support xxx_opt flag on protoc

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

@@ -32,6 +32,7 @@ import groovy.transform.CompileStatic
 import groovy.transform.PackageScope
 import org.gradle.api.Named
 import org.gradle.api.file.FileCollection
+import org.gradle.util.VersionNumber
 
 /**
  * Locates an executable that can either be found locally or downloaded from
@@ -50,6 +51,8 @@ class ExecutableLocator implements Named {
   private FileCollection artifactFiles
   private String simplifiedArtifactName
 
+  private VersionNumber version = VersionNumber.UNKNOWN
+
   ExecutableLocator(String name) {
     this.name = name
   }
@@ -76,6 +79,10 @@ class ExecutableLocator implements Named {
     this.artifact = null
   }
 
+  void setVersion(VersionNumber version) {
+    this.version = version
+  }
+
   String getArtifact() {
     return artifact
   }
@@ -84,6 +91,10 @@ class ExecutableLocator implements Named {
     return path
   }
 
+  VersionNumber getVersion() {
+    return version
+  }
+
   @PackageScope
   FileCollection getArtifactFiles() {
     Preconditions.checkState(path == null, 'Not artifact based')

src/main/groovy/com/google/protobuf/gradle/GenerateProtoTask.groovy

@@ -62,6 +62,7 @@ import org.gradle.api.tasks.PathSensitivity
 import org.gradle.api.tasks.SkipWhenEmpty
 import org.gradle.api.tasks.SourceSet
 import org.gradle.api.tasks.TaskAction
+import org.gradle.util.VersionNumber
 
 import javax.annotation.Nullable
 import javax.inject.Inject
@@ -165,7 +166,7 @@ public abstract class GenerateProtoTask extends DefaultTask {
   // - Without options: --java_out=/path/to/output
   // - With options: --java_out=option1,option2:/path/to/output
   // This method generates the prefix out of the given options.
-  static String makeOptionsPrefix(List<String> options) {
+  static String assembleOptions(List<String> options) {
     StringBuilder prefix = new StringBuilder()
     if (!options.isEmpty()) {
       options.each { option ->
@@ -174,7 +175,6 @@ public abstract class GenerateProtoTask extends DefaultTask {
         }
         prefix.append(option)
       }
-      prefix.append(':')
     }
     return prefix.toString()
   }
@@ -622,8 +622,16 @@ public abstract class GenerateProtoTask extends DefaultTask {
 
     // Handle code generation built-ins
     builtins.each { builtin ->
-      String outPrefix = makeOptionsPrefix(builtin.options)
-      baseCmd += "--${builtin.name}_out=${outPrefix}${getOutputDir(builtin)}".toString()
+      String options = assembleOptions(builtin.options)
+      if (toolsLocator.protoc.version == VersionNumber.UNKNOWN ||
+              VersionNumber.parse("3.2.0") >= toolsLocator.protoc.version) {
+        if (!options.isBlank())
+          options += ":"
+        baseCmd += "--${name}_out=${options}${getOutputDir(builtin)}".toString()
+      } else {
+        baseCmd += "--${builtin.name}_out=${getOutputDir(builtin)}".toString()
+        baseCmd += "--${builtin.name}_opt=$options".toString()
+      }
     }
 
     Map<String, ExecutableLocator> executableLocations = toolsLocator.plugins.asMap
@@ -636,8 +644,16 @@ public abstract class GenerateProtoTask extends DefaultTask {
       } else {
         logger.warn "protoc plugin '${name}' not defined. Trying to use 'protoc-gen-${name}' from system path"
       }
-      String pluginOutPrefix = makeOptionsPrefix(plugin.options)
-      baseCmd += "--${name}_out=${pluginOutPrefix}${getOutputDir(plugin)}".toString()
+      String options = assembleOptions(plugin.options)
+      if (toolsLocator.protoc.version == VersionNumber.UNKNOWN ||
+              VersionNumber.parse("3.2.0") >= toolsLocator.protoc.version) {
+        if (!options.isBlank())
+          options += ":"
+        baseCmd += "--${name}_out=${options}${getOutputDir(plugin)}".toString()
+      } else {
+      baseCmd += "--${name}_out=${getOutputDir(plugin)}".toString()
+      baseCmd += "--${name}_opt=$options".toString()
+    }
     }
 
     if (generateDescriptorSet) {

src/main/groovy/com/google/protobuf/gradle/ToolsLocator.groovy

@@ -34,6 +34,10 @@ import org.gradle.api.NamedDomainObjectContainer
 import org.gradle.api.Project
 import org.gradle.api.artifacts.Configuration
 import org.gradle.api.artifacts.Dependency
+import org.gradle.util.VersionNumber
+
+import java.nio.file.Files
+import java.nio.file.Paths
 
 /**
  * Holds locations of all external executables, i.e., protoc and plugins.
@@ -82,6 +86,7 @@ class ToolsLocator {
     } else if (protoc.path == null) {
       protoc.path = 'protoc'
     }
+    protoc.version = determineProtocVersion(protoc)
     for (ExecutableLocator pluginLocator in plugins) {
       if (pluginLocator.artifact != null) {
         resolveLocator(project, pluginLocator)
@@ -111,4 +116,17 @@ class ToolsLocator {
     Dependency dep = project.dependencies.add(config.name, notation)
     locator.resolve(config.fileCollection(dep), "$groupId:$artifact:$version".toString())
   }
+
+  private VersionNumber determineProtocVersion(ExecutableLocator executableLocator) {
+    if (executableLocator.artifact != null) {
+      String[] parts = executableLocator.simplifiedArtifactName.split(":")
+      return VersionNumber.parse(parts[2])
+    } else if (executableLocator.path != null && Files.isExecutable(Paths.get(executableLocator.path))) {
+      Process process = new ProcessBuilder(executableLocator.path, "--version").start()
+      BufferedReader reader = new BufferedReader(new InputStreamReader(process.getInputStream()))
+      String version = reader.readLine().replace("libprotoc ", "")
+      return VersionNumber.parse(version)
+    }
+    return VersionNumber.UNKNOWN
+  }
 }