// Copyright 2015 The Bazel Authors. All rights reserved.
//
// 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.devtools.build.lib.analysis.config;
/**
* Dynamic transition to the host configuration.
*/
public final class HostTransition implements PatchTransition {
public static final HostTransition INSTANCE = new HostTransition();
private HostTransition() {}
@Override
public BuildOptions apply(BuildOptions options) {
if (options.get(BuildConfiguration.Options.class).isHost) {
// If the input already comes from the host configuration, just return the existing values.
//
// We don't do this just for convenience: if an
// {@link com.google.devtools.build.lib.runtime.proto.InvocationPolicyOuterClass.InvocationPolicy}
// overrides option defaults, {@link FragmentOptions#getHost} won't honor that policy. That's
// because it uses its own options parser that's not aware of the policy. This can create
// problems for, e.g., {@link JavaOptions#getHost}, which promotes --host_foo flags to
// --foo flags. That works the first time you do it (since both of the original values
// were policy-processed). But not subsequent times.
//
// There are various ways to solve this problem (pass the policy to host options computation,
// manually set host.hostFoo = original.hostFoo). But those raise larger questions about the
// nature of host/target relationships, so for the time being this is a straightforward
// and practical fix.
return options.clone();
} else {
return options.createHostOptions(false);
}
}
@Override
public boolean defaultsToSelf() { return false; }
}