Update ExecutableLocator to be compatible with the Gradle Provider API

[aSemy]

I would like to use Protobuf Plugin for Gradle to generate some TypeScript.

I am using Gradle Node Plugin to install ts-protoc-gen.

I've tried to set the path of the ts-protoc-gen executable, however, I get an error

FAILURE: Build failed with an exception.
* What went wrong:
Could not determine the dependencies of task ':generateProto'.
> Not yet resolved
* Try:
> Run with --info or --debug option to get more log output.
> Run with --scan to get full insights.
> Get more help at https://help.gradle.org.
* Exception is:
org.gradle.api.internal.tasks.TaskDependencyResolveException: Could not determine the dependencies of task ':generateProto'.
	at org.gradle.api.internal.tasks.CachingTaskDependencyResolveContext.getDependencies(CachingTaskDependencyResolveContext.java:68)
	at org.gradle.execution.plan.TaskDependencyResolver.resolveDependenciesFor(TaskDependencyResolver.java:49)
	...
Caused by: java.lang.IllegalStateException: Not yet resolved
	at com.google.protobuf.gradle.Preconditions.checkState(Preconditions.java:45)
	at com.google.protobuf.gradle.ExecutableLocator.getSimplifiedArtifactName(ExecutableLocator.groovy:97)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at com.google.protobuf.gradle.GenerateProtoTask$_getReleaseExecutableLocators_closure7.doCall(GenerateProtoTask.groovy:354)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at com.google.protobuf.gradle.GenerateProtoTask.getReleaseExecutableLocators(GenerateProtoTask.groovy:354)
	at com.google.protobuf.gradle.GenerateProtoTask.access$0(GenerateProtoTask.groovy)
	at com.google.protobuf.gradle.GenerateProtoTask$_getExecutables_closure6.doCall(GenerateProtoTask.groovy:346)
	at com.google.protobuf.gradle.GenerateProtoTask$_getExecutables_closure6.call(GenerateProtoTask.groovy)
	at org.gradle.api.internal.provider.DefaultProvider.calculateOwnValue(DefaultProvider.java:72)
	at org.gradle.api.internal.provider.AbstractMinimalProvider.calculateOwnPresentValue(AbstractMinimalProvider.java:73)
	at org.gradle.api.internal.provider.AbstractMinimalProvider.get(AbstractMinimalProvider.java:93)
	at org.gradle.api.internal.provider.ProviderResolutionStrategy$2.resolve(ProviderResolutionStrategy.java:33)
	at org.gradle.api.internal.file.collections.ProviderBackedFileCollection.visitDependencies(ProviderBackedFileCollection.java:57)
	at org.gradle.api.internal.tasks.CachingTaskDependencyResolveContext$TaskGraphImpl.getNodeValues(CachingTaskDependencyResolveContext.java:103)
	at org.gradle.internal.graph.CachingDirectedGraphWalker$GraphWithEmptyEdges.getNodeValues(CachingDirectedGraphWalker.java:213)
	at org.gradle.internal.graph.CachingDirectedGraphWalker.doSearch(CachingDirectedGraphWalker.java:121)
	at org.gradle.internal.graph.CachingDirectedGraphWalker.findValues(CachingDirectedGraphWalker.java:73)
	at org.gradle.api.internal.tasks.CachingTaskDependencyResolveContext.getDependencies(CachingTaskDependencyResolveContext.java:66)
	... 149 more
BUILD FAILED in 2s

I think this is caused by Protobuf Plugin for Gradle trying to evaluate the path in the configuration phase, before the Npm install task has run.

Example

Here is a very brief example showing how I am currently registering ts-protoc-gen with Protobuf Plugin for Gradle.

// build.gradle.kts
import org.gradle.internal.os.OperatingSystem

plugins {
    id("com.google.protobuf") version "0.9.4"
    id("com.github.node-gradle.node") version "5.0.0"
}

val npmCleanInstall by tasks.registering(NpmTask::class) {
    group = project.name
    args.addAll("clean-install")
}

tasks.generateProto {
    dependsOn(npmCleanInstall)
}

protobuf {
    plugins {
        register("ts") {
            val protocGenTsPath = node.nodeProjectDir
                .map { it.dir("node_modules/ts-protoc-gen/bin/protoc-gen-ts") }
                .map { protocGenTs ->
                    val ext = (if (OperatingSystem.current().isWindows) ".cmd" else "")
                    protocGenTs.asFile.invariantSeparatorsPath + ext
                }

            path = protocGenTsPath.get()
        }
    }
}

ExecutableLocator.path only accepts a String, so unfortunately this breaks Gradle lazy configuration

Proposal

Change the type of ExecutableLocator.path from String to RegularFileProperty. This would allow for the path to be set lazily.

protobuf-gradle-plugin/src/main/groovy/com/google/protobuf/gradle/ExecutableLocator.groovy

Line 48 in ff4fe68

private String path

    private RegularFileProperty path

This change would be backwards compatible - getPath()/setPath() could still exist (but should probably be @Deprecated).