Decl(omitTypeTestErrors01.ts, 11, 1))
+>baz : Symbol(baz, Decl(omitTypeTestErrors01.ts, 13, 24))
+>Baz : Symbol(Baz, Decl(omitTypeTestErrors01.ts, 6, 33))
+
+    return baz.b;
+>baz : Symbol(baz, Decl(omitTypeTestErrors01.ts, 13, 24))
+}
+
+
diff --git a/tests/baselines/reference/omitTypeTestErrors01.types b/tests/baselines/reference/omitTypeTestErrors01.types
new file mode 100644
index 0000000000000..e7282016868d6
--- /dev/null
+++ b/tests/baselines/reference/omitTypeTestErrors01.types
@@ -0,0 +1,39 @@
+=== tests/cases/compiler/omitTypeTestErrors01.ts ===
+interface Foo {
+    a: string;
+>a : string
+
+    b: number;
+>b : number
+
+    c: boolean;
+>c : boolean
+}
+
+export type Bar = Omit<Foo, "c">;
+>Bar : Pick<Foo, "a" | "b">
+
+export type Baz = Omit<Foo, "b" | "c">;
+>Baz : Pick<Foo, "a">
+
+export function getBarC(bar: Bar) {
+>getBarC : (bar: Pick<Foo, "a" | "b">) => any
+>bar : Pick<Foo, "a" | "b">
+
+    return bar.c;
+>bar.c : any
+>bar : Pick<Foo, "a" | "b">
+>c : any
+}
+
+export function getBazB(baz: Baz) {
+>getBazB : (baz: Pick<Foo, "a">) => any
+>baz : Pick<Foo, "a">
+
+    return baz.b;
+>baz.b : any
+>baz : Pick<Foo, "a">
+>b : any
+}
+
+
diff --git a/tests/baselines/reference/omitTypeTests01.js b/tests/baselines/reference/omitTypeTests01.js
new file mode 100644
index 0000000000000..af244b8b02b39
--- /dev/null
+++ b/tests/baselines/reference/omitTypeTests01.js
@@ -0,0 +1,44 @@
+//// [omitTypeTests01.ts]
+interface Foo {
+    a: string;
+    b: number;
+    c: boolean;
+}
+
+export type Bar = Omit<Foo, "c">;
+export type Baz = Omit<Foo, "b" | "c">;
+
+export function getBarA(bar: Bar) {
+    return bar.a;
+}
+
+export function getBazA(baz: Baz) {
+    return baz.a;
+}
+
+
+
+//// [omitTypeTests01.js]
+"use strict";
+exports.__esModule = true;
+function getBarA(bar) {
+    return bar.a;
+}
+exports.getBarA = getBarA;
+function getBazA(baz) {
+    return baz.a;
+}
+exports.getBazA = getBazA;
+
+
+//// [omitTypeTests01.d.ts]
+interface Foo {
+    a: string;
+    b: number;
+    c: boolean;
+}
+export declare type Bar = Omit<Foo, "c">;
+export declare type Baz = Omit<Foo, "b" | "c">;
+export declare function getBarA(bar: Bar): string;
+export declare function getBazA(baz: Baz): string;
+export {};
diff --git a/tests/baselines/reference/omitTypeTests01.symbols b/tests/baselines/reference/omitTypeTests01.symbols
new file mode 100644
index 0000000000000..d614f65daff03
--- /dev/null
+++ b/tests/baselines/reference/omitTypeTests01.symbols
@@ -0,0 +1,47 @@
+=== tests/cases/compiler/omitTypeTests01.ts ===
+interface Foo {
+>Foo : Symbol(Foo, Decl(omitTypeTests01.ts, 0, 0))
+
+    a: string;
+>a : Symbol(Foo.a, Decl(omitTypeTests01.ts, 0, 15))
+
+    b: number;
+>b : Symbol(Foo.b, Decl(omitTypeTests01.ts, 1, 14))
+
+    c: boolean;
+>c : Symbol(Foo.c, Decl(omitTypeTests01.ts, 2, 14))
+}
+
+export type Bar = Omit<Foo, "c">;
+>Bar : Symbol(Bar, Decl(omitTypeTests01.ts, 4, 1))
+>Omit : Symbol(Omit, Decl(lib.es5.d.ts, --, --))
+>Foo : Symbol(Foo, Decl(omitTypeTests01.ts, 0, 0))
+
+export type Baz = Omit<Foo, "b" | "c">;
+>Baz : Symbol(Baz, Decl(omitTypeTests01.ts, 6, 33))
+>Omit : Symbol(Omit, Decl(lib.es5.d.ts, --, --))
+>Foo : Symbol(Foo, Decl(omitTypeTests01.ts, 0, 0))
+
+export function getBarA(bar: Bar) {
+>getBarA : Symbol(getBarA, Decl(omitTypeTests01.ts, 7, 39))
+>bar : Symbol(bar, Decl(omitTypeTests01.ts, 9, 24))
+>Bar : Symbol(Bar, Decl(omitTypeTests01.ts, 4, 1))
+
+    return bar.a;
+>bar.a : Symbol(a, Decl(omitTypeTests01.ts, 0, 15))
+>bar : Symbol(bar, Decl(omitTypeTests01.ts, 9, 24))
+>a : Symbol(a, Decl(omitTypeTests01.ts, 0, 15))
+}
+
+export function getBazA(baz: Baz) {
+>getBazA : Symbol(getBazA, Decl(omitTypeTests01.ts, 11, 1))
+>baz : Symbol(baz, Decl(omitTypeTests01.ts, 13, 24))
+>Baz : Symbol(Baz, Decl(omitTypeTests01.ts, 6, 33))
+
+    return baz.a;
+>baz.a : Symbol(a, Decl(omitTypeTests01.ts, 0, 15))
+>baz : Symbol(baz, Decl(omitTypeTests01.ts, 13, 24))
+>a : Symbol(a, Decl(omitTypeTests01.ts, 0, 15))
+}
+
+
diff --git a/tests/baselines/reference/omitTypeTests01.types b/tests/baselines/reference/omitTypeTests01.types
new file mode 100644
index 0000000000000..c07894ee2dcf6
--- /dev/null
+++ b/tests/baselines/reference/omitTypeTests01.types
@@ -0,0 +1,39 @@
+=== tests/cases/compiler/omitTypeTests01.ts ===
+interface Foo {
+    a: string;
+>a : string
+
+    b: number;
+>b : number
+
+    c: boolean;
+>c : boolean
+}
+
+export type Bar = Omit<Foo, "c">;
+>Bar : Pick<Foo, "a" | "b">
+
+export type Baz = Omit<Foo, "b" | "c">;
+>Baz : Pick<Foo, "a">
+
+export function getBarA(bar: Bar) {
+>getBarA : (bar: Pick<Foo, "a" | "b">) => string
+>bar : Pick<Foo, "a" | "b">
+
+    return bar.a;
+>bar.a : string
+>bar : Pick<Foo, "a" | "b">
+>a : string
+}
+
+export function getBazA(baz: Baz) {
+>getBazA : (baz: Pick<Foo, "a">) => string
+>baz : Pick<Foo, "a">
+
+    return baz.a;
+>baz.a : string
+>baz : Pick<Foo, "a">
+>a : string
+}
+
+

From 57938e6cc23ac8f9aededab1adc252b249153407 Mon Sep 17 00:00:00 2001
From: Daniel Rosenwasser <Daniel.Rosenwasser@microsoft.com>
Date: Wed, 24 Apr 2019 16:57:20 -0700
Subject: [PATCH 3/4] Make `Omit` alias its own mapped type so that references
 to it never expand to `Pick<...>`.

---
 src/lib/es5.d.ts | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/lib/es5.d.ts b/src/lib/es5.d.ts
index de4a612d3919f..994fb1d765330 100644
--- a/src/lib/es5.d.ts
+++ b/src/lib/es5.d.ts
@@ -1446,7 +1446,9 @@ type Extract<T, U> = T extends U ? T : never;
 /**
  * Construct a type with the properties of T except for those in type K.
  */
-type Omit<T, K extends keyof any> = Pick<T, Exclude<keyof T, K>>;
+type Omit<T, K extends keyof any> = {
+    [P in Exclude<keyof T, K>]: T[P]
+};
 
 /**
  * Exclude null and undefined from T

From a34f9880ea86901c5fd3a749866e2dd9837560be Mon Sep 17 00:00:00 2001
From: Daniel Rosenwasser <Daniel.Rosenwasser@microsoft.com>
Date: Wed, 24 Apr 2019 17:01:28 -0700
Subject: [PATCH 4/4] Accepted baselines.

---
 .../reference/omitTypeTestErrors01.errors.txt    |  8 ++++----
 .../reference/omitTypeTestErrors01.types         | 16 ++++++++--------
 .../baselines/reference/omitTypeTests01.symbols  |  8 ++++----
 tests/baselines/reference/omitTypeTests01.types  | 16 ++++++++--------
 4 files changed, 24 insertions(+), 24 deletions(-)

diff --git a/tests/baselines/reference/omitTypeTestErrors01.errors.txt b/tests/baselines/reference/omitTypeTestErrors01.errors.txt
index a66ab384b8935..6b65e292b55f4 100644
--- a/tests/baselines/reference/omitTypeTestErrors01.errors.txt
+++ b/tests/baselines/reference/omitTypeTestErrors01.errors.txt
@@ -1,5 +1,5 @@
-tests/cases/compiler/omitTypeTestErrors01.ts(11,16): error TS2339: Property 'c' does not exist on type 'Pick<Foo, "a" | "b">'.
-tests/cases/compiler/omitTypeTestErrors01.ts(15,16): error TS2339: Property 'b' does not exist on type 'Pick<Foo, "a">'.
+tests/cases/compiler/omitTypeTestErrors01.ts(11,16): error TS2339: Property 'c' does not exist on type 'Omit<Foo, "c">'.
+tests/cases/compiler/omitTypeTestErrors01.ts(15,16): error TS2339: Property 'b' does not exist on type 'Omit<Foo, "c" | "b">'.
 
 
 ==== tests/cases/compiler/omitTypeTestErrors01.ts (2 errors) ====
@@ -15,13 +15,13 @@ tests/cases/compiler/omitTypeTestErrors01.ts(15,16): error TS2339: Property 'b'
     export function getBarC(bar: Bar) {
         return bar.c;
                    ~
-!!! error TS2339: Property 'c' does not exist on type 'Pick<Foo, "a" | "b">'.
+!!! error TS2339: Property 'c' does not exist on type 'Omit<Foo, "c">'.
     }
     
     export function getBazB(baz: Baz) {
         return baz.b;
                    ~
-!!! error TS2339: Property 'b' does not exist on type 'Pick<Foo, "a">'.
+!!! error TS2339: Property 'b' does not exist on type 'Omit<Foo, "c" | "b">'.
     }
     
     
\ No newline at end of file
diff --git a/tests/baselines/reference/omitTypeTestErrors01.types b/tests/baselines/reference/omitTypeTestErrors01.types
index e7282016868d6..4b286c2c89cbf 100644
--- a/tests/baselines/reference/omitTypeTestErrors01.types
+++ b/tests/baselines/reference/omitTypeTestErrors01.types
@@ -11,28 +11,28 @@ interface Foo {
 }
 
 export type Bar = Omit<Foo, "c">;
->Bar : Pick<Foo, "a" | "b">
+>Bar : Omit<Foo, "c">
 
 export type Baz = Omit<Foo, "b" | "c">;
->Baz : Pick<Foo, "a">
+>Baz : Omit<Foo, "c" | "b">
 
 export function getBarC(bar: Bar) {
->getBarC : (bar: Pick<Foo, "a" | "b">) => any
->bar : Pick<Foo, "a" | "b">
+>getBarC : (bar: Omit<Foo, "c">) => any
+>bar : Omit<Foo, "c">
 
     return bar.c;
 >bar.c : any
->bar : Pick<Foo, "a" | "b">
+>bar : Omit<Foo, "c">
 >c : any
 }
 
 export function getBazB(baz: Baz) {
->getBazB : (baz: Pick<Foo, "a">) => any
->baz : Pick<Foo, "a">
+>getBazB : (baz: Omit<Foo, "c" | "b">) => any
+>baz : Omit<Foo, "c" | "b">
 
     return baz.b;
 >baz.b : any
->baz : Pick<Foo, "a">
+>baz : Omit<Foo, "c" | "b">
 >b : any
 }
 
diff --git a/tests/baselines/reference/omitTypeTests01.symbols b/tests/baselines/reference/omitTypeTests01.symbols
index d614f65daff03..93b492917855a 100644
--- a/tests/baselines/reference/omitTypeTests01.symbols
+++ b/tests/baselines/reference/omitTypeTests01.symbols
@@ -28,9 +28,9 @@ export function getBarA(bar: Bar) {
 >Bar : Symbol(Bar, Decl(omitTypeTests01.ts, 4, 1))
 
     return bar.a;
->bar.a : Symbol(a, Decl(omitTypeTests01.ts, 0, 15))
+>bar.a : Symbol(a)
 >bar : Symbol(bar, Decl(omitTypeTests01.ts, 9, 24))
->a : Symbol(a, Decl(omitTypeTests01.ts, 0, 15))
+>a : Symbol(a)
 }
 
 export function getBazA(baz: Baz) {
@@ -39,9 +39,9 @@ export function getBazA(baz: Baz) {
 >Baz : Symbol(Baz, Decl(omitTypeTests01.ts, 6, 33))
 
     return baz.a;
->baz.a : Symbol(a, Decl(omitTypeTests01.ts, 0, 15))
+>baz.a : Symbol(a)
 >baz : Symbol(baz, Decl(omitTypeTests01.ts, 13, 24))
->a : Symbol(a, Decl(omitTypeTests01.ts, 0, 15))
+>a : Symbol(a)
 }
 
 
diff --git a/tests/baselines/reference/omitTypeTests01.types b/tests/baselines/reference/omitTypeTests01.types
index c07894ee2dcf6..549fcccc0f2f8 100644
--- a/tests/baselines/reference/omitTypeTests01.types
+++ b/tests/baselines/reference/omitTypeTests01.types
@@ -11,28 +11,28 @@ interface Foo {
 }
 
 export type Bar = Omit<Foo, "c">;
->Bar : Pick<Foo, "a" | "b">
+>Bar : Omit<Foo, "c">
 
 export type Baz = Omit<Foo, "b" | "c">;
->Baz : Pick<Foo, "a">
+>Baz : Omit<Foo, "c" | "b">
 
 export function getBarA(bar: Bar) {
->getBarA : (bar: Pick<Foo, "a" | "b">) => string
->bar : Pick<Foo, "a" | "b">
+>getBarA : (bar: Omit<Foo, "c">) => string
+>bar : Omit<Foo, "c">
 
     return bar.a;
 >bar.a : string
->bar : Pick<Foo, "a" | "b">
+>bar : Omit<Foo, "c">
 >a : string
 }
 
 export function getBazA(baz: Baz) {
->getBazA : (baz: Pick<Foo, "a">) => string
->baz : Pick<Foo, "a">
+>getBazA : (baz: Omit<Foo, "c" | "b">) => string
+>baz : Omit<Foo, "c" | "b">
 
     return baz.a;
 >baz.a : string
->baz : Pick<Foo, "a">
+>baz : Omit<Foo, "c" | "b">
 >a : string
 }