Embed BuildInfo in plugin.

- Display version, etc. info on startup
- Warn if using an unofficial release
- Determine whether build was clean (git-wise)
- Prevents publishing from unclean working dir

Fixes #394

Uses https://github.com/madvay/git-build-info plugin

.gitignore

@@ -9,3 +9,4 @@ j2objc-gradle.iml
 gradlew.bat
 
 local.properties
+src-gen/

CONTRIBUTING.md

@@ -236,10 +236,14 @@ published versions on plugins.gradle.org.  All branches and tags are on the
 `j2objc-contrib/j2objc-gradle` repository, not any forks.  The steps are:
 
 1.  Determine the version number.  Use https://semver.org to guide which
-slot in the version number should be bumped.  We'll call this `vX.Y.Z`.
-2.  As a separate commit, bump the version number in `build.gradle` and add a
-brief section at the top of [CHANGELOG.md](CHANGELOG.md) indicating key
-functionality and quality improvements.
+slot in the version number should be bumped.  We'll call this `vX.Y.Z`.  Note that
+this does not have to be the `-SNAPSHOT` version in build.gradle - that number
+was auto-incremented after the last release and may not reflect the extent
+of API changes which, per semantic versioning, whether to increment major, minor,
+or patch numbers.
+2.  As a separate commit, update the version number in `build.gradle`, removing the
+`-SNAPSHOT` suffix if any, and add a brief section at the top of
+[CHANGELOG.md](CHANGELOG.md) indicating key functionality and quality improvements.
 File a PR, and merge that PR into the release branch.
 3.  Tag the merge commit where that PR is merged into master as `vX.Y.Z` and push
 that tag to the repository.  It is important that this is not the commit for the PR.
@@ -255,6 +259,10 @@ git push upstream v0.4.1-alpha
 ./gradlew clean build publishPlugins
 ```
 
+5.  Push a new PR that increments build.gradle to `vX.Y.(Z+1)-SNAPSHOT`.  `-SNAPSHOT`
+is standard convention for marking an unofficial build (if users happen to get their
+hands on one built directly from source).
+
 ### Hotfixes
 
 Currently the development is manageable, such that release branching can be isolated

build.gradle

@@ -13,11 +13,11 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-
 // Based on https://plugins.gradle.org/docs/publish-plugin
 
 plugins {
     id "com.gradle.plugin-publish" version "0.9.0"
+    id "com.madvay.tools.build.gitbuildinfo" version "0.1.2-alpha"
 }
 apply plugin: 'groovy'
 
@@ -32,7 +32,11 @@ task wrapper(type: Wrapper) {
 }
 
 group = 'com.github.j2objccontrib.j2objcgradle'
-version = '0.4.2-alpha'
+
+// A suffix of -SNAPSHOT means this is not an official release of the
+// system, but built from an intermediate source tree.  See
+// CONTRIBUTING.md on how to update this version number.
+version = '0.4.3-alpha-SNAPSHOT'
 
 test {
     testLogging {
@@ -68,3 +72,8 @@ project.tasks.all {
         it.from(project.file('src/main/resources/'))
     }
 }
+
+buildStamp {
+    repoBaseUrl "https://github.com/j2objc-contrib/j2objc-gradle/tree/"
+    packageName "com.github.j2objccontrib.j2objcgradle"
+}

gradle/wrapper/gradle-wrapper.properties

@@ -1,4 +1,4 @@
-#Thu Jun 04 17:07:20 PDT 2015
+#Sun Aug 23 09:54:12 PDT 2015
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME

src/main/groovy/com/github/j2objccontrib/j2objcgradle/J2objcPlugin.groovy

@@ -39,6 +39,22 @@ class J2objcPlugin implements Plugin<Project> {
 
     @Override
     void apply(Project project) {
+        String version = BuildInfo.VERSION
+        String commit = BuildInfo.GIT_COMMIT
+        String url = BuildInfo.URL
+        String timestamp = BuildInfo.TIMESTAMP
+        project.logger.info("j2objc-gradle plugin: Version $version, Commit: $commit, Built: $timestamp, URL: $url")
+        if (!BuildInfo.GIT_IS_CLEAN) {
+            project.logger.error('j2objc-gradle plugin was built with local modification.\n' +
+                                 'If you encounter issues, please use an official release from:\n' +
+                                 '    https://github.com/j2objc-contrib/j2objc-gradle/releases')
+        }
+        if (version.contains('SNAPSHOT')) {
+            project.logger.warn('j2objc-gradle plugin was built outside of an official release.\n' +
+                                'If you encounter issues, please use an official release from:\n' +
+                                '    https://github.com/j2objc-contrib/j2objc-gradle/releases')
+        }
+
         // This avoids a lot of "project." prefixes, such as "project.tasks.create"
         project.with {
             Utils.checkMinGradleVersion(GradleVersion.current())