addressed PR feedback

Author: vladima

src/compiler/checker.ts

@@ -9811,17 +9811,19 @@ namespace ts {
             return aggregatedTypes;
         }
 
-        // TypeScript Specification 1.0 (6.3) - July 2014
-        // An explicitly typed function whose return type isn't the Void or the Any type
-        // must have at least one return statement somewhere in its body.
-        // An exception to this rule is if the function implementation consists of a single 'throw' statement.
-        // @param returnType - return type of the function, can be undefined if return type is not explicitly specified 
+        /* 
+         *TypeScript Specification 1.0 (6.3) - July 2014
+         * An explicitly typed function whose return type isn't the Void or the Any type
+         * must have at least one return statement somewhere in its body.
+         * An exception to this rule is if the function implementation consists of a single 'throw' statement.
+         * @param returnType - return type of the function, can be undefined if return type is not explicitly specified
+         */
         function checkAllCodePathsInNonVoidFunctionReturnOrThrow(func: FunctionLikeDeclaration, returnType: Type): void {
             if (!produceDiagnostics) {
                 return;
             }
 
-            // Functions with explicitly specified return type which is either 'void' or 'any' don't need any return expressions.
+            // Functions with with an explicitly specified 'void' or 'any' return type don't need any return expressions.
             if (returnType && (returnType === voidType || isTypeAny(returnType))) {
                 return;
             }

tests/baselines/reference/reachabilityChecks7.errors.txt

@@ -0,0 +1,21 @@
+tests/cases/compiler/reachabilityChecks7.ts(3,16): error TS7030: Not all code paths return a value.
+tests/cases/compiler/reachabilityChecks7.ts(6,9): error TS7030: Not all code paths return a value.
+
+
+==== tests/cases/compiler/reachabilityChecks7.ts (2 errors) ====
+    
+    // async function without return type annotation - error
+    async function f1() {    
+                   ~~
+!!! error TS7030: Not all code paths return a value.
+    }
+    
+    let x = async function() {
+            ~~~~~
+!!! error TS7030: Not all code paths return a value.
+    }
+    
+    // async function with which promised type is void - return can be omitted
+    async function f2(): Promise<void> {
+        
+    }

tests/baselines/reference/reachabilityChecks7.js

@@ -0,0 +1,42 @@
+//// [reachabilityChecks7.ts]
+
+// async function without return type annotation - error
+async function f1() {    
+}
+
+let x = async function() {
+}
+
+// async function with which promised type is void - return can be omitted
+async function f2(): Promise<void> {
+    
+}
+
+//// [reachabilityChecks7.js]
+var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promise, generator) {
+    return new Promise(function (resolve, reject) {
+        generator = generator.call(thisArg, _arguments);
+        function cast(value) { return value instanceof Promise && value.constructor === Promise ? value : new Promise(function (resolve) { resolve(value); }); }
+        function onfulfill(value) { try { step("next", value); } catch (e) { reject(e); } }
+        function onreject(value) { try { step("throw", value); } catch (e) { reject(e); } }
+        function step(verb, value) {
+            var result = generator[verb](value);
+            result.done ? resolve(result.value) : cast(result.value).then(onfulfill, onreject);
+        }
+        step("next", void 0);
+    });
+};
+// async function without return type annotation - error
+function f1() {
+    return __awaiter(this, void 0, Promise, function* () {
+    });
+}
+let x = function () {
+    return __awaiter(this, void 0, Promise, function* () {
+    });
+};
+// async function with which promised type is void - return can be omitted
+function f2() {
+    return __awaiter(this, void 0, Promise, function* () {
+    });
+}

tests/cases/compiler/reachabilityChecks7.ts

@@ -0,0 +1,14 @@
+// @target: ES6
+// @noImplicitReturns: true
+
+// async function without return type annotation - error
+async function f1() {    
+}
+
+let x = async function() {
+}
+
+// async function with which promised type is void - return can be omitted
+async function f2(): Promise<void> {
+    
+}