symbols in type guards

Author: JsonFreeman

src/compiler/checker.ts

@@ -4767,7 +4767,7 @@ module ts {
                 if (assumeTrue) {
                     // Assumed result is true. If check was not for a primitive type, remove all primitive types
                     if (!typeInfo) {
-                        return removeTypesFromUnionType(type, /*typeKind*/ TypeFlags.StringLike | TypeFlags.NumberLike | TypeFlags.Boolean, /*isOfTypeKind*/ true);
+                        return removeTypesFromUnionType(type, /*typeKind*/ TypeFlags.StringLike | TypeFlags.NumberLike | TypeFlags.Boolean | TypeFlags.ESSymbol, /*isOfTypeKind*/ true);
                     }
                     // Check was for a primitive type, return that primitive type if it is a subtype
                     if (isTypeSubtypeOf(typeInfo.type, type)) {

tests/baselines/reference/symbolType17.js

@@ -0,0 +1,21 @@
+//// [symbolType17.ts]
+interface Foo { prop }
+var x: symbol | Foo;
+
+x;
+if (typeof x === "symbol") {
+    x;
+}
+else {
+    x;
+}
+
+//// [symbolType17.js]
+var x;
+x;
+if (typeof x === "symbol") {
+    x;
+}
+else {
+    x;
+}

tests/baselines/reference/symbolType17.types

@@ -0,0 +1,24 @@
+=== tests/cases/conformance/es6/Symbols/symbolType17.ts ===
+interface Foo { prop }
+>Foo : Foo
+>prop : any
+
+var x: symbol | Foo;
+>x : symbol | Foo
+>Foo : Foo
+
+x;
+>x : symbol | Foo
+
+if (typeof x === "symbol") {
+>typeof x === "symbol" : boolean
+>typeof x : string
+>x : symbol | Foo
+
+    x;
+>x : symbol
+}
+else {
+    x;
+>x : Foo
+}

tests/baselines/reference/symbolType18.js

@@ -0,0 +1,21 @@
+//// [symbolType18.ts]
+interface Foo { prop }
+var x: symbol | Foo;
+
+x;
+if (typeof x === "object") {
+    x;
+}
+else {
+    x;
+}
+
+//// [symbolType18.js]
+var x;
+x;
+if (typeof x === "object") {
+    x;
+}
+else {
+    x;
+}

tests/baselines/reference/symbolType18.types

@@ -0,0 +1,24 @@
+=== tests/cases/conformance/es6/Symbols/symbolType18.ts ===
+interface Foo { prop }
+>Foo : Foo
+>prop : any
+
+var x: symbol | Foo;
+>x : symbol | Foo
+>Foo : Foo
+
+x;
+>x : symbol | Foo
+
+if (typeof x === "object") {
+>typeof x === "object" : boolean
+>typeof x : string
+>x : symbol | Foo
+
+    x;
+>x : Foo
+}
+else {
+    x;
+>x : symbol | Foo
+}

tests/baselines/reference/symbolType19.js

@@ -0,0 +1,24 @@
+//// [symbolType19.ts]
+enum E { }
+var x: symbol | E;
+
+x;
+if (typeof x === "number") {
+    x;
+}
+else {
+    x;
+}
+
+//// [symbolType19.js]
+var E;
+(function (E) {
+})(E || (E = {}));
+var x;
+x;
+if (typeof x === "number") {
+    x;
+}
+else {
+    x;
+}

tests/baselines/reference/symbolType19.types

@@ -0,0 +1,23 @@
+=== tests/cases/conformance/es6/Symbols/symbolType19.ts ===
+enum E { }
+>E : E
+
+var x: symbol | E;
+>x : symbol | E
+>E : E
+
+x;
+>x : symbol | E
+
+if (typeof x === "number") {
+>typeof x === "number" : boolean
+>typeof x : string
+>x : symbol | E
+
+    x;
+>x : E
+}
+else {
+    x;
+>x : symbol
+}

tests/cases/conformance/es6/Symbols/symbolType17.ts

@@ -0,0 +1,11 @@
+//@target: ES6
+interface Foo { prop }
+var x: symbol | Foo;
+
+x;
+if (typeof x === "symbol") {
+    x;
+}
+else {
+    x;
+}

tests/cases/conformance/es6/Symbols/symbolType18.ts

@@ -0,0 +1,11 @@
+//@target: ES6
+interface Foo { prop }
+var x: symbol | Foo;
+
+x;
+if (typeof x === "object") {
+    x;
+}
+else {
+    x;
+}

tests/cases/conformance/es6/Symbols/symbolType19.ts

@@ -0,0 +1,11 @@
+//@target: ES6
+enum E { }
+var x: symbol | E;
+
+x;
+if (typeof x === "number") {
+    x;
+}
+else {
+    x;
+}