diff --git a/src/compiler/binder.ts b/src/compiler/binder.ts
index 16f2a59a58d..c29c761c28a 100644
--- a/src/compiler/binder.ts
+++ b/src/compiler/binder.ts
@@ -9,6 +9,21 @@ namespace ts {
         Instantiated    = 1,
         ConstEnumOnly   = 2
     }
+    
+    const enum Reachability {
+        Unintialized        = 1 << 0,
+        Reachable           = 1 << 1,
+        Unreachable         = 1 << 2,
+        ReportedUnreachable = 1 << 3
+    }
+    
+    function or(state1: Reachability, state2: Reachability): Reachability {
+        return (state1 | state2) & Reachability.Reachable
+            ? Reachability.Reachable
+            : (state1 & state2) & Reachability.ReportedUnreachable
+                ? Reachability.ReportedUnreachable
+                : Reachability.Unreachable;
+    }
 
     export function getModuleInstanceState(node: Node): ModuleInstanceState {
         // A module is uninstantiated if it contains only
@@ -77,18 +92,25 @@ namespace ts {
         IsContainerWithLocals = IsContainer | HasLocals
     }
 
-    export function bindSourceFile(file: SourceFile) {
+    export function bindSourceFile(file: SourceFile, options: CompilerOptions) {
         let start = new Date().getTime();
-        bindSourceFileWorker(file);
+        bindSourceFileWorker(file, options);
         bindTime += new Date().getTime() - start;
     }
 
-    function bindSourceFileWorker(file: SourceFile) {
+    function bindSourceFileWorker(file: SourceFile, options: CompilerOptions) {
         let parent: Node;
         let container: Node;
         let blockScopeContainer: Node;
         let lastContainer: Node;
 
+        // state used by reachability checks
+        let hasExplicitReturn: boolean;
+        let currentReachabilityState: Reachability;
+        let labelStack: Reachability[];
+        let labels: Map<number>;
+        let implicitLabels: number[];
+        
         // If this file is an external module, then it is automatically in strict-mode according to
         // ES6.  If it is not an external module, then we'll determine if it is in strict mode or
         // not depending on if we see "use strict" in certain places (or if we hit a class/namespace).
@@ -329,12 +351,273 @@ namespace ts {
                 blockScopeContainer.locals = undefined;
             }
 
-            forEachChild(node, bind);
+            bindWithReachabilityChecks(node);
 
             container = saveContainer;
             parent = saveParent;
             blockScopeContainer = savedBlockScopeContainer;
         }
+        
+        function shouldSaveReachabilityState(n: Node): boolean {
+            return n.kind === SyntaxKind.SourceFile || n.kind === SyntaxKind.ModuleBlock || isFunctionLike(n);
+        }
+        
+        function bindWithReachabilityChecks(node: Node): void {
+            let savedReachabilityState: Reachability;
+            let savedLabelStack: Reachability[];
+            let savedLabels: Map<number>;
+            let savedImplicitLabels: number[];
+            let savedHasExplicitReturn: boolean;
+            
+            let saveState = shouldSaveReachabilityState(node);
+            if (saveState) {
+                savedReachabilityState = currentReachabilityState;
+                savedLabelStack = labelStack;
+                savedLabels = labels;
+                savedImplicitLabels = implicitLabels;
+                savedHasExplicitReturn = hasExplicitReturn;
+                
+                currentReachabilityState = Reachability.Reachable;
+                hasExplicitReturn = false;
+                labelStack = labels = implicitLabels = undefined;
+            }
+
+            if (!bindReachableStatement(node)) {
+                forEachChild(node, bind);
+            }
+            
+            if (currentReachabilityState === Reachability.Reachable && isFunctionLike(node) && nodeIsPresent((<FunctionLikeDeclaration>node).body)) {
+                node.flags |= NodeFlags.HasImplicitReturn;
+                if (hasExplicitReturn) {
+                    node.flags |= NodeFlags.HasExplicitReturn;
+                }
+            }
+
+            if (saveState) {
+                hasExplicitReturn = savedHasExplicitReturn;
+                currentReachabilityState = savedReachabilityState;
+                labelStack = savedLabelStack;
+                labels = savedLabels;
+                implicitLabels = savedImplicitLabels;
+            }
+        }
+
+        function bindReachableStatement(n: Node): boolean {
+            if (checkUnreachable(n)) {
+                return false;
+            }
+
+            switch(n.kind) {
+                case SyntaxKind.WhileStatement:
+                    return bindWhileStatement(<WhileStatement>n);
+                case SyntaxKind.DoStatement:
+                    return bindDoStatement(<DoStatement>n);
+                case SyntaxKind.ForStatement:
+                    return bindForStatement(<ForStatement>n);
+                case SyntaxKind.ForInStatement:
+                case SyntaxKind.ForOfStatement:
+                    return bindForInOrForOfStatement(<ForInStatement | ForOfStatement>n);
+                case SyntaxKind.IfStatement:
+                    return bindIfStatement(<IfStatement>n);
+                case SyntaxKind.ReturnStatement:
+                case SyntaxKind.ThrowStatement:
+                    return bindReturnOrThrow(<ReturnStatement | ThrowStatement>n);
+                case SyntaxKind.BreakStatement:
+                case SyntaxKind.ContinueStatement:
+                    return bindBreakOrContinueStatement(<BreakOrContinueStatement>n);
+                case SyntaxKind.TryStatement:
+                    return bindTryStatement(<TryStatement>n);
+                case SyntaxKind.SwitchStatement:
+                    return bindSwitchStatement(<SwitchStatement>n);
+                case SyntaxKind.CaseBlock:
+                    return bindCaseBlock(<CaseBlock>n);
+                case SyntaxKind.LabeledStatement:
+                    return bindLabeledStatement(<LabeledStatement>n);
+                default:
+                    return false;
+            }
+        }
+
+        function bindWhileStatement(n: WhileStatement): boolean {
+            const preWhileState = 
+                n.expression.kind === SyntaxKind.FalseKeyword ? Reachability.Unreachable : currentReachabilityState;
+            const postWhileState = 
+                n.expression.kind === SyntaxKind.TrueKeyword ? Reachability.Unreachable : currentReachabilityState;
+
+            // bind expressions (don't affect reachability)
+            bind(n.expression);
+            
+            currentReachabilityState = preWhileState;
+            const postWhileLabel = pushImplicitLabel();
+            bind(n.statement);
+            popImplicitLabel(postWhileLabel, postWhileState)
+            
+            return true;
+        }
+
+        function bindDoStatement(n: DoStatement): boolean {
+            const preDoState = currentReachabilityState;
+
+            const postDoLabel = pushImplicitLabel();
+            bind(n.statement);
+            var postDoState = n.expression.kind === SyntaxKind.TrueKeyword ? Reachability.Unreachable : preDoState;
+            popImplicitLabel(postDoLabel, postDoState);
+
+            // bind expressions (don't affect reachability)
+            bind(n.expression);
+
+            return true;
+        }
+        
+        function bindForStatement(n: ForStatement): boolean {
+            const preForState = currentReachabilityState;
+            const postForLabel = pushImplicitLabel();
+
+            // bind expressions (don't affect reachability)
+            bind(n.initializer);
+            bind(n.condition);
+            bind(n.incrementor);
+
+            bind(n.statement);
+
+            // for statement is considered infinite when it condition is either omitted or is true keyword
+            // - for(..;;..)
+            // - for(..;true;..)
+            const isInfiniteLoop = (!n.condition || n.condition.kind === SyntaxKind.TrueKeyword);
+            const postForState = isInfiniteLoop ? Reachability.Unreachable : preForState;
+            popImplicitLabel(postForLabel, postForState);
+
+            return true;
+        }
+
+        function bindForInOrForOfStatement(n: ForInStatement | ForOfStatement): boolean {
+            const preStatementState = currentReachabilityState;
+            const postStatementLabel = pushImplicitLabel();
+            
+            // bind expressions (don't affect reachability)
+            bind(n.initializer);
+            bind(n.expression);
+
+            bind(n.statement);
+            popImplicitLabel(postStatementLabel, preStatementState);
+
+            return true;
+        }
+
+        function bindIfStatement(n: IfStatement): boolean {
+            const ifTrueState = n.expression.kind === SyntaxKind.FalseKeyword ? Reachability.Unreachable : currentReachabilityState;
+            const ifFalseState = n.expression.kind === SyntaxKind.TrueKeyword ? Reachability.Unreachable : currentReachabilityState;
+
+            currentReachabilityState = ifTrueState;
+
+            // bind expression (don't affect reachability)
+            bind(n.expression);
+
+            bind(n.thenStatement);
+            if (n.elseStatement) {
+                const preElseState = currentReachabilityState;
+                currentReachabilityState = ifFalseState;
+                bind(n.elseStatement);
+                currentReachabilityState = or(currentReachabilityState, preElseState);
+            }
+            else {
+                currentReachabilityState = or(currentReachabilityState, ifFalseState);
+            }
+
+            return true;
+        }
+
+        function bindReturnOrThrow(n: ReturnStatement | ThrowStatement): boolean {
+            // bind expression (don't affect reachability)
+            bind(n.expression);
+            if (n.kind === SyntaxKind.ReturnStatement) {
+                hasExplicitReturn = true;
+            }
+            currentReachabilityState = Reachability.Unreachable;
+
+            return true;
+        }
+
+        function bindBreakOrContinueStatement(n: BreakOrContinueStatement): boolean {
+            // call bind on label (don't affect reachability)
+            bind(n.label);
+            if (n.kind === SyntaxKind.BreakStatement) {
+                jumpToLabel(n.label, currentReachabilityState);
+            }
+            else {
+                jumpToLabel(n.label, Reachability.Unreachable);  // touch label so it will be marked a used
+            }
+            currentReachabilityState = Reachability.Unreachable;
+
+            return true;
+        } 
+
+        function bindTryStatement(n: TryStatement): boolean {
+            // catch\finally blocks has the same reachability as try block
+            const preTryState = currentReachabilityState;
+            bind(n.tryBlock);
+            const postTryState = currentReachabilityState;
+
+            currentReachabilityState = preTryState;
+            bind(n.catchClause);
+            const postCatchState = currentReachabilityState;
+
+            currentReachabilityState = preTryState;
+            bind(n.finallyBlock);
+
+            // post catch/finally state is reachable if
+            // - post try state is reachable - control flow can fall out of try block
+            // - post catch state is reachable - control flow can fall out of catch block
+            currentReachabilityState = or(postTryState, postCatchState);
+
+            return true;
+        }
+
+        function bindSwitchStatement(n: SwitchStatement): boolean {
+            const preSwitchState = currentReachabilityState;
+            const postSwitchLabel = pushImplicitLabel();
+
+            // bind expression (don't affect reachability)
+            bind(n.expression);
+
+            bind(n.caseBlock);
+            
+            const hasDefault = forEach(n.caseBlock.clauses, c => c.kind === SyntaxKind.DefaultClause);
+
+            // post switch state is unreachable if switch is exaustive (has a default case ) and does not have fallthrough from the last case
+            var postSwitchState = hasDefault && currentReachabilityState !== Reachability.Reachable ? Reachability.Unreachable : preSwitchState;
+
+            popImplicitLabel(postSwitchLabel, postSwitchState);
+
+            return true;
+        }
+
+        function bindCaseBlock(n: CaseBlock): boolean {
+            const startState = currentReachabilityState;
+
+            for(let clause of n.clauses) {
+                currentReachabilityState = startState;
+                bind(clause);
+                if (clause.statements.length && currentReachabilityState === Reachability.Reachable && options.noFallthroughCasesInSwitch) {
+                    errorOnFirstToken(clause, Diagnostics.Fallthrough_case_in_switch);
+                }
+            }
+
+            return true;
+        }
+
+        function bindLabeledStatement(n: LabeledStatement): boolean {
+            // call bind on label (don't affect reachability)
+            bind(n.label);
+
+            var ok = pushNamedLabel(n.label);
+            bind(n.statement);
+            if (ok) {
+                popNamedLabel(n.label, currentReachabilityState);
+            }
+
+            return true;
+        }
 
         function getContainerFlags(node: Node): ContainerFlags {
             switch (node.kind) {
@@ -472,17 +755,6 @@ namespace ts {
                 : declareSymbol(file.locals, undefined, node, symbolFlags, symbolExcludes);
         }
 
-        function isAmbientContext(node: Node): boolean {
-            while (node) {
-                if (node.flags & NodeFlags.Ambient) {
-                    return true;
-                }
-
-                node = node.parent;
-            }
-            return false;
-        }
-
         function hasExportDeclarations(node: ModuleDeclaration | SourceFile): boolean {
             let body = node.kind === SyntaxKind.SourceFile ? node : (<ModuleDeclaration>node).body;
             if (body.kind === SyntaxKind.SourceFile || body.kind === SyntaxKind.ModuleBlock) {
@@ -498,7 +770,7 @@ namespace ts {
         function setExportContextFlag(node: ModuleDeclaration | SourceFile) {
             // A declaration source file or ambient module declaration that contains no export declarations (but possibly regular
             // declarations with export modifiers) is an export context in which declarations are implicitly exported.
-            if (isAmbientContext(node) && !hasExportDeclarations(node)) {
+            if (isInAmbientContext(node) && !hasExportDeclarations(node)) {
                 node.flags |= NodeFlags.ExportContext;
             }
             else {
@@ -750,11 +1022,11 @@ namespace ts {
         function checkStrictModeWithStatement(node: WithStatement) {
             // Grammar checking for withStatement
             if (inStrictMode) {
-                grammarErrorOnFirstToken(node, Diagnostics.with_statements_are_not_allowed_in_strict_mode);
+                errorOnFirstToken(node, Diagnostics.with_statements_are_not_allowed_in_strict_mode);
             }
         }
 
-        function grammarErrorOnFirstToken(node: Node, message: DiagnosticMessage, arg0?: any, arg1?: any, arg2?: any) {
+        function errorOnFirstToken(node: Node, message: DiagnosticMessage, arg0?: any, arg1?: any, arg2?: any) {
             let span = getSpanOfTokenAtPosition(file, node.pos);
             file.bindDiagnostics.push(createFileDiagnostic(file, span.start, span.length, message, arg0, arg1, arg2));
         }
@@ -764,6 +1036,10 @@ namespace ts {
         }
 
         function bind(node: Node) {
+            if (!node) {
+                return;
+            }
+            
             node.parent = parent;
 
             let savedInStrictMode = inStrictMode;
@@ -1065,5 +1341,123 @@ namespace ts {
                 ? bindAnonymousDeclaration(node, symbolFlags, "__computed")
                 : declareSymbolAndAddToSymbolTable(node, symbolFlags, symbolExcludes);
         }
+
+        // reachability checks
+
+        function pushNamedLabel(name: Identifier): boolean {
+            initializeReachabilityStateIfNecessary();
+            
+            if (hasProperty(labels, name.text)) {
+                return false;
+            }
+            labels[name.text] = labelStack.push(Reachability.Unintialized) - 1;
+            return true;
+        }
+        
+        function pushImplicitLabel(): number {
+            initializeReachabilityStateIfNecessary();
+            
+            let index = labelStack.push(Reachability.Unintialized) - 1;
+            implicitLabels.push(index);
+            return index;
+        }
+        
+        function popNamedLabel(label: Identifier, outerState: Reachability): void {
+            initializeReachabilityStateIfNecessary();
+            
+            let index = labels[label.text];
+            Debug.assert(index !== undefined);
+            Debug.assert(labelStack.length == index + 1);
+            
+            labels[label.text] = undefined;
+            
+            setCurrentStateAtLabel(labelStack.pop(), outerState, label);
+        }
+        
+        function popImplicitLabel(implicitLabelIndex: number, outerState: Reachability): void {
+            initializeReachabilityStateIfNecessary();
+            
+            Debug.assert(labelStack.length === implicitLabelIndex + 1, `Label stack: ${labelStack.length}, index:${implicitLabelIndex}`);
+            let i = implicitLabels.pop();
+            Debug.assert(implicitLabelIndex === i, `i: ${i}, index: ${implicitLabelIndex}`);
+            setCurrentStateAtLabel(labelStack.pop(), outerState, /*name*/ undefined);
+        }
+        
+        function setCurrentStateAtLabel(innerMergedState: Reachability, outerState: Reachability, label: Identifier): void {
+            initializeReachabilityStateIfNecessary();
+            
+            if (innerMergedState === Reachability.Unintialized) {
+                if (label && options.noUnusedLabels) {
+                    file.bindDiagnostics.push(createDiagnosticForNode(label, Diagnostics.Unused_label));
+                }
+                currentReachabilityState = outerState;
+            }
+            else {
+                currentReachabilityState = or(innerMergedState, outerState);
+            }
+        }
+        
+        function jumpToLabel(label: Identifier, outerState: Reachability): void {
+            initializeReachabilityStateIfNecessary();
+            
+            const index = label ? labels[label.text] : lastOrUndefined(implicitLabels);
+            if (index === undefined) {
+                // reference to unknown label or
+                // break/continue used outside of loops
+                return;
+            }
+            const stateAtLabel = labelStack[index];
+            labelStack[index] = stateAtLabel === Reachability.Unintialized ? outerState : or(stateAtLabel, outerState);
+        }
+
+        function checkUnreachable(node: Node): boolean {
+            switch(currentReachabilityState) {
+                case Reachability.Unreachable:
+                    const reportError =
+                        isStatement(node) ||
+                        node.kind === SyntaxKind.ClassDeclaration ||
+                        node.kind === SyntaxKind.ModuleDeclaration ||
+                        (node.kind === SyntaxKind.EnumDeclaration && (!isConstEnumDeclaration(node) || options.preserveConstEnums));
+
+                    if (reportError) {
+                        currentReachabilityState = Reachability.ReportedUnreachable;
+                        
+                        // unreachable code is reported if
+                        // - user has explicitly asked about it AND
+                        // - statement is in ambient context (statements in ambient context is already an error so we shoult not report extras) AND
+                        //   - node is not variable statement OR
+                        //   - node is block scoped variable statement OR
+                        //   - node is not block scoped variable statement and at least one variable declaration has initializer
+                        //   Rationale: we don't want to report errors on non-initialized var's since they are hoisted
+                        //   On the other side we do want to report errors on non-initialized 'lets' because of TDZ  
+                        const reportUnreachableCode = 
+                            options.noUnreachableCode &&
+                            !isInAmbientContext(node) &&
+                            (
+                                node.kind !== SyntaxKind.VariableStatement ||
+                                getCombinedNodeFlags((<VariableStatement>node).declarationList) & NodeFlags.BlockScoped ||
+                                forEach((<VariableStatement>node).declarationList.declarations, d => d.initializer)
+                            )
+
+                        if (reportUnreachableCode) {
+                            file.bindDiagnostics.push(createDiagnosticForNode(node, Diagnostics.Unreachable_code_detected));
+                        }
+                    }
+                case Reachability.ReportedUnreachable:
+                    return true;
+                default:
+                    return false;
+            }
+        }
+
+        function initializeReachabilityStateIfNecessary(): void {
+            if (labels) {
+                return;
+            }
+            currentReachabilityState = Reachability.Reachable;
+            labels = {};
+            labelStack = [];
+            implicitLabels = [];
+        }
     }
 }
diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index f71009c7b65..0d795be0091 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -158,6 +158,8 @@ namespace ts {
         let getGlobalPromiseConstructorLikeType: () => ObjectType;
         let getGlobalThenableType: () => ObjectType;
 
+        let jsxElementClassType: Type;
+
         let tupleTypes: Map<TupleType> = {};
         let unionTypes: Map<UnionType> = {};
         let intersectionTypes: Map<IntersectionType> = {};
@@ -7560,7 +7562,6 @@ namespace ts {
             return prop || unknownSymbol;
         }
 
-        let jsxElementClassType: Type = undefined;
         function getJsxGlobalElementClassType(): Type {
             if (!jsxElementClassType) {
                 jsxElementClassType = getExportedTypeFromNamespace(JsxNames.JSX, JsxNames.ElementClass);
@@ -9277,21 +9278,11 @@ namespace ts {
             return aggregatedTypes;
         }
 
-        function bodyContainsAReturnStatement(funcBody: Block) {
-            return forEachReturnStatement(funcBody, returnStatement => {
-                return true;
-            });
-        }
-
-        function bodyContainsSingleThrowStatement(body: Block) {
-            return (body.statements.length === 1) && (body.statements[0].kind === SyntaxKind.ThrowStatement);
-        }
-
         // 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.
-        function checkIfNonVoidFunctionHasReturnExpressionsOrSingleThrowStatment(func: FunctionLikeDeclaration, returnType: Type): void {
+        function checkAllCodePathsInNonVoidFunctionReturnOrThrow(func: FunctionLikeDeclaration, returnType: Type): void {
             if (!produceDiagnostics) {
                 return;
             }
@@ -9302,26 +9293,20 @@ namespace ts {
             }
 
             // If all we have is a function signature, or an arrow function with an expression body, then there is nothing to check.
-            if (nodeIsMissing(func.body) || func.body.kind !== SyntaxKind.Block) {
+            // also if HasImplicitReturnValue flags is not set this means that all codepaths in function body end with return of throw
+            if (nodeIsMissing(func.body) || func.body.kind !== SyntaxKind.Block || !(func.flags & NodeFlags.HasImplicitReturn)) {
                 return;
             }
-
-            let bodyBlock = <Block>func.body;
-
-            // Ensure the body has at least one return expression.
-            if (bodyContainsAReturnStatement(bodyBlock)) {
-                return;
+            
+            if (func.flags & NodeFlags.HasExplicitReturn) {
+                if (compilerOptions.noImplicitReturns) {
+                    error(func.type, Diagnostics.Not_all_code_paths_return_a_value);
+                }
             }
-
-            // If there are no return expressions, then we need to check if
-            // the function body consists solely of a throw statement;
-            // this is to make an exception for unimplemented functions.
-            if (bodyContainsSingleThrowStatement(bodyBlock)) {
-                return;
+            else {
+                // This function does not conform to the specification.
+                error(func.type, Diagnostics.A_function_whose_declared_type_is_neither_void_nor_any_must_return_a_value);
             }
-
-            // This function does not conform to the specification.
-            error(func.type, Diagnostics.A_function_whose_declared_type_is_neither_void_nor_any_must_return_a_value_or_consist_of_a_single_throw_statement);
         }
 
         function checkFunctionExpressionOrObjectLiteralMethod(node: FunctionExpression | MethodDeclaration, contextualMapper?: TypeMapper): Type {
@@ -9401,7 +9386,7 @@ namespace ts {
             }
 
             if (returnType && !node.asteriskToken) {
-                checkIfNonVoidFunctionHasReturnExpressionsOrSingleThrowStatment(node, isAsync ? promisedType : returnType);
+                checkAllCodePathsInNonVoidFunctionReturnOrThrow(node, isAsync ? promisedType : returnType);
             }
 
             if (node.body) {
@@ -10579,8 +10564,15 @@ namespace ts {
                 checkGrammarFunctionLikeDeclaration(node) || checkGrammarAccessor(node) || checkGrammarComputedPropertyName(node.name);
 
                 if (node.kind === SyntaxKind.GetAccessor) {
-                    if (!isInAmbientContext(node) && nodeIsPresent(node.body) && !(bodyContainsAReturnStatement(<Block>node.body) || bodyContainsSingleThrowStatement(<Block>node.body))) {
-                        error(node.name, Diagnostics.A_get_accessor_must_return_a_value_or_consist_of_a_single_throw_statement);
+                    if (!isInAmbientContext(node) && nodeIsPresent(node.body) && (node.flags & NodeFlags.HasImplicitReturn)) {
+                        if (node.flags & NodeFlags.HasExplicitReturn) {
+                            if (compilerOptions.noImplicitReturns) {
+                                error(node.name, Diagnostics.Not_all_code_paths_return_a_value);
+                            }
+                        }
+                        else {
+                            error(node.name, Diagnostics.A_get_accessor_must_return_a_value);
+                        }
                     }
                 }
 
@@ -11505,7 +11497,7 @@ namespace ts {
                     promisedType = checkAsyncFunctionReturnType(node);
                 }
 
-                checkIfNonVoidFunctionHasReturnExpressionsOrSingleThrowStatment(node, isAsync ? promisedType : returnType);
+                checkAllCodePathsInNonVoidFunctionReturnOrThrow(node, isAsync ? promisedType : returnType);
             }
 
             if (produceDiagnostics && !node.type) {
@@ -14524,7 +14516,7 @@ namespace ts {
         function initializeTypeChecker() {
             // Bind all source files and propagate errors
             forEach(host.getSourceFiles(), file => {
-                bindSourceFile(file);
+                bindSourceFile(file, compilerOptions);
             });
 
             // Initialize global symbol table
diff --git a/src/compiler/commandLineParser.ts b/src/compiler/commandLineParser.ts
index c56a18b3ab2..c773be4dfb8 100644
--- a/src/compiler/commandLineParser.ts
+++ b/src/compiler/commandLineParser.ts
@@ -244,7 +244,27 @@ namespace ts {
                 "classic": ModuleResolutionKind.Classic
             },
             description: Diagnostics.Specifies_module_resolution_strategy_Colon_node_Node_or_classic_TypeScript_pre_1_6
-        }        
+        },
+        {
+            name: "noUnusedLabels",
+            type: "boolean",
+            description: Diagnostics.Report_error_on_unused_labels
+        },
+        {
+            name: "noImplicitReturns",
+            type: "boolean",
+            description: Diagnostics.Report_error_when_not_all_code_paths_in_function_return_a_value
+        },
+        {
+            name: "noFallthroughCasesInSwitch",
+            type: "boolean",
+            description: Diagnostics.Report_errors_for_fallthrough_cases_in_switch_statement
+        },
+        {
+            name: "noUnreachableCode",
+            type: "boolean",
+            description: Diagnostics.Report_errors_on_unreachable_code
+        }
     ];
 
     /* @internal */
diff --git a/src/compiler/diagnosticInformationMap.generated.ts b/src/compiler/diagnosticInformationMap.generated.ts
index f7351bf6912..2fc382c1ea9 100644
--- a/src/compiler/diagnosticInformationMap.generated.ts
+++ b/src/compiler/diagnosticInformationMap.generated.ts
@@ -256,7 +256,7 @@ namespace ts {
         Neither_type_0_nor_type_1_is_assignable_to_the_other: { code: 2352, category: DiagnosticCategory.Error, key: "Neither type '{0}' nor type '{1}' is assignable to the other." },
         Object_literal_may_only_specify_known_properties_and_0_does_not_exist_in_type_1: { code: 2353, category: DiagnosticCategory.Error, key: "Object literal may only specify known properties, and '{0}' does not exist in type '{1}'." },
         No_best_common_type_exists_among_return_expressions: { code: 2354, category: DiagnosticCategory.Error, key: "No best common type exists among return expressions." },
-        A_function_whose_declared_type_is_neither_void_nor_any_must_return_a_value_or_consist_of_a_single_throw_statement: { code: 2355, category: DiagnosticCategory.Error, key: "A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement." },
+        A_function_whose_declared_type_is_neither_void_nor_any_must_return_a_value: { code: 2355, category: DiagnosticCategory.Error, key: "A function whose declared type is neither 'void' nor 'any' must return a value." },
         An_arithmetic_operand_must_be_of_type_any_number_or_an_enum_type: { code: 2356, category: DiagnosticCategory.Error, key: "An arithmetic operand must be of type 'any', 'number' or an enum type." },
         The_operand_of_an_increment_or_decrement_operator_must_be_a_variable_property_or_indexer: { code: 2357, category: DiagnosticCategory.Error, key: "The operand of an increment or decrement operator must be a variable, property or indexer." },
         The_left_hand_side_of_an_instanceof_expression_must_be_of_type_any_an_object_type_or_a_type_parameter: { code: 2358, category: DiagnosticCategory.Error, key: "The left-hand side of an 'instanceof' expression must be of type 'any', an object type or a type parameter." },
@@ -277,7 +277,7 @@ namespace ts {
         Duplicate_number_index_signature: { code: 2375, category: DiagnosticCategory.Error, key: "Duplicate number index signature." },
         A_super_call_must_be_the_first_statement_in_the_constructor_when_a_class_contains_initialized_properties_or_has_parameter_properties: { code: 2376, category: DiagnosticCategory.Error, key: "A 'super' call must be the first statement in the constructor when a class contains initialized properties or has parameter properties." },
         Constructors_for_derived_classes_must_contain_a_super_call: { code: 2377, category: DiagnosticCategory.Error, key: "Constructors for derived classes must contain a 'super' call." },
-        A_get_accessor_must_return_a_value_or_consist_of_a_single_throw_statement: { code: 2378, category: DiagnosticCategory.Error, key: "A 'get' accessor must return a value or consist of a single 'throw' statement." },
+        A_get_accessor_must_return_a_value: { code: 2378, category: DiagnosticCategory.Error, key: "A 'get' accessor must return a value." },
         Getter_and_setter_accessors_do_not_agree_in_visibility: { code: 2379, category: DiagnosticCategory.Error, key: "Getter and setter accessors do not agree in visibility." },
         get_and_set_accessor_must_have_the_same_type: { code: 2380, category: DiagnosticCategory.Error, key: "'get' and 'set' accessor must have the same type." },
         A_signature_with_an_implementation_cannot_use_a_string_literal_type: { code: 2381, category: DiagnosticCategory.Error, key: "A signature with an implementation cannot use a string literal type." },
@@ -570,6 +570,10 @@ namespace ts {
         Initializes_a_TypeScript_project_and_creates_a_tsconfig_json_file: { code: 6070, category: DiagnosticCategory.Message, key: "Initializes a TypeScript project and creates a tsconfig.json file." },
         Successfully_created_a_tsconfig_json_file: { code: 6071, category: DiagnosticCategory.Message, key: "Successfully created a tsconfig.json file." },
         Suppress_excess_property_checks_for_object_literals: { code: 6072, category: DiagnosticCategory.Message, key: "Suppress excess property checks for object literals." },
+        Report_error_on_unused_labels: { code: 6073, category: DiagnosticCategory.Message, key: "Report error on unused labels." },
+        Report_error_when_not_all_code_paths_in_function_return_a_value: { code: 6074, category: DiagnosticCategory.Message, key: "Report error when not all code paths in function return a value." },
+        Report_errors_for_fallthrough_cases_in_switch_statement: { code: 6075, category: DiagnosticCategory.Message, key: "Report errors for fallthrough cases in switch statement." },
+        Report_errors_on_unreachable_code: { code: 6076, category: DiagnosticCategory.Message, key: "Report errors on unreachable code." },
         Variable_0_implicitly_has_an_1_type: { code: 7005, category: DiagnosticCategory.Error, key: "Variable '{0}' implicitly has an '{1}' type." },
         Parameter_0_implicitly_has_an_1_type: { code: 7006, category: DiagnosticCategory.Error, key: "Parameter '{0}' implicitly has an '{1}' type." },
         Member_0_implicitly_has_an_1_type: { code: 7008, category: DiagnosticCategory.Error, key: "Member '{0}' implicitly has an '{1}' type." },
@@ -587,6 +591,10 @@ namespace ts {
         Function_implicitly_has_return_type_any_because_it_does_not_have_a_return_type_annotation_and_is_referenced_directly_or_indirectly_in_one_of_its_return_expressions: { code: 7024, category: DiagnosticCategory.Error, key: "Function implicitly has return type 'any' because it does not have a return type annotation and is referenced directly or indirectly in one of its return expressions." },
         Generator_implicitly_has_type_0_because_it_does_not_yield_any_values_Consider_supplying_a_return_type: { code: 7025, category: DiagnosticCategory.Error, key: "Generator implicitly has type '{0}' because it does not yield any values. Consider supplying a return type." },
         JSX_element_implicitly_has_type_any_because_no_interface_JSX_0_exists: { code: 7026, category: DiagnosticCategory.Error, key: "JSX element implicitly has type 'any' because no interface 'JSX.{0}' exists" },
+        Unreachable_code_detected: { code: 7027, category: DiagnosticCategory.Error, key: "Unreachable code detected." },
+        Unused_label: { code: 7028, category: DiagnosticCategory.Error, key: "Unused label." },
+        Fallthrough_case_in_switch: { code: 7029, category: DiagnosticCategory.Error, key: "Fallthrough case in switch." },
+        Not_all_code_paths_return_a_value: { code: 7030, category: DiagnosticCategory.Error, key: "Not all code paths return a value." },
         You_cannot_rename_this_element: { code: 8000, category: DiagnosticCategory.Error, key: "You cannot rename this element." },
         You_cannot_rename_elements_that_are_defined_in_the_standard_TypeScript_library: { code: 8001, category: DiagnosticCategory.Error, key: "You cannot rename elements that are defined in the standard TypeScript library." },
         import_can_only_be_used_in_a_ts_file: { code: 8002, category: DiagnosticCategory.Error, key: "'import ... =' can only be used in a .ts file." },
diff --git a/src/compiler/diagnosticMessages.json b/src/compiler/diagnosticMessages.json
index 9fd08ef9bca..d62b837ea5b 100644
--- a/src/compiler/diagnosticMessages.json
+++ b/src/compiler/diagnosticMessages.json
@@ -1013,7 +1013,7 @@
         "category": "Error",
         "code": 2354
     },
-    "A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement.": {
+    "A function whose declared type is neither 'void' nor 'any' must return a value.": {
         "category": "Error",
         "code": 2355
     },
@@ -1097,7 +1097,7 @@
         "category": "Error",
         "code": 2377
     },
-    "A 'get' accessor must return a value or consist of a single 'throw' statement.": {
+    "A 'get' accessor must return a value.": {
         "category": "Error",
         "code": 2378
     },
@@ -2270,7 +2270,22 @@
         "category": "Message",
         "code": 6072
     },
-
+    "Report error on unused labels.": {
+        "category": "Message",
+        "code": 6073
+    },
+    "Report error when not all code paths in function return a value.": {
+        "category": "Message",
+        "code": 6074
+    },
+    "Report errors for fallthrough cases in switch statement.": {
+        "category": "Message",
+        "code": 6075
+    },
+    "Report errors on unreachable code.": {
+        "category": "Message",
+        "code": 6076
+    },
     "Variable '{0}' implicitly has an '{1}' type.": {
         "category": "Error",
         "code": 7005
@@ -2339,8 +2354,22 @@
         "category": "Error",
         "code": 7026
     },
-
-
+    "Unreachable code detected.": {
+        "category": "Error",
+        "code": 7027
+    },
+    "Unused label.": {
+        "category": "Error",
+        "code": 7028
+    },
+    "Fallthrough case in switch.": {
+        "category": "Error",
+        "code": 7029
+    },
+    "Not all code paths return a value.": {
+        "category": "Error",
+        "code": 7030
+    },    
     "You cannot rename this element.": {
         "category": "Error",
         "code": 8000
diff --git a/src/compiler/types.ts b/src/compiler/types.ts
index 47182e39527..0d2526cef98 100644
--- a/src/compiler/types.ts
+++ b/src/compiler/types.ts
@@ -376,6 +376,8 @@ namespace ts {
         OctalLiteral =      0x00010000,  // Octal numeric literal
         Namespace =         0x00020000,  // Namespace declaration
         ExportContext =     0x00040000,  // Export context (initialized by binding)
+        HasImplicitReturn =     0x00080000,  // If function implicitly returns on one of codepaths (initialized by binding)
+        HasExplicitReturn =     0x00100000,  // If function has explicit reachable return on one of codepaths (initialized by binding)
 
         Modifier = Export | Ambient | Public | Private | Protected | Static | Abstract | Default | Async,
         AccessibilityModifier = Public | Private | Protected,
@@ -2057,7 +2059,11 @@ namespace ts {
         experimentalDecorators?: boolean;
         experimentalAsyncFunctions?: boolean;
         emitDecoratorMetadata?: boolean;
-        moduleResolution?: ModuleResolutionKind
+        moduleResolution?: ModuleResolutionKind,
+        noUnusedLabels?: boolean,
+        noImplicitReturns?: boolean,
+        noFallthroughCasesInSwitch?: boolean,
+        noUnreachableCode?: boolean,
         /* @internal */ stripInternal?: boolean;
 
         // Skip checking lib.d.ts to help speed up tests.
diff --git a/src/harness/harness.ts b/src/harness/harness.ts
index f65a4f88730..a23f19e36b7 100644
--- a/src/harness/harness.ts
+++ b/src/harness/harness.ts
@@ -1242,6 +1242,18 @@ module Harness {
                                           setting.value.toLowerCase() === "preserve" ? ts.JsxEmit.Preserve :
                                           ts.JsxEmit.None;
                             break;
+                        case "nounusedlabels":
+                            options.noUnusedLabels = setting.value === "true"
+                            break;
+                        case "noimplicitreturns":
+                            options.noImplicitReturns = setting.value === "true"
+                            break;
+                        case "nofallthroughcasesinswitch":
+                            options.noFallthroughCasesInSwitch = setting.value === "true"
+                            break;
+                        case "nounreachablecode":
+                            options.noUnreachableCode = setting.value === "true"
+                            break;
 
                         default:
                             throw new Error("Unsupported compiler setting " + setting.flag);
diff --git a/src/services/breakpoints.ts b/src/services/breakpoints.ts
index 227ba6a7970..e307b21979e 100644
--- a/src/services/breakpoints.ts
+++ b/src/services/breakpoints.ts
@@ -446,7 +446,7 @@ namespace ts.BreakpointResolver {
                         // fall through.
 
                     case SyntaxKind.CatchClause:
-                        return spanInNode(lastOrUndefined((<Block>node.parent).statements));;
+                        return spanInNode(lastOrUndefined((<Block>node.parent).statements));
 
                     case SyntaxKind.CaseBlock:
                         // breakpoint in last statement of the last clause
@@ -493,9 +493,6 @@ namespace ts.BreakpointResolver {
                     default:
                         return spanInNode(node.parent);
                 }
-
-                // Default to parent node
-                return spanInNode(node.parent);
             }
 
             function spanInColonToken(node: Node): TextSpan {
diff --git a/src/services/formatting/smartIndenter.ts b/src/services/formatting/smartIndenter.ts
index ebbf09e9feb..760ee16a507 100644
--- a/src/services/formatting/smartIndenter.ts
+++ b/src/services/formatting/smartIndenter.ts
@@ -340,7 +340,6 @@ namespace ts.formatting {
                             return node;
                     }
                 }
-                return node;
             }
         }
 
diff --git a/src/services/navigateTo.ts b/src/services/navigateTo.ts
index bc506bc22f9..2a0abba8695 100644
--- a/src/services/navigateTo.ts
+++ b/src/services/navigateTo.ts
@@ -6,6 +6,9 @@ namespace ts.NavigateTo {
         let patternMatcher = createPatternMatcher(searchValue);
         let rawItems: RawNavigateToItem[] = [];
 
+        // This means "compare in a case insensitive manner."
+        let baseSensitivity: Intl.CollatorOptions = { sensitivity: "base" };
+
         // Search the declarations in all files and output matched NavigateToItem into array of NavigateToItem[] 
         forEach(program.getSourceFiles(), sourceFile => {
             cancellationToken.throwIfCancellationRequested();
@@ -162,8 +165,6 @@ namespace ts.NavigateTo {
             return bestMatchKind;
         }
 
-        // This means "compare in a case insensitive manner."
-        let baseSensitivity: Intl.CollatorOptions = { sensitivity: "base" };
         function compareNavigateToItems(i1: RawNavigateToItem, i2: RawNavigateToItem) {
             // TODO(cyrusn): get the gamut of comparisons that VS already uses here.
             // Right now we just sort by kind first, and then by name of the item.
diff --git a/src/services/services.ts b/src/services/services.ts
index 752fb93cd00..44d9786566b 100644
--- a/src/services/services.ts
+++ b/src/services/services.ts
@@ -4863,7 +4863,7 @@ namespace ts {
                         else if (!isFunctionLike(node)) {
                             forEachChild(node, aggregate);
                         }
-                    };
+                    }
                 }
 
                 /**
@@ -4910,7 +4910,7 @@ namespace ts {
                         else if (!isFunctionLike(node)) {
                             forEachChild(node, aggregate);
                         }
-                    };
+                    }
                 }
 
                 function ownsBreakOrContinueStatement(owner: Node, statement: BreakOrContinueStatement): boolean {
@@ -6219,8 +6219,6 @@ namespace ts {
             }
 
             return SemanticMeaning.Value | SemanticMeaning.Type | SemanticMeaning.Namespace;
-
-            Debug.fail("Unknown declaration type");
         }
 
         function isTypeReference(node: Node): boolean {
diff --git a/src/services/shims.ts b/src/services/shims.ts
index 307062cebd8..ace438b2778 100644
--- a/src/services/shims.ts
+++ b/src/services/shims.ts
@@ -320,7 +320,6 @@ namespace ts {
             // TODO: should this be '==='?
             if (settingsJson == null || settingsJson == "") {
                 throw Error("LanguageServiceShimHostAdapter.getCompilationSettings: empty compilationSettings");
-                return null;
             }
             return <CompilerOptions>JSON.parse(settingsJson);
         }
diff --git a/tests/baselines/reference/ParameterList5.errors.txt b/tests/baselines/reference/ParameterList5.errors.txt
index 02b86633b95..618ce740915 100644
--- a/tests/baselines/reference/ParameterList5.errors.txt
+++ b/tests/baselines/reference/ParameterList5.errors.txt
@@ -1,4 +1,4 @@
-tests/cases/compiler/ParameterList5.ts(1,15): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement.
+tests/cases/compiler/ParameterList5.ts(1,15): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value.
 tests/cases/compiler/ParameterList5.ts(1,16): error TS2369: A parameter property is only allowed in a constructor implementation.
 tests/cases/compiler/ParameterList5.ts(1,29): error TS2304: Cannot find name 'C'.
 
@@ -6,7 +6,7 @@ tests/cases/compiler/ParameterList5.ts(1,29): error TS2304: Cannot find name 'C'
 ==== tests/cases/compiler/ParameterList5.ts (3 errors) ====
     function A(): (public B) => C {
                   ~~~~~~~~~~~~~~~
-!!! error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement.
+!!! error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value.
                    ~~~~~~~~
 !!! error TS2369: A parameter property is only allowed in a constructor implementation.
                                 ~
diff --git a/tests/baselines/reference/YieldExpression17_es6.errors.txt b/tests/baselines/reference/YieldExpression17_es6.errors.txt
index bc262212526..f987517371f 100644
--- a/tests/baselines/reference/YieldExpression17_es6.errors.txt
+++ b/tests/baselines/reference/YieldExpression17_es6.errors.txt
@@ -1,5 +1,5 @@
 tests/cases/conformance/es6/yieldExpressions/YieldExpression17_es6.ts(1,15): error TS1056: Accessors are only available when targeting ECMAScript 5 and higher.
-tests/cases/conformance/es6/yieldExpressions/YieldExpression17_es6.ts(1,15): error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+tests/cases/conformance/es6/yieldExpressions/YieldExpression17_es6.ts(1,15): error TS2378: A 'get' accessor must return a value.
 tests/cases/conformance/es6/yieldExpressions/YieldExpression17_es6.ts(1,23): error TS1163: A 'yield' expression is only allowed in a generator body.
 
 
@@ -8,6 +8,6 @@ tests/cases/conformance/es6/yieldExpressions/YieldExpression17_es6.ts(1,23): err
                   ~~~
 !!! error TS1056: Accessors are only available when targeting ECMAScript 5 and higher.
                   ~~~
-!!! error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+!!! error TS2378: A 'get' accessor must return a value.
                           ~~~~~
 !!! error TS1163: A 'yield' expression is only allowed in a generator body.
\ No newline at end of file
diff --git a/tests/baselines/reference/asyncArrowFunction10_es6.errors.txt b/tests/baselines/reference/asyncArrowFunction10_es6.errors.txt
index 2476eaec6e3..08e59e69b9f 100644
--- a/tests/baselines/reference/asyncArrowFunction10_es6.errors.txt
+++ b/tests/baselines/reference/asyncArrowFunction10_es6.errors.txt
@@ -1,7 +1,7 @@
 tests/cases/conformance/async/es6/asyncArrowFunction/asyncArrowFunction10_es6.ts(2,11): error TS2304: Cannot find name 'async'.
 tests/cases/conformance/async/es6/asyncArrowFunction/asyncArrowFunction10_es6.ts(2,17): error TS1005: ',' expected.
 tests/cases/conformance/async/es6/asyncArrowFunction/asyncArrowFunction10_es6.ts(2,20): error TS1005: '=' expected.
-tests/cases/conformance/async/es6/asyncArrowFunction/asyncArrowFunction10_es6.ts(2,24): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement.
+tests/cases/conformance/async/es6/asyncArrowFunction/asyncArrowFunction10_es6.ts(2,24): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value.
 tests/cases/conformance/async/es6/asyncArrowFunction/asyncArrowFunction10_es6.ts(4,11): error TS2304: Cannot find name 'await'.
 
 
@@ -15,7 +15,7 @@ tests/cases/conformance/async/es6/asyncArrowFunction/asyncArrowFunction10_es6.ts
                        ~
 !!! error TS1005: '=' expected.
                            ~~~~~~~~~~~~~
-!!! error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement.
+!!! error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value.
        // Legal to use 'await' in a type context.
        var v: await;
               ~~~~~
diff --git a/tests/baselines/reference/asyncFunctionDeclaration12_es6.errors.txt b/tests/baselines/reference/asyncFunctionDeclaration12_es6.errors.txt
index 978492f0744..43df8e21659 100644
--- a/tests/baselines/reference/asyncFunctionDeclaration12_es6.errors.txt
+++ b/tests/baselines/reference/asyncFunctionDeclaration12_es6.errors.txt
@@ -1,6 +1,6 @@
 tests/cases/conformance/async/es6/functionDeclarations/asyncFunctionDeclaration12_es6.ts(1,24): error TS1005: '(' expected.
 tests/cases/conformance/async/es6/functionDeclarations/asyncFunctionDeclaration12_es6.ts(1,29): error TS1005: '=' expected.
-tests/cases/conformance/async/es6/functionDeclarations/asyncFunctionDeclaration12_es6.ts(1,33): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement.
+tests/cases/conformance/async/es6/functionDeclarations/asyncFunctionDeclaration12_es6.ts(1,33): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value.
 tests/cases/conformance/async/es6/functionDeclarations/asyncFunctionDeclaration12_es6.ts(1,47): error TS1005: '=>' expected.
 
 
@@ -11,6 +11,6 @@ tests/cases/conformance/async/es6/functionDeclarations/asyncFunctionDeclaration1
                                 ~
 !!! error TS1005: '=' expected.
                                     ~~~~~~~~~~~~~
-!!! error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement.
+!!! error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value.
                                                   ~
 !!! error TS1005: '=>' expected.
\ No newline at end of file
diff --git a/tests/baselines/reference/asyncGetter_es6.errors.txt b/tests/baselines/reference/asyncGetter_es6.errors.txt
index 5f5a9f6b1d7..f6deea16d06 100644
--- a/tests/baselines/reference/asyncGetter_es6.errors.txt
+++ b/tests/baselines/reference/asyncGetter_es6.errors.txt
@@ -1,5 +1,5 @@
 tests/cases/conformance/async/es6/asyncGetter_es6.ts(2,3): error TS1042: 'async' modifier cannot be used here.
-tests/cases/conformance/async/es6/asyncGetter_es6.ts(2,13): error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+tests/cases/conformance/async/es6/asyncGetter_es6.ts(2,13): error TS2378: A 'get' accessor must return a value.
 
 
 ==== tests/cases/conformance/async/es6/asyncGetter_es6.ts (2 errors) ====
@@ -8,6 +8,6 @@ tests/cases/conformance/async/es6/asyncGetter_es6.ts(2,13): error TS2378: A 'get
       ~~~~~
 !!! error TS1042: 'async' modifier cannot be used here.
                 ~~~
-!!! error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+!!! error TS2378: A 'get' accessor must return a value.
       }
     }
\ No newline at end of file
diff --git a/tests/baselines/reference/computedPropertyNames2_ES5.errors.txt b/tests/baselines/reference/computedPropertyNames2_ES5.errors.txt
index 2fbf68b4437..e704126c055 100644
--- a/tests/baselines/reference/computedPropertyNames2_ES5.errors.txt
+++ b/tests/baselines/reference/computedPropertyNames2_ES5.errors.txt
@@ -1,5 +1,5 @@
-tests/cases/conformance/es6/computedProperties/computedPropertyNames2_ES5.ts(6,9): error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
-tests/cases/conformance/es6/computedProperties/computedPropertyNames2_ES5.ts(8,16): error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+tests/cases/conformance/es6/computedProperties/computedPropertyNames2_ES5.ts(6,9): error TS2378: A 'get' accessor must return a value.
+tests/cases/conformance/es6/computedProperties/computedPropertyNames2_ES5.ts(8,16): error TS2378: A 'get' accessor must return a value.
 
 
 ==== tests/cases/conformance/es6/computedProperties/computedPropertyNames2_ES5.ts (2 errors) ====
@@ -10,10 +10,10 @@ tests/cases/conformance/es6/computedProperties/computedPropertyNames2_ES5.ts(8,1
         static [methodName]() { }
         get [accessorName]() { }
             ~~~~~~~~~~~~~~
-!!! error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+!!! error TS2378: A 'get' accessor must return a value.
         set [accessorName](v) { }
         static get [accessorName]() { }
                    ~~~~~~~~~~~~~~
-!!! error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+!!! error TS2378: A 'get' accessor must return a value.
         static set [accessorName](v) { }
     }
\ No newline at end of file
diff --git a/tests/baselines/reference/computedPropertyNames2_ES6.errors.txt b/tests/baselines/reference/computedPropertyNames2_ES6.errors.txt
index 3f18a8764b4..6b294981638 100644
--- a/tests/baselines/reference/computedPropertyNames2_ES6.errors.txt
+++ b/tests/baselines/reference/computedPropertyNames2_ES6.errors.txt
@@ -1,5 +1,5 @@
-tests/cases/conformance/es6/computedProperties/computedPropertyNames2_ES6.ts(6,9): error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
-tests/cases/conformance/es6/computedProperties/computedPropertyNames2_ES6.ts(8,16): error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+tests/cases/conformance/es6/computedProperties/computedPropertyNames2_ES6.ts(6,9): error TS2378: A 'get' accessor must return a value.
+tests/cases/conformance/es6/computedProperties/computedPropertyNames2_ES6.ts(8,16): error TS2378: A 'get' accessor must return a value.
 
 
 ==== tests/cases/conformance/es6/computedProperties/computedPropertyNames2_ES6.ts (2 errors) ====
@@ -10,10 +10,10 @@ tests/cases/conformance/es6/computedProperties/computedPropertyNames2_ES6.ts(8,1
         static [methodName]() { }
         get [accessorName]() { }
             ~~~~~~~~~~~~~~
-!!! error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+!!! error TS2378: A 'get' accessor must return a value.
         set [accessorName](v) { }
         static get [accessorName]() { }
                    ~~~~~~~~~~~~~~
-!!! error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+!!! error TS2378: A 'get' accessor must return a value.
         static set [accessorName](v) { }
     }
\ No newline at end of file
diff --git a/tests/baselines/reference/computedPropertyNames3_ES5.errors.txt b/tests/baselines/reference/computedPropertyNames3_ES5.errors.txt
index a31965dc69e..fd6f8e8bdc1 100644
--- a/tests/baselines/reference/computedPropertyNames3_ES5.errors.txt
+++ b/tests/baselines/reference/computedPropertyNames3_ES5.errors.txt
@@ -1,9 +1,9 @@
 tests/cases/conformance/es6/computedProperties/computedPropertyNames3_ES5.ts(4,12): error TS2464: A computed property name must be of type 'string', 'number', 'symbol', or 'any'.
-tests/cases/conformance/es6/computedProperties/computedPropertyNames3_ES5.ts(5,9): error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+tests/cases/conformance/es6/computedProperties/computedPropertyNames3_ES5.ts(5,9): error TS2378: A 'get' accessor must return a value.
 tests/cases/conformance/es6/computedProperties/computedPropertyNames3_ES5.ts(5,9): error TS2464: A computed property name must be of type 'string', 'number', 'symbol', or 'any'.
 tests/cases/conformance/es6/computedProperties/computedPropertyNames3_ES5.ts(5,17): error TS1102: 'delete' cannot be called on an identifier in strict mode.
 tests/cases/conformance/es6/computedProperties/computedPropertyNames3_ES5.ts(6,9): error TS2464: A computed property name must be of type 'string', 'number', 'symbol', or 'any'.
-tests/cases/conformance/es6/computedProperties/computedPropertyNames3_ES5.ts(7,16): error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+tests/cases/conformance/es6/computedProperties/computedPropertyNames3_ES5.ts(7,16): error TS2378: A 'get' accessor must return a value.
 tests/cases/conformance/es6/computedProperties/computedPropertyNames3_ES5.ts(7,16): error TS2464: A computed property name must be of type 'string', 'number', 'symbol', or 'any'.
 
 
@@ -16,7 +16,7 @@ tests/cases/conformance/es6/computedProperties/computedPropertyNames3_ES5.ts(7,1
 !!! error TS2464: A computed property name must be of type 'string', 'number', 'symbol', or 'any'.
         get [delete id]() { }
             ~~~~~~~~~~~
-!!! error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+!!! error TS2378: A 'get' accessor must return a value.
             ~~~~~~~~~~~
 !!! error TS2464: A computed property name must be of type 'string', 'number', 'symbol', or 'any'.
                     ~~
@@ -26,7 +26,7 @@ tests/cases/conformance/es6/computedProperties/computedPropertyNames3_ES5.ts(7,1
 !!! error TS2464: A computed property name must be of type 'string', 'number', 'symbol', or 'any'.
         static get [<String>""]() { }
                    ~~~~~~~~~~~~
-!!! error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+!!! error TS2378: A 'get' accessor must return a value.
                    ~~~~~~~~~~~~
 !!! error TS2464: A computed property name must be of type 'string', 'number', 'symbol', or 'any'.
         static set [id.toString()](v) { }
diff --git a/tests/baselines/reference/computedPropertyNames3_ES6.errors.txt b/tests/baselines/reference/computedPropertyNames3_ES6.errors.txt
index b9009112347..4299437777d 100644
--- a/tests/baselines/reference/computedPropertyNames3_ES6.errors.txt
+++ b/tests/baselines/reference/computedPropertyNames3_ES6.errors.txt
@@ -1,9 +1,9 @@
 tests/cases/conformance/es6/computedProperties/computedPropertyNames3_ES6.ts(4,12): error TS2464: A computed property name must be of type 'string', 'number', 'symbol', or 'any'.
-tests/cases/conformance/es6/computedProperties/computedPropertyNames3_ES6.ts(5,9): error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+tests/cases/conformance/es6/computedProperties/computedPropertyNames3_ES6.ts(5,9): error TS2378: A 'get' accessor must return a value.
 tests/cases/conformance/es6/computedProperties/computedPropertyNames3_ES6.ts(5,9): error TS2464: A computed property name must be of type 'string', 'number', 'symbol', or 'any'.
 tests/cases/conformance/es6/computedProperties/computedPropertyNames3_ES6.ts(5,17): error TS1102: 'delete' cannot be called on an identifier in strict mode.
 tests/cases/conformance/es6/computedProperties/computedPropertyNames3_ES6.ts(6,9): error TS2464: A computed property name must be of type 'string', 'number', 'symbol', or 'any'.
-tests/cases/conformance/es6/computedProperties/computedPropertyNames3_ES6.ts(7,16): error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+tests/cases/conformance/es6/computedProperties/computedPropertyNames3_ES6.ts(7,16): error TS2378: A 'get' accessor must return a value.
 tests/cases/conformance/es6/computedProperties/computedPropertyNames3_ES6.ts(7,16): error TS2464: A computed property name must be of type 'string', 'number', 'symbol', or 'any'.
 
 
@@ -16,7 +16,7 @@ tests/cases/conformance/es6/computedProperties/computedPropertyNames3_ES6.ts(7,1
 !!! error TS2464: A computed property name must be of type 'string', 'number', 'symbol', or 'any'.
         get [delete id]() { }
             ~~~~~~~~~~~
-!!! error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+!!! error TS2378: A 'get' accessor must return a value.
             ~~~~~~~~~~~
 !!! error TS2464: A computed property name must be of type 'string', 'number', 'symbol', or 'any'.
                     ~~
@@ -26,7 +26,7 @@ tests/cases/conformance/es6/computedProperties/computedPropertyNames3_ES6.ts(7,1
 !!! error TS2464: A computed property name must be of type 'string', 'number', 'symbol', or 'any'.
         static get [<String>""]() { }
                    ~~~~~~~~~~~~
-!!! error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+!!! error TS2378: A 'get' accessor must return a value.
                    ~~~~~~~~~~~~
 !!! error TS2464: A computed property name must be of type 'string', 'number', 'symbol', or 'any'.
         static set [id.toString()](v) { }
diff --git a/tests/baselines/reference/conflictingTypeAnnotatedVar.errors.txt b/tests/baselines/reference/conflictingTypeAnnotatedVar.errors.txt
index 0b667108b5f..afae9d40431 100644
--- a/tests/baselines/reference/conflictingTypeAnnotatedVar.errors.txt
+++ b/tests/baselines/reference/conflictingTypeAnnotatedVar.errors.txt
@@ -1,8 +1,8 @@
 tests/cases/compiler/conflictingTypeAnnotatedVar.ts(1,5): error TS2300: Duplicate identifier 'foo'.
 tests/cases/compiler/conflictingTypeAnnotatedVar.ts(2,10): error TS2300: Duplicate identifier 'foo'.
-tests/cases/compiler/conflictingTypeAnnotatedVar.ts(2,17): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement.
+tests/cases/compiler/conflictingTypeAnnotatedVar.ts(2,17): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value.
 tests/cases/compiler/conflictingTypeAnnotatedVar.ts(3,10): error TS2300: Duplicate identifier 'foo'.
-tests/cases/compiler/conflictingTypeAnnotatedVar.ts(3,17): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement.
+tests/cases/compiler/conflictingTypeAnnotatedVar.ts(3,17): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value.
 
 
 ==== tests/cases/compiler/conflictingTypeAnnotatedVar.ts (5 errors) ====
@@ -13,9 +13,9 @@ tests/cases/compiler/conflictingTypeAnnotatedVar.ts(3,17): error TS2355: A funct
              ~~~
 !!! error TS2300: Duplicate identifier 'foo'.
                     ~~~~~~
-!!! error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement.
+!!! error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value.
     function foo(): number { }
              ~~~
 !!! error TS2300: Duplicate identifier 'foo'.
                     ~~~~~~
-!!! error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement.
\ No newline at end of file
+!!! error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value.
\ No newline at end of file
diff --git a/tests/baselines/reference/errorOnContextuallyTypedReturnType.errors.txt b/tests/baselines/reference/errorOnContextuallyTypedReturnType.errors.txt
index 5b66a377307..403e79b8742 100644
--- a/tests/baselines/reference/errorOnContextuallyTypedReturnType.errors.txt
+++ b/tests/baselines/reference/errorOnContextuallyTypedReturnType.errors.txt
@@ -1,6 +1,6 @@
 tests/cases/compiler/errorOnContextuallyTypedReturnType.ts(1,5): error TS2322: Type '() => void' is not assignable to type '() => boolean'.
   Type 'void' is not assignable to type 'boolean'.
-tests/cases/compiler/errorOnContextuallyTypedReturnType.ts(2,37): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement.
+tests/cases/compiler/errorOnContextuallyTypedReturnType.ts(2,37): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value.
 
 
 ==== tests/cases/compiler/errorOnContextuallyTypedReturnType.ts (2 errors) ====
@@ -10,5 +10,5 @@ tests/cases/compiler/errorOnContextuallyTypedReturnType.ts(2,37): error TS2355:
 !!! error TS2322:   Type 'void' is not assignable to type 'boolean'.
     var n2: () => boolean = function ():boolean { }; // expect an error here
                                         ~~~~~~~
-!!! error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement.
+!!! error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value.
     
\ No newline at end of file
diff --git a/tests/baselines/reference/functionImplementationErrors.errors.txt b/tests/baselines/reference/functionImplementationErrors.errors.txt
index 0c74588c316..1ab438e340b 100644
--- a/tests/baselines/reference/functionImplementationErrors.errors.txt
+++ b/tests/baselines/reference/functionImplementationErrors.errors.txt
@@ -2,10 +2,9 @@ tests/cases/conformance/functions/functionImplementationErrors.ts(2,10): error T
 tests/cases/conformance/functions/functionImplementationErrors.ts(6,19): error TS2354: No best common type exists among return expressions.
 tests/cases/conformance/functions/functionImplementationErrors.ts(10,10): error TS2354: No best common type exists among return expressions.
 tests/cases/conformance/functions/functionImplementationErrors.ts(16,10): error TS2354: No best common type exists among return expressions.
-tests/cases/conformance/functions/functionImplementationErrors.ts(25,16): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement.
+tests/cases/conformance/functions/functionImplementationErrors.ts(25,16): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value.
 tests/cases/conformance/functions/functionImplementationErrors.ts(30,17): error TS2373: Initializer of parameter 'n' cannot reference identifier 'm' declared after it.
 tests/cases/conformance/functions/functionImplementationErrors.ts(35,17): error TS2373: Initializer of parameter 'n' cannot reference identifier 'm' declared after it.
-tests/cases/conformance/functions/functionImplementationErrors.ts(40,28): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement.
 tests/cases/conformance/functions/functionImplementationErrors.ts(49,10): error TS2354: No best common type exists among return expressions.
 tests/cases/conformance/functions/functionImplementationErrors.ts(53,10): error TS2354: No best common type exists among return expressions.
 tests/cases/conformance/functions/functionImplementationErrors.ts(57,11): error TS2354: No best common type exists among return expressions.
@@ -14,7 +13,7 @@ tests/cases/conformance/functions/functionImplementationErrors.ts(65,11): error
 tests/cases/conformance/functions/functionImplementationErrors.ts(69,11): error TS2354: No best common type exists among return expressions.
 
 
-==== tests/cases/conformance/functions/functionImplementationErrors.ts (14 errors) ====
+==== tests/cases/conformance/functions/functionImplementationErrors.ts (13 errors) ====
     // FunctionExpression with no return type annotation with multiple return statements with unrelated types
     var f1 = function () {
              ~~~~~~~~
@@ -52,7 +51,7 @@ tests/cases/conformance/functions/functionImplementationErrors.ts(69,11): error
     // Function implemetnation with non -void return type annotation with no return
     function f5(): number {
                    ~~~~~~
-!!! error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement.
+!!! error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value.
     }
     
     var m;
@@ -72,8 +71,6 @@ tests/cases/conformance/functions/functionImplementationErrors.ts(69,11): error
     // FunctionExpression with non -void return type annotation with a throw, no return, and other code
     // Should be error but isn't
     undefined === function (): number {
-                               ~~~~~~
-!!! error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement.
         throw undefined;
         var x = 4;
     };
diff --git a/tests/baselines/reference/functionWithThrowButNoReturn1.errors.txt b/tests/baselines/reference/functionWithThrowButNoReturn1.errors.txt
deleted file mode 100644
index 72f45da8d97..00000000000
--- a/tests/baselines/reference/functionWithThrowButNoReturn1.errors.txt
+++ /dev/null
@@ -1,11 +0,0 @@
-tests/cases/compiler/functionWithThrowButNoReturn1.ts(1,16): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement.
-
-
-==== tests/cases/compiler/functionWithThrowButNoReturn1.ts (1 errors) ====
-    function fn(): number {
-                   ~~~~~~
-!!! error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement.
-      throw new Error('NYI');
-      var t;
-    }
-    
\ No newline at end of file
diff --git a/tests/baselines/reference/functionWithThrowButNoReturn1.symbols b/tests/baselines/reference/functionWithThrowButNoReturn1.symbols
new file mode 100644
index 00000000000..7dde523701d
--- /dev/null
+++ b/tests/baselines/reference/functionWithThrowButNoReturn1.symbols
@@ -0,0 +1,11 @@
+=== tests/cases/compiler/functionWithThrowButNoReturn1.ts ===
+function fn(): number {
+>fn : Symbol(fn, Decl(functionWithThrowButNoReturn1.ts, 0, 0))
+
+  throw new Error('NYI');
+>Error : Symbol(Error, Decl(lib.d.ts, 876, 38), Decl(lib.d.ts, 889, 11))
+
+  var t;
+>t : Symbol(t, Decl(functionWithThrowButNoReturn1.ts, 2, 5))
+}
+
diff --git a/tests/baselines/reference/functionWithThrowButNoReturn1.types b/tests/baselines/reference/functionWithThrowButNoReturn1.types
new file mode 100644
index 00000000000..c136d8a4076
--- /dev/null
+++ b/tests/baselines/reference/functionWithThrowButNoReturn1.types
@@ -0,0 +1,13 @@
+=== tests/cases/compiler/functionWithThrowButNoReturn1.ts ===
+function fn(): number {
+>fn : () => number
+
+  throw new Error('NYI');
+>new Error('NYI') : Error
+>Error : ErrorConstructor
+>'NYI' : string
+
+  var t;
+>t : any
+}
+
diff --git a/tests/baselines/reference/functionsMissingReturnStatementsAndExpressions.errors.txt b/tests/baselines/reference/functionsMissingReturnStatementsAndExpressions.errors.txt
index 2c5ff15f863..88b0c8d5e14 100644
--- a/tests/baselines/reference/functionsMissingReturnStatementsAndExpressions.errors.txt
+++ b/tests/baselines/reference/functionsMissingReturnStatementsAndExpressions.errors.txt
@@ -1,15 +1,13 @@
-tests/cases/compiler/functionsMissingReturnStatementsAndExpressions.ts(2,16): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement.
-tests/cases/compiler/functionsMissingReturnStatementsAndExpressions.ts(64,17): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement.
-tests/cases/compiler/functionsMissingReturnStatementsAndExpressions.ts(94,16): error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
-tests/cases/compiler/functionsMissingReturnStatementsAndExpressions.ts(112,16): error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+tests/cases/compiler/functionsMissingReturnStatementsAndExpressions.ts(2,16): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value.
+tests/cases/compiler/functionsMissingReturnStatementsAndExpressions.ts(94,16): error TS2378: A 'get' accessor must return a value.
 tests/cases/compiler/functionsMissingReturnStatementsAndExpressions.ts(117,5): error TS1003: Identifier expected.
 
 
-==== tests/cases/compiler/functionsMissingReturnStatementsAndExpressions.ts (5 errors) ====
+==== tests/cases/compiler/functionsMissingReturnStatementsAndExpressions.ts (3 errors) ====
     
     function f1(): string {
                    ~~~~~~
-!!! error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement.
+!!! error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value.
         // errors because there are no return statements
     }
     
@@ -72,8 +70,6 @@ tests/cases/compiler/functionsMissingReturnStatementsAndExpressions.ts(117,5): e
     }
     
     function f14(): number {
-                    ~~~~~~
-!!! error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement.
         // Not fine, since we can *only* consist of a single throw statement
         // if no return statements are present but we are annotated.
         throw undefined;
@@ -105,7 +101,7 @@ tests/cases/compiler/functionsMissingReturnStatementsAndExpressions.ts(117,5): e
     class C {
         public get m1() {
                    ~~
-!!! error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+!!! error TS2378: A 'get' accessor must return a value.
             // Errors; get accessors must return a value.
         }
     
@@ -124,8 +120,6 @@ tests/cases/compiler/functionsMissingReturnStatementsAndExpressions.ts(117,5): e
         }
     
         public get m5() {
-                   ~~
-!!! error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
             // Not fine, since we can *only* consist of a single throw statement
             // if no return statements are present but we are a get accessor.
             throw null;
diff --git a/tests/baselines/reference/getterMissingReturnError.errors.txt b/tests/baselines/reference/getterMissingReturnError.errors.txt
index 8900cc5e78f..e504de07ef4 100644
--- a/tests/baselines/reference/getterMissingReturnError.errors.txt
+++ b/tests/baselines/reference/getterMissingReturnError.errors.txt
@@ -1,5 +1,5 @@
 tests/cases/compiler/getterMissingReturnError.ts(2,16): error TS1056: Accessors are only available when targeting ECMAScript 5 and higher.
-tests/cases/compiler/getterMissingReturnError.ts(2,16): error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+tests/cases/compiler/getterMissingReturnError.ts(2,16): error TS2378: A 'get' accessor must return a value.
 
 
 ==== tests/cases/compiler/getterMissingReturnError.ts (2 errors) ====
@@ -8,7 +8,7 @@ tests/cases/compiler/getterMissingReturnError.ts(2,16): error TS2378: A 'get' ac
                    ~~
 !!! error TS1056: Accessors are only available when targeting ECMAScript 5 and higher.
                    ~~
-!!! error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+!!! error TS2378: A 'get' accessor must return a value.
     
         }
     }
diff --git a/tests/baselines/reference/invalidReturnStatements.errors.txt b/tests/baselines/reference/invalidReturnStatements.errors.txt
index 780166e07c2..6fbe961cd54 100644
--- a/tests/baselines/reference/invalidReturnStatements.errors.txt
+++ b/tests/baselines/reference/invalidReturnStatements.errors.txt
@@ -1,7 +1,7 @@
-tests/cases/conformance/statements/returnStatements/invalidReturnStatements.ts(2,17): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement.
-tests/cases/conformance/statements/returnStatements/invalidReturnStatements.ts(3,17): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement.
-tests/cases/conformance/statements/returnStatements/invalidReturnStatements.ts(4,17): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement.
-tests/cases/conformance/statements/returnStatements/invalidReturnStatements.ts(5,17): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement.
+tests/cases/conformance/statements/returnStatements/invalidReturnStatements.ts(2,17): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value.
+tests/cases/conformance/statements/returnStatements/invalidReturnStatements.ts(3,17): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value.
+tests/cases/conformance/statements/returnStatements/invalidReturnStatements.ts(4,17): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value.
+tests/cases/conformance/statements/returnStatements/invalidReturnStatements.ts(5,17): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value.
 tests/cases/conformance/statements/returnStatements/invalidReturnStatements.ts(16,29): error TS2322: Type '{ id: number; }' is not assignable to type 'D'.
   Property 'name' is missing in type '{ id: number; }'.
 tests/cases/conformance/statements/returnStatements/invalidReturnStatements.ts(18,29): error TS2322: Type 'C' is not assignable to type 'D'.
@@ -12,16 +12,16 @@ tests/cases/conformance/statements/returnStatements/invalidReturnStatements.ts(1
     // all the following should be error
     function fn1(): number {  }
                     ~~~~~~
-!!! error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement.
+!!! error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value.
     function fn2(): string { }
                     ~~~~~~
-!!! error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement.
+!!! error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value.
     function fn3(): boolean { }
                     ~~~~~~~
-!!! error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement.
+!!! error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value.
     function fn4(): Date {  }
                     ~~~~
-!!! error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement.
+!!! error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value.
     function fn7(): any {  } // should be valid: any includes void
     
     interface I { id: number }
diff --git a/tests/baselines/reference/methodInAmbientClass1.errors.txt b/tests/baselines/reference/methodInAmbientClass1.errors.txt
index 05183378a85..7032d715629 100644
--- a/tests/baselines/reference/methodInAmbientClass1.errors.txt
+++ b/tests/baselines/reference/methodInAmbientClass1.errors.txt
@@ -1,4 +1,4 @@
-tests/cases/compiler/methodInAmbientClass1.ts(2,12): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement.
+tests/cases/compiler/methodInAmbientClass1.ts(2,12): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value.
 tests/cases/compiler/methodInAmbientClass1.ts(2,20): error TS1184: An implementation cannot be declared in ambient contexts.
 
 
@@ -6,7 +6,7 @@ tests/cases/compiler/methodInAmbientClass1.ts(2,20): error TS1184: An implementa
         declare class Foo {
         	fn(): boolean {
         	      ~~~~~~~
-!!! error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement.
+!!! error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value.
         	              ~
 !!! error TS1184: An implementation cannot be declared in ambient contexts.
         	}
diff --git a/tests/baselines/reference/missingReturnStatement.errors.txt b/tests/baselines/reference/missingReturnStatement.errors.txt
index c7cedd793de..8926d22be3d 100644
--- a/tests/baselines/reference/missingReturnStatement.errors.txt
+++ b/tests/baselines/reference/missingReturnStatement.errors.txt
@@ -1,4 +1,4 @@
-tests/cases/compiler/missingReturnStatement.ts(3,22): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement.
+tests/cases/compiler/missingReturnStatement.ts(3,22): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value.
 
 
 ==== tests/cases/compiler/missingReturnStatement.ts (1 errors) ====
@@ -6,7 +6,7 @@ tests/cases/compiler/missingReturnStatement.ts(3,22): error TS2355: A function w
         export class Bug {
             public foo():string {
                          ~~~~~~
-!!! error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement.
+!!! error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value.
             }
         }    
     }
diff --git a/tests/baselines/reference/missingReturnStatement1.errors.txt b/tests/baselines/reference/missingReturnStatement1.errors.txt
index de471f90ac4..9d3cf78411e 100644
--- a/tests/baselines/reference/missingReturnStatement1.errors.txt
+++ b/tests/baselines/reference/missingReturnStatement1.errors.txt
@@ -1,11 +1,11 @@
-tests/cases/compiler/missingReturnStatement1.ts(2,12): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement.
+tests/cases/compiler/missingReturnStatement1.ts(2,12): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value.
 
 
 ==== tests/cases/compiler/missingReturnStatement1.ts (1 errors) ====
     class Foo {
         foo(): number {
                ~~~~~~
-!!! error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement.
+!!! error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value.
             //return 4;
         }
     }
diff --git a/tests/baselines/reference/multiLineErrors.errors.txt b/tests/baselines/reference/multiLineErrors.errors.txt
index 23a6278b4fb..70366aeabed 100644
--- a/tests/baselines/reference/multiLineErrors.errors.txt
+++ b/tests/baselines/reference/multiLineErrors.errors.txt
@@ -1,4 +1,4 @@
-tests/cases/compiler/multiLineErrors.ts(3,22): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement.
+tests/cases/compiler/multiLineErrors.ts(3,22): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value.
 tests/cases/compiler/multiLineErrors.ts(21,1): error TS2322: Type 'A2' is not assignable to type 'A1'.
   Types of property 'x' are incompatible.
     Type '{ y: string; }' is not assignable to type '{ y: number; }'.
@@ -17,7 +17,7 @@ tests/cases/compiler/multiLineErrors.ts(21,1): error TS2322: Type 'A2' is not as
     ~~~~~~~~~~~~~~
     }
     ~
-!!! error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement.
+!!! error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value.
     {
         var x = 4;
         var y = 10;
diff --git a/tests/baselines/reference/objectLiteralMemberWithModifiers2.errors.txt b/tests/baselines/reference/objectLiteralMemberWithModifiers2.errors.txt
index e939725ea6e..be2bea5e241 100644
--- a/tests/baselines/reference/objectLiteralMemberWithModifiers2.errors.txt
+++ b/tests/baselines/reference/objectLiteralMemberWithModifiers2.errors.txt
@@ -1,5 +1,5 @@
 tests/cases/compiler/objectLiteralMemberWithModifiers2.ts(1,22): error TS1056: Accessors are only available when targeting ECMAScript 5 and higher.
-tests/cases/compiler/objectLiteralMemberWithModifiers2.ts(1,22): error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+tests/cases/compiler/objectLiteralMemberWithModifiers2.ts(1,22): error TS2378: A 'get' accessor must return a value.
 
 
 ==== tests/cases/compiler/objectLiteralMemberWithModifiers2.ts (2 errors) ====
@@ -7,4 +7,4 @@ tests/cases/compiler/objectLiteralMemberWithModifiers2.ts(1,22): error TS2378: A
                          ~~~
 !!! error TS1056: Accessors are only available when targeting ECMAScript 5 and higher.
                          ~~~
-!!! error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
\ No newline at end of file
+!!! error TS2378: A 'get' accessor must return a value.
\ No newline at end of file
diff --git a/tests/baselines/reference/objectLiteralWithSemicolons5.errors.txt b/tests/baselines/reference/objectLiteralWithSemicolons5.errors.txt
index 7373c3d535d..5a24f29252c 100644
--- a/tests/baselines/reference/objectLiteralWithSemicolons5.errors.txt
+++ b/tests/baselines/reference/objectLiteralWithSemicolons5.errors.txt
@@ -1,7 +1,7 @@
 tests/cases/compiler/objectLiteralWithSemicolons5.ts(1,20): error TS1005: ',' expected.
 tests/cases/compiler/objectLiteralWithSemicolons5.ts(1,25): error TS2304: Cannot find name 'b'.
 tests/cases/compiler/objectLiteralWithSemicolons5.ts(1,26): error TS1005: ',' expected.
-tests/cases/compiler/objectLiteralWithSemicolons5.ts(1,32): error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+tests/cases/compiler/objectLiteralWithSemicolons5.ts(1,32): error TS2378: A 'get' accessor must return a value.
 tests/cases/compiler/objectLiteralWithSemicolons5.ts(1,41): error TS1005: ',' expected.
 
 
@@ -14,6 +14,6 @@ tests/cases/compiler/objectLiteralWithSemicolons5.ts(1,41): error TS1005: ',' ex
                              ~
 !!! error TS1005: ',' expected.
                                    ~~~
-!!! error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+!!! error TS2378: A 'get' accessor must return a value.
                                             ~
 !!! error TS1005: ',' expected.
\ No newline at end of file
diff --git a/tests/baselines/reference/parserAccessors1.errors.txt b/tests/baselines/reference/parserAccessors1.errors.txt
index 8c5033da0c4..2ef8d4e37ab 100644
--- a/tests/baselines/reference/parserAccessors1.errors.txt
+++ b/tests/baselines/reference/parserAccessors1.errors.txt
@@ -1,9 +1,9 @@
-tests/cases/conformance/parser/ecmascript5/Accessors/parserAccessors1.ts(2,9): error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+tests/cases/conformance/parser/ecmascript5/Accessors/parserAccessors1.ts(2,9): error TS2378: A 'get' accessor must return a value.
 
 
 ==== tests/cases/conformance/parser/ecmascript5/Accessors/parserAccessors1.ts (1 errors) ====
     class C {
         get Foo() { }
             ~~~
-!!! error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+!!! error TS2378: A 'get' accessor must return a value.
     }
\ No newline at end of file
diff --git a/tests/baselines/reference/parserAccessors10.errors.txt b/tests/baselines/reference/parserAccessors10.errors.txt
index a5228f47443..d6a2b99eaca 100644
--- a/tests/baselines/reference/parserAccessors10.errors.txt
+++ b/tests/baselines/reference/parserAccessors10.errors.txt
@@ -1,9 +1,9 @@
-tests/cases/conformance/parser/ecmascript5/Accessors/parserAccessors10.ts(2,14): error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+tests/cases/conformance/parser/ecmascript5/Accessors/parserAccessors10.ts(2,14): error TS2378: A 'get' accessor must return a value.
 
 
 ==== tests/cases/conformance/parser/ecmascript5/Accessors/parserAccessors10.ts (1 errors) ====
     var v = {
       public get foo() { }
                  ~~~
-!!! error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+!!! error TS2378: A 'get' accessor must return a value.
     };
\ No newline at end of file
diff --git a/tests/baselines/reference/parserAccessors3.errors.txt b/tests/baselines/reference/parserAccessors3.errors.txt
index 2987b606451..5411cd544eb 100644
--- a/tests/baselines/reference/parserAccessors3.errors.txt
+++ b/tests/baselines/reference/parserAccessors3.errors.txt
@@ -1,7 +1,7 @@
-tests/cases/conformance/parser/ecmascript5/Accessors/parserAccessors3.ts(1,15): error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+tests/cases/conformance/parser/ecmascript5/Accessors/parserAccessors3.ts(1,15): error TS2378: A 'get' accessor must return a value.
 
 
 ==== tests/cases/conformance/parser/ecmascript5/Accessors/parserAccessors3.ts (1 errors) ====
     var v = { get Foo() { } };
                   ~~~
-!!! error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
\ No newline at end of file
+!!! error TS2378: A 'get' accessor must return a value.
\ No newline at end of file
diff --git a/tests/baselines/reference/parserAccessors7.errors.txt b/tests/baselines/reference/parserAccessors7.errors.txt
index 857833a7673..3938280e6d5 100644
--- a/tests/baselines/reference/parserAccessors7.errors.txt
+++ b/tests/baselines/reference/parserAccessors7.errors.txt
@@ -1,5 +1,5 @@
 tests/cases/conformance/parser/ecmascript5/Accessors/parserAccessors7.ts(1,15): error TS1054: A 'get' accessor cannot have parameters.
-tests/cases/conformance/parser/ecmascript5/Accessors/parserAccessors7.ts(1,15): error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+tests/cases/conformance/parser/ecmascript5/Accessors/parserAccessors7.ts(1,15): error TS2378: A 'get' accessor must return a value.
 
 
 ==== tests/cases/conformance/parser/ecmascript5/Accessors/parserAccessors7.ts (2 errors) ====
@@ -7,4 +7,4 @@ tests/cases/conformance/parser/ecmascript5/Accessors/parserAccessors7.ts(1,15):
                   ~~~
 !!! error TS1054: A 'get' accessor cannot have parameters.
                   ~~~
-!!! error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
\ No newline at end of file
+!!! error TS2378: A 'get' accessor must return a value.
\ No newline at end of file
diff --git a/tests/baselines/reference/parserComputedPropertyName4.errors.txt b/tests/baselines/reference/parserComputedPropertyName4.errors.txt
index bfc78b162fd..3430e75b82f 100644
--- a/tests/baselines/reference/parserComputedPropertyName4.errors.txt
+++ b/tests/baselines/reference/parserComputedPropertyName4.errors.txt
@@ -1,10 +1,10 @@
-tests/cases/conformance/parser/ecmascript6/ComputedPropertyNames/parserComputedPropertyName4.ts(1,15): error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+tests/cases/conformance/parser/ecmascript6/ComputedPropertyNames/parserComputedPropertyName4.ts(1,15): error TS2378: A 'get' accessor must return a value.
 tests/cases/conformance/parser/ecmascript6/ComputedPropertyNames/parserComputedPropertyName4.ts(1,16): error TS2304: Cannot find name 'e'.
 
 
 ==== tests/cases/conformance/parser/ecmascript6/ComputedPropertyNames/parserComputedPropertyName4.ts (2 errors) ====
     var v = { get [e]() { } };
                   ~~~
-!!! error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+!!! error TS2378: A 'get' accessor must return a value.
                    ~
 !!! error TS2304: Cannot find name 'e'.
\ No newline at end of file
diff --git a/tests/baselines/reference/parserComputedPropertyName5.errors.txt b/tests/baselines/reference/parserComputedPropertyName5.errors.txt
index 07cc6f3a9f0..09c38ecbef5 100644
--- a/tests/baselines/reference/parserComputedPropertyName5.errors.txt
+++ b/tests/baselines/reference/parserComputedPropertyName5.errors.txt
@@ -1,10 +1,10 @@
-tests/cases/conformance/parser/ecmascript6/ComputedPropertyNames/parserComputedPropertyName5.ts(1,22): error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+tests/cases/conformance/parser/ecmascript6/ComputedPropertyNames/parserComputedPropertyName5.ts(1,22): error TS2378: A 'get' accessor must return a value.
 tests/cases/conformance/parser/ecmascript6/ComputedPropertyNames/parserComputedPropertyName5.ts(1,23): error TS2304: Cannot find name 'e'.
 
 
 ==== tests/cases/conformance/parser/ecmascript6/ComputedPropertyNames/parserComputedPropertyName5.ts (2 errors) ====
     var v = { public get [e]() { } };
                          ~~~
-!!! error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+!!! error TS2378: A 'get' accessor must return a value.
                           ~
 !!! error TS2304: Cannot find name 'e'.
\ No newline at end of file
diff --git a/tests/baselines/reference/parserES3Accessors1.errors.txt b/tests/baselines/reference/parserES3Accessors1.errors.txt
index 5e2ca9f97bc..9c6dbf0e76f 100644
--- a/tests/baselines/reference/parserES3Accessors1.errors.txt
+++ b/tests/baselines/reference/parserES3Accessors1.errors.txt
@@ -1,5 +1,5 @@
 tests/cases/conformance/parser/ecmascript3/Accessors/parserES3Accessors1.ts(2,9): error TS1056: Accessors are only available when targeting ECMAScript 5 and higher.
-tests/cases/conformance/parser/ecmascript3/Accessors/parserES3Accessors1.ts(2,9): error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+tests/cases/conformance/parser/ecmascript3/Accessors/parserES3Accessors1.ts(2,9): error TS2378: A 'get' accessor must return a value.
 
 
 ==== tests/cases/conformance/parser/ecmascript3/Accessors/parserES3Accessors1.ts (2 errors) ====
@@ -8,5 +8,5 @@ tests/cases/conformance/parser/ecmascript3/Accessors/parserES3Accessors1.ts(2,9)
             ~~~
 !!! error TS1056: Accessors are only available when targeting ECMAScript 5 and higher.
             ~~~
-!!! error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+!!! error TS2378: A 'get' accessor must return a value.
     }
\ No newline at end of file
diff --git a/tests/baselines/reference/parserES3Accessors3.errors.txt b/tests/baselines/reference/parserES3Accessors3.errors.txt
index 6d262e2a855..70ab3f2072e 100644
--- a/tests/baselines/reference/parserES3Accessors3.errors.txt
+++ b/tests/baselines/reference/parserES3Accessors3.errors.txt
@@ -1,5 +1,5 @@
 tests/cases/conformance/parser/ecmascript3/Accessors/parserES3Accessors3.ts(1,15): error TS1056: Accessors are only available when targeting ECMAScript 5 and higher.
-tests/cases/conformance/parser/ecmascript3/Accessors/parserES3Accessors3.ts(1,15): error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+tests/cases/conformance/parser/ecmascript3/Accessors/parserES3Accessors3.ts(1,15): error TS2378: A 'get' accessor must return a value.
 
 
 ==== tests/cases/conformance/parser/ecmascript3/Accessors/parserES3Accessors3.ts (2 errors) ====
@@ -7,4 +7,4 @@ tests/cases/conformance/parser/ecmascript3/Accessors/parserES3Accessors3.ts(1,15
                   ~~~
 !!! error TS1056: Accessors are only available when targeting ECMAScript 5 and higher.
                   ~~~
-!!! error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
\ No newline at end of file
+!!! error TS2378: A 'get' accessor must return a value.
\ No newline at end of file
diff --git a/tests/baselines/reference/parserES5ComputedPropertyName4.errors.txt b/tests/baselines/reference/parserES5ComputedPropertyName4.errors.txt
index cfb12152c94..854bb364842 100644
--- a/tests/baselines/reference/parserES5ComputedPropertyName4.errors.txt
+++ b/tests/baselines/reference/parserES5ComputedPropertyName4.errors.txt
@@ -1,10 +1,10 @@
-tests/cases/conformance/parser/ecmascript5/ComputedPropertyNames/parserES5ComputedPropertyName4.ts(1,15): error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+tests/cases/conformance/parser/ecmascript5/ComputedPropertyNames/parserES5ComputedPropertyName4.ts(1,15): error TS2378: A 'get' accessor must return a value.
 tests/cases/conformance/parser/ecmascript5/ComputedPropertyNames/parserES5ComputedPropertyName4.ts(1,16): error TS2304: Cannot find name 'e'.
 
 
 ==== tests/cases/conformance/parser/ecmascript5/ComputedPropertyNames/parserES5ComputedPropertyName4.ts (2 errors) ====
     var v = { get [e]() { } };
                   ~~~
-!!! error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+!!! error TS2378: A 'get' accessor must return a value.
                    ~
 !!! error TS2304: Cannot find name 'e'.
\ No newline at end of file
diff --git a/tests/baselines/reference/parserErrorRecovery_Block3.errors.txt b/tests/baselines/reference/parserErrorRecovery_Block3.errors.txt
index 9d391e39007..e6033d05215 100644
--- a/tests/baselines/reference/parserErrorRecovery_Block3.errors.txt
+++ b/tests/baselines/reference/parserErrorRecovery_Block3.errors.txt
@@ -1,18 +1,18 @@
-tests/cases/conformance/parser/ecmascript5/ErrorRecovery/Blocks/parserErrorRecovery_Block3.ts(2,18): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement.
+tests/cases/conformance/parser/ecmascript5/ErrorRecovery/Blocks/parserErrorRecovery_Block3.ts(2,18): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value.
 tests/cases/conformance/parser/ecmascript5/ErrorRecovery/Blocks/parserErrorRecovery_Block3.ts(4,5): error TS1128: Declaration or statement expected.
-tests/cases/conformance/parser/ecmascript5/ErrorRecovery/Blocks/parserErrorRecovery_Block3.ts(4,18): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement.
+tests/cases/conformance/parser/ecmascript5/ErrorRecovery/Blocks/parserErrorRecovery_Block3.ts(4,18): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value.
 
 
 ==== tests/cases/conformance/parser/ecmascript5/ErrorRecovery/Blocks/parserErrorRecovery_Block3.ts (3 errors) ====
     class C  {
         private a(): boolean {
                      ~~~~~~~
-!!! error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement.
+!!! error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value.
     
         private b(): boolean {
         ~~~~~~~
 !!! error TS1128: Declaration or statement expected.
                      ~~~~~~~
-!!! error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement.
+!!! error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value.
         }
     }
\ No newline at end of file
diff --git a/tests/baselines/reference/parserGetAccessorWithTypeParameters1.errors.txt b/tests/baselines/reference/parserGetAccessorWithTypeParameters1.errors.txt
index 0cf731cb516..09502f6b888 100644
--- a/tests/baselines/reference/parserGetAccessorWithTypeParameters1.errors.txt
+++ b/tests/baselines/reference/parserGetAccessorWithTypeParameters1.errors.txt
@@ -1,5 +1,5 @@
 tests/cases/conformance/parser/ecmascript5/Accessors/parserGetAccessorWithTypeParameters1.ts(2,7): error TS1094: An accessor cannot have type parameters.
-tests/cases/conformance/parser/ecmascript5/Accessors/parserGetAccessorWithTypeParameters1.ts(2,7): error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+tests/cases/conformance/parser/ecmascript5/Accessors/parserGetAccessorWithTypeParameters1.ts(2,7): error TS2378: A 'get' accessor must return a value.
 
 
 ==== tests/cases/conformance/parser/ecmascript5/Accessors/parserGetAccessorWithTypeParameters1.ts (2 errors) ====
@@ -8,5 +8,5 @@ tests/cases/conformance/parser/ecmascript5/Accessors/parserGetAccessorWithTypePa
           ~~~
 !!! error TS1094: An accessor cannot have type parameters.
           ~~~
-!!! error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+!!! error TS2378: A 'get' accessor must return a value.
     }
\ No newline at end of file
diff --git a/tests/baselines/reference/parserMemberAccessor1.errors.txt b/tests/baselines/reference/parserMemberAccessor1.errors.txt
index aa7cdcdafa3..2a3fd7d7028 100644
--- a/tests/baselines/reference/parserMemberAccessor1.errors.txt
+++ b/tests/baselines/reference/parserMemberAccessor1.errors.txt
@@ -1,10 +1,10 @@
-tests/cases/conformance/parser/ecmascript5/MemberAccessorDeclarations/parserMemberAccessor1.ts(2,7): error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+tests/cases/conformance/parser/ecmascript5/MemberAccessorDeclarations/parserMemberAccessor1.ts(2,7): error TS2378: A 'get' accessor must return a value.
 
 
 ==== tests/cases/conformance/parser/ecmascript5/MemberAccessorDeclarations/parserMemberAccessor1.ts (1 errors) ====
     class C {
       get foo() { }
           ~~~
-!!! error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+!!! error TS2378: A 'get' accessor must return a value.
       set foo(a) { }
     }
\ No newline at end of file
diff --git a/tests/baselines/reference/parserMemberAccessorDeclaration1.errors.txt b/tests/baselines/reference/parserMemberAccessorDeclaration1.errors.txt
index ac96e7d94b7..c2db31a5398 100644
--- a/tests/baselines/reference/parserMemberAccessorDeclaration1.errors.txt
+++ b/tests/baselines/reference/parserMemberAccessorDeclaration1.errors.txt
@@ -1,9 +1,9 @@
-tests/cases/conformance/parser/ecmascript5/MemberAccessorDeclarations/parserMemberAccessorDeclaration1.ts(2,7): error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+tests/cases/conformance/parser/ecmascript5/MemberAccessorDeclarations/parserMemberAccessorDeclaration1.ts(2,7): error TS2378: A 'get' accessor must return a value.
 
 
 ==== tests/cases/conformance/parser/ecmascript5/MemberAccessorDeclarations/parserMemberAccessorDeclaration1.ts (1 errors) ====
     class C {
       get a() { }
           ~
-!!! error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+!!! error TS2378: A 'get' accessor must return a value.
     }
\ No newline at end of file
diff --git a/tests/baselines/reference/parserMemberAccessorDeclaration10.errors.txt b/tests/baselines/reference/parserMemberAccessorDeclaration10.errors.txt
index 9a04674d6d7..ece110db165 100644
--- a/tests/baselines/reference/parserMemberAccessorDeclaration10.errors.txt
+++ b/tests/baselines/reference/parserMemberAccessorDeclaration10.errors.txt
@@ -1,5 +1,5 @@
 tests/cases/conformance/parser/ecmascript5/MemberAccessorDeclarations/parserMemberAccessorDeclaration10.ts(2,5): error TS1031: 'export' modifier cannot appear on a class element.
-tests/cases/conformance/parser/ecmascript5/MemberAccessorDeclarations/parserMemberAccessorDeclaration10.ts(2,16): error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+tests/cases/conformance/parser/ecmascript5/MemberAccessorDeclarations/parserMemberAccessorDeclaration10.ts(2,16): error TS2378: A 'get' accessor must return a value.
 
 
 ==== tests/cases/conformance/parser/ecmascript5/MemberAccessorDeclarations/parserMemberAccessorDeclaration10.ts (2 errors) ====
@@ -8,5 +8,5 @@ tests/cases/conformance/parser/ecmascript5/MemberAccessorDeclarations/parserMemb
         ~~~~~~
 !!! error TS1031: 'export' modifier cannot appear on a class element.
                    ~~~
-!!! error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+!!! error TS2378: A 'get' accessor must return a value.
     }
\ No newline at end of file
diff --git a/tests/baselines/reference/parserMemberAccessorDeclaration12.errors.txt b/tests/baselines/reference/parserMemberAccessorDeclaration12.errors.txt
index 0d14a2adab8..a4ea29518d1 100644
--- a/tests/baselines/reference/parserMemberAccessorDeclaration12.errors.txt
+++ b/tests/baselines/reference/parserMemberAccessorDeclaration12.errors.txt
@@ -1,5 +1,5 @@
 tests/cases/conformance/parser/ecmascript5/MemberAccessorDeclarations/parserMemberAccessorDeclaration12.ts(2,8): error TS1054: A 'get' accessor cannot have parameters.
-tests/cases/conformance/parser/ecmascript5/MemberAccessorDeclarations/parserMemberAccessorDeclaration12.ts(2,8): error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+tests/cases/conformance/parser/ecmascript5/MemberAccessorDeclarations/parserMemberAccessorDeclaration12.ts(2,8): error TS2378: A 'get' accessor must return a value.
 
 
 ==== tests/cases/conformance/parser/ecmascript5/MemberAccessorDeclarations/parserMemberAccessorDeclaration12.ts (2 errors) ====
@@ -8,5 +8,5 @@ tests/cases/conformance/parser/ecmascript5/MemberAccessorDeclarations/parserMemb
            ~~~
 !!! error TS1054: A 'get' accessor cannot have parameters.
            ~~~
-!!! error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+!!! error TS2378: A 'get' accessor must return a value.
     }
\ No newline at end of file
diff --git a/tests/baselines/reference/parserMemberAccessorDeclaration2.errors.txt b/tests/baselines/reference/parserMemberAccessorDeclaration2.errors.txt
index 69e87dff659..7b66bee844f 100644
--- a/tests/baselines/reference/parserMemberAccessorDeclaration2.errors.txt
+++ b/tests/baselines/reference/parserMemberAccessorDeclaration2.errors.txt
@@ -1,9 +1,9 @@
-tests/cases/conformance/parser/ecmascript5/MemberAccessorDeclarations/parserMemberAccessorDeclaration2.ts(2,7): error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+tests/cases/conformance/parser/ecmascript5/MemberAccessorDeclarations/parserMemberAccessorDeclaration2.ts(2,7): error TS2378: A 'get' accessor must return a value.
 
 
 ==== tests/cases/conformance/parser/ecmascript5/MemberAccessorDeclarations/parserMemberAccessorDeclaration2.ts (1 errors) ====
     class C {
       get "b"() { }
           ~~~
-!!! error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+!!! error TS2378: A 'get' accessor must return a value.
     }
\ No newline at end of file
diff --git a/tests/baselines/reference/parserMemberAccessorDeclaration3.errors.txt b/tests/baselines/reference/parserMemberAccessorDeclaration3.errors.txt
index 93a1a5d14e1..a37fe230f76 100644
--- a/tests/baselines/reference/parserMemberAccessorDeclaration3.errors.txt
+++ b/tests/baselines/reference/parserMemberAccessorDeclaration3.errors.txt
@@ -1,9 +1,9 @@
-tests/cases/conformance/parser/ecmascript5/MemberAccessorDeclarations/parserMemberAccessorDeclaration3.ts(2,7): error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+tests/cases/conformance/parser/ecmascript5/MemberAccessorDeclarations/parserMemberAccessorDeclaration3.ts(2,7): error TS2378: A 'get' accessor must return a value.
 
 
 ==== tests/cases/conformance/parser/ecmascript5/MemberAccessorDeclarations/parserMemberAccessorDeclaration3.ts (1 errors) ====
     class C {
       get 0() { }
           ~
-!!! error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+!!! error TS2378: A 'get' accessor must return a value.
     }
\ No newline at end of file
diff --git a/tests/baselines/reference/parserMemberAccessorDeclaration7.errors.txt b/tests/baselines/reference/parserMemberAccessorDeclaration7.errors.txt
index b7f67da49b7..2b0bd40a4f2 100644
--- a/tests/baselines/reference/parserMemberAccessorDeclaration7.errors.txt
+++ b/tests/baselines/reference/parserMemberAccessorDeclaration7.errors.txt
@@ -1,5 +1,5 @@
 tests/cases/conformance/parser/ecmascript5/MemberAccessorDeclarations/parserMemberAccessorDeclaration7.ts(2,12): error TS1028: Accessibility modifier already seen.
-tests/cases/conformance/parser/ecmascript5/MemberAccessorDeclarations/parserMemberAccessorDeclaration7.ts(2,23): error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+tests/cases/conformance/parser/ecmascript5/MemberAccessorDeclarations/parserMemberAccessorDeclaration7.ts(2,23): error TS2378: A 'get' accessor must return a value.
 
 
 ==== tests/cases/conformance/parser/ecmascript5/MemberAccessorDeclarations/parserMemberAccessorDeclaration7.ts (2 errors) ====
@@ -8,5 +8,5 @@ tests/cases/conformance/parser/ecmascript5/MemberAccessorDeclarations/parserMemb
                ~~~~~~
 !!! error TS1028: Accessibility modifier already seen.
                           ~~~
-!!! error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+!!! error TS2378: A 'get' accessor must return a value.
     }
\ No newline at end of file
diff --git a/tests/baselines/reference/parserMemberAccessorDeclaration8.errors.txt b/tests/baselines/reference/parserMemberAccessorDeclaration8.errors.txt
index e5a39c149f6..67ba09b8c72 100644
--- a/tests/baselines/reference/parserMemberAccessorDeclaration8.errors.txt
+++ b/tests/baselines/reference/parserMemberAccessorDeclaration8.errors.txt
@@ -1,5 +1,5 @@
 tests/cases/conformance/parser/ecmascript5/MemberAccessorDeclarations/parserMemberAccessorDeclaration8.ts(2,12): error TS1030: 'static' modifier already seen.
-tests/cases/conformance/parser/ecmascript5/MemberAccessorDeclarations/parserMemberAccessorDeclaration8.ts(2,23): error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+tests/cases/conformance/parser/ecmascript5/MemberAccessorDeclarations/parserMemberAccessorDeclaration8.ts(2,23): error TS2378: A 'get' accessor must return a value.
 
 
 ==== tests/cases/conformance/parser/ecmascript5/MemberAccessorDeclarations/parserMemberAccessorDeclaration8.ts (2 errors) ====
@@ -8,5 +8,5 @@ tests/cases/conformance/parser/ecmascript5/MemberAccessorDeclarations/parserMemb
                ~~~~~~
 !!! error TS1030: 'static' modifier already seen.
                           ~~~
-!!! error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+!!! error TS2378: A 'get' accessor must return a value.
     }
\ No newline at end of file
diff --git a/tests/baselines/reference/parserMemberAccessorDeclaration9.errors.txt b/tests/baselines/reference/parserMemberAccessorDeclaration9.errors.txt
index 2da32a5807b..31d001aeafc 100644
--- a/tests/baselines/reference/parserMemberAccessorDeclaration9.errors.txt
+++ b/tests/baselines/reference/parserMemberAccessorDeclaration9.errors.txt
@@ -1,5 +1,5 @@
 tests/cases/conformance/parser/ecmascript5/MemberAccessorDeclarations/parserMemberAccessorDeclaration9.ts(2,12): error TS1029: 'public' modifier must precede 'static' modifier.
-tests/cases/conformance/parser/ecmascript5/MemberAccessorDeclarations/parserMemberAccessorDeclaration9.ts(2,23): error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+tests/cases/conformance/parser/ecmascript5/MemberAccessorDeclarations/parserMemberAccessorDeclaration9.ts(2,23): error TS2378: A 'get' accessor must return a value.
 
 
 ==== tests/cases/conformance/parser/ecmascript5/MemberAccessorDeclarations/parserMemberAccessorDeclaration9.ts (2 errors) ====
@@ -8,5 +8,5 @@ tests/cases/conformance/parser/ecmascript5/MemberAccessorDeclarations/parserMemb
                ~~~~~~
 !!! error TS1029: 'public' modifier must precede 'static' modifier.
                           ~~~
-!!! error TS2378: A 'get' accessor must return a value or consist of a single 'throw' statement.
+!!! error TS2378: A 'get' accessor must return a value.
     }
\ No newline at end of file
diff --git a/tests/baselines/reference/parserParameterList5.errors.txt b/tests/baselines/reference/parserParameterList5.errors.txt
index 231a5bbb162..5f0899fa1a2 100644
--- a/tests/baselines/reference/parserParameterList5.errors.txt
+++ b/tests/baselines/reference/parserParameterList5.errors.txt
@@ -1,4 +1,4 @@
-tests/cases/conformance/parser/ecmascript5/ParameterLists/parserParameterList5.ts(1,15): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement.
+tests/cases/conformance/parser/ecmascript5/ParameterLists/parserParameterList5.ts(1,15): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value.
 tests/cases/conformance/parser/ecmascript5/ParameterLists/parserParameterList5.ts(1,16): error TS2369: A parameter property is only allowed in a constructor implementation.
 tests/cases/conformance/parser/ecmascript5/ParameterLists/parserParameterList5.ts(1,29): error TS2304: Cannot find name 'C'.
 
@@ -6,7 +6,7 @@ tests/cases/conformance/parser/ecmascript5/ParameterLists/parserParameterList5.t
 ==== tests/cases/conformance/parser/ecmascript5/ParameterLists/parserParameterList5.ts (3 errors) ====
     function A(): (public B) => C {
                   ~~~~~~~~~~~~~~~
-!!! error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement.
+!!! error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value.
                    ~~~~~~~~
 !!! error TS2369: A parameter property is only allowed in a constructor implementation.
                                 ~
diff --git a/tests/baselines/reference/reachabilityChecks1.errors.txt b/tests/baselines/reference/reachabilityChecks1.errors.txt
new file mode 100644
index 00000000000..ebf1019e7e9
--- /dev/null
+++ b/tests/baselines/reference/reachabilityChecks1.errors.txt
@@ -0,0 +1,70 @@
+tests/cases/compiler/reachabilityChecks1.ts(3,1): error TS7027: Unreachable code detected.
+tests/cases/compiler/reachabilityChecks1.ts(7,5): error TS7027: Unreachable code detected.
+tests/cases/compiler/reachabilityChecks1.ts(22,11): error TS7027: Unreachable code detected.
+tests/cases/compiler/reachabilityChecks1.ts(28,12): error TS7027: Unreachable code detected.
+tests/cases/compiler/reachabilityChecks1.ts(35,10): error TS7027: Unreachable code detected.
+tests/cases/compiler/reachabilityChecks1.ts(44,16): error TS7027: Unreachable code detected.
+
+
+==== tests/cases/compiler/reachabilityChecks1.ts (6 errors) ====
+    
+    while (true);
+    var x = 1;
+    ~~~~~~~~~~
+!!! error TS7027: Unreachable code detected.
+    
+    module A {
+        while (true);
+        let x;
+        ~~~~~~
+!!! error TS7027: Unreachable code detected.
+    }
+    
+    function f1(x) {
+        if (x) {
+            return;
+        }
+        else {
+            throw new Error("123");
+        }
+        var x;
+    }
+    
+    function f2() {
+        return;
+        class A {
+              ~
+!!! error TS7027: Unreachable code detected.
+        }
+    }
+    
+    module B {
+        for (; ;);
+        module C {
+               ~
+!!! error TS7027: Unreachable code detected.
+        }
+    }
+    
+    function f3() {
+        do {
+        } while (true);
+        enum E {
+             ~
+!!! error TS7027: Unreachable code detected.
+            X = 1
+        }
+    }
+    
+    function f4() {
+        if (true) {
+            throw new Error();
+        }
+        const enum E {
+                   ~
+!!! error TS7027: Unreachable code detected.
+            X = 1
+        }
+    }
+    
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/reachabilityChecks1.js b/tests/baselines/reference/reachabilityChecks1.js
new file mode 100644
index 00000000000..3f9ca87422a
--- /dev/null
+++ b/tests/baselines/reference/reachabilityChecks1.js
@@ -0,0 +1,100 @@
+//// [reachabilityChecks1.ts]
+
+while (true);
+var x = 1;
+
+module A {
+    while (true);
+    let x;
+}
+
+function f1(x) {
+    if (x) {
+        return;
+    }
+    else {
+        throw new Error("123");
+    }
+    var x;
+}
+
+function f2() {
+    return;
+    class A {
+    }
+}
+
+module B {
+    for (; ;);
+    module C {
+    }
+}
+
+function f3() {
+    do {
+    } while (true);
+    enum E {
+        X = 1
+    }
+}
+
+function f4() {
+    if (true) {
+        throw new Error();
+    }
+    const enum E {
+        X = 1
+    }
+}
+
+
+
+//// [reachabilityChecks1.js]
+while (true)
+    ;
+var x = 1;
+var A;
+(function (A) {
+    while (true)
+        ;
+    var x;
+})(A || (A = {}));
+function f1(x) {
+    if (x) {
+        return;
+    }
+    else {
+        throw new Error("123");
+    }
+    var x;
+}
+function f2() {
+    return;
+    var A = (function () {
+        function A() {
+        }
+        return A;
+    })();
+}
+var B;
+(function (B) {
+    for (;;)
+        ;
+})(B || (B = {}));
+function f3() {
+    do {
+    } while (true);
+    var E;
+    (function (E) {
+        E[E["X"] = 1] = "X";
+    })(E || (E = {}));
+}
+function f4() {
+    if (true) {
+        throw new Error();
+    }
+    var E;
+    (function (E) {
+        E[E["X"] = 1] = "X";
+    })(E || (E = {}));
+}
diff --git a/tests/baselines/reference/reachabilityChecks2.js b/tests/baselines/reference/reachabilityChecks2.js
new file mode 100644
index 00000000000..80534c0d7de
--- /dev/null
+++ b/tests/baselines/reference/reachabilityChecks2.js
@@ -0,0 +1,9 @@
+//// [reachabilityChecks2.ts]
+
+while (true) { }
+const enum E { X }
+
+
+
+//// [reachabilityChecks2.js]
+while (true) { }
diff --git a/tests/baselines/reference/reachabilityChecks2.symbols b/tests/baselines/reference/reachabilityChecks2.symbols
new file mode 100644
index 00000000000..d289304dffa
--- /dev/null
+++ b/tests/baselines/reference/reachabilityChecks2.symbols
@@ -0,0 +1,8 @@
+=== tests/cases/compiler/reachabilityChecks2.ts ===
+
+while (true) { }
+const enum E { X }
+>E : Symbol(E, Decl(reachabilityChecks2.ts, 1, 16))
+>X : Symbol(E.X, Decl(reachabilityChecks2.ts, 2, 14))
+
+
diff --git a/tests/baselines/reference/reachabilityChecks2.types b/tests/baselines/reference/reachabilityChecks2.types
new file mode 100644
index 00000000000..38dad87c6a1
--- /dev/null
+++ b/tests/baselines/reference/reachabilityChecks2.types
@@ -0,0 +1,10 @@
+=== tests/cases/compiler/reachabilityChecks2.ts ===
+
+while (true) { }
+>true : boolean
+
+const enum E { X }
+>E : E
+>X : E
+
+
diff --git a/tests/baselines/reference/reachabilityChecks3.errors.txt b/tests/baselines/reference/reachabilityChecks3.errors.txt
new file mode 100644
index 00000000000..993ab571b2e
--- /dev/null
+++ b/tests/baselines/reference/reachabilityChecks3.errors.txt
@@ -0,0 +1,16 @@
+tests/cases/compiler/reachabilityChecks3.ts(3,1): error TS7028: Unused label.
+
+
+==== tests/cases/compiler/reachabilityChecks3.ts (1 errors) ====
+    
+    let x = 1;
+    loop: while (true) {
+    ~~~~
+!!! error TS7028: Unused label.
+        if (x == 100) {
+            break;
+        }
+        else {
+            x++;
+        }
+    }
\ No newline at end of file
diff --git a/tests/baselines/reference/reachabilityChecks3.js b/tests/baselines/reference/reachabilityChecks3.js
new file mode 100644
index 00000000000..4de316d1ddc
--- /dev/null
+++ b/tests/baselines/reference/reachabilityChecks3.js
@@ -0,0 +1,22 @@
+//// [reachabilityChecks3.ts]
+
+let x = 1;
+loop: while (true) {
+    if (x == 100) {
+        break;
+    }
+    else {
+        x++;
+    }
+}
+
+//// [reachabilityChecks3.js]
+var x = 1;
+loop: while (true) {
+    if (x == 100) {
+        break;
+    }
+    else {
+        x++;
+    }
+}
diff --git a/tests/baselines/reference/reachabilityChecks4.errors.txt b/tests/baselines/reference/reachabilityChecks4.errors.txt
new file mode 100644
index 00000000000..ba9519462e7
--- /dev/null
+++ b/tests/baselines/reference/reachabilityChecks4.errors.txt
@@ -0,0 +1,20 @@
+tests/cases/compiler/reachabilityChecks4.ts(7,9): error TS7029: Fallthrough case in switch.
+
+
+==== tests/cases/compiler/reachabilityChecks4.ts (1 errors) ====
+    
+    function foo(x, y) {
+        switch (x) {
+            case 1:
+            case 2:
+                return 1;
+            case 3:
+            ~~~~
+!!! error TS7029: Fallthrough case in switch.
+                if (y) {
+                    return 2;
+                }
+            case 4:
+                return 3;
+        }
+    }
\ No newline at end of file
diff --git a/tests/baselines/reference/reachabilityChecks4.js b/tests/baselines/reference/reachabilityChecks4.js
new file mode 100644
index 00000000000..588644c5a05
--- /dev/null
+++ b/tests/baselines/reference/reachabilityChecks4.js
@@ -0,0 +1,30 @@
+//// [reachabilityChecks4.ts]
+
+function foo(x, y) {
+    switch (x) {
+        case 1:
+        case 2:
+            return 1;
+        case 3:
+            if (y) {
+                return 2;
+            }
+        case 4:
+            return 3;
+    }
+}
+
+//// [reachabilityChecks4.js]
+function foo(x, y) {
+    switch (x) {
+        case 1:
+        case 2:
+            return 1;
+        case 3:
+            if (y) {
+                return 2;
+            }
+        case 4:
+            return 3;
+    }
+}
diff --git a/tests/baselines/reference/reachabilityChecks5.errors.txt b/tests/baselines/reference/reachabilityChecks5.errors.txt
new file mode 100644
index 00000000000..c30dfa71817
--- /dev/null
+++ b/tests/baselines/reference/reachabilityChecks5.errors.txt
@@ -0,0 +1,162 @@
+tests/cases/compiler/reachabilityChecks5.ts(6,17): error TS7030: Not all code paths return a value.
+tests/cases/compiler/reachabilityChecks5.ts(19,17): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value.
+tests/cases/compiler/reachabilityChecks5.ts(31,17): error TS7030: Not all code paths return a value.
+tests/cases/compiler/reachabilityChecks5.ts(41,17): error TS7030: Not all code paths return a value.
+tests/cases/compiler/reachabilityChecks5.ts(52,17): error TS7030: Not all code paths return a value.
+tests/cases/compiler/reachabilityChecks5.ts(80,17): error TS7030: Not all code paths return a value.
+tests/cases/compiler/reachabilityChecks5.ts(86,13): error TS7027: Unreachable code detected.
+tests/cases/compiler/reachabilityChecks5.ts(94,17): error TS7030: Not all code paths return a value.
+tests/cases/compiler/reachabilityChecks5.ts(116,18): error TS7030: Not all code paths return a value.
+tests/cases/compiler/reachabilityChecks5.ts(123,13): error TS7027: Unreachable code detected.
+
+
+==== tests/cases/compiler/reachabilityChecks5.ts (10 errors) ====
+    
+    function f0(x): number {
+        while (true);
+    }
+    
+    function f1(x): number {
+                    ~~~~~~
+!!! error TS7030: Not all code paths return a value.
+        if (x) {
+            return 1
+        }
+    }
+    
+    function f2(x): number {
+        while (x) {
+            throw new Error();
+        }
+        return 1;
+    }
+    
+    function f3(x): number {
+                    ~~~~~~
+!!! error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value.
+        while (x) {
+            throw new Error();
+        }
+    }
+    
+    function f3_1 (x): number {
+        while (x) {
+        }
+        throw new Error();
+    }
+    
+    function f4(x): number {
+                    ~~~~~~
+!!! error TS7030: Not all code paths return a value.
+        try {
+            if (x) {
+                return 1;
+            }
+        }
+        catch (e) {
+        }
+    }
+    
+    function f5(x): number {
+                    ~~~~~~
+!!! error TS7030: Not all code paths return a value.
+        try {
+            if (x) {
+                return 1;
+            }
+        }
+        catch (e) {
+            return 2;
+        }
+    }
+    
+    function f6(x): number {
+                    ~~~~~~
+!!! error TS7030: Not all code paths return a value.
+        try {
+            if (x) {
+                return 1;
+            }
+            else 
+            {
+                throw new Error();
+            }
+        }
+        catch (e) {
+        }
+    }
+    
+    function f7(x): number {
+        try {
+            if (x) {
+                return 1;
+            }
+            else {
+                throw new Error();
+            }
+        }
+        catch (e) {
+            return 1;
+        }
+    }
+    
+    function f8(x): number {
+                    ~~~~~~
+!!! error TS7030: Not all code paths return a value.
+        try {
+            if (true) {
+                x++;
+            }
+            else {
+                return 1;
+                ~~~~~~~~~
+!!! error TS7027: Unreachable code detected.
+            }
+        }
+        catch (e) {
+            return 1;
+        }
+    }
+    
+    function f9(x): number {
+                    ~~~~~~
+!!! error TS7030: Not all code paths return a value.
+        try {
+            while (false) {
+                return 1;
+            }
+        }
+        catch (e) {
+            return 1;
+        }
+    }
+    
+    function f10(x): number {
+        try {
+            do {
+                x++;
+            } while (true);
+        }
+        catch (e) {
+            return 1;
+        }
+    }
+    
+    function f11(x): number {
+                     ~~~~~~
+!!! error TS7030: Not all code paths return a value.
+        test:
+        try {
+            do {
+                do {
+                    break test;
+                } while (true);
+                x++;
+                ~~~~
+!!! error TS7027: Unreachable code detected.
+            } while (true);
+        }
+        catch (e) {
+            return 1;
+        }
+    }
\ No newline at end of file
diff --git a/tests/baselines/reference/reachabilityChecks5.js b/tests/baselines/reference/reachabilityChecks5.js
new file mode 100644
index 00000000000..a6c507ac87b
--- /dev/null
+++ b/tests/baselines/reference/reachabilityChecks5.js
@@ -0,0 +1,247 @@
+//// [reachabilityChecks5.ts]
+
+function f0(x): number {
+    while (true);
+}
+
+function f1(x): number {
+    if (x) {
+        return 1
+    }
+}
+
+function f2(x): number {
+    while (x) {
+        throw new Error();
+    }
+    return 1;
+}
+
+function f3(x): number {
+    while (x) {
+        throw new Error();
+    }
+}
+
+function f3_1 (x): number {
+    while (x) {
+    }
+    throw new Error();
+}
+
+function f4(x): number {
+    try {
+        if (x) {
+            return 1;
+        }
+    }
+    catch (e) {
+    }
+}
+
+function f5(x): number {
+    try {
+        if (x) {
+            return 1;
+        }
+    }
+    catch (e) {
+        return 2;
+    }
+}
+
+function f6(x): number {
+    try {
+        if (x) {
+            return 1;
+        }
+        else 
+        {
+            throw new Error();
+        }
+    }
+    catch (e) {
+    }
+}
+
+function f7(x): number {
+    try {
+        if (x) {
+            return 1;
+        }
+        else {
+            throw new Error();
+        }
+    }
+    catch (e) {
+        return 1;
+    }
+}
+
+function f8(x): number {
+    try {
+        if (true) {
+            x++;
+        }
+        else {
+            return 1;
+        }
+    }
+    catch (e) {
+        return 1;
+    }
+}
+
+function f9(x): number {
+    try {
+        while (false) {
+            return 1;
+        }
+    }
+    catch (e) {
+        return 1;
+    }
+}
+
+function f10(x): number {
+    try {
+        do {
+            x++;
+        } while (true);
+    }
+    catch (e) {
+        return 1;
+    }
+}
+
+function f11(x): number {
+    test:
+    try {
+        do {
+            do {
+                break test;
+            } while (true);
+            x++;
+        } while (true);
+    }
+    catch (e) {
+        return 1;
+    }
+}
+
+//// [reachabilityChecks5.js]
+function f0(x) {
+    while (true)
+        ;
+}
+function f1(x) {
+    if (x) {
+        return 1;
+    }
+}
+function f2(x) {
+    while (x) {
+        throw new Error();
+    }
+    return 1;
+}
+function f3(x) {
+    while (x) {
+        throw new Error();
+    }
+}
+function f3_1(x) {
+    while (x) {
+    }
+    throw new Error();
+}
+function f4(x) {
+    try {
+        if (x) {
+            return 1;
+        }
+    }
+    catch (e) {
+    }
+}
+function f5(x) {
+    try {
+        if (x) {
+            return 1;
+        }
+    }
+    catch (e) {
+        return 2;
+    }
+}
+function f6(x) {
+    try {
+        if (x) {
+            return 1;
+        }
+        else {
+            throw new Error();
+        }
+    }
+    catch (e) {
+    }
+}
+function f7(x) {
+    try {
+        if (x) {
+            return 1;
+        }
+        else {
+            throw new Error();
+        }
+    }
+    catch (e) {
+        return 1;
+    }
+}
+function f8(x) {
+    try {
+        if (true) {
+            x++;
+        }
+        else {
+            return 1;
+        }
+    }
+    catch (e) {
+        return 1;
+    }
+}
+function f9(x) {
+    try {
+        while (false) {
+            return 1;
+        }
+    }
+    catch (e) {
+        return 1;
+    }
+}
+function f10(x) {
+    try {
+        do {
+            x++;
+        } while (true);
+    }
+    catch (e) {
+        return 1;
+    }
+}
+function f11(x) {
+    test: try {
+        do {
+            do {
+                break test;
+            } while (true);
+            x++;
+        } while (true);
+    }
+    catch (e) {
+        return 1;
+    }
+}
diff --git a/tests/baselines/reference/recursiveFunctionTypes.errors.txt b/tests/baselines/reference/recursiveFunctionTypes.errors.txt
index c69549403c4..8d5303c0669 100644
--- a/tests/baselines/reference/recursiveFunctionTypes.errors.txt
+++ b/tests/baselines/reference/recursiveFunctionTypes.errors.txt
@@ -2,8 +2,8 @@ tests/cases/compiler/recursiveFunctionTypes.ts(1,35): error TS2322: Type 'number
 tests/cases/compiler/recursiveFunctionTypes.ts(3,5): error TS2322: Type '() => typeof fn' is not assignable to type 'number'.
 tests/cases/compiler/recursiveFunctionTypes.ts(4,5): error TS2322: Type '() => typeof fn' is not assignable to type '() => number'.
   Type '() => typeof fn' is not assignable to type 'number'.
-tests/cases/compiler/recursiveFunctionTypes.ts(11,16): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement.
-tests/cases/compiler/recursiveFunctionTypes.ts(12,16): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement.
+tests/cases/compiler/recursiveFunctionTypes.ts(11,16): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value.
+tests/cases/compiler/recursiveFunctionTypes.ts(12,16): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value.
 tests/cases/compiler/recursiveFunctionTypes.ts(17,5): error TS2322: Type '() => I<typeof f3>' is not assignable to type 'number'.
 tests/cases/compiler/recursiveFunctionTypes.ts(22,5): error TS2345: Argument of type 'number' is not assignable to parameter of type '(t: typeof g) => void'.
 tests/cases/compiler/recursiveFunctionTypes.ts(25,1): error TS2322: Type 'number' is not assignable to type '() => any'.
@@ -34,10 +34,10 @@ tests/cases/compiler/recursiveFunctionTypes.ts(43,4): error TS2345: Argument of
     
     function f2(): typeof g2 { } 
                    ~~~~~~~~~
-!!! error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement.
+!!! error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value.
     function g2(): typeof f2 { } 
                    ~~~~~~~~~
-!!! error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement.
+!!! error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value.
     
     interface I<T> { }
     function f3(): I<typeof f3> { return f3; }
diff --git a/tests/baselines/reference/returnTypeParameter.errors.txt b/tests/baselines/reference/returnTypeParameter.errors.txt
index 11c0888f47c..1bd9f6a63f6 100644
--- a/tests/baselines/reference/returnTypeParameter.errors.txt
+++ b/tests/baselines/reference/returnTypeParameter.errors.txt
@@ -1,11 +1,11 @@
-tests/cases/compiler/returnTypeParameter.ts(1,22): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement.
+tests/cases/compiler/returnTypeParameter.ts(1,22): error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value.
 tests/cases/compiler/returnTypeParameter.ts(2,34): error TS2304: Cannot find name 'T'.
 
 
 ==== tests/cases/compiler/returnTypeParameter.ts (2 errors) ====
     function f<T>(a: T): T { } // error, no return statement
                          ~
-!!! error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value or consist of a single 'throw' statement.
+!!! error TS2355: A function whose declared type is neither 'void' nor 'any' must return a value.
     function f2<T>(a: T): T { return T; } // bug was that this satisfied the return statement requirement
                                      ~
 !!! error TS2304: Cannot find name 'T'.
\ No newline at end of file
diff --git a/tests/cases/compiler/reachabilityChecks1.ts b/tests/cases/compiler/reachabilityChecks1.ts
new file mode 100644
index 00000000000..bc7662486a6
--- /dev/null
+++ b/tests/cases/compiler/reachabilityChecks1.ts
@@ -0,0 +1,50 @@
+// @noUnreachableCode: true
+// @preserveConstEnums: true
+
+while (true);
+var x = 1;
+
+module A {
+    while (true);
+    let x;
+}
+
+function f1(x) {
+    if (x) {
+        return;
+    }
+    else {
+        throw new Error("123");
+    }
+    var x;
+}
+
+function f2() {
+    return;
+    class A {
+    }
+}
+
+module B {
+    for (; ;);
+    module C {
+    }
+}
+
+function f3() {
+    do {
+    } while (true);
+    enum E {
+        X = 1
+    }
+}
+
+function f4() {
+    if (true) {
+        throw new Error();
+    }
+    const enum E {
+        X = 1
+    }
+}
+
diff --git a/tests/cases/compiler/reachabilityChecks2.ts b/tests/cases/compiler/reachabilityChecks2.ts
new file mode 100644
index 00000000000..fc8d53bde8f
--- /dev/null
+++ b/tests/cases/compiler/reachabilityChecks2.ts
@@ -0,0 +1,6 @@
+// @noUnreachableCode: true
+// @preserveConstEnums: false
+
+while (true) { }
+const enum E { X }
+
diff --git a/tests/cases/compiler/reachabilityChecks3.ts b/tests/cases/compiler/reachabilityChecks3.ts
new file mode 100644
index 00000000000..362c64e1349
--- /dev/null
+++ b/tests/cases/compiler/reachabilityChecks3.ts
@@ -0,0 +1,11 @@
+// @noUnusedLabels: true
+
+let x = 1;
+loop: while (true) {
+    if (x == 100) {
+        break;
+    }
+    else {
+        x++;
+    }
+}
\ No newline at end of file
diff --git a/tests/cases/compiler/reachabilityChecks4.ts b/tests/cases/compiler/reachabilityChecks4.ts
new file mode 100644
index 00000000000..f07395ac38e
--- /dev/null
+++ b/tests/cases/compiler/reachabilityChecks4.ts
@@ -0,0 +1,15 @@
+// @noFallthroughCasesInSwitch: true
+
+function foo(x, y) {
+    switch (x) {
+        case 1:
+        case 2:
+            return 1;
+        case 3:
+            if (y) {
+                return 2;
+            }
+        case 4:
+            return 3;
+    }
+}
\ No newline at end of file
diff --git a/tests/cases/compiler/reachabilityChecks5.ts b/tests/cases/compiler/reachabilityChecks5.ts
new file mode 100644
index 00000000000..24134e238b9
--- /dev/null
+++ b/tests/cases/compiler/reachabilityChecks5.ts
@@ -0,0 +1,131 @@
+// @noUnreachableCode: true
+// @noImplicitReturns: true
+
+function f0(x): number {
+    while (true);
+}
+
+function f1(x): number {
+    if (x) {
+        return 1
+    }
+}
+
+function f2(x): number {
+    while (x) {
+        throw new Error();
+    }
+    return 1;
+}
+
+function f3(x): number {
+    while (x) {
+        throw new Error();
+    }
+}
+
+function f3_1 (x): number {
+    while (x) {
+    }
+    throw new Error();
+}
+
+function f4(x): number {
+    try {
+        if (x) {
+            return 1;
+        }
+    }
+    catch (e) {
+    }
+}
+
+function f5(x): number {
+    try {
+        if (x) {
+            return 1;
+        }
+    }
+    catch (e) {
+        return 2;
+    }
+}
+
+function f6(x): number {
+    try {
+        if (x) {
+            return 1;
+        }
+        else 
+        {
+            throw new Error();
+        }
+    }
+    catch (e) {
+    }
+}
+
+function f7(x): number {
+    try {
+        if (x) {
+            return 1;
+        }
+        else {
+            throw new Error();
+        }
+    }
+    catch (e) {
+        return 1;
+    }
+}
+
+function f8(x): number {
+    try {
+        if (true) {
+            x++;
+        }
+        else {
+            return 1;
+        }
+    }
+    catch (e) {
+        return 1;
+    }
+}
+
+function f9(x): number {
+    try {
+        while (false) {
+            return 1;
+        }
+    }
+    catch (e) {
+        return 1;
+    }
+}
+
+function f10(x): number {
+    try {
+        do {
+            x++;
+        } while (true);
+    }
+    catch (e) {
+        return 1;
+    }
+}
+
+function f11(x): number {
+    test:
+    try {
+        do {
+            do {
+                break test;
+            } while (true);
+            x++;
+        } while (true);
+    }
+    catch (e) {
+        return 1;
+    }
+}
\ No newline at end of file