Add new method on interface Boolean to ensure it is not assignable from other types

src/lib/core.d.ts

@@ -426,6 +426,8 @@ interface StringConstructor {
 declare var String: StringConstructor;
 
 interface Boolean {
+    /** Returns the primitive value of the specified object. */
+    valueOf(): boolean;
 }
 
 interface BooleanConstructor {

tests/baselines/reference/assignFromBooleanInterface2.errors.txt

@@ -1,8 +1,12 @@
+tests/cases/conformance/types/primitives/boolean/assignFromBooleanInterface2.ts(14,1): error TS2322: Type 'NotBoolean' is not assignable to type 'Boolean'.
+  Types of property 'valueOf' are incompatible.
+    Type '() => Object' is not assignable to type '() => boolean'.
+      Type 'Object' is not assignable to type 'boolean'.
 tests/cases/conformance/types/primitives/boolean/assignFromBooleanInterface2.ts(19,1): error TS2322: Type 'Boolean' is not assignable to type 'boolean'.
 tests/cases/conformance/types/primitives/boolean/assignFromBooleanInterface2.ts(20,1): error TS2322: Type 'NotBoolean' is not assignable to type 'boolean'.
 
 
-==== tests/cases/conformance/types/primitives/boolean/assignFromBooleanInterface2.ts (2 errors) ====
+==== tests/cases/conformance/types/primitives/boolean/assignFromBooleanInterface2.ts (3 errors) ====
     interface Boolean {
         doStuff(): string;
     }
@@ -17,6 +21,11 @@ tests/cases/conformance/types/primitives/boolean/assignFromBooleanInterface2.ts(
 
     a = x;
     a = b;
+    ~
+!!! error TS2322: Type 'NotBoolean' is not assignable to type 'Boolean'.
+!!! error TS2322:   Types of property 'valueOf' are incompatible.
+!!! error TS2322:     Type '() => Object' is not assignable to type '() => boolean'.
+!!! error TS2322:       Type 'Object' is not assignable to type 'boolean'.
 
     b = a;
     b = x;

tests/baselines/reference/booleanAssignment.errors.txt

@@ -0,0 +1,38 @@
+tests/cases/compiler/booleanAssignment.ts(2,1): error TS2322: Type 'number' is not assignable to type 'Boolean'.
+  Types of property 'valueOf' are incompatible.
+    Type '() => Object' is not assignable to type '() => boolean'.
+      Type 'Object' is not assignable to type 'boolean'.
+tests/cases/compiler/booleanAssignment.ts(3,1): error TS2322: Type 'string' is not assignable to type 'Boolean'.
+  Types of property 'valueOf' are incompatible.
+    Type '() => Object' is not assignable to type '() => boolean'.
+tests/cases/compiler/booleanAssignment.ts(4,1): error TS2322: Type '{}' is not assignable to type 'Boolean'.
+  Types of property 'valueOf' are incompatible.
+    Type '() => Object' is not assignable to type '() => boolean'.
+
+
+==== tests/cases/compiler/booleanAssignment.ts (3 errors) ====
+    var b = new Boolean();
+    b = 1; // Error
+    ~
+!!! error TS2322: Type 'number' is not assignable to type 'Boolean'.
+!!! error TS2322:   Types of property 'valueOf' are incompatible.
+!!! error TS2322:     Type '() => Object' is not assignable to type '() => boolean'.
+!!! error TS2322:       Type 'Object' is not assignable to type 'boolean'.
+    b = "a"; // Error
+    ~
+!!! error TS2322: Type 'string' is not assignable to type 'Boolean'.
+!!! error TS2322:   Types of property 'valueOf' are incompatible.
+!!! error TS2322:     Type '() => Object' is not assignable to type '() => boolean'.
+    b = {}; // Error
+    ~
+!!! error TS2322: Type '{}' is not assignable to type 'Boolean'.
+!!! error TS2322:   Types of property 'valueOf' are incompatible.
+!!! error TS2322:     Type '() => Object' is not assignable to type '() => boolean'.
+
+    var o = {};
+    o = b; // OK
+
+    b = true; // OK
+
+    var b2:boolean;
+    b = b2; // OK

tests/baselines/reference/booleanAssignment.js

@@ -0,0 +1,24 @@
+//// [booleanAssignment.ts]
+var b = new Boolean();
+b = 1; // Error
+b = "a"; // Error
+b = {}; // Error
+
+var o = {};
+o = b; // OK
+
+b = true; // OK
+
+var b2:boolean;
+b = b2; // OK
+
+//// [booleanAssignment.js]
+var b = new Boolean();
+b = 1; // Error
+b = "a"; // Error
+b = {}; // Error
+var o = {};
+o = b; // OK
+b = true; // OK
+var b2;
+b = b2; // OK

tests/baselines/reference/templateStringsArrayTypeDefinedInES5Mode.errors.txt

@@ -1,5 +1,5 @@
 tests/cases/compiler/templateStringsArrayTypeDefinedInES5Mode.ts(10,3): error TS1159: Tagged templates are only available when targeting ECMAScript 6 and higher.
-lib.d.ts(513,11): error TS2300: Duplicate identifier 'TemplateStringsArray'.
+lib.d.ts(515,11): error TS2300: Duplicate identifier 'TemplateStringsArray'.
 tests/cases/compiler/templateStringsArrayTypeDefinedInES5Mode.ts(2,7): error TS2300: Duplicate identifier 'TemplateStringsArray'.
 tests/cases/compiler/templateStringsArrayTypeDefinedInES5Mode.ts(8,3): error TS2345: Argument of type '{ [x: number]: undefined; }' is not assignable to parameter of type 'TemplateStringsArray'.
   Property 'raw' is missing in type '{ [x: number]: undefined; }'.

tests/baselines/reference/templateStringsArrayTypeRedefinedInES6Mode.errors.txt

@@ -1,4 +1,4 @@
-lib.d.ts(513,11): error TS2300: Duplicate identifier 'TemplateStringsArray'.
+lib.d.ts(515,11): error TS2300: Duplicate identifier 'TemplateStringsArray'.
 tests/cases/compiler/templateStringsArrayTypeRedefinedInES6Mode.ts(2,7): error TS2300: Duplicate identifier 'TemplateStringsArray'.
 tests/cases/compiler/templateStringsArrayTypeRedefinedInES6Mode.ts(8,3): error TS2345: Argument of type '{ [x: number]: undefined; }' is not assignable to parameter of type 'TemplateStringsArray'.
   Property 'raw' is missing in type '{ [x: number]: undefined; }'.

tests/cases/compiler/booleanAssignment.ts

@@ -0,0 +1,12 @@
+var b = new Boolean();
+b = 1; // Error
+b = "a"; // Error
+b = {}; // Error
+
+var o = {};
+o = b; // OK
+
+b = true; // OK
+
+var b2:boolean;
+b = b2; // OK