diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 3708ea3582c3d..f24f72491b04d 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -1054,7 +1054,7 @@ namespace ts {
             if (node.moduleReference.kind === SyntaxKind.ExternalModuleReference) {
                 return resolveExternalModuleSymbol(resolveExternalModuleName(node, getExternalModuleImportEqualsDeclarationExpression(node)));
             }
-            return getSymbolOfPartOfRightHandSideOfImportEquals(<EntityName>node.moduleReference, node);
+            return getSymbolOfPartOfRightHandSideOfImportEquals(<EntityName>node.moduleReference);
         }
 
         function getTargetOfImportClause(node: ImportClause): Symbol {
@@ -1267,7 +1267,7 @@ namespace ts {
         }
 
         // This function is only for imports with entity names
-        function getSymbolOfPartOfRightHandSideOfImportEquals(entityName: EntityName, importDeclaration: ImportEqualsDeclaration, dontResolveAlias?: boolean): Symbol {
+        function getSymbolOfPartOfRightHandSideOfImportEquals(entityName: EntityName, dontResolveAlias?: boolean): Symbol {
             // There are three things we might try to look for. In the following examples,
             // the search term is enclosed in |...|:
             //
@@ -2583,7 +2583,7 @@ namespace ts {
                 }
             }
 
-            function buildDisplayForTypeArgumentsAndDelimiters(typeParameters: TypeParameter[], mapper: TypeMapper, writer: SymbolWriter, enclosingDeclaration?: Node, flags?: TypeFormatFlags, symbolStack?: Symbol[]) {
+            function buildDisplayForTypeArgumentsAndDelimiters(typeParameters: TypeParameter[], mapper: TypeMapper, writer: SymbolWriter, enclosingDeclaration?: Node) {
                 if (typeParameters && typeParameters.length) {
                     writePunctuation(writer, SyntaxKind.LessThanToken);
                     let flags = TypeFormatFlags.InFirstTypeArgument;
@@ -4795,7 +4795,7 @@ namespace ts {
                 const typeParameters = classType ? classType.localTypeParameters :
                     declaration.typeParameters ? getTypeParametersFromDeclaration(declaration.typeParameters) :
                         getTypeParametersFromJSDocTemplate(declaration);
-                const returnType = getSignatureReturnTypeFromDeclaration(declaration, minArgumentCount, isJSConstructSignature, classType);
+                const returnType = getSignatureReturnTypeFromDeclaration(declaration, isJSConstructSignature, classType);
                 const typePredicate = declaration.type && declaration.type.kind === SyntaxKind.TypePredicate ?
                     createTypePredicateFromTypePredicateNode(declaration.type as TypePredicateNode) :
                     undefined;
@@ -4805,7 +4805,7 @@ namespace ts {
             return links.resolvedSignature;
         }
 
-        function getSignatureReturnTypeFromDeclaration(declaration: SignatureDeclaration, minArgumentCount: number, isJSConstructSignature: boolean, classType: Type) {
+        function getSignatureReturnTypeFromDeclaration(declaration: SignatureDeclaration, isJSConstructSignature: boolean, classType: Type) {
             if (isJSConstructSignature) {
                 return getTypeFromTypeNode(declaration.parameters[0].type);
             }
@@ -5170,10 +5170,7 @@ namespace ts {
             return undefined;
         }
 
-        function resolveTypeReferenceName(
-            node: TypeReferenceNode | ExpressionWithTypeArguments | JSDocTypeReference,
-            typeReferenceName: EntityNameExpression | EntityName) {
-
+        function resolveTypeReferenceName(typeReferenceName: EntityNameExpression | EntityName) {
             if (!typeReferenceName) {
                 return unknownSymbol;
             }
@@ -5211,7 +5208,7 @@ namespace ts {
                 let type: Type;
                 if (node.kind === SyntaxKind.JSDocTypeReference) {
                     const typeReferenceName = getTypeReferenceName(node);
-                    symbol = resolveTypeReferenceName(node, typeReferenceName);
+                    symbol = resolveTypeReferenceName(typeReferenceName);
                     type = getTypeReferenceType(node, symbol);
                 }
                 else {
@@ -6673,8 +6670,8 @@ namespace ts {
                 }
                 if (source.flags & TypeFlags.Union && target.flags & TypeFlags.Union ||
                     source.flags & TypeFlags.Intersection && target.flags & TypeFlags.Intersection) {
-                    if (result = eachTypeRelatedToSomeType(<UnionOrIntersectionType>source, <UnionOrIntersectionType>target, /*reportErrors*/ false)) {
-                        if (result &= eachTypeRelatedToSomeType(<UnionOrIntersectionType>target, <UnionOrIntersectionType>source, /*reportErrors*/ false)) {
+                    if (result = eachTypeRelatedToSomeType(<UnionOrIntersectionType>source, <UnionOrIntersectionType>target)) {
+                        if (result &= eachTypeRelatedToSomeType(<UnionOrIntersectionType>target, <UnionOrIntersectionType>source)) {
                             return result;
                         }
                     }
@@ -6735,7 +6732,7 @@ namespace ts {
                 return false;
             }
 
-            function eachTypeRelatedToSomeType(source: UnionOrIntersectionType, target: UnionOrIntersectionType, reportErrors: boolean): Ternary {
+            function eachTypeRelatedToSomeType(source: UnionOrIntersectionType, target: UnionOrIntersectionType): Ternary {
                 let result = Ternary.True;
                 const sourceTypes = source.types;
                 for (const sourceType of sourceTypes) {
@@ -11772,7 +11769,7 @@ namespace ts {
                 // If the effective argument is 'undefined', then it is an argument that is present but is synthetic.
                 if (arg === undefined || arg.kind !== SyntaxKind.OmittedExpression) {
                     const paramType = getTypeAtPosition(signature, i);
-                    let argType = getEffectiveArgumentType(node, i, arg);
+                    let argType = getEffectiveArgumentType(node, i);
 
                     // If the effective argument type is 'undefined', there is no synthetic type
                     // for the argument. In that case, we should check the argument.
@@ -11858,7 +11855,7 @@ namespace ts {
                 if (arg === undefined || arg.kind !== SyntaxKind.OmittedExpression) {
                     // Check spread elements against rest type (from arity check we know spread argument corresponds to a rest parameter)
                     const paramType = getTypeAtPosition(signature, i);
-                    let argType = getEffectiveArgumentType(node, i, arg);
+                    let argType = getEffectiveArgumentType(node, i);
 
                     // If the effective argument type is 'undefined', there is no synthetic type
                     // for the argument. In that case, we should check the argument.
@@ -12151,7 +12148,7 @@ namespace ts {
         /**
           * Gets the effective argument type for an argument in a call expression.
           */
-        function getEffectiveArgumentType(node: CallLikeExpression, argIndex: number, arg: Expression): Type {
+        function getEffectiveArgumentType(node: CallLikeExpression, argIndex: number): Type {
             // Decorators provide special arguments, a tagged template expression provides
             // a special first argument, and string literals get string literal types
             // unless we're reporting errors
@@ -13556,15 +13553,15 @@ namespace ts {
             return booleanType;
         }
 
-        function checkObjectLiteralAssignment(node: ObjectLiteralExpression, sourceType: Type, contextualMapper?: TypeMapper): Type {
+        function checkObjectLiteralAssignment(node: ObjectLiteralExpression, sourceType: Type): Type {
             const properties = node.properties;
             for (const p of properties) {
-                checkObjectLiteralDestructuringPropertyAssignment(sourceType, p, contextualMapper);
+                checkObjectLiteralDestructuringPropertyAssignment(sourceType, p);
             }
             return sourceType;
         }
 
-        function checkObjectLiteralDestructuringPropertyAssignment(objectLiteralType: Type, property: ObjectLiteralElementLike, contextualMapper?: TypeMapper) {
+        function checkObjectLiteralDestructuringPropertyAssignment(objectLiteralType: Type, property: ObjectLiteralElementLike) {
             if (property.kind === SyntaxKind.PropertyAssignment || property.kind === SyntaxKind.ShorthandPropertyAssignment) {
                 const name = <PropertyName>(<PropertyAssignment>property).name;
                 if (name.kind === SyntaxKind.ComputedPropertyName) {
@@ -13679,7 +13676,7 @@ namespace ts {
                 target = (<BinaryExpression>target).left;
             }
             if (target.kind === SyntaxKind.ObjectLiteralExpression) {
-                return checkObjectLiteralAssignment(<ObjectLiteralExpression>target, sourceType, contextualMapper);
+                return checkObjectLiteralAssignment(<ObjectLiteralExpression>target, sourceType);
             }
             if (target.kind === SyntaxKind.ArrayLiteralExpression) {
                 return checkArrayLiteralAssignment(<ArrayLiteralExpression>target, sourceType, contextualMapper);
@@ -18588,7 +18585,7 @@ namespace ts {
                 // Since we already checked for ExportAssignment, this really could only be an Import
                 const importEqualsDeclaration = <ImportEqualsDeclaration>getAncestor(entityName, SyntaxKind.ImportEqualsDeclaration);
                 Debug.assert(importEqualsDeclaration !== undefined);
-                return getSymbolOfPartOfRightHandSideOfImportEquals(<EntityName>entityName, importEqualsDeclaration, /*dontResolveAlias*/ true);
+                return getSymbolOfPartOfRightHandSideOfImportEquals(<EntityName>entityName, /*dontResolveAlias*/ true);
             }
 
             if (isRightSideOfQualifiedNameOrPropertyAccess(entityName)) {
@@ -19971,7 +19968,7 @@ namespace ts {
             }
         }
 
-        function checkGrammarTypeParameterList(node: FunctionLikeDeclaration, typeParameters: NodeArray<TypeParameterDeclaration>, file: SourceFile): boolean {
+        function checkGrammarTypeParameterList(typeParameters: NodeArray<TypeParameterDeclaration>, file: SourceFile): boolean {
             if (checkGrammarForDisallowedTrailingComma(typeParameters)) {
                 return true;
             }
@@ -20022,7 +20019,7 @@ namespace ts {
         function checkGrammarFunctionLikeDeclaration(node: FunctionLikeDeclaration): boolean {
             // Prevent cascading error by short-circuit
             const file = getSourceFileOfNode(node);
-            return checkGrammarDecorators(node) || checkGrammarModifiers(node) || checkGrammarTypeParameterList(node, node.typeParameters, file) ||
+            return checkGrammarDecorators(node) || checkGrammarModifiers(node) || checkGrammarTypeParameterList(node.typeParameters, file) ||
                 checkGrammarParameterList(node.parameters) || checkGrammarArrowFunction(node, file);
         }
 
@@ -20208,7 +20205,7 @@ namespace ts {
             }
         }
 
-        function checkGrammarForInvalidQuestionMark(node: Declaration, questionToken: Node, message: DiagnosticMessage): boolean {
+        function checkGrammarForInvalidQuestionMark(questionToken: Node, message: DiagnosticMessage): boolean {
             if (questionToken) {
                 return grammarErrorOnNode(questionToken, message);
             }
@@ -20254,7 +20251,7 @@ namespace ts {
                 let currentKind: number;
                 if (prop.kind === SyntaxKind.PropertyAssignment || prop.kind === SyntaxKind.ShorthandPropertyAssignment) {
                     // Grammar checking for computedPropertyName and shorthandPropertyAssignment
-                    checkGrammarForInvalidQuestionMark(prop, (<PropertyAssignment>prop).questionToken, Diagnostics.An_object_member_cannot_be_declared_optional);
+                    checkGrammarForInvalidQuestionMark((<PropertyAssignment>prop).questionToken, Diagnostics.An_object_member_cannot_be_declared_optional);
                     if (name.kind === SyntaxKind.NumericLiteral) {
                         checkGrammarNumericLiteral(<NumericLiteral>name);
                     }
@@ -20438,7 +20435,7 @@ namespace ts {
             }
 
             if (node.parent.kind === SyntaxKind.ObjectLiteralExpression) {
-                if (checkGrammarForInvalidQuestionMark(node, node.questionToken, Diagnostics.An_object_member_cannot_be_declared_optional)) {
+                if (checkGrammarForInvalidQuestionMark(node.questionToken, Diagnostics.An_object_member_cannot_be_declared_optional)) {
                     return true;
                 }
                 else if (node.body === undefined) {
diff --git a/src/compiler/comments.ts b/src/compiler/comments.ts
index 116a8e849a373..cd96981c09303 100644
--- a/src/compiler/comments.ts
+++ b/src/compiler/comments.ts
@@ -188,7 +188,7 @@ namespace ts {
             }
         }
 
-        function emitLeadingComment(commentPos: number, commentEnd: number, kind: SyntaxKind, hasTrailingNewLine: boolean, rangePos: number) {
+        function emitLeadingComment(commentPos: number, commentEnd: number, _kind: SyntaxKind, hasTrailingNewLine: boolean, rangePos: number) {
             if (!hasWrittenComment) {
                 emitNewLineBeforeLeadingCommentOfPosition(currentLineMap, writer, rangePos, commentPos);
                 hasWrittenComment = true;
@@ -211,7 +211,7 @@ namespace ts {
             forEachTrailingCommentToEmit(pos, emitTrailingComment);
         }
 
-        function emitTrailingComment(commentPos: number, commentEnd: number, kind: SyntaxKind, hasTrailingNewLine: boolean) {
+        function emitTrailingComment(commentPos: number, commentEnd: number, _kind: SyntaxKind, hasTrailingNewLine: boolean) {
             // trailing comments are emitted at space/*trailing comment1 */space/*trailing comment2*/
             if (!writer.isAtStartOfLine()) {
                 writer.write(" ");
@@ -242,7 +242,7 @@ namespace ts {
             }
         }
 
-        function emitTrailingCommentOfPosition(commentPos: number, commentEnd: number, kind: SyntaxKind, hasTrailingNewLine: boolean) {
+        function emitTrailingCommentOfPosition(commentPos: number, commentEnd: number, _kind: SyntaxKind, hasTrailingNewLine: boolean) {
             // trailing comments of a position are emitted at /*trailing comment1 */space/*trailing comment*/space
 
             emitPos(commentPos);
diff --git a/src/compiler/core.ts b/src/compiler/core.ts
index b41f382badf65..2f77b3040b36e 100644
--- a/src/compiler/core.ts
+++ b/src/compiler/core.ts
@@ -903,7 +903,7 @@ namespace ts {
             return t => compose(a(t));
         }
         else {
-            return t => u => u;
+            return _ => u => u;
         }
     }
 
@@ -943,7 +943,7 @@ namespace ts {
     function formatStringFromArgs(text: string, args: { [index: number]: string; }, baseIndex?: number): string {
         baseIndex = baseIndex || 0;
 
-        return text.replace(/{(\d+)}/g, (match, index?) => args[+index + baseIndex]);
+        return text.replace(/{(\d+)}/g, (_match, index?) => args[+index + baseIndex]);
     }
 
     export let localizedDiagnosticMessages: Map<string> = undefined;
@@ -982,7 +982,7 @@ namespace ts {
     }
 
     /* internal */
-    export function formatMessage(dummy: any, message: DiagnosticMessage): string {
+    export function formatMessage(_dummy: any, message: DiagnosticMessage): string {
         let text = getLocaleSpecificMessage(message);
 
         if (arguments.length > 2) {
@@ -1623,7 +1623,7 @@ namespace ts {
         basePaths: string[];
     }
 
-    export function getFileMatcherPatterns(path: string, extensions: string[], excludes: string[], includes: string[], useCaseSensitiveFileNames: boolean, currentDirectory: string): FileMatcherPatterns {
+    export function getFileMatcherPatterns(path: string, excludes: string[], includes: string[], useCaseSensitiveFileNames: boolean, currentDirectory: string): FileMatcherPatterns {
         path = normalizePath(path);
         currentDirectory = normalizePath(currentDirectory);
         const absolutePath = combinePaths(currentDirectory, path);
@@ -1640,7 +1640,7 @@ namespace ts {
         path = normalizePath(path);
         currentDirectory = normalizePath(currentDirectory);
 
-        const patterns = getFileMatcherPatterns(path, extensions, excludes, includes, useCaseSensitiveFileNames, currentDirectory);
+        const patterns = getFileMatcherPatterns(path, excludes, includes, useCaseSensitiveFileNames, currentDirectory);
 
         const regexFlag = useCaseSensitiveFileNames ? "" : "i";
         const includeFileRegex = patterns.includeFilePattern && new RegExp(patterns.includeFilePattern, regexFlag);
@@ -1874,11 +1874,11 @@ namespace ts {
         this.declarations = undefined;
     }
 
-    function Type(this: Type, checker: TypeChecker, flags: TypeFlags) {
+    function Type(this: Type, _checker: TypeChecker, flags: TypeFlags) {
         this.flags = flags;
     }
 
-    function Signature(checker: TypeChecker) {
+    function Signature() {
     }
 
     function Node(this: Node, kind: SyntaxKind, pos: number, end: number) {
@@ -1911,9 +1911,6 @@ namespace ts {
     }
 
     export namespace Debug {
-        declare var process: any;
-        declare var require: any;
-
         export let currentAssertionLevel = AssertionLevel.None;
 
         export function shouldAssert(level: AssertionLevel): boolean {
diff --git a/src/compiler/declarationEmitter.ts b/src/compiler/declarationEmitter.ts
index 8bcce86c31fac..27751a1dfc240 100644
--- a/src/compiler/declarationEmitter.ts
+++ b/src/compiler/declarationEmitter.ts
@@ -63,7 +63,7 @@ namespace ts {
         let isCurrentFileExternalModule: boolean;
         let reportedDeclarationError = false;
         let errorNameNode: DeclarationName;
-        const emitJsDocComments = compilerOptions.removeComments ? function (declaration: Node) { } : writeJsDocComments;
+        const emitJsDocComments = compilerOptions.removeComments ? () => {} : writeJsDocComments;
         const emit = compilerOptions.stripInternal ? stripInternal : emitNode;
         let noDeclare: boolean;
 
@@ -580,7 +580,7 @@ namespace ts {
                 writeAsynchronousModuleElements(nodes);
             }
 
-            function getDefaultExportAccessibilityDiagnostic(diagnostic: SymbolAccessibilityResult): SymbolAccessibilityDiagnostic {
+            function getDefaultExportAccessibilityDiagnostic(): SymbolAccessibilityDiagnostic {
                 return {
                     diagnosticMessage: Diagnostics.Default_export_of_the_module_has_or_is_using_private_name_0,
                     errorNode: node
@@ -710,7 +710,7 @@ namespace ts {
             }
             writer.writeLine();
 
-            function getImportEntityNameVisibilityError(symbolAccessibilityResult: SymbolAccessibilityResult): SymbolAccessibilityDiagnostic {
+            function getImportEntityNameVisibilityError(): SymbolAccessibilityDiagnostic {
                 return {
                     diagnosticMessage: Diagnostics.Import_declaration_0_is_using_private_name_1,
                     errorNode: node,
@@ -888,7 +888,7 @@ namespace ts {
             writeLine();
             enclosingDeclaration = prevEnclosingDeclaration;
 
-            function getTypeAliasDeclarationVisibilityError(symbolAccessibilityResult: SymbolAccessibilityResult): SymbolAccessibilityDiagnostic {
+            function getTypeAliasDeclarationVisibilityError(): SymbolAccessibilityDiagnostic {
                 return {
                     diagnosticMessage: Diagnostics.Exported_type_alias_0_has_or_is_using_private_name_1,
                     errorNode: node.type,
@@ -955,7 +955,7 @@ namespace ts {
                     }
                 }
 
-                function getTypeParameterConstraintVisibilityError(symbolAccessibilityResult: SymbolAccessibilityResult): SymbolAccessibilityDiagnostic {
+                function getTypeParameterConstraintVisibilityError(): SymbolAccessibilityDiagnostic {
                     // Type parameter constraints are named by user so we should always be able to name it
                     let diagnosticMessage: DiagnosticMessage;
                     switch (node.parent.kind) {
@@ -1029,7 +1029,7 @@ namespace ts {
                     resolver.writeBaseConstructorTypeOfClass(<ClassLikeDeclaration>enclosingDeclaration, enclosingDeclaration, TypeFormatFlags.UseTypeOfFunction | TypeFormatFlags.UseTypeAliasValue, writer);
                 }
 
-                function getHeritageClauseVisibilityError(symbolAccessibilityResult: SymbolAccessibilityResult): SymbolAccessibilityDiagnostic {
+                function getHeritageClauseVisibilityError(): SymbolAccessibilityDiagnostic {
                     let diagnosticMessage: DiagnosticMessage;
                     // Heritage clause is written by user so it can always be named
                     if (node.parent.parent.kind === SyntaxKind.ClassDeclaration) {
@@ -1743,7 +1743,7 @@ namespace ts {
             }
             return addedBundledEmitReference;
 
-            function getDeclFileName(emitFileNames: EmitFileNames, sourceFiles: SourceFile[], isBundledEmit: boolean) {
+            function getDeclFileName(emitFileNames: EmitFileNames, _sourceFiles: SourceFile[], isBundledEmit: boolean) {
                 // Dont add reference path to this file if it is a bundled emit and caller asked not emit bundled file path
                 if (isBundledEmit && !addBundledFileReference) {
                     return;
diff --git a/src/compiler/emitter.ts b/src/compiler/emitter.ts
index 16f7e5a1c8a2f..1051c9adca961 100644
--- a/src/compiler/emitter.ts
+++ b/src/compiler/emitter.ts
@@ -14,7 +14,7 @@ namespace ts {
     }
 
     const id = (s: SourceFile) => s;
-    const nullTransformers: Transformer[] = [ctx => id];
+    const nullTransformers: Transformer[] = [_ => id];
 
     // targetSourceFile is when users only want one file in entire project to be emitted. This is used in compileOnSave feature
     export function emitFiles(resolver: EmitResolver, host: EmitHost, targetSourceFile: SourceFile, emitOnlyDtsFiles?: boolean): EmitResult {
@@ -593,7 +593,7 @@ const _super = (function (geti, seti) {
                 case SyntaxKind.ExpressionWithTypeArguments:
                     return emitExpressionWithTypeArguments(<ExpressionWithTypeArguments>node);
                 case SyntaxKind.ThisType:
-                    return emitThisType(<ThisTypeNode>node);
+                    return emitThisType();
                 case SyntaxKind.LiteralType:
                     return emitLiteralType(<LiteralTypeNode>node);
 
@@ -609,7 +609,7 @@ const _super = (function (geti, seti) {
                 case SyntaxKind.TemplateSpan:
                     return emitTemplateSpan(<TemplateSpan>node);
                 case SyntaxKind.SemicolonClassElement:
-                    return emitSemicolonClassElement(<SemicolonClassElement>node);
+                    return emitSemicolonClassElement();
 
                 // Statements
                 case SyntaxKind.Block:
@@ -617,7 +617,7 @@ const _super = (function (geti, seti) {
                 case SyntaxKind.VariableStatement:
                     return emitVariableStatement(<VariableStatement>node);
                 case SyntaxKind.EmptyStatement:
-                    return emitEmptyStatement(<EmptyStatement>node);
+                    return emitEmptyStatement();
                 case SyntaxKind.ExpressionStatement:
                     return emitExpressionStatement(<ExpressionStatement>node);
                 case SyntaxKind.IfStatement:
@@ -1014,7 +1014,7 @@ const _super = (function (geti, seti) {
             write(";");
         }
 
-        function emitSemicolonClassElement(node: SemicolonClassElement) {
+        function emitSemicolonClassElement() {
             write(";");
         }
 
@@ -1084,7 +1084,7 @@ const _super = (function (geti, seti) {
             write(")");
         }
 
-        function emitThisType(node: ThisTypeNode) {
+        function emitThisType() {
             write("this");
         }
 
@@ -1397,7 +1397,7 @@ const _super = (function (geti, seti) {
         // Statements
         //
 
-        function emitBlock(node: Block, format?: ListFormat) {
+        function emitBlock(node: Block) {
             if (isSingleLineEmptyBlock(node)) {
                 writeToken(SyntaxKind.OpenBraceToken, node.pos, /*contextNode*/ node);
                 write(" ");
@@ -1425,7 +1425,7 @@ const _super = (function (geti, seti) {
             write(";");
         }
 
-        function emitEmptyStatement(node: EmptyStatement) {
+        function emitEmptyStatement() {
             write(";");
         }
 
@@ -1623,13 +1623,13 @@ const _super = (function (geti, seti) {
 
                     if (getEmitFlags(node) & EmitFlags.ReuseTempVariableScope) {
                         emitSignatureHead(node);
-                        emitBlockFunctionBody(node, body);
+                        emitBlockFunctionBody(body);
                     }
                     else {
                         const savedTempFlags = tempFlags;
                         tempFlags = 0;
                         emitSignatureHead(node);
-                        emitBlockFunctionBody(node, body);
+                        emitBlockFunctionBody(body);
                         tempFlags = savedTempFlags;
                     }
 
@@ -1656,7 +1656,7 @@ const _super = (function (geti, seti) {
             emitWithPrefix(": ", node.type);
         }
 
-        function shouldEmitBlockFunctionBodyOnSingleLine(parentNode: Node, body: Block) {
+        function shouldEmitBlockFunctionBodyOnSingleLine(body: Block) {
             // We must emit a function body as a single-line body in the following case:
             // * The body has NodeEmitFlags.SingleLine specified.
 
@@ -1694,12 +1694,12 @@ const _super = (function (geti, seti) {
             return true;
         }
 
-        function emitBlockFunctionBody(parentNode: Node, body: Block) {
+        function emitBlockFunctionBody(body: Block) {
             write(" {");
             increaseIndent();
 
             emitBodyWithDetachedComments(body, body.statements,
-                shouldEmitBlockFunctionBodyOnSingleLine(parentNode, body)
+                shouldEmitBlockFunctionBodyOnSingleLine(body)
                     ? emitBlockFunctionBodyOnSingleLine
                     : emitBlockFunctionBodyWorker);
 
diff --git a/src/compiler/moduleNameResolver.ts b/src/compiler/moduleNameResolver.ts
index 4ebdc59e6ddfd..3fa54f127e1e6 100644
--- a/src/compiler/moduleNameResolver.ts
+++ b/src/compiler/moduleNameResolver.ts
@@ -5,7 +5,7 @@ namespace ts {
 
     /* @internal */
     export function trace(host: ModuleResolutionHost, message: DiagnosticMessage, ...args: any[]): void;
-    export function trace(host: ModuleResolutionHost, message: DiagnosticMessage): void {
+    export function trace(host: ModuleResolutionHost): void {
         host.trace(formatMessage.apply(undefined, arguments));
     }
 
diff --git a/src/compiler/parser.ts b/src/compiler/parser.ts
index 62ae61e4cb432..8cdbf956d42a8 100644
--- a/src/compiler/parser.ts
+++ b/src/compiler/parser.ts
@@ -572,10 +572,10 @@ namespace ts {
         // attached to the EOF token.
         let parseErrorBeforeNextFinishedNode = false;
 
-        export function parseSourceFile(fileName: string, _sourceText: string, languageVersion: ScriptTarget, _syntaxCursor: IncrementalParser.SyntaxCursor, setParentNodes?: boolean, scriptKind?: ScriptKind): SourceFile {
+        export function parseSourceFile(fileName: string, sourceText: string, languageVersion: ScriptTarget, syntaxCursor: IncrementalParser.SyntaxCursor, setParentNodes?: boolean, scriptKind?: ScriptKind): SourceFile {
             scriptKind = ensureScriptKind(fileName, scriptKind);
 
-            initializeState(fileName, _sourceText, languageVersion, _syntaxCursor, scriptKind);
+            initializeState(sourceText, languageVersion, syntaxCursor, scriptKind);
 
             const result = parseSourceFileWorker(fileName, languageVersion, setParentNodes, scriptKind);
 
@@ -589,7 +589,7 @@ namespace ts {
             return scriptKind === ScriptKind.TSX || scriptKind === ScriptKind.JSX || scriptKind === ScriptKind.JS ? LanguageVariant.JSX : LanguageVariant.Standard;
         }
 
-        function initializeState(fileName: string, _sourceText: string, languageVersion: ScriptTarget, _syntaxCursor: IncrementalParser.SyntaxCursor, scriptKind: ScriptKind) {
+        function initializeState(_sourceText: string, languageVersion: ScriptTarget, _syntaxCursor: IncrementalParser.SyntaxCursor, scriptKind: ScriptKind) {
             NodeConstructor = objectAllocator.getNodeConstructor();
             TokenConstructor = objectAllocator.getTokenConstructor();
             IdentifierConstructor = objectAllocator.getIdentifierConstructor();
@@ -5259,7 +5259,7 @@ namespace ts {
             parseExpected(SyntaxKind.ClassKeyword);
             node.name = parseNameOfClassDeclarationOrExpression();
             node.typeParameters = parseTypeParameters();
-            node.heritageClauses = parseHeritageClauses(/*isClassHeritageClause*/ true);
+            node.heritageClauses = parseHeritageClauses();
 
             if (parseExpected(SyntaxKind.OpenBraceToken)) {
                 // ClassTail[Yield,Await] : (Modified) See 14.5
@@ -5289,7 +5289,7 @@ namespace ts {
             return token() === SyntaxKind.ImplementsKeyword && lookAhead(nextTokenIsIdentifierOrKeyword);
         }
 
-        function parseHeritageClauses(isClassHeritageClause: boolean): NodeArray<HeritageClause> {
+        function parseHeritageClauses(): NodeArray<HeritageClause> {
             // ClassTail[Yield,Await] : (Modified) See 14.5
             //      ClassHeritage[?Yield,?Await]opt { ClassBody[?Yield,?Await]opt }
 
@@ -5337,7 +5337,7 @@ namespace ts {
             parseExpected(SyntaxKind.InterfaceKeyword);
             node.name = parseIdentifier();
             node.typeParameters = parseTypeParameters();
-            node.heritageClauses = parseHeritageClauses(/*isClassHeritageClause*/ false);
+            node.heritageClauses = parseHeritageClauses();
             node.members = parseObjectTypeMembers();
             return addJSDocComment(finishNode(node));
         }
@@ -5817,7 +5817,7 @@ namespace ts {
             }
 
             export function parseJSDocTypeExpressionForTests(content: string, start: number, length: number) {
-                initializeState("file.js", content, ScriptTarget.Latest, /*_syntaxCursor:*/ undefined, ScriptKind.JS);
+                initializeState(content, ScriptTarget.Latest, /*_syntaxCursor:*/ undefined, ScriptKind.JS);
                 sourceFile = createSourceFile("file.js", ScriptTarget.Latest, ScriptKind.JS);
                 scanner.setText(content, start, length);
                 currentToken = scanner.scan();
@@ -6134,7 +6134,7 @@ namespace ts {
             }
 
             export function parseIsolatedJSDocComment(content: string, start: number, length: number) {
-                initializeState("file.js", content, ScriptTarget.Latest, /*_syntaxCursor:*/ undefined, ScriptKind.JS);
+                initializeState(content, ScriptTarget.Latest, /*_syntaxCursor:*/ undefined, ScriptKind.JS);
                 sourceFile = <SourceFile>{ languageVariant: LanguageVariant.Standard, text: content };
                 const jsDoc = parseJSDocCommentWorker(start, length);
                 const diagnostics = parseDiagnostics;
diff --git a/src/compiler/performance.ts b/src/compiler/performance.ts
index e8f064e81cdf3..a48eb117e28b9 100644
--- a/src/compiler/performance.ts
+++ b/src/compiler/performance.ts
@@ -12,7 +12,7 @@ namespace ts.performance {
 
     const profilerEvent = typeof onProfilerEvent === "function" && onProfilerEvent.profiler === true
             ? onProfilerEvent
-            : (markName: string) => { };
+            : (_markName: string) => { };
 
     let enabled = false;
     let profilerStart = 0;
diff --git a/src/compiler/program.ts b/src/compiler/program.ts
index 06e9f6f30f1d8..b34791b71983d 100644
--- a/src/compiler/program.ts
+++ b/src/compiler/program.ts
@@ -724,7 +724,7 @@ namespace ts {
             }
         }
 
-        function getSyntacticDiagnosticsForFile(sourceFile: SourceFile, cancellationToken: CancellationToken): Diagnostic[] {
+        function getSyntacticDiagnosticsForFile(sourceFile: SourceFile): Diagnostic[] {
             return sourceFile.parseDiagnostics;
         }
 
@@ -761,7 +761,7 @@ namespace ts {
                 // Instead, we just report errors for using TypeScript-only constructs from within a
                 // JavaScript file.
                 const checkDiagnostics = isSourceFileJavaScript(sourceFile) ?
-                    getJavaScriptSemanticDiagnosticsForFile(sourceFile, cancellationToken) :
+                    getJavaScriptSemanticDiagnosticsForFile(sourceFile) :
                     typeChecker.getDiagnostics(sourceFile, cancellationToken);
                 const fileProcessingDiagnosticsInFile = fileProcessingDiagnostics.getDiagnostics(sourceFile.fileName);
                 const programDiagnosticsInFile = programDiagnostics.getDiagnostics(sourceFile.fileName);
@@ -770,7 +770,7 @@ namespace ts {
             });
         }
 
-        function getJavaScriptSemanticDiagnosticsForFile(sourceFile: SourceFile, cancellationToken: CancellationToken): Diagnostic[] {
+        function getJavaScriptSemanticDiagnosticsForFile(sourceFile: SourceFile): Diagnostic[] {
             return runWithCancellationToken(() => {
                 const diagnostics: Diagnostic[] = [];
                 walk(sourceFile);
@@ -977,7 +977,7 @@ namespace ts {
         }
 
         function processRootFile(fileName: string, isDefaultLib: boolean) {
-            processSourceFile(normalizePath(fileName), isDefaultLib, /*isReference*/ true);
+            processSourceFile(normalizePath(fileName), isDefaultLib);
         }
 
         function fileReferenceIsEqualTo(a: FileReference, b: FileReference): boolean {
@@ -1088,7 +1088,7 @@ namespace ts {
         /**
           * 'isReference' indicates whether the file was brought in via a reference directive (rather than an import declaration)
           */
-        function processSourceFile(fileName: string, isDefaultLib: boolean, isReference: boolean, refFile?: SourceFile, refPos?: number, refEnd?: number) {
+        function processSourceFile(fileName: string, isDefaultLib: boolean, refFile?: SourceFile, refPos?: number, refEnd?: number) {
             let diagnosticArgument: string[];
             let diagnostic: DiagnosticMessage;
             if (hasExtension(fileName)) {
@@ -1096,7 +1096,7 @@ namespace ts {
                     diagnostic = Diagnostics.File_0_has_unsupported_extension_The_only_supported_extensions_are_1;
                     diagnosticArgument = [fileName, "'" + supportedExtensions.join("', '") + "'"];
                 }
-                else if (!findSourceFile(fileName, toPath(fileName, currentDirectory, getCanonicalFileName), isDefaultLib, isReference, refFile, refPos, refEnd)) {
+                else if (!findSourceFile(fileName, toPath(fileName, currentDirectory, getCanonicalFileName), isDefaultLib, refFile, refPos, refEnd)) {
                     diagnostic = Diagnostics.File_0_not_found;
                     diagnosticArgument = [fileName];
                 }
@@ -1106,13 +1106,13 @@ namespace ts {
                 }
             }
             else {
-                const nonTsFile: SourceFile = options.allowNonTsExtensions && findSourceFile(fileName, toPath(fileName, currentDirectory, getCanonicalFileName), isDefaultLib, isReference, refFile, refPos, refEnd);
+                const nonTsFile: SourceFile = options.allowNonTsExtensions && findSourceFile(fileName, toPath(fileName, currentDirectory, getCanonicalFileName), isDefaultLib, refFile, refPos, refEnd);
                 if (!nonTsFile) {
                     if (options.allowNonTsExtensions) {
                         diagnostic = Diagnostics.File_0_not_found;
                         diagnosticArgument = [fileName];
                     }
-                    else if (!forEach(supportedExtensions, extension => findSourceFile(fileName + extension, toPath(fileName + extension, currentDirectory, getCanonicalFileName), isDefaultLib, isReference, refFile, refPos, refEnd))) {
+                    else if (!forEach(supportedExtensions, extension => findSourceFile(fileName + extension, toPath(fileName + extension, currentDirectory, getCanonicalFileName), isDefaultLib, refFile, refPos, refEnd))) {
                         diagnostic = Diagnostics.File_0_not_found;
                         fileName += ".ts";
                         diagnosticArgument = [fileName];
@@ -1141,7 +1141,7 @@ namespace ts {
         }
 
         // Get source file from normalized fileName
-        function findSourceFile(fileName: string, path: Path, isDefaultLib: boolean, isReference: boolean, refFile?: SourceFile, refPos?: number, refEnd?: number): SourceFile {
+        function findSourceFile(fileName: string, path: Path, isDefaultLib: boolean, refFile?: SourceFile, refPos?: number, refEnd?: number): SourceFile {
             if (filesByName.contains(path)) {
                 const file = filesByName.get(path);
                 // try to check if we've already seen this file but with a different casing in path
@@ -1155,18 +1155,18 @@ namespace ts {
                 if (file && sourceFilesFoundSearchingNodeModules[file.path] && currentNodeModulesDepth == 0) {
                     sourceFilesFoundSearchingNodeModules[file.path] = false;
                     if (!options.noResolve) {
-                        processReferencedFiles(file, getDirectoryPath(fileName), isDefaultLib);
+                        processReferencedFiles(file, isDefaultLib);
                         processTypeReferenceDirectives(file);
                     }
 
                     modulesWithElidedImports[file.path] = false;
-                    processImportedModules(file, getDirectoryPath(fileName));
+                    processImportedModules(file);
                 }
                 // See if we need to reprocess the imports due to prior skipped imports
                 else if (file && modulesWithElidedImports[file.path]) {
                     if (currentNodeModulesDepth < maxNodeModulesJsDepth) {
                         modulesWithElidedImports[file.path] = false;
-                        processImportedModules(file, getDirectoryPath(fileName));
+                        processImportedModules(file);
                     }
                 }
 
@@ -1202,14 +1202,13 @@ namespace ts {
 
                 skipDefaultLib = skipDefaultLib || file.hasNoDefaultLib;
 
-                const basePath = getDirectoryPath(fileName);
                 if (!options.noResolve) {
-                    processReferencedFiles(file, basePath, isDefaultLib);
+                    processReferencedFiles(file, isDefaultLib);
                     processTypeReferenceDirectives(file);
                 }
 
                 // always process imported modules to record module name resolutions
-                processImportedModules(file, basePath);
+                processImportedModules(file);
 
                 if (isDefaultLib) {
                     files.unshift(file);
@@ -1222,10 +1221,10 @@ namespace ts {
             return file;
         }
 
-        function processReferencedFiles(file: SourceFile, basePath: string, isDefaultLib: boolean) {
+        function processReferencedFiles(file: SourceFile, isDefaultLib: boolean) {
             forEach(file.referencedFiles, ref => {
                 const referencedFileName = resolveTripleslashReference(ref.fileName, file.fileName);
-                processSourceFile(referencedFileName, isDefaultLib, /*isReference*/ true, file, ref.pos, ref.end);
+                processSourceFile(referencedFileName, isDefaultLib, file, ref.pos, ref.end);
             });
         }
 
@@ -1256,7 +1255,7 @@ namespace ts {
             if (resolvedTypeReferenceDirective) {
                 if (resolvedTypeReferenceDirective.primary) {
                     // resolved from the primary path
-                    processSourceFile(resolvedTypeReferenceDirective.resolvedFileName, /*isDefaultLib*/ false, /*isReference*/ true, refFile, refPos, refEnd);
+                    processSourceFile(resolvedTypeReferenceDirective.resolvedFileName, /*isDefaultLib*/ false, refFile, refPos, refEnd);
                 }
                 else {
                     // If we already resolved to this file, it must have been a secondary reference. Check file contents
@@ -1276,7 +1275,7 @@ namespace ts {
                     }
                     else {
                         // First resolution of this library
-                        processSourceFile(resolvedTypeReferenceDirective.resolvedFileName, /*isDefaultLib*/ false, /*isReference*/ true, refFile, refPos, refEnd);
+                        processSourceFile(resolvedTypeReferenceDirective.resolvedFileName, /*isDefaultLib*/ false, refFile, refPos, refEnd);
                     }
                 }
             }
@@ -1302,7 +1301,7 @@ namespace ts {
             return host.getCanonicalFileName(fileName);
         }
 
-        function processImportedModules(file: SourceFile, basePath: string) {
+        function processImportedModules(file: SourceFile) {
             collectExternalModuleReferences(file);
             if (file.imports.length || file.moduleAugmentations.length) {
                 file.resolvedModules = createMap<ResolvedModule>();
@@ -1333,7 +1332,7 @@ namespace ts {
                     else if (shouldAddFile) {
                         findSourceFile(resolution.resolvedFileName,
                                 toPath(resolution.resolvedFileName, currentDirectory, getCanonicalFileName),
-                                /*isDefaultLib*/ false, /*isReference*/ false,
+                                /*isDefaultLib*/ false,
                                 file,
                                 skipTrivia(file.text, file.imports[i].pos),
                                 file.imports[i].end);
@@ -1541,7 +1540,7 @@ namespace ts {
             if (!options.noEmit && !options.suppressOutputPathCheck) {
                 const emitHost = getEmitHost();
                 const emitFilesSeen = createFileMap<boolean>(!host.useCaseSensitiveFileNames() ? key => key.toLocaleLowerCase() : undefined);
-                forEachExpectedEmitFile(emitHost, (emitFileNames, sourceFiles, isBundledEmit) => {
+                forEachExpectedEmitFile(emitHost, (emitFileNames) => {
                     verifyEmitFilePath(emitFileNames.jsFilePath, emitFilesSeen);
                     verifyEmitFilePath(emitFileNames.declarationFilePath, emitFilesSeen);
                 });
@@ -1553,13 +1552,13 @@ namespace ts {
                     const emitFilePath = toPath(emitFileName, currentDirectory, getCanonicalFileName);
                     // Report error if the output overwrites input file
                     if (filesByName.contains(emitFilePath)) {
-                        createEmitBlockingDiagnostics(emitFileName, emitFilePath, Diagnostics.Cannot_write_file_0_because_it_would_overwrite_input_file);
+                        createEmitBlockingDiagnostics(emitFileName, Diagnostics.Cannot_write_file_0_because_it_would_overwrite_input_file);
                     }
 
                     // Report error if multiple files write into same file
                     if (emitFilesSeen.contains(emitFilePath)) {
                         // Already seen the same emit file - report error
-                        createEmitBlockingDiagnostics(emitFileName, emitFilePath, Diagnostics.Cannot_write_file_0_because_it_would_be_overwritten_by_multiple_input_files);
+                        createEmitBlockingDiagnostics(emitFileName, Diagnostics.Cannot_write_file_0_because_it_would_be_overwritten_by_multiple_input_files);
                     }
                     else {
                         emitFilesSeen.set(emitFilePath, true);
@@ -1568,7 +1567,7 @@ namespace ts {
             }
         }
 
-        function createEmitBlockingDiagnostics(emitFileName: string, emitFilePath: Path, message: DiagnosticMessage) {
+        function createEmitBlockingDiagnostics(emitFileName: string, message: DiagnosticMessage) {
             hasEmitBlockingDiagnostics.set(toPath(emitFileName, currentDirectory, getCanonicalFileName), true);
             programDiagnostics.add(createCompilerDiagnostic(message, emitFileName));
         }
diff --git a/src/compiler/scanner.ts b/src/compiler/scanner.ts
index b79106766daef..ab76c7ffa19a4 100644
--- a/src/compiler/scanner.ts
+++ b/src/compiler/scanner.ts
@@ -723,7 +723,7 @@ namespace ts {
         return iterateCommentRanges(/*reduce*/ true, text, pos, /*trailing*/ true, cb, state, initial);
     }
 
-    function appendCommentRange(pos: number, end: number, kind: SyntaxKind, hasTrailingNewLine: boolean, state: any, comments: CommentRange[]) {
+    function appendCommentRange(pos: number, end: number, kind: SyntaxKind, hasTrailingNewLine: boolean, _state: any, comments: CommentRange[]) {
         if (!comments) {
             comments = [];
         }
diff --git a/src/compiler/sys.ts b/src/compiler/sys.ts
index 1efa1e2b010dd..585fb60df32a6 100644
--- a/src/compiler/sys.ts
+++ b/src/compiler/sys.ts
@@ -46,13 +46,9 @@ namespace ts {
     }
 
     declare var require: any;
-    declare var module: any;
     declare var process: any;
     declare var global: any;
     declare var __filename: string;
-    declare var Buffer: {
-        new (str: string, encoding?: string): any;
-    };
 
     declare class Enumerator {
         public atEnd(): boolean;
@@ -324,7 +320,7 @@ namespace ts {
             const platform: string = _os.platform();
             const useCaseSensitiveFileNames = isFileSystemCaseSensitive();
 
-            function readFile(fileName: string, encoding?: string): string {
+            function readFile(fileName: string, _encoding?: string): string {
                 if (!fileExists(fileName)) {
                     return undefined;
                 }
@@ -576,7 +572,7 @@ namespace ts {
                 args: ChakraHost.args,
                 useCaseSensitiveFileNames: !!ChakraHost.useCaseSensitiveFileNames,
                 write: ChakraHost.echo,
-                readFile(path: string, encoding?: string) {
+                readFile(path: string, _encoding?: string) {
                     // encoding is automatically handled by the implementation in ChakraHost
                     return ChakraHost.readFile(path);
                 },
@@ -595,9 +591,9 @@ namespace ts {
                 getExecutingFilePath: () => ChakraHost.executingFile,
                 getCurrentDirectory: () => ChakraHost.currentDirectory,
                 getDirectories: ChakraHost.getDirectories,
-                getEnvironmentVariable: ChakraHost.getEnvironmentVariable || ((name: string) => ""),
+                getEnvironmentVariable: ChakraHost.getEnvironmentVariable || (() => ""),
                 readDirectory: (path: string, extensions?: string[], excludes?: string[], includes?: string[]) => {
-                    const pattern = getFileMatcherPatterns(path, extensions, excludes, includes, !!ChakraHost.useCaseSensitiveFileNames, ChakraHost.currentDirectory);
+                    const pattern = getFileMatcherPatterns(path, excludes, includes, !!ChakraHost.useCaseSensitiveFileNames, ChakraHost.currentDirectory);
                     return ChakraHost.readDirectory(path, extensions, pattern.basePaths, pattern.excludePattern, pattern.includeFilePattern, pattern.includeDirectoryPattern);
                 },
                 exit: ChakraHost.quit,
diff --git a/src/compiler/transformer.ts b/src/compiler/transformer.ts
index e1e83a6b8508a..b27c8f6e79f8e 100644
--- a/src/compiler/transformer.ts
+++ b/src/compiler/transformer.ts
@@ -165,7 +165,7 @@ namespace ts {
             hoistFunctionDeclaration,
             startLexicalEnvironment,
             endLexicalEnvironment,
-            onSubstituteNode: (emitContext, node) => node,
+            onSubstituteNode: (_emitContext, node) => node,
             enableSubstitution,
             isSubstitutionEnabled,
             onEmitNode: (node, emitContext, emitCallback) => emitCallback(node, emitContext),
diff --git a/src/compiler/transformers/destructuring.ts b/src/compiler/transformers/destructuring.ts
index c7219866df7a9..3eaa1b764a98a 100644
--- a/src/compiler/transformers/destructuring.ts
+++ b/src/compiler/transformers/destructuring.ts
@@ -51,7 +51,7 @@ namespace ts {
             location = value;
         }
 
-        flattenDestructuring(context, node, value, location, emitAssignment, emitTempVariableAssignment, visitor);
+        flattenDestructuring(node, value, location, emitAssignment, emitTempVariableAssignment, visitor);
 
         if (needsValue) {
             expressions.push(value);
@@ -87,13 +87,12 @@ namespace ts {
      * @param visitor An optional visitor to use to visit expressions.
      */
     export function flattenParameterDestructuring(
-        context: TransformationContext,
         node: ParameterDeclaration,
         value: Expression,
         visitor?: (node: Node) => VisitResult<Node>) {
         const declarations: VariableDeclaration[] = [];
 
-        flattenDestructuring(context, node, value, node, emitAssignment, emitTempVariableAssignment, visitor);
+        flattenDestructuring(node, value, node, emitAssignment, emitTempVariableAssignment, visitor);
 
         return declarations;
 
@@ -123,7 +122,6 @@ namespace ts {
      * @param visitor An optional visitor to use to visit expressions.
      */
     export function flattenVariableDestructuring(
-        context: TransformationContext,
         node: VariableDeclaration,
         value?: Expression,
         visitor?: (node: Node) => VisitResult<Node>,
@@ -131,7 +129,7 @@ namespace ts {
         const declarations: VariableDeclaration[] = [];
 
         let pendingAssignments: Expression[];
-        flattenDestructuring(context, node, value, node, emitAssignment, emitTempVariableAssignment, visitor);
+        flattenDestructuring(node, value, node, emitAssignment, emitTempVariableAssignment, visitor);
 
         return declarations;
 
@@ -180,7 +178,6 @@ namespace ts {
      * @param visitor An optional visitor to use to visit expressions.
      */
     export function flattenVariableDestructuringToExpression(
-        context: TransformationContext,
         node: VariableDeclaration,
         recordTempVariable: (name: Identifier) => void,
         nameSubstitution?: (name: Identifier) => Expression,
@@ -188,7 +185,7 @@ namespace ts {
 
         const pendingAssignments: Expression[] = [];
 
-        flattenDestructuring(context, node, /*value*/ undefined, node, emitAssignment, emitTempVariableAssignment, visitor);
+        flattenDestructuring(node, /*value*/ undefined, node, emitAssignment, emitTempVariableAssignment, visitor);
 
         const expression = inlineExpressions(pendingAssignments);
         aggregateTransformFlags(expression);
@@ -219,7 +216,6 @@ namespace ts {
     }
 
     function flattenDestructuring(
-        context: TransformationContext,
         root: VariableDeclaration | ParameterDeclaration | BindingElement | BinaryExpression,
         value: Expression,
         location: TextRange,
diff --git a/src/compiler/transformers/es2015.ts b/src/compiler/transformers/es2015.ts
index bb2e8ac2aa501..9972f339c1652 100644
--- a/src/compiler/transformers/es2015.ts
+++ b/src/compiler/transformers/es2015.ts
@@ -396,7 +396,7 @@ namespace ts {
                     return visitYieldExpression(<YieldExpression>node);
 
                 case SyntaxKind.SuperKeyword:
-                    return visitSuperKeyword(<PrimaryExpression>node);
+                    return visitSuperKeyword();
 
                 case SyntaxKind.YieldExpression:
                     // `yield` will be handled by a generators transform.
@@ -1118,7 +1118,7 @@ namespace ts {
                         createVariableStatement(
                             /*modifiers*/ undefined,
                             createVariableDeclarationList(
-                                flattenParameterDestructuring(context, parameter, temp, visitor)
+                                flattenParameterDestructuring(parameter, temp, visitor)
                             )
                         ),
                         EmitFlags.CustomPrologue
@@ -1690,7 +1690,7 @@ namespace ts {
                     if (decl.initializer) {
                         let assignment: Expression;
                         if (isBindingPattern(decl.name)) {
-                            assignment = flattenVariableDestructuringToExpression(context, decl, hoistVariableDeclaration, /*nameSubstitution*/ undefined, visitor);
+                            assignment = flattenVariableDestructuringToExpression(decl, hoistVariableDeclaration, /*nameSubstitution*/ undefined, visitor);
                         }
                         else {
                             assignment = createBinary(<Identifier>decl.name, SyntaxKind.EqualsToken, visitNode(decl.initializer, visitor, isExpression));
@@ -1843,7 +1843,7 @@ namespace ts {
             if (isBindingPattern(node.name)) {
                 const recordTempVariablesInLine = !enclosingVariableStatement
                     || !hasModifier(enclosingVariableStatement, ModifierFlags.Export);
-                return flattenVariableDestructuring(context, node, /*value*/ undefined, visitor,
+                return flattenVariableDestructuring(node, /*value*/ undefined, visitor,
                     recordTempVariablesInLine ? undefined : hoistVariableDeclaration);
             }
 
@@ -1946,7 +1946,6 @@ namespace ts {
                     // This works whether the declaration is a var, let, or const.
                     // It will use rhsIterationValue _a[_i] as the initializer.
                     const declarations = flattenVariableDestructuring(
-                        context,
                         firstOriginalDeclaration,
                         createElementAccess(rhsReference, counter),
                         visitor
@@ -2539,15 +2538,15 @@ namespace ts {
                         break;
 
                     case SyntaxKind.PropertyAssignment:
-                        expressions.push(transformPropertyAssignmentToExpression(node, <PropertyAssignment>property, receiver, node.multiLine));
+                        expressions.push(transformPropertyAssignmentToExpression(<PropertyAssignment>property, receiver, node.multiLine));
                         break;
 
                     case SyntaxKind.ShorthandPropertyAssignment:
-                        expressions.push(transformShorthandPropertyAssignmentToExpression(node, <ShorthandPropertyAssignment>property, receiver, node.multiLine));
+                        expressions.push(transformShorthandPropertyAssignmentToExpression(<ShorthandPropertyAssignment>property, receiver, node.multiLine));
                         break;
 
                     case SyntaxKind.MethodDeclaration:
-                        expressions.push(transformObjectLiteralMethodDeclarationToExpression(node, <MethodDeclaration>property, receiver, node.multiLine));
+                        expressions.push(transformObjectLiteralMethodDeclarationToExpression(<MethodDeclaration>property, receiver, node.multiLine));
                         break;
 
                     default:
@@ -2564,7 +2563,7 @@ namespace ts {
          * @param property The PropertyAssignment node.
          * @param receiver The receiver for the assignment.
          */
-        function transformPropertyAssignmentToExpression(node: ObjectLiteralExpression, property: PropertyAssignment, receiver: Expression, startsOnNewLine: boolean) {
+        function transformPropertyAssignmentToExpression(property: PropertyAssignment, receiver: Expression, startsOnNewLine: boolean) {
             const expression = createAssignment(
                 createMemberAccessForPropertyName(
                     receiver,
@@ -2586,7 +2585,7 @@ namespace ts {
          * @param property The ShorthandPropertyAssignment node.
          * @param receiver The receiver for the assignment.
          */
-        function transformShorthandPropertyAssignmentToExpression(node: ObjectLiteralExpression, property: ShorthandPropertyAssignment, receiver: Expression, startsOnNewLine: boolean) {
+        function transformShorthandPropertyAssignmentToExpression(property: ShorthandPropertyAssignment, receiver: Expression, startsOnNewLine: boolean) {
             const expression = createAssignment(
                 createMemberAccessForPropertyName(
                     receiver,
@@ -2608,7 +2607,7 @@ namespace ts {
          * @param method The MethodDeclaration node.
          * @param receiver The receiver for the assignment.
          */
-        function transformObjectLiteralMethodDeclarationToExpression(node: ObjectLiteralExpression, method: MethodDeclaration, receiver: Expression, startsOnNewLine: boolean) {
+        function transformObjectLiteralMethodDeclarationToExpression(method: MethodDeclaration, receiver: Expression, startsOnNewLine: boolean) {
             const expression = createAssignment(
                 createMemberAccessForPropertyName(
                     receiver,
@@ -2798,7 +2797,7 @@ namespace ts {
             // expressions into an array literal.
             const numElements = elements.length;
             const segments = flatten(
-                spanMap(elements, partitionSpreadElement, (partition, visitPartition, start, end) =>
+                spanMap(elements, partitionSpreadElement, (partition, visitPartition, _start, end) =>
                     visitPartition(partition, multiLine, hasTrailingComma && end === numElements)
                 )
             );
@@ -2820,7 +2819,7 @@ namespace ts {
                 : visitSpanOfNonSpreadElements;
         }
 
-        function visitSpanOfSpreadElements(chunk: Expression[], multiLine: boolean, hasTrailingComma: boolean): VisitResult<Expression> {
+        function visitSpanOfSpreadElements(chunk: Expression[]): VisitResult<Expression> {
             return map(chunk, visitExpressionOfSpreadElement);
         }
 
@@ -3009,7 +3008,7 @@ namespace ts {
         /**
          * Visits the `super` keyword
          */
-        function visitSuperKeyword(node: PrimaryExpression): LeftHandSideExpression {
+        function visitSuperKeyword(): LeftHandSideExpression {
             return enclosingNonAsyncFunctionBody
                 && isClassElement(enclosingNonAsyncFunctionBody)
                 && !hasModifier(enclosingNonAsyncFunctionBody, ModifierFlags.Static)
diff --git a/src/compiler/transformers/generators.ts b/src/compiler/transformers/generators.ts
index aaf9014c5cc6a..200e5ec72962d 100644
--- a/src/compiler/transformers/generators.ts
+++ b/src/compiler/transformers/generators.ts
@@ -956,7 +956,7 @@ namespace ts {
          * @param elements The elements to visit.
          * @param multiLine Whether array literals created should be emitted on multiple lines.
          */
-        function visitElements(elements: NodeArray<Expression>, multiLine: boolean) {
+        function visitElements(elements: NodeArray<Expression>, _multiLine?: boolean) {
             // [source]
             //      ar = [1, yield, 2];
             //
@@ -1102,7 +1102,7 @@ namespace ts {
                     createFunctionApply(
                         cacheExpression(visitNode(target, visitor, isLeftHandSideExpression)),
                         thisArg,
-                        visitElements(node.arguments, /*multiLine*/ false),
+                        visitElements(node.arguments),
                         /*location*/ node
                     ),
                     node
@@ -1131,7 +1131,7 @@ namespace ts {
                         createFunctionApply(
                             cacheExpression(visitNode(target, visitor, isExpression)),
                             thisArg,
-                            visitElements(node.arguments, /*multiLine*/ false)
+                            visitElements(node.arguments)
                         ),
                         /*typeArguments*/ undefined,
                         [],
diff --git a/src/compiler/transformers/module/es2015.ts b/src/compiler/transformers/module/es2015.ts
index 23fb444b6ff1e..93aa108617a5b 100644
--- a/src/compiler/transformers/module/es2015.ts
+++ b/src/compiler/transformers/module/es2015.ts
@@ -22,7 +22,8 @@ namespace ts {
         function visitor(node: Node): VisitResult<Node> {
             switch (node.kind) {
                 case SyntaxKind.ImportEqualsDeclaration:
-                    return visitImportEqualsDeclaration(<ImportEqualsDeclaration>node);
+                    // Elide `import=` as it is not legal with --module ES6
+                    return undefined;
                 case SyntaxKind.ExportAssignment:
                     return visitExportAssignment(<ExportAssignment>node);
             }
@@ -30,11 +31,6 @@ namespace ts {
             return node;
         }
 
-        function visitImportEqualsDeclaration(node: ImportEqualsDeclaration): VisitResult<ImportEqualsDeclaration> {
-            // Elide `import=` as it is not legal with --module ES6
-            return undefined;
-        }
-
         function visitExportAssignment(node: ExportAssignment): VisitResult<ExportAssignment> {
             // Elide `export=` as it is not legal with --module ES6
             return node.isExportEquals ? undefined : node;
diff --git a/src/compiler/transformers/module/module.ts b/src/compiler/transformers/module/module.ts
index 1cca7a21777f5..1f56670c93274 100644
--- a/src/compiler/transformers/module/module.ts
+++ b/src/compiler/transformers/module/module.ts
@@ -680,7 +680,6 @@ namespace ts {
             const name = node.name;
             if (isBindingPattern(name)) {
                 return flattenVariableDestructuringToExpression(
-                    context,
                     node,
                     hoistVariableDeclaration,
                     getModuleMemberName,
diff --git a/src/compiler/transformers/module/system.ts b/src/compiler/transformers/module/system.ts
index 775d8fc34f9b5..61f2d5c05099e 100644
--- a/src/compiler/transformers/module/system.ts
+++ b/src/compiler/transformers/module/system.ts
@@ -646,7 +646,7 @@ namespace ts {
             }
             else {
                 // If the variable has a BindingPattern, flatten the variable into multiple assignment expressions.
-                return flattenVariableDestructuringToExpression(context, node, hoistVariableDeclaration);
+                return flattenVariableDestructuringToExpression(node, hoistVariableDeclaration);
             }
         }
 
@@ -795,7 +795,7 @@ namespace ts {
             const name = firstDeclaration.name;
             return isIdentifier(name)
                 ? name
-                : flattenVariableDestructuringToExpression(context, firstDeclaration, hoistVariableDeclaration);
+                : flattenVariableDestructuringToExpression(firstDeclaration, hoistVariableDeclaration);
         }
 
         /**
diff --git a/src/compiler/transformers/ts.ts b/src/compiler/transformers/ts.ts
index a1190efee102c..925869da3857f 100644
--- a/src/compiler/transformers/ts.ts
+++ b/src/compiler/transformers/ts.ts
@@ -580,7 +580,7 @@ namespace ts {
             //      HasLexicalDeclaration (N) : Determines if the argument identifier has a binding in this environment record that was created using
             //                                  a lexical declaration such as a LexicalDeclaration or a ClassDeclaration.
             if (staticProperties.length) {
-                addInitializedPropertyStatements(statements, node, staticProperties, getLocalName(node, /*noSourceMaps*/ true));
+                addInitializedPropertyStatements(statements, staticProperties, getLocalName(node, /*noSourceMaps*/ true));
             }
 
             // Write any decorators of the node.
@@ -822,7 +822,7 @@ namespace ts {
                 // the body of a class with static initializers.
                 setEmitFlags(classExpression, EmitFlags.Indented | getEmitFlags(classExpression));
                 expressions.push(startOnNewLine(createAssignment(temp, classExpression)));
-                addRange(expressions, generateInitializedPropertyExpressions(node, staticProperties, temp));
+                addRange(expressions, generateInitializedPropertyExpressions(staticProperties, temp));
                 expressions.push(startOnNewLine(temp));
                 return inlineExpressions(expressions);
             }
@@ -868,7 +868,7 @@ namespace ts {
             }
 
             const parameters = transformConstructorParameters(constructor);
-            const body = transformConstructorBody(node, constructor, hasExtendsClause, parameters);
+            const body = transformConstructorBody(node, constructor, hasExtendsClause);
 
             //  constructor(${parameters}) {
             //      ${body}
@@ -922,9 +922,8 @@ namespace ts {
          * @param node The current class.
          * @param constructor The current class constructor.
          * @param hasExtendsClause A value indicating whether the class has an extends clause.
-         * @param parameters The transformed parameters for the constructor.
          */
-        function transformConstructorBody(node: ClassExpression | ClassDeclaration, constructor: ConstructorDeclaration, hasExtendsClause: boolean, parameters: ParameterDeclaration[]) {
+        function transformConstructorBody(node: ClassExpression | ClassDeclaration, constructor: ConstructorDeclaration, hasExtendsClause: boolean) {
             const statements: Statement[] = [];
             let indexOfFirstStatement = 0;
 
@@ -976,7 +975,7 @@ namespace ts {
             //  }
             //
             const properties = getInitializedProperties(node, /*isStatic*/ false);
-            addInitializedPropertyStatements(statements, node, properties, createThis());
+            addInitializedPropertyStatements(statements, properties, createThis());
 
             if (constructor) {
                 // The class already had a constructor, so we should add the existing statements, skipping the initial super call.
@@ -1116,13 +1115,12 @@ namespace ts {
         /**
          * Generates assignment statements for property initializers.
          *
-         * @param node The class node.
          * @param properties An array of property declarations to transform.
          * @param receiver The receiver on which each property should be assigned.
          */
-        function addInitializedPropertyStatements(statements: Statement[], node: ClassExpression | ClassDeclaration, properties: PropertyDeclaration[], receiver: LeftHandSideExpression) {
+        function addInitializedPropertyStatements(statements: Statement[], properties: PropertyDeclaration[], receiver: LeftHandSideExpression) {
             for (const property of properties) {
-                const statement = createStatement(transformInitializedProperty(node, property, receiver));
+                const statement = createStatement(transformInitializedProperty(property, receiver));
                 setSourceMapRange(statement, moveRangePastModifiers(property));
                 setCommentRange(statement, property);
                 statements.push(statement);
@@ -1132,14 +1130,13 @@ namespace ts {
         /**
          * Generates assignment expressions for property initializers.
          *
-         * @param node The class node.
          * @param properties An array of property declarations to transform.
          * @param receiver The receiver on which each property should be assigned.
          */
-        function generateInitializedPropertyExpressions(node: ClassExpression | ClassDeclaration, properties: PropertyDeclaration[], receiver: LeftHandSideExpression) {
+        function generateInitializedPropertyExpressions(properties: PropertyDeclaration[], receiver: LeftHandSideExpression) {
             const expressions: Expression[] = [];
             for (const property of properties) {
-                const expression = transformInitializedProperty(node, property, receiver);
+                const expression = transformInitializedProperty(property, receiver);
                 expression.startsOnNewLine = true;
                 setSourceMapRange(expression, moveRangePastModifiers(property));
                 setCommentRange(expression, property);
@@ -1152,11 +1149,10 @@ namespace ts {
         /**
          * Transforms a property initializer into an assignment statement.
          *
-         * @param node The class containing the property.
          * @param property The property declaration.
          * @param receiver The object receiving the property assignment.
          */
-        function transformInitializedProperty(node: ClassExpression | ClassDeclaration, property: PropertyDeclaration, receiver: LeftHandSideExpression) {
+        function transformInitializedProperty(property: PropertyDeclaration, receiver: LeftHandSideExpression) {
             const propertyName = visitPropertyNameOfClassElement(property);
             const initializer = visitNode(property.initializer, visitor, isExpression);
             const memberAccess = createMemberAccessForPropertyName(receiver, propertyName, /*location*/ propertyName);
@@ -2423,7 +2419,6 @@ namespace ts {
             const name = node.name;
             if (isBindingPattern(name)) {
                 return flattenVariableDestructuringToExpression(
-                    context,
                     node,
                     hoistVariableDeclaration,
                     getNamespaceMemberNameWithSourceMapsAndWithoutComments,
diff --git a/src/compiler/tsc.ts b/src/compiler/tsc.ts
index b39c017384e16..aa277c9b5070d 100644
--- a/src/compiler/tsc.ts
+++ b/src/compiler/tsc.ts
@@ -29,7 +29,7 @@ namespace ts {
         }
     }
 
-    function reportEmittedFiles(files: string[], host: CompilerHost): void {
+    function reportEmittedFiles(files: string[]): void {
         if (!files || files.length == 0) {
             return;
         }
@@ -111,7 +111,7 @@ namespace ts {
         return count;
     }
 
-    function getDiagnosticText(message: DiagnosticMessage, ...args: any[]): string {
+    function getDiagnosticText(_message: DiagnosticMessage, ..._args: any[]): string {
         const diagnostic = createCompilerDiagnostic.apply(undefined, arguments);
         return <string>diagnostic.messageText;
     }
@@ -456,7 +456,7 @@ namespace ts {
             const sourceFile = hostGetSourceFile(fileName, languageVersion, onError);
             if (sourceFile && isWatchSet(compilerOptions) && sys.watchFile) {
                 // Attach a file watcher
-                sourceFile.fileWatcher = sys.watchFile(sourceFile.fileName, (fileName: string, removed?: boolean) => sourceFileChanged(sourceFile, removed));
+                sourceFile.fileWatcher = sys.watchFile(sourceFile.fileName, (_fileName: string, removed?: boolean) => sourceFileChanged(sourceFile, removed));
             }
             return sourceFile;
         }
@@ -617,7 +617,7 @@ namespace ts {
 
             reportDiagnostics(sortAndDeduplicateDiagnostics(diagnostics), compilerHost);
 
-            reportEmittedFiles(emitOutput.emittedFiles, compilerHost);
+            reportEmittedFiles(emitOutput.emittedFiles);
 
             if (emitOutput.emitSkipped && diagnostics.length > 0) {
                 // If the emitter didn't emit anything, then pass that value along.
diff --git a/src/compiler/tsconfig.json b/src/compiler/tsconfig.json
index 65ba20f18d260..a6c03d1b680bc 100644
--- a/src/compiler/tsconfig.json
+++ b/src/compiler/tsconfig.json
@@ -9,7 +9,9 @@
         "sourceMap": true,
         "declaration": true,
         "stripInternal": true,
-        "target": "es5"
+        "target": "es5",
+        "noUnusedLocals": true,
+        "noUnusedParameters": true
     },
     "files": [
         "core.ts",
diff --git a/src/compiler/utilities.ts b/src/compiler/utilities.ts
index efdac40c2870f..55374a1cd7483 100644
--- a/src/compiler/utilities.ts
+++ b/src/compiler/utilities.ts
@@ -2566,7 +2566,7 @@ namespace ts {
         const options = host.getCompilerOptions();
         // Emit on each source file
         if (options.outFile || options.out) {
-            onBundledEmit(host, sourceFiles);
+            onBundledEmit(sourceFiles);
         }
         else {
             for (const sourceFile of sourceFiles) {
@@ -2599,7 +2599,7 @@ namespace ts {
             action(jsFilePath, sourceMapFilePath, declarationFilePath, [sourceFile], /*isBundledEmit*/ false);
         }
 
-        function onBundledEmit(host: EmitHost, sourceFiles: SourceFile[]) {
+        function onBundledEmit(sourceFiles: SourceFile[]) {
             if (sourceFiles.length) {
                 const jsFilePath = options.outFile || options.out;
                 const sourceMapFilePath = getSourceMapFilePath(jsFilePath, options);
diff --git a/src/compiler/visitor.ts b/src/compiler/visitor.ts
index 8dca78fec9794..5c152c88e4795 100644
--- a/src/compiler/visitor.ts
+++ b/src/compiler/visitor.ts
@@ -1331,18 +1331,18 @@ namespace ts {
     export namespace Debug {
         export const failNotOptional = shouldAssert(AssertionLevel.Normal)
             ? (message?: string) => assert(false, message || "Node not optional.")
-            : (message?: string) => {};
+            : () => {};
 
         export const failBadSyntaxKind = shouldAssert(AssertionLevel.Normal)
             ? (node: Node, message?: string) => assert(false, message || "Unexpected node.", () => `Node ${formatSyntaxKind(node.kind)} was unexpected.`)
-            : (node: Node, message?: string) => {};
+            : () => {};
 
         export const assertNode = shouldAssert(AssertionLevel.Normal)
             ? (node: Node, test: (node: Node) => boolean, message?: string) => assert(
                     test === undefined || test(node),
                     message || "Unexpected node.",
                     () => `Node ${formatSyntaxKind(node.kind)} did not pass test '${getFunctionName(test)}'.`)
-            : (node: Node, test: (node: Node) => boolean, message?: string) => {};
+            : () => {};
 
         function getFunctionName(func: Function) {
             if (typeof func !== "function") {
diff --git a/src/services/shims.ts b/src/services/shims.ts
index 7ed1786640d7f..571f009d86645 100644
--- a/src/services/shims.ts
+++ b/src/services/shims.ts
@@ -444,7 +444,7 @@ namespace ts {
         }
 
         public readDirectory(path: string, extensions?: string[], exclude?: string[], include?: string[], depth?: number): string[] {
-            const pattern = getFileMatcherPatterns(path, extensions, exclude, include,
+            const pattern = getFileMatcherPatterns(path, exclude, include,
                 this.shimHost.useCaseSensitiveFileNames(), this.shimHost.getCurrentDirectory());
             return JSON.parse(this.shimHost.readDirectory(
                 path,
@@ -509,7 +509,7 @@ namespace ts {
             // Wrap the API changes for 2.0 release. This try/catch
             // should be removed once TypeScript 2.0 has shipped.
             try {
-                const pattern = getFileMatcherPatterns(rootDir, extensions, exclude, include,
+                const pattern = getFileMatcherPatterns(rootDir, exclude, include,
                     this.shimHost.useCaseSensitiveFileNames(), this.shimHost.getCurrentDirectory());
                 return JSON.parse(this.shimHost.readDirectory(
                     rootDir,