Merge pull request #2379 from asger-semmle/typescript-fixes

TS: A bunch of TypeScript fixes
2026-07-21 03:08:25 +02:00 · 2019-11-22 13:31:30 +01:00
parent 846600e855 ec8ced7963
commit 5d34806e50
58 changed files with 3116 additions and 80 deletions
--- a/javascript/extractor/lib/typescript/package.json
+++ b/javascript/extractor/lib/typescript/package.json
@@ -8,7 +8,8 @@
        "build": "tsc --project tsconfig.json",
        "check": "tsc --noEmit --project . && tslint --project .",
        "lint": "tslint --project .",
-        "lint-fix": "tslint --project . --fix"
+        "lint-fix": "tslint --project . --fix",
+        "watch": "tsc -p . -w --sourceMap"
    },
    "devDependencies": {
        "@types/node": "12.7.11",
--- a/javascript/extractor/lib/typescript/src/ast_extractor.ts
+++ b/javascript/extractor/lib/typescript/src/ast_extractor.ts
@@ -198,7 +198,9 @@ export function augmentAst(ast: AugmentedSourceFile, code: string, project: Proj
                    : null;
                let type = contextualType || typeChecker.getTypeAtLocation(node);
                if (type != null) {
-                    let id = typeTable.buildType(type);
+                    let parent = node.parent;
+                    let unfoldAlias = ts.isTypeAliasDeclaration(parent) && node === parent.type;
+                    let id = typeTable.buildType(type, unfoldAlias);
                    if (id != null) {
                        node.$type = id;
                    }
--- a/javascript/extractor/lib/typescript/src/main.ts
+++ b/javascript/extractor/lib/typescript/src/main.ts
@@ -253,7 +253,7 @@ function handleOpenProjectCommand(command: OpenProjectCommand) {
        fileExists: (path: string) => fs.existsSync(path),
        readFile: ts.sys.readFile,
    };
-    let config = ts.parseJsonConfigFileContent(tsConfig, parseConfigHost, basePath);
+    let config = ts.parseJsonConfigFileContent(tsConfig.config, parseConfigHost, basePath);
    let project = new Project(tsConfigFilename, config, state.typeTable);
    project.load();

@@ -272,7 +272,9 @@ function handleOpenProjectCommand(command: OpenProjectCommand) {
    });

    for (let typeRoot of typeRoots || []) {
-        traverseTypeRoot(typeRoot, "");
+        if (fs.existsSync(typeRoot) && fs.statSync(typeRoot).isDirectory()) {
+            traverseTypeRoot(typeRoot, "");
+        }
    }

    for (let sourceFile of program.getSourceFiles()) {
--- a/javascript/extractor/lib/typescript/src/type_table.ts
+++ b/javascript/extractor/lib/typescript/src/type_table.ts
@@ -92,6 +92,20 @@ function isTypeofCandidateSymbol(symbol: ts.Symbol) {

 const signatureKinds = [ts.SignatureKind.Call, ts.SignatureKind.Construct];

+/**
+ * Bitmask of flags set on a signature, but not exposed in the public API.
+ */
+const enum InternalSignatureFlags {
+  HasRestParameter = 1
+}
+
+/**
+ * Signature interface with some internal properties exposed.
+ */
+interface AugmentedSignature extends ts.Signature {
+  flags?: InternalSignatureFlags;
+}
+
 /**
 * Encodes property lookup tuples `(baseType, name, property)` as three
 * staggered arrays.
@@ -102,6 +116,16 @@ interface PropertyLookupTable {
  propertyTypes: number[];
 }

+/**
+ * Encodes `(aliasType, underlyingType)` tuples as two staggered arrays.
+ *
+ * Such a tuple denotes that `aliasType` is an alias for `underlyingType`.
+ */
+interface TypeAliasTable {
+  aliasTypes: number[];
+  underlyingTypes: number[];
+}
+
 /**
 * Encodes type signature tuples `(baseType, kind, index, signature)` as four
 * staggered arrays.
@@ -287,6 +311,11 @@ export class TypeTable {
    propertyTypes: [],
  };

+  private typeAliases: TypeAliasTable = {
+    aliasTypes: [],
+    underlyingTypes: [],
+  };
+
  private signatureMappings: SignatureTable = {
    baseTypes: [],
    kinds: [],
@@ -304,7 +333,7 @@ export class TypeTable {
    propertyTypes: [],
  };

-  private buildTypeWorklist: [ts.Type, number][] = [];
+  private buildTypeWorklist: [ts.Type, number, boolean][] = [];

  private expansiveTypes: Map<number, boolean> = new Map();

@@ -372,9 +401,9 @@ export class TypeTable {
  /**
   * Gets the canonical ID for the given type, generating a fresh ID if necessary.
   */
-  public buildType(type: ts.Type): number | null {
+  public buildType(type: ts.Type, unfoldAlias: boolean): number | null {
    this.isInShallowTypeContext = false;
-    let id = this.getId(type);
+    let id = this.getId(type, unfoldAlias);
    this.iterateBuildTypeWorklist();
    if (id == null) return null;
    return id;
@@ -385,7 +414,7 @@ export class TypeTable {
   *
   * Returns `null` if we do not support extraction of this type.
   */
-  public getId(type: ts.Type): number | null {
+  public getId(type: ts.Type, unfoldAlias: boolean): number | null {
    if (this.typeRecursionDepth > 100) {
      // Ignore infinitely nested anonymous types, such as `{x: {x: {x: ... }}}`.
      // Such a type can't be written directly with TypeScript syntax (as it would need to be named),
@@ -397,19 +426,19 @@ export class TypeTable {
      type = this.typeChecker.getBaseTypeOfLiteralType(type);
    }
    ++this.typeRecursionDepth;
-    let content = this.getTypeString(type);
+    let content = this.getTypeString(type, unfoldAlias);
    --this.typeRecursionDepth;
    if (content == null) return null; // Type not supported.
    let id = this.typeIds.get(content);
    if (id == null) {
-      let stringValue = this.stringifyType(type);
+      let stringValue = this.stringifyType(type, unfoldAlias);
      if (stringValue == null) {
        return null; // Type not supported.
      }
      id = this.typeIds.size;
      this.typeIds.set(content, id);
      this.typeToStringValues.push(stringValue);
-      this.buildTypeWorklist.push([type, id]);
+      this.buildTypeWorklist.push([type, id, unfoldAlias]);
      this.typeExtractionState.push(
        this.isInShallowTypeContext ? TypeExtractionState.PendingShallow : TypeExtractionState.PendingFull);
      // If the type is the self-type for a named type (not a generic instantiation of it),
@@ -426,20 +455,20 @@ export class TypeTable {
        this.typeExtractionState[id] = TypeExtractionState.PendingFull;
      } else if (state === TypeExtractionState.DoneShallow) {
        this.typeExtractionState[id] = TypeExtractionState.PendingFull;
-        this.buildTypeWorklist.push([type, id]);
+        this.buildTypeWorklist.push([type, id, unfoldAlias]);
      }
    }
    return id;
  }

-  private stringifyType(type: ts.Type): string {
+  private stringifyType(type: ts.Type, unfoldAlias: boolean): string {
+    let formatFlags = unfoldAlias
+        ? ts.TypeFormatFlags.InTypeAlias
+        : ts.TypeFormatFlags.UseAliasDefinedOutsideCurrentScope;
    let toStringValue: string;
    // Some types can't be stringified. Just discard the type if we can't stringify it.
    try {
-      toStringValue = this.typeChecker.typeToString(
-            type,
-            undefined,
-            ts.TypeFormatFlags.UseAliasDefinedOutsideCurrentScope);
+      toStringValue = this.typeChecker.typeToString(type, undefined, formatFlags);
    } catch (e) {
      console.warn("Recovered from a compiler crash while stringifying a type. Discarding the type.");
      console.warn(e.stack);
@@ -477,9 +506,9 @@ export class TypeTable {
  /**
   * Gets a string representing the kind and contents of the given type.
   */
-  private getTypeString(type: AugmentedType): string | null {
+  private getTypeString(type: AugmentedType, unfoldAlias: boolean): string | null {
    // Reference to a type alias.
-    if (type.aliasSymbol != null) {
+    if (!unfoldAlias && type.aliasSymbol != null) {
      let tag = "reference;" + this.getSymbolId(type.aliasSymbol);
      return type.aliasTypeArguments == null
          ? tag
@@ -499,7 +528,7 @@ export class TypeTable {
      if (flags & ts.TypeFlags.TypeVariable) {
        let enclosingType = getEnclosingTypeOfThisType(type);
        if (enclosingType != null) {
-          return "this;" + this.getId(enclosingType);
+          return "this;" + this.getId(enclosingType, false);
        } else if (symbol.parent == null) {
          // The type variable is bound on a call signature. Only extract it by name.
          return "lextypevar;" + symbol.name;
@@ -730,7 +759,7 @@ export class TypeTable {
  private makeTypeStringVector(tag: string, types: ReadonlyArray<ts.Type>, length = types.length): string | null {
    let hash = tag;
    for (let i = 0; i < length; ++i) {
-      let id = this.getId(types[i]);
+      let id = this.getId(types[i], false);
      if (id == null) return null;
      hash += ";" + id;
    }
@@ -748,7 +777,7 @@ export class TypeTable {
    for (let property of type.getProperties()) {
      let propertyType = this.typeChecker.getTypeOfSymbolAtLocation(property, this.arbitraryAstNode);
      if (propertyType == null) return null;
-      let propertyTypeId = this.getId(propertyType);
+      let propertyTypeId = this.getId(propertyType, false);
      if (propertyTypeId == null) return null;
      hash += ";p" + this.getSymbolId(property) + ';' + propertyTypeId;
    }
@@ -761,13 +790,13 @@ export class TypeTable {
    }
    let indexType = type.getStringIndexType();
    if (indexType != null) {
-      let indexTypeId = this.getId(indexType);
+      let indexTypeId = this.getId(indexType, false);
      if (indexTypeId == null) return null;
      hash += ";s" + indexTypeId;
    }
    indexType = type.getNumberIndexType();
    if (indexType != null) {
-      let indexTypeId = this.getId(indexType);
+      let indexTypeId = this.getId(indexType, false);
      if (indexTypeId == null) return null;
      hash += ";i" + indexTypeId;
    }
@@ -789,6 +818,7 @@ export class TypeTable {
      typeStrings: Array.from(this.typeIds.keys()),
      typeToStringValues: this.typeToStringValues,
      propertyLookups: this.propertyLookups,
+      typeAliases: this.typeAliases,
      symbolStrings: Array.from(this.symbolIds.keys()),
      moduleMappings: this.moduleMappings,
      globalMappings: this.globalMappings,
@@ -812,10 +842,17 @@ export class TypeTable {
    let worklist = this.buildTypeWorklist;
    let typeExtractionState = this.typeExtractionState;
    while (worklist.length > 0) {
-      let [type, id] = worklist.pop();
+      let [type, id, unfoldAlias] = worklist.pop();
      let isShallowContext = typeExtractionState[id] === TypeExtractionState.PendingShallow;
      if (isShallowContext && !isTypeAlwaysSafeToExpand(type)) {
        typeExtractionState[id] = TypeExtractionState.DoneShallow;
+      } else if (type.aliasSymbol != null && !unfoldAlias) {
+        typeExtractionState[id] = TypeExtractionState.DoneFull;
+        let underlyingTypeId = this.getId(type, true);
+        if (underlyingTypeId != null) {
+          this.typeAliases.aliasTypes.push(id);
+          this.typeAliases.underlyingTypes.push(underlyingTypeId);
+        }
      } else {
        typeExtractionState[id] = TypeExtractionState.DoneFull;
        this.isInShallowTypeContext = isShallowContext || this.isExpansiveTypeReference(type);
@@ -847,7 +884,7 @@ export class TypeTable {
    for (let symbol of props) {
      let propertyType = this.typeChecker.getTypeOfSymbolAtLocation(symbol, this.arbitraryAstNode);
      if (propertyType == null) continue;
-      let propertyTypeId = this.getId(propertyType);
+      let propertyTypeId = this.getId(propertyType, false);
      if (propertyTypeId == null) continue;
      this.propertyLookups.baseTypes.push(id);
      this.propertyLookups.names.push(symbol.name);
@@ -879,7 +916,7 @@ export class TypeTable {
  /**
   * Returns a unique string for the given call/constructor signature.
   */
-  private getSignatureString(kind: ts.SignatureKind, signature: ts.Signature): string {
+  private getSignatureString(kind: ts.SignatureKind, signature: AugmentedSignature): string {
    let parameters = signature.getParameters();
    let numberOfTypeParameters = signature.typeParameters == null
        ? 0
@@ -892,27 +929,51 @@ export class TypeTable {
        break;
      }
    }
-    let returnTypeId = this.getId(signature.getReturnType());
+    let hasRestParam = (signature.flags & InternalSignatureFlags.HasRestParameter) !== 0;
+    let restParameterTag = '';
+    if (hasRestParam) {
+      if (requiredParameters === parameters.length) {
+        // Do not count the rest parameter as a required parameter
+        requiredParameters = parameters.length - 1;
+      }
+      if (parameters.length === 0) return null;
+      let restParameter = parameters[parameters.length - 1];
+      let restParameterType = this.typeChecker.getTypeOfSymbolAtLocation(restParameter, this.arbitraryAstNode);
+      if (restParameterType == null) return null;
+      let restParameterTypeId = this.getId(restParameterType, false);
+      if (restParameterTypeId == null) return null;
+      restParameterTag = '' + restParameterTypeId;
+    }
+    let returnTypeId = this.getId(signature.getReturnType(), false);
    if (returnTypeId == null) {
      return null;
    }
-    let tag = `${kind};${numberOfTypeParameters};${requiredParameters};${returnTypeId}`;
+    let tag = `${kind};${numberOfTypeParameters};${requiredParameters};${restParameterTag};${returnTypeId}`;
    for (let typeParameter of signature.typeParameters || []) {
      tag += ";" + typeParameter.symbol.name;
      let constraint = typeParameter.getConstraint();
      let constraintId: number;
-      if (constraint == null || (constraintId = this.getId(constraint)) == null) {
+      if (constraint == null || (constraintId = this.getId(constraint, false)) == null) {
        tag += ";";
      } else {
        tag += ";" + constraintId;
      }
    }
-    for (let parameter of parameters) {
+    for (let paramIndex = 0; paramIndex < parameters.length; ++paramIndex) {
+      let parameter = parameters[paramIndex];
      let parameterType = this.typeChecker.getTypeOfSymbolAtLocation(parameter, this.arbitraryAstNode);
      if (parameterType == null) {
        return null;
      }
-      let parameterTypeId = this.getId(parameterType);
+      let isRestParameter = hasRestParam && (paramIndex === parameters.length - 1);
+      if (isRestParameter) {
+        // The type of the rest parameter is the array type, but we wish to extract the non-array type.
+        if (!isTypeReference(parameterType)) return null;
+        let typeArguments = parameterType.typeArguments;
+        if (typeArguments == null || typeArguments.length === 0) return null;
+        parameterType = typeArguments[0];
+      }
+      let parameterTypeId = this.getId(parameterType, false);
      if (parameterTypeId == null) {
        return null;
      }
@@ -946,7 +1007,7 @@ export class TypeTable {

  private extractIndexer(baseType: number, indexType: ts.Type, table: IndexerTable) {
    if (indexType == null) return;
-    let indexTypeId = this.getId(indexType);
+    let indexTypeId = this.getId(indexType, false);
    if (indexTypeId == null) return;
    table.baseTypes.push(baseType);
    table.propertyTypes.push(indexTypeId);
@@ -1017,7 +1078,7 @@ export class TypeTable {
    let selfType = this.getSelfType(type);
    if (selfType != null) {
      this.checkExpansiveness(selfType);
-      let id = this.getId(selfType);
+      let id = this.getId(selfType, false);
      return this.expansiveTypes.get(id);
    }
    return false;
@@ -1086,7 +1147,7 @@ export class TypeTable {
    search(type, 0);

    function search(type: ts.TypeReference, expansionDepth: number): number | null {
-      let id = typeTable.getId(type);
+      let id = typeTable.getId(type, false);
      if (id == null) return null;

      let index = indexTable.get(id);
--- a/javascript/extractor/src/com/semmle/js/ast/AFunction.java
+++ b/javascript/extractor/src/com/semmle/js/ast/AFunction.java
@@ -3,6 +3,7 @@ package com.semmle.js.ast;
 import com.semmle.ts.ast.DecoratorList;
 import com.semmle.ts.ast.ITypeExpression;
 import com.semmle.ts.ast.TypeParameter;
+import com.semmle.util.data.IntList;
 import java.util.ArrayList;
 import java.util.List;

@@ -18,6 +19,9 @@ public class AFunction<B> {
  private final List<ITypeExpression> parameterTypes;
  private final ITypeExpression thisParameterType;
  private final List<DecoratorList> parameterDecorators;
+  private final IntList optionalParameterIndices;
+
+  public static final IntList noOptionalParams = IntList.create(0, 0);

  public AFunction(
      Identifier id,
@@ -29,7 +33,8 @@ public class AFunction<B> {
      List<ITypeExpression> parameterTypes,
      List<DecoratorList> parameterDecorators,
      ITypeExpression returnType,
-      ITypeExpression thisParameterType) {
+      ITypeExpression thisParameterType,
+      IntList optionalParameterIndices) {
    this.id = id;
    this.params = new ArrayList<IPattern>(params.size());
    this.defaults = new ArrayList<Expression>(params.size());
@@ -42,6 +47,7 @@ public class AFunction<B> {
    this.returnType = returnType;
    this.thisParameterType = thisParameterType;
    this.parameterDecorators = parameterDecorators;
+    this.optionalParameterIndices = optionalParameterIndices;

    IPattern rest = null;
    for (Expression param : params) {
@@ -143,4 +149,8 @@ public class AFunction<B> {
  public List<DecoratorList> getParameterDecorators() {
    return parameterDecorators;
  }
+
+  public IntList getOptionalParmaeterIndices() {
+    return optionalParameterIndices;
+  }
 }
--- a/javascript/extractor/src/com/semmle/js/ast/AFunctionExpression.java
+++ b/javascript/extractor/src/com/semmle/js/ast/AFunctionExpression.java
@@ -3,6 +3,7 @@ package com.semmle.js.ast;
 import com.semmle.ts.ast.DecoratorList;
 import com.semmle.ts.ast.ITypeExpression;
 import com.semmle.ts.ast.TypeParameter;
+import com.semmle.util.data.IntList;
 import java.util.List;

 /**
@@ -26,7 +27,8 @@ public abstract class AFunctionExpression extends Expression implements IFunctio
      List<ITypeExpression> parameterTypes,
      List<DecoratorList> parameterDecorators,
      ITypeExpression returnType,
-      ITypeExpression thisParameterType) {
+      ITypeExpression thisParameterType,
+      IntList optionalParameterIndices) {
    super(type, loc);
    this.fn =
        new AFunction<Node>(
@@ -39,7 +41,8 @@ public abstract class AFunctionExpression extends Expression implements IFunctio
            parameterTypes,
            parameterDecorators,
            returnType,
-            thisParameterType);
+            thisParameterType,
+            optionalParameterIndices);
  }

  public AFunctionExpression(String type, SourceLocation loc, AFunction<? extends Node> fn) {
@@ -155,4 +158,8 @@ public abstract class AFunctionExpression extends Expression implements IFunctio
  public void setDeclaredSignatureId(int id) {
    declaredSignature = id;
  }
+
+  public IntList getOptionalParameterIndices() {
+    return fn.getOptionalParmaeterIndices();
+  }
 }
--- a/javascript/extractor/src/com/semmle/js/ast/ArrowFunctionExpression.java
+++ b/javascript/extractor/src/com/semmle/js/ast/ArrowFunctionExpression.java
@@ -2,6 +2,7 @@ package com.semmle.js.ast;

 import com.semmle.ts.ast.ITypeExpression;
 import com.semmle.ts.ast.TypeParameter;
+import com.semmle.util.data.IntList;
 import java.util.Collections;
 import java.util.List;

@@ -21,7 +22,8 @@ public class ArrowFunctionExpression extends AFunctionExpression {
        Collections.emptyList(),
        Collections.emptyList(),
        null,
-        null);
+        null,
+        AFunction.noOptionalParams);
  }

  public ArrowFunctionExpression(
@@ -32,7 +34,8 @@ public class ArrowFunctionExpression extends AFunctionExpression {
      Boolean async,
      List<TypeParameter> typeParameters,
      List<ITypeExpression> parameterTypes,
-      ITypeExpression returnType) {
+      ITypeExpression returnType,
+      IntList optionalParameterIndices) {
    super(
        "ArrowFunctionExpression",
        loc,
@@ -45,7 +48,8 @@ public class ArrowFunctionExpression extends AFunctionExpression {
        parameterTypes,
        Collections.emptyList(),
        returnType,
-        null);
+        null,
+        optionalParameterIndices);
  }

  @Override
--- a/javascript/extractor/src/com/semmle/js/ast/FunctionDeclaration.java
+++ b/javascript/extractor/src/com/semmle/js/ast/FunctionDeclaration.java
@@ -3,6 +3,7 @@ package com.semmle.js.ast;
 import com.semmle.ts.ast.DecoratorList;
 import com.semmle.ts.ast.ITypeExpression;
 import com.semmle.ts.ast.TypeParameter;
+import com.semmle.util.data.IntList;
 import java.util.Collections;
 import java.util.List;

@@ -41,7 +42,8 @@ public class FunctionDeclaration extends Statement implements IFunction {
            Collections.emptyList(),
            Collections.emptyList(),
            null,
-            null),
+            null,
+            AFunction.noOptionalParams),
        false);
  }

@@ -56,7 +58,8 @@ public class FunctionDeclaration extends Statement implements IFunction {
      List<TypeParameter> typeParameters,
      List<ITypeExpression> parameterTypes,
      ITypeExpression returnType,
-      ITypeExpression thisParameterType) {
+      ITypeExpression thisParameterType,
+      IntList optionalParameterIndices) {
    this(
        loc,
        new AFunction<>(
@@ -69,7 +72,8 @@ public class FunctionDeclaration extends Statement implements IFunction {
            parameterTypes,
            Collections.emptyList(),
            returnType,
-            thisParameterType),
+            thisParameterType,
+            optionalParameterIndices),
        hasDeclareKeyword);
  }

@@ -207,4 +211,8 @@ public class FunctionDeclaration extends Statement implements IFunction {
  public void setDeclaredSignatureId(int id) {
    declaredSignature = id;
  }
+
+  public IntList getOptionalParameterIndices() {
+    return fn.getOptionalParmaeterIndices();
+  }
 }
--- a/javascript/extractor/src/com/semmle/js/ast/FunctionExpression.java
+++ b/javascript/extractor/src/com/semmle/js/ast/FunctionExpression.java
@@ -3,6 +3,7 @@ package com.semmle.js.ast;
 import com.semmle.ts.ast.DecoratorList;
 import com.semmle.ts.ast.ITypeExpression;
 import com.semmle.ts.ast.TypeParameter;
+import com.semmle.util.data.IntList;
 import java.util.Collections;
 import java.util.List;

@@ -27,7 +28,8 @@ public class FunctionExpression extends AFunctionExpression {
        Collections.emptyList(),
        Collections.emptyList(),
        null,
-        null);
+        null,
+        AFunction.noOptionalParams);
  }

  public FunctionExpression(
@@ -41,7 +43,8 @@ public class FunctionExpression extends AFunctionExpression {
      List<ITypeExpression> parameterTypes,
      List<DecoratorList> parameterDecorators,
      ITypeExpression returnType,
-      ITypeExpression thisParameterType) {
+      ITypeExpression thisParameterType,
+      IntList optionalParameterIndices) {
    super(
        "FunctionExpression",
        loc,
@@ -54,7 +57,8 @@ public class FunctionExpression extends AFunctionExpression {
        parameterTypes,
        parameterDecorators,
        returnType,
-        thisParameterType);
+        thisParameterType,
+        optionalParameterIndices);
  }

  public FunctionExpression(SourceLocation loc, AFunction<? extends Node> fn) {
--- a/javascript/extractor/src/com/semmle/js/ast/IFunction.java
+++ b/javascript/extractor/src/com/semmle/js/ast/IFunction.java
@@ -5,6 +5,7 @@ import com.semmle.ts.ast.INodeWithSymbol;
 import com.semmle.ts.ast.ITypeExpression;
 import com.semmle.ts.ast.ITypedAstNode;
 import com.semmle.ts.ast.TypeParameter;
+import com.semmle.util.data.IntList;
 import java.util.List;

 /** A function declaration or expression. */
@@ -75,4 +76,6 @@ public interface IFunction extends IStatementContainer, INodeWithSymbol, ITypedA
  public int getDeclaredSignatureId();

  public void setDeclaredSignatureId(int id);
+
+  public IntList getOptionalParameterIndices();
 }
--- a/javascript/extractor/src/com/semmle/js/ast/NodeCopier.java
+++ b/javascript/extractor/src/com/semmle/js/ast/NodeCopier.java
@@ -45,6 +45,7 @@ import com.semmle.ts.ast.TypeParameter;
 import com.semmle.ts.ast.TypeofTypeExpr;
 import com.semmle.ts.ast.UnaryTypeExpr;
 import com.semmle.ts.ast.UnionTypeExpr;
+import com.semmle.util.data.IntList;
 import java.util.ArrayList;
 import java.util.List;

@@ -70,6 +71,10 @@ public class NodeCopier implements Visitor<Void, INode> {
    return result;
  }

+  private IntList copy(IntList list) {
+    return new IntList(list);
+  }
+
  @Override
  public AssignmentExpression visit(AssignmentExpression nd, Void q) {
    return new AssignmentExpression(
@@ -138,7 +143,8 @@ public class NodeCopier implements Visitor<Void, INode> {
        copy(nd.getTypeParameters()),
        copy(nd.getParameterTypes()),
        copy(nd.getReturnType()),
-        copy(nd.getThisParameterType()));
+        copy(nd.getThisParameterType()),
+        copy(nd.getOptionalParameterIndices()));
  }

  @Override
@@ -367,7 +373,8 @@ public class NodeCopier implements Visitor<Void, INode> {
        copy(nd.getParameterTypes()),
        copy(nd.getParameterDecorators()),
        copy(nd.getReturnType()),
-        copy(nd.getThisParameterType()));
+        copy(nd.getThisParameterType()),
+        copy(nd.getOptionalParameterIndices()));
  }

  @Override
@@ -427,7 +434,8 @@ public class NodeCopier implements Visitor<Void, INode> {
        nd.isAsync(),
        copy(nd.getTypeParameters()),
        copy(nd.getParameterTypes()),
-        copy(nd.getReturnType()));
+        copy(nd.getReturnType()),
+        copy(nd.getOptionalParameterIndices()));
  }

  @Override
--- a/javascript/extractor/src/com/semmle/js/extractor/ASTExtractor.java
+++ b/javascript/extractor/src/com/semmle/js/extractor/ASTExtractor.java
@@ -900,7 +900,12 @@ public class ASTExtractor {
      for (IPattern param : nd.getAllParams()) {
        scopeManager.addNames(
            scopeManager.collectDeclaredNames(param, isStrict, false, DeclKind.var));
-        visit(param, key, i, IdContext.varDecl);
+        Label paramKey = visit(param, key, i, IdContext.varDecl);
+
+        // Extract optional parameters
+        if (nd.getOptionalParameterIndices().contains(i)) {
+          trapwriter.addTuple("isOptionalParameterDeclaration", paramKey);
+        }
        ++i;
      }

@@ -1393,7 +1398,8 @@ public class ASTExtractor {
              Collections.emptyList(),
              Collections.emptyList(),
              null,
-              null);
+              null,
+              AFunction.noOptionalParams);
      String fnSrc = hasSuperClass ? "(...args) { super(...args); }" : "() {}";
      SourceLocation fnloc = fakeLoc(fnSrc, loc);
      FunctionExpression fn = new FunctionExpression(fnloc, fndef);
--- a/javascript/extractor/src/com/semmle/js/extractor/AutoBuild.java
+++ b/javascript/extractor/src/com/semmle/js/extractor/AutoBuild.java
@@ -578,6 +578,11 @@ public class AutoBuild {
        for (File sourceFile : project.getSourceFiles()) {
          Path sourcePath = sourceFile.toPath();
          if (!files.contains(normalizePath(sourcePath))) continue;
+          if (!FileType.TYPESCRIPT.getExtensions().contains(FileUtil.extension(sourcePath))) {
+            // For the time being, skip non-TypeScript files, even if the TypeScript
+            // compiler can parse them for us.
+            continue;
+          }
          if (!extractedFiles.contains(sourcePath)) {
            typeScriptFiles.add(sourcePath.toFile());
          }
--- a/javascript/extractor/src/com/semmle/js/extractor/Main.java
+++ b/javascript/extractor/src/com/semmle/js/extractor/Main.java
@@ -37,7 +37,7 @@ public class Main {
   * A version identifier that should be updated every time the extractor changes in such a way that
   * it may produce different tuples for the same file under the same {@link ExtractorConfig}.
   */
-  public static final String EXTRACTOR_VERSION = "2019-11-17";
+  public static final String EXTRACTOR_VERSION = "2019-11-19";

  public static final Pattern NEWLINE = Pattern.compile("\n");

@@ -147,7 +147,8 @@ public class Main {
      List<File> filesToExtract = new ArrayList<>();
      for (File sourceFile : project.getSourceFiles()) {
        if (files.contains(normalizeFile(sourceFile))
-            && !extractedFiles.contains(sourceFile.getAbsoluteFile())) {
+            && !extractedFiles.contains(sourceFile.getAbsoluteFile())
+            && FileType.TYPESCRIPT.getExtensions().contains(FileUtil.extension(sourceFile))) {
          filesToExtract.add(sourceFile);
        }
      }
--- a/javascript/extractor/src/com/semmle/js/parser/TypeScriptASTConverter.java
+++ b/javascript/extractor/src/com/semmle/js/parser/TypeScriptASTConverter.java
@@ -143,6 +143,7 @@ import com.semmle.ts.ast.TypeofTypeExpr;
 import com.semmle.ts.ast.UnaryTypeExpr;
 import com.semmle.ts.ast.UnionTypeExpr;
 import com.semmle.util.collections.CollectionUtil;
+import com.semmle.util.data.IntList;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.LinkedHashMap;
@@ -804,7 +805,8 @@ public class TypeScriptASTConverter {
            hasModifier(node, "AsyncKeyword"),
            convertChildrenNotNull(node, "typeParameters"),
            convertParameterTypes(node),
-            convertChildAsType(node, "type"));
+            convertChildAsType(node, "type"),
+            getOptionalParameterIndices(node));
    attachDeclaredSignature(function, node);
    return function;
  }
@@ -1063,7 +1065,8 @@ public class TypeScriptASTConverter {
            paramTypes,
            paramDecorators,
            null,
-            null);
+            null,
+            getOptionalParameterIndices(node));
    attachSymbolInformation(value, node);
    attachStaticType(value, node);
    attachDeclaredSignature(value, node);
@@ -1262,7 +1265,8 @@ public class TypeScriptASTConverter {
            typeParameters,
            paramTypes,
            returnType,
-            thisParam);
+            thisParam,
+            getOptionalParameterIndices(node));
    attachSymbolInformation(function, node);
    attachStaticType(function, node);
    attachDeclaredSignature(function, node);
@@ -1291,7 +1295,8 @@ public class TypeScriptASTConverter {
            paramTypes,
            paramDecorators,
            returnType,
-            thisParam);
+            thisParam,
+            getOptionalParameterIndices(node));
    attachStaticType(function, node);
    attachDeclaredSignature(function, node);
    return function;
@@ -1645,7 +1650,8 @@ public class TypeScriptASTConverter {
            paramTypes,
            paramDecorators,
            returnType,
-            thisType);
+            thisType,
+            getOptionalParameterIndices(node));
    attachSymbolInformation(function, node);
    attachStaticType(function, node);
    attachDeclaredSignature(function, node);
@@ -1890,6 +1896,18 @@ public class TypeScriptASTConverter {
    return result;
  }

+  private IntList getOptionalParameterIndices(JsonObject function) throws ParseError {
+    IntList list = IntList.create(0);
+    int index = -1;
+    for (JsonElement param : getProperParameters(function)) {
+      ++index;
+      if (param.getAsJsonObject().has("questionToken")) {
+        list.add(index);
+      }
+    }
+    return list;
+  }
+
  private List<FieldDefinition> convertParameterFields(JsonObject function) throws ParseError {
    List<FieldDefinition> result = new ArrayList<>();
    int index = -1;
--- a/javascript/extractor/src/com/semmle/js/parser/TypeScriptParser.java
+++ b/javascript/extractor/src/com/semmle/js/parser/TypeScriptParser.java
@@ -291,10 +291,10 @@ public class TypeScriptParser {
    LogbackUtils.getLogger(AbstractProcessBuilder.class).setLevel(Level.INFO);
    String explicitPath = Env.systemEnv().get(PARSER_WRAPPER_PATH_ENV_VAR);
    String semmleDistVar = Env.systemEnv().get(Env.Var.SEMMLE_DIST.name());
-    if (semmleDistVar != null && !semmleDistVar.isEmpty()) {
-      parserWrapper = new File(semmleDistVar, "tools/typescript-parser-wrapper/main.js");
-    } else if (explicitPath != null) {
+    if (explicitPath != null) {
      parserWrapper = new File(explicitPath);
+    } else if (semmleDistVar != null && !semmleDistVar.isEmpty()) {
+      parserWrapper = new File(semmleDistVar, "tools/typescript-parser-wrapper/main.js");
    } else {
      throw new CatastrophicError(
          "Could not find TypeScript parser: " + Env.Var.SEMMLE_DIST.name() + " is not set.");
--- a/javascript/extractor/src/com/semmle/ts/extractor/TypeExtractor.java
+++ b/javascript/extractor/src/com/semmle/ts/extractor/TypeExtractor.java
@@ -81,6 +81,7 @@ public class TypeExtractor {
      extractType(i);
    }
    extractPropertyLookups(table.getPropertyLookups());
+    extractTypeAliases(table.getTypeAliases());
    for (int i = 0; i < table.getNumberOfSymbols(); ++i) {
      extractSymbol(i);
    }
@@ -161,6 +162,19 @@ public class TypeExtractor {
    }
  }

+  private void extractTypeAliases(JsonObject aliases) {
+    JsonArray aliasTypes = aliases.get("aliasTypes").getAsJsonArray();
+    JsonArray underlyingTypes = aliases.get("underlyingTypes").getAsJsonArray();
+    for (int i = 0; i < aliasTypes.size(); ++i) {
+      int aliasType = aliasTypes.get(i).getAsInt();
+      int underlyingType = underlyingTypes.get(i).getAsInt();
+      trapWriter.addTuple(
+          "type_alias",
+          trapWriter.globalID("type;" + aliasType),
+          trapWriter.globalID("type;" + underlyingType));
+    }
+  }
+
  private void extractSymbol(int index) {
    // Format is: kind;decl;parent;name
    String[] parts = split(table.getSymbolString(index), 4);
@@ -187,13 +201,18 @@ public class TypeExtractor {

  private void extractSignature(int index) {
    // Format is:
-    // kind;numTypeParams;requiredParams;returnType(;paramName;paramType)*
+    // kind;numTypeParams;requiredParams;restParamType;returnType(;paramName;paramType)*
    String[] parts = split(table.getSignatureString(index));
    Label label = trapWriter.globalID("signature;" + index);
    int kind = Integer.parseInt(parts[0]);
    int numberOfTypeParameters = Integer.parseInt(parts[1]);
    int requiredParameters = Integer.parseInt(parts[2]);
-    Label returnType = trapWriter.globalID("type;" + parts[3]);
+    String restParamTypeTag = parts[3];
+    if (!restParamTypeTag.isEmpty()) {
+      trapWriter.addTuple(
+          "signature_rest_parameter", label, trapWriter.globalID("type;" + restParamTypeTag));
+    }
+    Label returnType = trapWriter.globalID("type;" + parts[4]);
    trapWriter.addTuple(
        "signature_types",
        label,
@@ -202,9 +221,9 @@ public class TypeExtractor {
        numberOfTypeParameters,
        requiredParameters);
    trapWriter.addTuple("signature_contains_type", returnType, label, -1);
-    int numberOfParameters = (parts.length - 4) / 2; // includes type parameters
+    int numberOfParameters = (parts.length - 5) / 2; // includes type parameters
    for (int i = 0; i < numberOfParameters; ++i) {
-      int partIndex = 4 + (2 * i);
+      int partIndex = 5 + (2 * i);
      String paramName = parts[partIndex];
      String paramTypeId = parts[partIndex + 1];
      if (paramTypeId.length() > 0) { // Unconstrained type parameters have an empty type ID.
--- a/javascript/extractor/src/com/semmle/ts/extractor/TypeTable.java
+++ b/javascript/extractor/src/com/semmle/ts/extractor/TypeTable.java
@@ -12,6 +12,7 @@ public class TypeTable {
  private final JsonArray typeStrings;
  private final JsonArray typeToStringValues;
  private final JsonObject propertyLookups;
+  private final JsonObject typeAliases;
  private final JsonArray symbolStrings;
  private final JsonObject moduleMappings;
  private final JsonObject globalMappings;
@@ -27,6 +28,7 @@ public class TypeTable {
    this.typeStrings = typeTable.get("typeStrings").getAsJsonArray();
    this.typeToStringValues = typeTable.get("typeToStringValues").getAsJsonArray();
    this.propertyLookups = typeTable.get("propertyLookups").getAsJsonObject();
+    this.typeAliases = typeTable.get("typeAliases").getAsJsonObject();
    this.symbolStrings = typeTable.get("symbolStrings").getAsJsonArray();
    this.moduleMappings = typeTable.get("moduleMappings").getAsJsonObject();
    this.globalMappings = typeTable.get("globalMappings").getAsJsonObject();
@@ -51,6 +53,10 @@ public class TypeTable {
    return propertyLookups;
  }

+  public JsonObject getTypeAliases() {
+    return typeAliases;
+  }
+
  public int getNumberOfTypes() {
    return typeStrings.size();
  }
--- a/javascript/ql/src/semmle/javascript/TypeScript.qll
+++ b/javascript/ql/src/semmle/javascript/TypeScript.qll
@@ -1816,7 +1816,7 @@ class Type extends @type {
   *
   * For example, for a type `(S & T) | U` this gets the types `S`, `T`, and `U`.
   */
-  Type unfold() {
+  Type unfoldUnionAndIntersection() {
    not result instanceof UnionOrIntersectionType and
    (
      result = this
@@ -1829,6 +1829,27 @@ class Type extends @type {
    )
  }

+  /**
+   * Repeatedly unfolds unions, intersections, and type aliases and gets any of the underlying types,
+   * or this type itself if it is not a union or intersection.
+   *
+   * For example, the type `(S & T) | U` unfolds to `S`, `T`, and `U`.
+   *
+   * If this is a type alias, the alias is itself included in the result, but this is not the case for intermediate type aliases.
+   * For example:
+   * ```js
+   * type One = number | string;
+   * type Two = One | Function & {x: string};
+   * One; // unfolds to number, string, and One
+   * Two; // unfolds to number, string, One, Function, {x: string}, and Two
+   * ```
+   */
+  Type unfold() {
+    result = unfoldUnionAndIntersection()
+    or
+    result = this.(TypeAliasReference).getAliasedType().unfoldUnionAndIntersection()
+  }
+
  /**
   * Holds if this refers to the given named type, or is declared as a subtype thereof,
   * or is a union or intersection containing such a type.
@@ -2287,6 +2308,24 @@ class EnumLiteralType extends TypeReference {
  EnumMember getEnumMember() { result = declaration }
 }

+/**
+ * A type that refers to a type alias.
+ */
+class TypeAliasReference extends TypeReference {
+  TypeAliasReference() {
+    type_alias(this, _)
+  }
+
+  /**
+   * Gets the type behind the type alias.
+   *
+   * For example, for `type B<T> = T[][]`, this maps the type `B<number>` to `number[][]`.
+   */
+  Type getAliasedType() {
+    type_alias(this, result)
+  }
+}
+
 /**
 * An anonymous interface type, such as `{ x: number }`.
 */
@@ -2516,17 +2555,19 @@ class CallSignatureType extends @signature_type {
  predicate hasTypeParameters() { getNumTypeParameter() > 0 }

  /**
-   * Gets the type of the `n`th parameter of this signature.
+   * Gets the type of the `n`th parameter declared in this signature.
+   *
+   * If the `n`th parameter is a rest parameter `...T[]`, gets type `T`.
   */
  Type getParameter(int n) { n >= 0 and result = getChild(n + getNumTypeParameter()) }

  /**
-   * Gets the type of a parameter of this signature.
+   * Gets the type of a parameter of this signature, including the rest parameter, if any.
   */
  Type getAParameter() { result = getParameter(_) }

  /**
-   * Gets the number of parameters.
+   * Gets the number of parameters, including the rest parameter, if any.
   */
  int getNumParameter() { result = count(int i | exists(getParameter(i))) }

@@ -2538,7 +2579,7 @@ class CallSignatureType extends @signature_type {

  /**
   * Gets the number of optional parameters, that is,
-   * parameters that are marked as optional with the `?` suffix.
+   * parameters that are marked as optional with the `?` suffix or is a rest parameter.
   */
  int getNumOptionalParameter() { result = getNumParameter() - getNumRequiredParameter() }

@@ -2552,7 +2593,9 @@ class CallSignatureType extends @signature_type {
  }

  /**
-   * Holds if the `n`th parameter is declared optional with the `?` suffix.
+   * Holds if the `n`th parameter is declared optional with the `?` suffix or is the rest parameter.
+   *
+   * Note that rest parameters are not considered optional in this sense.
   */
  predicate isOptionalParameter(int n) {
    exists(getParameter(n)) and
@@ -2571,6 +2614,30 @@ class CallSignatureType extends @signature_type {
   * Gets the name of a parameter of this signature.
   */
  string getAParameterName() { result = getParameterName(_) }
+
+  /**
+   * Holds if this signature declares a rest parameter, such as `(x: number, ...y: string[])`.
+   */
+  predicate hasRestParameter() { signature_rest_parameter(this, _) }
+
+  /**
+   * Gets the type of the rest parameter, if any.
+   *
+   * For example, for the signature `(...y: string[])`, this gets the type `string`.
+   */
+  Type getRestParameterType() {
+    hasRestParameter() and
+    result = getParameter(getNumParameter() - 1)
+  }
+
+  /**
+   * Gets the type of the rest parameter as an array, if it exists.
+   *
+   * For example, for the signature `(...y: string[])`, this gets the type `string[]`.
+   */
+  PlainArrayType getRestParameterArrayType() {
+    signature_rest_parameter(this, result)
+  }
 }

 /**
--- a/javascript/ql/src/semmle/javascript/Variables.qll
+++ b/javascript/ql/src/semmle/javascript/Variables.qll
@@ -749,6 +749,21 @@ class Parameter extends BindingPattern {
  JSDocTag getJSDocTag() {
    none() // overridden in SimpleParameter
  }
+
+  /**
+   * Holds if this is a parameter declared optional with the `?` token.
+   *
+   * Note that this does not hold for rest parameters, and does not in general
+   * hold for parameters with defaults.
+   *
+   * For example, `x`, is declared optional below:
+   * ```
+   * function f(x?: number) {}
+   * ```
+   */
+  predicate isDeclaredOptional() {
+    isOptionalParameterDeclaration(this)
+  }
 }

 /**
--- a/javascript/ql/src/semmlecode.javascript.dbscheme
+++ b/javascript/ql/src/semmlecode.javascript.dbscheme
@@ -520,6 +520,7 @@ hasProtectedKeyword (int id: @property ref);
 hasReadonlyKeyword (int id: @property ref);
 isOptionalMember (int id: @property ref);
 hasDefiniteAssignmentAssertion (int id: @field_or_vardeclarator ref);
+isOptionalParameterDeclaration (unique int parameter: @pattern ref);

 #keyset[constructor, param_index]
 parameter_fields(
@@ -703,6 +704,10 @@ type_property(
  varchar(900) name: string ref,
  int propertyType: @type ref);

+type_alias(
+  unique int aliasType: @type ref,
+  int underlyingType: @type ref);
+
@literaltype = @stringliteraltype | @numberliteraltype | @booleanliteraltype | @bigintliteraltype;
@type_with_literal_value = @stringliteraltype | @numberliteraltype | @bigintliteraltype;
 type_literal_value(
@@ -717,6 +722,11 @@ signature_types (
  int required_params: int ref
 );

+signature_rest_parameter(
+  unique int sig: @signature_type ref,
+  int rest_param_arra_type: @type ref
+);
+
 case @signature_type.kind of
  0 = @function_signature_type
 | 1 = @constructor_signature_type
--- a/javascript/ql/src/semmlecode.javascript.dbscheme.stats
+++ b/javascript/ql/src/semmlecode.javascript.dbscheme.stats
@@ -8006,6 +8006,17 @@
 <dependencies/>
 </relation>
 <relation>
+<name>isOptionalParameterDeclaration</name>
+<cardinality>3966</cardinality>
+<columnsizes>
+<e>
+<k>parameter</k>
+<v>3966</v>
+</e>
+</columnsizes>
+<dependencies/>
+</relation>
+<relation>
 <name>parameter_fields</name>
 <cardinality>2693</cardinality>
 <columnsizes>
@@ -13516,6 +13527,54 @@
 <dependencies/>
 </relation>
 <relation>
+<name>type_alias</name>
+<cardinality>1386</cardinality>
+<columnsizes>
+<e>
+<k>aliasType</k>
+<v>1386</v>
+</e>
+<e>
+<k>underlyingType</k>
+<v>1361</v>
+</e>
+</columnsizes>
+<dependencies>
+<dep>
+<src>underlyingType</src>
+<trg>aliasType</trg>
+<val>
+<hist>
+<budget>12</budget>
+<bs>
+<b>
+<a>1</a>
+<b>2</b>
+<v>1</v>
+</b>
+</bs>
+</hist>
+</val>
+</dep>
+<dep>
+<src>aliasType</src>
+<trg>underlyingType</trg>
+<val>
+<hist>
+<budget>12</budget>
+<bs>
+<b>
+<a>1</a>
+<b>2</b>
+<v>1</v>
+</b>
+</bs>
+</hist>
+</val>
+</dep>
+</dependencies>
+</relation>
+<relation>
 <name>type_literal_value</name>
 <cardinality>31882</cardinality>
 <columnsizes>
@@ -14222,6 +14281,54 @@
 </dependencies>
 </relation>
 <relation>
+<name>signature_rest_parameter</name>
+<cardinality>19521</cardinality>
+<columnsizes>
+<e>
+<k>sig</k>
+<v>19521</v>
+</e>
+<e>
+<k>rest_param_arra_type</k>
+<v>14259</v>
+</e>
+</columnsizes>
+<dependencies>
+<dep>
+<src>rest_param_arra_type</src>
+<trg>sig</trg>
+<val>
+<hist>
+<budget>12</budget>
+<bs>
+<b>
+<a>1</a>
+<b>2</b>
+<v>1</v>
+</b>
+</bs>
+</hist>
+</val>
+</dep>
+<dep>
+<src>sig</src>
+<trg>rest_param_arra_type</trg>
+<val>
+<hist>
+<budget>12</budget>
+<bs>
+<b>
+<a>1</a>
+<b>2</b>
+<v>1</v>
+</b>
+</bs>
+</hist>
+</val>
+</dep>
+</dependencies>
+</relation>
+<relation>
 <name>type_contains_signature</name>
 <cardinality>87640</cardinality>
 <columnsizes>
--- a/javascript/ql/test/library-tests/TypeScript/CallSignatureTypes/test.expected
+++ b/javascript/ql/test/library-tests/TypeScript/CallSignatureTypes/test.expected
@@ -47,14 +47,39 @@ test_ExprSignature
 | tst.ts:45:15:45:15 | x | string |
 | tst.ts:46:3:46:25 | constru ... umber); | any |
 | tst.ts:46:15:46:15 | x | number |
+| tst.ts:50:3:50:36 | method( ... ing[]); | (x: number, ...y: string[]): any |
+| tst.ts:50:10:50:10 | x | number |
+| tst.ts:50:24:50:24 | y | string[] |
+| tst.ts:51:4:51:4 | x | number |
+| tst.ts:51:18:51:18 | y | string[] |
+| tst.ts:52:7:52:7 | x | number |
+| tst.ts:52:21:52:21 | y | string[] |
+| tst.ts:54:3:54:34 | method2 ... ing[]); | (x: number, y: string[]): any |
+| tst.ts:54:11:54:11 | x | number |
+| tst.ts:54:22:54:22 | y | string[] |
+| tst.ts:55:3:55:32 | method3 ... tring); | (x: number, y: string): any |
+| tst.ts:55:11:55:11 | x | number |
+| tst.ts:55:22:55:22 | y | string |
+| tst.ts:59:3:59:25 | method( ... ing[]); | (...y: string[]): any |
+| tst.ts:59:13:59:13 | y | string[] |
+| tst.ts:60:7:60:7 | y | string[] |
+| tst.ts:61:10:61:10 | y | string[] |
+| tst.ts:63:3:63:23 | method2 ... ing[]); | (y: string[]): any |
+| tst.ts:63:11:63:11 | y | string[] |
+| tst.ts:64:3:64:21 | method3(y: string); | (y: string): any |
+| tst.ts:64:11:64:11 | y | string |
 test_TypeReferenceSig
 | Callable | function | 0 | (x: number): string |
 | Newable | constructor | 0 | new (x: number): any |
+| OnlyRestParams | constructor | 0 | new (...y: string[]): any |
+| OnlyRestParams | function | 0 | (...y: string[]): any |
 | OverloadedCallable | function | 0 | (x: number): number |
 | OverloadedCallable | function | 1 | (x: string): string |
 | OverloadedCallable | function | 2 | (x: any): any |
 | OverloadedNewable | constructor | 0 | new (x: number): OverloadedNewable |
 | OverloadedNewable | constructor | 1 | new (x: any): any |
+| WithRestParams | constructor | 0 | new (x: number, ...y: string[]): any |
+| WithRestParams | function | 0 | (x: number, ...y: string[]): any |
 test_FunctionCallSig
 | tst.ts:2:3:2:22 | (x: number): string; | (x: number): string |
 | tst.ts:6:3:6:22 | (x: number): number; | (x: number): number |
@@ -72,3 +97,62 @@ test_FunctionCallSig
 | tst.ts:40:1:42:1 | functio ... oo");\\n} | (g: Generic<string>): string |
 | tst.ts:45:3:45:25 | constru ... tring); | new (x: string): C |
 | tst.ts:46:3:46:25 | constru ... umber); | new (x: number): C |
+| tst.ts:50:3:50:36 | method( ... ing[]); | (x: number, ...y: string[]): any |
+| tst.ts:51:3:51:30 | (x: num ... ing[]); | (x: number, ...y: string[]): any |
+| tst.ts:52:3:52:33 | new(x:  ... ing[]); | new (x: number, ...y: string[]): any |
+| tst.ts:54:3:54:34 | method2 ... ing[]); | (x: number, y: string[]): any |
+| tst.ts:55:3:55:32 | method3 ... tring); | (x: number, y: string): any |
+| tst.ts:59:3:59:25 | method( ... ing[]); | (...y: string[]): any |
+| tst.ts:60:3:60:19 | (...y: string[]); | (...y: string[]): any |
+| tst.ts:61:3:61:22 | new(...y: string[]); | new (...y: string[]): any |
+| tst.ts:63:3:63:23 | method2 ... ing[]); | (y: string[]): any |
+| tst.ts:64:3:64:21 | method3(y: string); | (y: string): any |
+test_getRestParameterType
+| (...items: (string \| ConcatArray<string>)[]): string[] | string \| ConcatArray<string> |
+| (...items: ConcatArray<string>[]): string[] | ConcatArray<string> |
+| (...items: string[]): number | string |
+| (...strings: string[]): string | string |
+| (...y: string[]): any | string |
+| (start: number, deleteCount: number, ...items: string[]): string[] | string |
+| (substring: string, ...args: any[]): string | any |
+| (x: number, ...y: string[]): any | string |
+| new (...y: string[]): any | string |
+| new (x: number, ...y: string[]): any | string |
+test_getRestParameterArray
+| (...items: (string \| ConcatArray<string>)[]): string[] | (string \| ConcatArray<string>)[] |
+| (...items: ConcatArray<string>[]): string[] | ConcatArray<string>[] |
+| (...items: string[]): number | string[] |
+| (...strings: string[]): string | string[] |
+| (...y: string[]): any | string[] |
+| (start: number, deleteCount: number, ...items: string[]): string[] | string[] |
+| (substring: string, ...args: any[]): string | any[] |
+| (x: number, ...y: string[]): any | string[] |
+| new (...y: string[]): any | string[] |
+| new (x: number, ...y: string[]): any | string[] |
+test_RestSig_getParameter
+| (...items: (string \| ConcatArray<string>)[]): string[] | 0 | items | string \| ConcatArray<string> |
+| (...items: ConcatArray<string>[]): string[] | 0 | items | ConcatArray<string> |
+| (...items: string[]): number | 0 | items | string |
+| (...strings: string[]): string | 0 | strings | string |
+| (...y: string[]): any | 0 | y | string |
+| (start: number, deleteCount: number, ...items: string[]): string[] | 0 | start | number |
+| (start: number, deleteCount: number, ...items: string[]): string[] | 1 | deleteCount | number |
+| (start: number, deleteCount: number, ...items: string[]): string[] | 2 | items | string |
+| (substring: string, ...args: any[]): string | 0 | substring | string |
+| (substring: string, ...args: any[]): string | 1 | args | any |
+| (x: number, ...y: string[]): any | 0 | x | number |
+| (x: number, ...y: string[]): any | 1 | y | string |
+| new (...y: string[]): any | 0 | y | string |
+| new (x: number, ...y: string[]): any | 0 | x | number |
+| new (x: number, ...y: string[]): any | 1 | y | string |
+test_RestSig_numRequiredParams
+| (...items: (string \| ConcatArray<string>)[]): string[] | 0 |
+| (...items: ConcatArray<string>[]): string[] | 0 |
+| (...items: string[]): number | 0 |
+| (...strings: string[]): string | 0 |
+| (...y: string[]): any | 0 |
+| (start: number, deleteCount: number, ...items: string[]): string[] | 2 |
+| (substring: string, ...args: any[]): string | 1 |
+| (x: number, ...y: string[]): any | 1 |
+| new (...y: string[]): any | 0 |
+| new (x: number, ...y: string[]): any | 1 |
--- a/javascript/ql/test/library-tests/TypeScript/CallSignatureTypes/test.ql
+++ b/javascript/ql/test/library-tests/TypeScript/CallSignatureTypes/test.ql
@@ -20,3 +20,22 @@ query predicate test_TypeReferenceSig(TypeReference type, SignatureKind kind, in
 query predicate test_FunctionCallSig(Function f, CallSignatureType sig) {
  sig = f.getCallSignature()
 }
+
+query Type test_getRestParameterType(CallSignatureType sig) {
+  result = sig.getRestParameterType()
+}
+
+query Type test_getRestParameterArray(CallSignatureType sig) {
+  result = sig.getRestParameterArrayType()
+}
+
+query predicate test_RestSig_getParameter(CallSignatureType sig, int n, string name, Type type) {
+  sig.hasRestParameter() and
+  name = sig.getParameterName(n) and
+  type = sig.getParameter(n)
+}
+
+query int test_RestSig_numRequiredParams(CallSignatureType sig) {
+  sig.hasRestParameter() and
+  result = sig.getNumRequiredParameter()
+}
--- a/javascript/ql/test/library-tests/TypeScript/CallSignatureTypes/tst.ts
+++ b/javascript/ql/test/library-tests/TypeScript/CallSignatureTypes/tst.ts
@@ -45,3 +45,21 @@ declare class C {
  constructor(x: string);
  constructor(x: number);
 }
+
+interface WithRestParams {
+  method(x: number, ...y: string[]);
+  (x: number, ...y: string[]);
+  new(x: number, ...y: string[]);
+
+  method2(x: number, y: string[]);
+  method3(x: number, y: string);
+}
+
+interface OnlyRestParams {
+  method(...y: string[]);
+  (...y: string[]);
+  new(...y: string[]);
+
+  method2(y: string[]);
+  method3(y: string);
+}
--- a/javascript/ql/test/library-tests/TypeScript/Nullability/Types.expected
+++ b/javascript/ql/test/library-tests/TypeScript/Nullability/Types.expected
@@ -0,0 +1,9 @@
+exprType
+| tst.ts:1:5:1:16 | stringOrNUll | string \| null |
+| tst.ts:2:5:2:21 | stringOrUndefined | string \| undefined |
+| tst.ts:3:5:3:27 | stringO ... defined | string \| null \| undefined |
+| tst.ts:4:5:4:16 | stringOrVoid | string \| void |
+| tst.ts:7:5:7:21 | stringOrNullAlias | string \| null |
+| tst.ts:8:5:8:32 | stringO ... defined | string \| null \| undefined |
+| tst.ts:10:5:10:23 | arrayOfStringOrNull | (string \| null)[] |
+unaliasedType
--- a/javascript/ql/test/library-tests/TypeScript/Nullability/Types.ql
+++ b/javascript/ql/test/library-tests/TypeScript/Nullability/Types.ql
@@ -0,0 +1,5 @@
+import javascript
+
+query Type exprType(Expr e) { result = e.getType() }
+
+query Type unaliasedType(TypeAliasReference ref) { result = ref.getAliasedType() }
--- a/javascript/ql/test/library-tests/TypeScript/Nullability/tsconfig.json
+++ b/javascript/ql/test/library-tests/TypeScript/Nullability/tsconfig.json
@@ -0,0 +1,6 @@
+{
+    "include": ["."],
+    "compilerOptions": {
+        "strict": true
+    }
+}
--- a/javascript/ql/test/library-tests/TypeScript/Nullability/tst.ts
+++ b/javascript/ql/test/library-tests/TypeScript/Nullability/tst.ts
@@ -0,0 +1,10 @@
+let stringOrNUll: string | null;
+let stringOrUndefined: string | undefined;
+let stringOrNullOrUndefined: string | null | undefined;
+let stringOrVoid: string | void;
+
+type StringOrNullAlias = string | null;
+let stringOrNullAlias: StringOrNullAlias;
+let stringOrNullAliasOrUndefined: StringOrNullAlias | undefined;
+
+let arrayOfStringOrNull: Array<string | null>;
--- a/javascript/ql/test/library-tests/TypeScript/OptionalParameters/OptionalParams.expected
+++ b/javascript/ql/test/library-tests/TypeScript/OptionalParameters/OptionalParams.expected
@@ -0,0 +1,15 @@
+| tst.ts:1:23:1:23 | y |
+| tst.ts:2:16:2:16 | y |
+| tst.ts:6:28:6:28 | y |
+| tst.ts:8:12:8:12 | x |
+| tst.ts:8:24:8:24 | y |
+| tst.ts:9:13:9:13 | x |
+| tst.ts:13:7:13:7 | x |
+| tst.ts:14:13:14:13 | x |
+| tst.ts:15:17:15:17 | y |
+| tst.ts:18:26:18:26 | y |
+| tst.ts:18:30:18:30 | z |
+| tst.ts:18:34:18:34 | w |
+| tst.ts:20:40:20:45 | {x, y} |
+| tst.ts:20:49:20:51 | [w] |
+| withDefault.ts:1:22:1:22 | x |
--- a/javascript/ql/test/library-tests/TypeScript/OptionalParameters/OptionalParams.ql
+++ b/javascript/ql/test/library-tests/TypeScript/OptionalParameters/OptionalParams.ql
@@ -0,0 +1,3 @@
+import javascript
+
+query Parameter optionalParams() { result.isDeclaredOptional() }
--- a/javascript/ql/test/library-tests/TypeScript/OptionalParameters/tst.ts
+++ b/javascript/ql/test/library-tests/TypeScript/OptionalParameters/tst.ts
@@ -0,0 +1,20 @@
+function f(x: number, y?: string) {
+    return (x, y?) => {};
+}
+
+class C {
+    constructor(x: number, y?: string) {}
+
+    method(x?: number, y?: string) {}
+    noTypes(x?) {}
+}
+
+interface I {
+    m(x?: number);
+    field: (x?: number) => void;
+    (x: number, y?: string): void;
+}
+
+function manyDefaults(x, y?, z?, w?) {}
+
+declare function optionalDestructuring({x, y}?, [w]?);
--- a/javascript/ql/test/library-tests/TypeScript/OptionalParameters/withDefault.ts
+++ b/javascript/ql/test/library-tests/TypeScript/OptionalParameters/withDefault.ts
@@ -0,0 +1 @@
+function withDefault(x? = 5) {} // not valid syntax
--- a/javascript/ql/test/library-tests/TypeScript/RegressionTests/AllowJs/main.ts
+++ b/javascript/ql/test/library-tests/TypeScript/RegressionTests/AllowJs/main.ts
@@ -0,0 +1,2 @@
+import f = require("./tst");
+f("world");
--- a/javascript/ql/test/library-tests/TypeScript/RegressionTests/AllowJs/test.expected
+++ b/javascript/ql/test/library-tests/TypeScript/RegressionTests/AllowJs/test.expected
@@ -0,0 +1,5 @@
+| main.ts:1:8:1:8 | f | (x: string) => string |
+| main.ts:1:20:1:26 | "./tst" | any |
+| main.ts:2:1:2:1 | f | (x: string) => string |
+| main.ts:2:1:2:10 | f("world") | string |
+| main.ts:2:3:2:9 | "world" | "world" |
--- a/javascript/ql/test/library-tests/TypeScript/RegressionTests/AllowJs/test.ql
+++ b/javascript/ql/test/library-tests/TypeScript/RegressionTests/AllowJs/test.ql
@@ -0,0 +1,4 @@
+import javascript
+
+from Expr e
+select e, e.getType()
--- a/javascript/ql/test/library-tests/TypeScript/RegressionTests/AllowJs/tsconfig.json
+++ b/javascript/ql/test/library-tests/TypeScript/RegressionTests/AllowJs/tsconfig.json
@@ -0,0 +1,6 @@
+{
+    "compilerOptions": {
+        "allowJs": true
+    },
+    "include": ["."]
+}
--- a/javascript/ql/test/library-tests/TypeScript/RegressionTests/AllowJs/tst.js
+++ b/javascript/ql/test/library-tests/TypeScript/RegressionTests/AllowJs/tst.js
@@ -0,0 +1,6 @@
+/**
+ * @param {String} x
+ */
+module.exports = function(x) {
+    return 'Hello ' + x;
+}
--- a/javascript/ql/test/library-tests/TypeScript/RegressionTests/MissingTypeRoot/test.expected
+++ b/javascript/ql/test/library-tests/TypeScript/RegressionTests/MissingTypeRoot/test.expected
@@ -0,0 +1 @@
+| tst.ts:0:0:0:0 | tst.ts |
--- a/javascript/ql/test/library-tests/TypeScript/RegressionTests/MissingTypeRoot/test.ql
+++ b/javascript/ql/test/library-tests/TypeScript/RegressionTests/MissingTypeRoot/test.ql
@@ -0,0 +1,4 @@
+import javascript
+
+from File file
+select file
--- a/javascript/ql/test/library-tests/TypeScript/RegressionTests/MissingTypeRoot/tsconfig.json
+++ b/javascript/ql/test/library-tests/TypeScript/RegressionTests/MissingTypeRoot/tsconfig.json
@@ -0,0 +1,6 @@
+{
+    "include": ["."],
+    "compilerOptions": {
+        "typeRoots": ["does-not-exist"]
+    }
+}
--- a/javascript/ql/test/library-tests/TypeScript/RegressionTests/MissingTypeRoot/tst.ts
+++ b/javascript/ql/test/library-tests/TypeScript/RegressionTests/MissingTypeRoot/tst.ts
@@ -0,0 +1 @@
+let x = 5;
--- a/javascript/ql/test/library-tests/TypeScript/RegressionTests/RecursiveTypeAlias/Test.expected
+++ b/javascript/ql/test/library-tests/TypeScript/RegressionTests/RecursiveTypeAlias/Test.expected
@@ -1,2 +0,0 @@
-| test.ts:3:1:7:6 | type Di ... \\n    T; | Disjunction<T> |
-| test.ts:9:8:9:65 | type Tr ... n<T>>>; | Disjunction<Disjunction<Disjunction<T>>> |
--- a/javascript/ql/test/library-tests/TypeScript/RegressionTests/RecursiveTypeAlias/tsconfig.json
+++ b/javascript/ql/test/library-tests/TypeScript/RegressionTests/RecursiveTypeAlias/tsconfig.json
@@ -1 +1,3 @@
-{}
+{
+    "include": ["."]
+}
--- a/javascript/ql/test/library-tests/TypeScript/RegressionTests/TypeRootFile/test.expected
+++ b/javascript/ql/test/library-tests/TypeScript/RegressionTests/TypeRootFile/test.expected
@@ -0,0 +1,2 @@
+| tst.ts:0:0:0:0 | tst.ts |
+| typeroot.d.ts:0:0:0:0 | typeroot.d.ts |
--- a/javascript/ql/test/library-tests/TypeScript/RegressionTests/TypeRootFile/test.ql
+++ b/javascript/ql/test/library-tests/TypeScript/RegressionTests/TypeRootFile/test.ql
@@ -0,0 +1,4 @@
+import javascript
+
+from File file
+select file
--- a/javascript/ql/test/library-tests/TypeScript/RegressionTests/TypeRootFile/tsconfig.json
+++ b/javascript/ql/test/library-tests/TypeScript/RegressionTests/TypeRootFile/tsconfig.json
@@ -0,0 +1,6 @@
+{
+    "include": ["."],
+    "compilerOptions": {
+        "typeRoots": ["typeroot.d.ts"]
+    }
+}
--- a/javascript/ql/test/library-tests/TypeScript/RegressionTests/TypeRootFile/tst.ts
+++ b/javascript/ql/test/library-tests/TypeScript/RegressionTests/TypeRootFile/tst.ts
@@ -0,0 +1 @@
+let x = 5;
--- a/javascript/ql/test/library-tests/TypeScript/RegressionTests/TypeRootFile/typeroot.d.ts
+++ b/javascript/ql/test/library-tests/TypeScript/RegressionTests/TypeRootFile/typeroot.d.ts
--- a/javascript/ql/test/library-tests/TypeScript/TypeAliases/TypeAliases.expected
+++ b/javascript/ql/test/library-tests/TypeScript/TypeAliases/TypeAliases.expected
@@ -1,3 +1,44 @@
+rightHandSide
+| tst.ts:1:1:1:16 | type A = number; | number |
+| tst.ts:2:1:2:16 | type B<T> = T[]; | T[] |
+| tst.ts:8:10:8:20 | type C = A; | number |
+| tst.ts:15:1:15:23 | type Un ...  \| Two; | One \| Two |
+| tst.ts:17:1:17:36 | type Un ... mber }; | (One & { x: number; }) \| (Two & { x: number; }) |
+| tst.ts:18:1:18:21 | type Un ... Union2; | (One & { x: number; }) \| (Two & { x: number; }) |
+| tst.ts:19:1:19:21 | type Un ... Union3; | (One & { x: number; }) \| (Two & { x: number; }) |
+| tst.ts:20:1:20:30 | type Un ... number; | number \| (One & { x: number; }) \| (Two & { x: n... |
+getAliasedType
+| B<T> | T[] |
+| B<number> | number[] |
+| Union | One \| Two |
+| Union2 | (One & { x: number; }) \| (Two & { x: number; }) |
+| Union5 | number \| (One & { x: number; }) \| (Two & { x: n... |
+getTypeArgument
+| B<T> | 0 | T |
+| B<number> | 0 | number |
+unfold
+| B<T> | B<T> |
+| B<T> | T[] |
+| B<number> | B<number> |
+| B<number> | number[] |
+| Union | One |
+| Union | Two |
+| Union | Union |
+| Union2 | One |
+| Union2 | Two |
+| Union2 | Union2 |
+| Union2 | { x: number; } |
+| Union5 | One |
+| Union5 | Two |
+| Union5 | Union5 |
+| Union5 | number |
+| Union5 | { x: number; } |
+#select
 | tst.ts:1:1:1:16 | type A = number; | tst.ts:1:6:1:6 | A | 0 | tst.ts:1:10:1:15 | number |
 | tst.ts:2:1:2:16 | type B<T> = T[]; | tst.ts:2:6:2:6 | B | 1 | tst.ts:2:13:2:15 | T[] |
 | tst.ts:8:10:8:20 | type C = A; | tst.ts:8:15:8:15 | C | 0 | tst.ts:8:19:8:19 | A |
+| tst.ts:15:1:15:23 | type Un ...  \| Two; | tst.ts:15:6:15:10 | Union | 0 | tst.ts:15:14:15:22 | One \| Two |
+| tst.ts:17:1:17:36 | type Un ... mber }; | tst.ts:17:6:17:11 | Union2 | 0 | tst.ts:17:15:17:35 | Union & ... umber } |
+| tst.ts:18:1:18:21 | type Un ... Union2; | tst.ts:18:6:18:11 | Union3 | 0 | tst.ts:18:15:18:20 | Union2 |
+| tst.ts:19:1:19:21 | type Un ... Union3; | tst.ts:19:6:19:11 | Union4 | 0 | tst.ts:19:15:19:20 | Union3 |
+| tst.ts:20:1:20:30 | type Un ... number; | tst.ts:20:6:20:11 | Union5 | 0 | tst.ts:20:15:20:29 | Union4 \| number |
--- a/javascript/ql/test/library-tests/TypeScript/TypeAliases/TypeAliases.ql
+++ b/javascript/ql/test/library-tests/TypeScript/TypeAliases/TypeAliases.ql
@@ -2,3 +2,19 @@ import javascript

 from TypeAliasDeclaration decl
 select decl, decl.getIdentifier(), decl.getNumTypeParameter(), decl.getDefinition()
+
+query Type rightHandSide(TypeAliasDeclaration decl) {
+  result = decl.getDefinition().getType()
+}
+
+query Type getAliasedType(TypeAliasReference ref) {
+  result = ref.getAliasedType()
+}
+
+query Type getTypeArgument(TypeAliasReference ref, int n) {
+  result = ref.getTypeArgument(n)
+}
+
+query Type unfold(TypeAliasReference t) {
+  result = t.unfold()
+}
--- a/javascript/ql/test/library-tests/TypeScript/TypeAliases/tsconfig.json
+++ b/javascript/ql/test/library-tests/TypeScript/TypeAliases/tsconfig.json
@@ -0,0 +1,3 @@
+{
+    "include": ["."]
+}
--- a/javascript/ql/test/library-tests/TypeScript/TypeAliases/tst.ts
+++ b/javascript/ql/test/library-tests/TypeScript/TypeAliases/tst.ts
@@ -8,3 +8,13 @@ namespace Q {
  export type C = A;
 }
 var z: Q.C;
+
+interface One { a: number }
+interface Two { b: number }
+
+type Union = One | Two;
+
+type Union2 = Union & { x: number };
+type Union3 = Union2;
+type Union4 = Union3;
+type Union5 = Union4 | number;
--- a/javascript/ql/test/library-tests/TypeScript/Types/GetTypeExprType.expected
+++ b/javascript/ql/test/library-tests/TypeScript/Types/GetTypeExprType.expected
@@ -74,7 +74,7 @@
 | type_alias.ts:5:6:5:17 | ValueOrArray | ValueOrArray<T> |
 | type_alias.ts:5:19:5:19 | T | T |
 | type_alias.ts:5:24:5:24 | T | T |
-| type_alias.ts:5:24:5:49 | T \| Arr ... ray<T>> | ValueOrArray<T> |
+| type_alias.ts:5:24:5:49 | T \| Arr ... ray<T>> | T \| ValueOrArray<T>[] |
 | type_alias.ts:5:28:5:32 | Array | T[] |
 | type_alias.ts:5:28:5:49 | Array<V ... ray<T>> | ValueOrArray<T>[] |
 | type_alias.ts:5:34:5:45 | ValueOrArray | ValueOrArray<T> |
@@ -84,7 +84,7 @@
 | type_alias.ts:7:8:7:27 | ValueOrArray<number> | ValueOrArray<number> |
 | type_alias.ts:7:21:7:26 | number | number |
 | type_alias.ts:9:6:9:9 | Json | Json |
-| type_alias.ts:10:5:15:12 | \| strin ...  Json[] | Json |
+| type_alias.ts:10:5:15:12 | \| strin ...  Json[] | string \| number \| boolean \| { [property: string... |
 | type_alias.ts:10:7:10:12 | string | string |
 | type_alias.ts:11:7:11:12 | number | number |
 | type_alias.ts:12:7:12:13 | boolean | boolean |
@@ -96,7 +96,7 @@
 | type_alias.ts:15:7:15:12 | Json[] | Json[] |
 | type_alias.ts:17:11:17:14 | Json | Json |
 | type_alias.ts:19:6:19:16 | VirtualNode | VirtualNode |
-| type_alias.ts:20:5:21:56 | \| strin ... Node[]] | VirtualNode |
+| type_alias.ts:20:5:21:56 | \| strin ... Node[]] | string \| [string, { [key: string]: any; }, ...V... |
 | type_alias.ts:20:7:20:12 | string | string |
 | type_alias.ts:21:7:21:56 | [string ... Node[]] | [string, { [key: string]: any; }, ...VirtualNod... |
 | type_alias.ts:21:8:21:13 | string | string |
@@ -123,7 +123,7 @@
 | type_definitions.ts:21:6:21:10 | Alias | Alias<T> |
 | type_definitions.ts:21:12:21:12 | T | T |
 | type_definitions.ts:21:17:21:17 | T | T |
-| type_definitions.ts:21:17:21:19 | T[] | Alias<T> |
+| type_definitions.ts:21:17:21:19 | T[] | T[] |
 | type_definitions.ts:22:26:22:30 | Alias | Alias<T> |
 | type_definitions.ts:22:26:22:38 | Alias<number> | Alias<number> |
 | type_definitions.ts:22:32:22:37 | number | number |
--- a/javascript/ql/test/library-tests/TypeScript/Types/tsconfig.json
+++ b/javascript/ql/test/library-tests/TypeScript/Types/tsconfig.json
@@ -1,5 +1,5 @@
 {
  "compilerOptions": {
-    "lib": ["es2015.symbol"]
+    "lib": ["es2015"]
  }
 }
--- a/javascript/upgrades/e2173e83ac503be4d7c18472a2d7ce636724510c/old.dbscheme
+++ b/javascript/upgrades/e2173e83ac503be4d7c18472a2d7ce636724510c/old.dbscheme
--- a/javascript/upgrades/e2173e83ac503be4d7c18472a2d7ce636724510c/semmlecode.javascript.dbscheme
+++ b/javascript/upgrades/e2173e83ac503be4d7c18472a2d7ce636724510c/semmlecode.javascript.dbscheme
--- a/javascript/upgrades/e2173e83ac503be4d7c18472a2d7ce636724510c/upgrade.properties
+++ b/javascript/upgrades/e2173e83ac503be4d7c18472a2d7ce636724510c/upgrade.properties
@@ -0,0 +1,2 @@
+description: improve TypeScript support for type aliases, rest parameters, and optional parameters
+compatibility: backwards
				`@@ -0,0 +1 @@`
				`function withDefault(x? = 5) {} // not valid syntax`