Added tests.

tests/cases/conformance/types/stringLiteral/stringLiteralTypesAsTags01.ts

@@ -0,0 +1,43 @@
+// @declaration: true
+
+type Kind = "A" | "B"
+
+interface Entity {
+    kind: Kind;
+}
+
+interface A extends Entity {
+    kind: "A";
+    a: number;
+}
+
+interface B extends Entity {
+    kind: "B";
+    b: string;
+}
+
+function hasKind(entity: Entity, kind: "A"): entity is A;
+function hasKind(entity: Entity, kind: "B"): entity is B;
+function hasKind(entity: Entity, kind: Kind): entity is Entity;
+function hasKind(entity: Entity, kind: Kind): boolean {
+    return kind === is;
+}
+
+let x: A = {
+    kind: "A",
+    a: 100,
+}
+
+if (hasKind(x, "A")) {
+    let a = x;
+}
+else {
+    let b = x;
+}
+
+if (!hasKind(x, "B")) {
+    let c = x;
+}
+else {
+    let d = x;
+}

tests/cases/conformance/types/stringLiteral/stringLiteralTypesInUnionTypes01.ts

@@ -0,0 +1,21 @@
+// @declaration: true
+
+type T = "foo" | "bar" | "baz";
+
+var x: "foo" | "bar" | "baz" = "foo";
+var y: T = "bar";
+
+if (x === "foo") {
+    let a = x;
+}
+else if (x !== "bar") {
+    let b = x || y;
+}
+else {
+    let c = x;
+    let d = y;
+    let e: (typeof x) | (typeof y) = c || d;
+}
+
+x = y;
+y = x;

tests/cases/conformance/types/stringLiteral/stringLiteralTypesInUnionTypes02.ts

@@ -0,0 +1,21 @@
+// @declaration: true
+
+type T = string | "foo" | "bar" | "baz";
+
+var x: "foo" | "bar" | "baz" | string = "foo";
+var y: T = "bar";
+
+if (x === "foo") {
+    let a = x;
+}
+else if (x !== "bar") {
+    let b = x || y;
+}
+else {
+    let c = x;
+    let d = y;
+    let e: (typeof x) | (typeof y) = c || d;
+}
+
+x = y;
+y = x;

tests/cases/conformance/types/stringLiteral/stringLiteralTypesInUnionTypes03.ts

@@ -0,0 +1,21 @@
+// @declaration: true
+
+type T = number | "foo" | "bar";
+
+var x: "foo" | "bar" | number;
+var y: T = "bar";
+
+if (x === "foo") {
+    let a = x;
+}
+else if (x !== "bar") {
+    let b = x || y;
+}
+else {
+    let c = x;
+    let d = y;
+    let e: (typeof x) | (typeof y) = c || d;
+}
+
+x = y;
+y = x;

tests/cases/conformance/types/stringLiteral/stringLiteralTypesInUnionTypes04.ts

@@ -0,0 +1,38 @@
+// @declaration: true
+
+type T = "" | "foo";
+
+let x: T = "";
+let y: T = "foo";
+
+if (x === "") {
+    let a = x;
+}
+
+if (x !== "") {
+    let b = x;
+}
+
+if (x == "") {
+    let c = x;
+}
+
+if (x != "") {
+    let d = x;
+}
+
+if (x) {
+    let e = x;
+}
+
+if (!x) {
+    let f = x;
+}
+
+if (!!x) {
+    let g = x;
+}
+
+if (!!!x) {
+    let h = x;
+}

tests/cases/conformance/types/stringLiteral/stringLiteralTypesInVariableDeclarations01.ts

@@ -0,0 +1,19 @@
+// @declaration: true
+
+let a: "";
+var b: "foo";
+let c: "bar";
+const d: "baz";
+
+a = "";
+b = "foo";
+c = "bar";
+
+let e: "" = "";
+var f: "foo" = "foo";
+let g: "bar" = "bar";
+const h: "baz" = "baz";
+
+e = "";
+f = "foo";
+g = "bar";

tests/cases/conformance/types/stringLiteral/stringLiteralTypesOverloads01.ts

@@ -0,0 +1,53 @@
+// @declaration: true
+
+type PrimitiveName = 'string' | 'number' | 'boolean';
+
+function getFalsyPrimitive(x: "string"): string;
+function getFalsyPrimitive(x: "number"): number;
+function getFalsyPrimitive(x: "boolean"): boolean;
+function getFalsyPrimitive(x: "boolean" | "string"): boolean | string;
+function getFalsyPrimitive(x: "boolean" | "number"): boolean | number;
+function getFalsyPrimitive(x: "number" | "string"): number | string;
+function getFalsyPrimitive(x: "number" | "string" | "boolean"): number | string | boolean;
+function getFalsyPrimitive(x: PrimitiveName) {
+    if (x === "string") {
+        return "";
+    }
+    if (x === "number") {
+        return 0;
+    }
+    if (x === "boolean") {
+        return false;
+    }
+
+    // Should be unreachable.
+    throw "Invalid value";
+}
+
+namespace Consts1 {
+    const EMPTY_STRING = getFalsyPrimitive("string");
+    const ZERO = getFalsyPrimitive('number');
+    const FALSE = getFalsyPrimitive("boolean");
+}
+
+const string: "string" = "string"
+const number: "number" = "number"
+const boolean: "boolean" = "boolean"
+
+const stringOrNumber = string || number;
+const stringOrBoolean = string || boolean;
+const booleanOrNumber = number || boolean;
+const stringOrBooleanOrNumber = stringOrBoolean || number;
+
+namespace Consts2 {
+    const EMPTY_STRING = getFalsyPrimitive(string);
+    const ZERO = getFalsyPrimitive(number);
+    const FALSE = getFalsyPrimitive(boolean);
+
+    const a = getFalsyPrimitive(stringOrNumber);
+    const b = getFalsyPrimitive(stringOrBoolean);
+    const c = getFalsyPrimitive(booleanOrNumber);
+    const d = getFalsyPrimitive(stringOrBooleanOrNumber);
+}
+
+

tests/cases/conformance/types/stringLiteral/stringLiteralTypesOverloads02.ts

@@ -0,0 +1,51 @@
+// @declaration: true
+
+function getFalsyPrimitive(x: "string"): string;
+function getFalsyPrimitive(x: "number"): number;
+function getFalsyPrimitive(x: "boolean"): boolean;
+function getFalsyPrimitive(x: "boolean" | "string"): boolean | string;
+function getFalsyPrimitive(x: "boolean" | "number"): boolean | number;
+function getFalsyPrimitive(x: "number" | "string"): number | string;
+function getFalsyPrimitive(x: "number" | "string" | "boolean"): number | string | boolean;
+function getFalsyPrimitive(x: string) {
+    if (x === "string") {
+        return "";
+    }
+    if (x === "number") {
+        return 0;
+    }
+    if (x === "boolean") {
+        return false;
+    }
+
+    // Should be unreachable.
+    throw "Invalid value";
+}
+
+namespace Consts1 {
+    const EMPTY_STRING = getFalsyPrimitive("string");
+    const ZERO = getFalsyPrimitive('number');
+    const FALSE = getFalsyPrimitive("boolean");
+}
+
+const string: "string" = "string"
+const number: "number" = "number"
+const boolean: "boolean" = "boolean"
+
+const stringOrNumber = string || number;
+const stringOrBoolean = string || boolean;
+const booleanOrNumber = number || boolean;
+const stringOrBooleanOrNumber = stringOrBoolean || number;
+
+namespace Consts2 {
+    const EMPTY_STRING = getFalsyPrimitive(string);
+    const ZERO = getFalsyPrimitive(number);
+    const FALSE = getFalsyPrimitive(boolean);
+
+    const a = getFalsyPrimitive(stringOrNumber);
+    const b = getFalsyPrimitive(stringOrBoolean);
+    const c = getFalsyPrimitive(booleanOrNumber);
+    const d = getFalsyPrimitive(stringOrBooleanOrNumber);
+}
+
+

tests/cases/conformance/types/stringLiteral/stringLiteralTypesTypePredicates01.ts

@@ -0,0 +1,25 @@
+// @declaration: true
+
+type Kind = "A" | "B"
+
+function kindIs(kind: Kind, is: "A"): kind is "A";
+function kindIs(kind: Kind, is: "B"): kind is "B";
+function kindIs(kind: Kind, is: Kind): boolean {
+    return kind === is;
+}
+
+var x: Kind = "A";
+
+if (kindIs(x, "A")) {
+    let a = x;
+}
+else {
+    let b = x;
+}
+
+if (!kindIs(x, "B")) {
+    let c = x;
+}
+else {
+    let d = x;
+}