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Closure Compiler is a JavaScript optimizing compiler. It parses your
JavaScript, analyzes it, removes dead code and rewrites and minimizes
what's left. It also checks syntax, variable references, and types, and
warns about common JavaScript pitfalls. It is used in many of Google's
JavaScript apps, including Gmail, Google Web Search, Google Maps, and
Google Docs.
/*
* Copyright 2017 The Closure Compiler Authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.google.javascript.jscomp;
import static com.google.common.base.Preconditions.checkState;
import com.google.auto.value.AutoValue;
import com.google.common.base.Splitter;
import com.google.common.base.Supplier;
import com.google.common.base.Suppliers;
import com.google.javascript.rhino.Node;
import com.google.javascript.rhino.jstype.FunctionType;
import com.google.javascript.rhino.jstype.JSType;
import com.google.javascript.rhino.jstype.ObjectType;
import java.io.Serializable;
import java.util.Iterator;
import java.util.List;
import java.util.Objects;
/**
* Signals that the first type and the second type have been
* used interchangeably.
*
* Type-based optimizations should take this into account
* so that they don't wreck code with type warnings.
*/
class TypeMismatch implements Serializable {
final JSType typeA;
final JSType typeB;
final Supplier error;
/**
* It's the responsibility of the class that creates the
* {@code TypeMismatch} to ensure that {@code a} and {@code b} are
* non-matching types.
*/
TypeMismatch(JSType a, JSType b, Supplier error) {
this.typeA = a;
this.typeB = b;
this.error = error;
}
static void registerIfMismatch(
List mismatches, List implicitInterfaceUses,
JSType found, JSType required, JSError error) {
if (found != null && required != null && !found.isSubtypeWithoutStructuralTyping(required)) {
registerMismatch(mismatches, implicitInterfaceUses, found, required, error);
}
}
/**
* In the old type checker, a type variable is considered unknown, so other types can be
* used as type variables, and vice versa, without warning. NTI correctly warns.
* However, we don't want to block disambiguation in these cases. So, to avoid types getting
* invalidated, we don't register the mismatch. Otherwise, to get good disambiguation,
* we would have to add casts all over the code base.
* TODO(dimvar): this can be made safe in the distant future where we have bounded generics
* *and* we have switched all the unsafe uses of type variables in the code base to use
* bounded generics.
*/
private static boolean bothAreNotTypeVariables(JSType found, JSType required) {
return !found.isTypeVariable() && !required.isTypeVariable();
}
static void registerMismatch(
List mismatches, List implicitInterfaceUses,
JSType found, JSType required, JSError error) {
// Don't register a mismatch for differences in null or undefined or if the
// code didn't downcast.
found = removeNullUndefinedAndTemplates(found);
required = removeNullUndefinedAndTemplates(required);
if (found.isSubtypeOf(required) || required.isSubtypeOf(found)) {
boolean strictMismatch =
!found.isSubtypeWithoutStructuralTyping(required)
&& !required.isSubtypeWithoutStructuralTyping(found);
if (strictMismatch && bothAreNotTypeVariables(found, required)) {
implicitInterfaceUses.add(new TypeMismatch(found, required, Suppliers.ofInstance(error)));
}
return;
}
if (bothAreNotTypeVariables(found, required)) {
mismatches.add(new TypeMismatch(found, required, Suppliers.ofInstance(error)));
}
if (found.isFunctionType() && required.isFunctionType()) {
FunctionType fnTypeA = found.toMaybeFunctionType();
FunctionType fnTypeB = required.toMaybeFunctionType();
Iterator paramItA = fnTypeA.getParameterTypes().iterator();
Iterator paramItB = fnTypeB.getParameterTypes().iterator();
while (paramItA.hasNext() && paramItB.hasNext()) {
TypeMismatch.registerIfMismatch(
mismatches, implicitInterfaceUses, paramItA.next(), paramItB.next(), error);
}
TypeMismatch.registerIfMismatch(
mismatches, implicitInterfaceUses,
fnTypeA.getReturnType(), fnTypeB.getReturnType(), error);
}
}
static void recordImplicitUseOfNativeObject(
List mismatches, Node node, JSType sourceType, JSType targetType) {
sourceType = sourceType.restrictByNotNullOrUndefined();
targetType = targetType.restrictByNotNullOrUndefined();
if (isInstanceOfObject(sourceType)
&& !isInstanceOfObject(targetType)
&& !targetType.isUnknownType()
&& bothAreNotTypeVariables(sourceType, targetType)) {
// We don't report a type error, but we still need to construct a JSError,
// for people who enable the invalidation diagnostics in DisambiguateProperties.
LazyError err =
LazyError.of(
"Implicit use of Object type: %s as type: %s", node, sourceType, targetType);
mismatches.add(new TypeMismatch(sourceType, targetType, err));
}
}
static void recordImplicitInterfaceUses(
List implicitInterfaceUses, Node node, JSType sourceType, JSType targetType) {
sourceType = removeNullUndefinedAndTemplates(sourceType);
targetType = removeNullUndefinedAndTemplates(targetType);
if (targetType.isUnknownType()) {
return;
}
boolean strictMismatch =
!sourceType.isSubtypeWithoutStructuralTyping(targetType)
&& !targetType.isSubtypeWithoutStructuralTyping(sourceType);
boolean mismatch = !sourceType.isSubtypeOf(targetType) && !targetType.isSubtypeOf(sourceType);
if ((strictMismatch || mismatch) && bothAreNotTypeVariables(sourceType, targetType)) {
// We don't report a type error, but we still need to construct a JSError,
// for people who enable the invalidation diagnostics in DisambiguateProperties.
LazyError err = LazyError.of("Implicit use of type %s as %s", node, sourceType, targetType);
implicitInterfaceUses.add(new TypeMismatch(sourceType, targetType, err));
}
}
private static boolean isInstanceOfObject(JSType type) {
// Some type whose class is Object
ObjectType obj = type.toMaybeObjectType();
if (obj != null && obj.isNativeObjectType() && "Object".equals(obj.getReferenceName())) {
return true;
}
return type.isRecordType() || type.isLiteralObject();
}
private static JSType removeNullUndefinedAndTemplates(JSType t) {
JSType result = t.restrictByNotNullOrUndefined();
ObjectType obj = result.toMaybeObjectType();
if (obj != null && obj.isTemplatizedType()) {
// We don't care about the specific specalization involved in the mismatch because all
// specializations share the same JS code.
return obj.toMaybeTemplatizedType().getRawType();
}
return result;
}
@Override public boolean equals(Object object) {
if (object instanceof TypeMismatch) {
TypeMismatch that = (TypeMismatch) object;
return (that.typeA.equals(this.typeA) && that.typeB.equals(this.typeB))
|| (that.typeB.equals(this.typeA) && that.typeA.equals(this.typeB));
}
return false;
}
@Override public int hashCode() {
return Objects.hash(typeA, typeB);
}
@Override public String toString() {
return "(" + typeA + ", " + typeB + ")";
}
@AutoValue
abstract static class LazyError implements Supplier, Serializable {
abstract String message();
abstract Node node();
abstract JSType sourceType();
abstract JSType targetType();
private static LazyError of(String message, Node node, JSType sourceType, JSType targetType) {
return new AutoValue_TypeMismatch_LazyError(message, node, sourceType, targetType);
}
@Override
public JSError get() {
// NOTE: GWT does not support String.format, so we work around it with a quick hack.
List parts = Splitter.on("%s").splitToList(message());
checkState(parts.size() == 3);
return JSError.make(
node(),
TypeValidator.TYPE_MISMATCH_WARNING,
parts.get(0) + sourceType() + parts.get(1) + targetType() + parts.get(2));
}
}
}