Calculate version using 'first-parent' only for release branches. For PRs calculate on latest released version. (#11385)

Calculate version using 'first-parent' only for release branches. For PRs calculate on latest released version.

Merged with master.

Changed code to use base class helpers.

Co-authored-by: alexey.kuznetsov <alexey.kuznetsov@datadoghq.com>

Author: AlexeyKuznetsov-DD

buildSrc/src/main/kotlin/datadog/gradle/plugin/version/TracerVersionPlugin.kt

@@ -48,9 +48,18 @@ class TracerVersionPlugin @Inject constructor(
       // Not a git repository
       extension.defaultVersion.get()
     } else {
+      val currentBranchProvider = gitCurrentBranchProvider(repoWorkingDirectory)
       providerFactory.zip(
-        gitDescribeProvider(extension, repoWorkingDirectory),
-        gitCurrentBranchProvider(repoWorkingDirectory)
+        currentBranchProvider.flatMap { currentBranch ->
+          // Use --first-parent only on release branches so they stay anchored to their own
+          // version line; feature branches pick up newer tags merged in from main.
+          gitDescribeProvider(
+            extension,
+            repoWorkingDirectory,
+            firstParent = currentBranch.startsWith("release/v")
+          )
+        },
+        currentBranchProvider
       ) { describeString, currentBranch ->
         toTracerVersion(describeString, extension) {
           when {
@@ -87,7 +96,8 @@ class TracerVersionPlugin @Inject constructor(
 
   private fun gitDescribeProvider(
     extension: TracerVersionExtension,
-    repoWorkingDirectory: File
+    repoWorkingDirectory: File,
+    firstParent: Boolean,
   ) = providerFactory.of(GitCommandValueSource::class.java) {
     parameters {
       val tagPrefix = extension.tagVersionPrefix.get()
@@ -96,10 +106,13 @@ class TracerVersionPlugin @Inject constructor(
         "describe",
         "--abbrev=8",
         "--tags",
-        "--first-parent",
         "--match=$tagPrefix[0-9].[0-9]*.[0-9]*",
       )
 
+      if (firstParent) {
+        gitCommand.add("--first-parent")
+      }
+
       if (extension.detectDirty.get()) {
         gitCommand.add("--dirty")
       }

buildSrc/src/test/kotlin/datadog/gradle/plugin/version/TracerVersionIntegrationTest.kt

@@ -144,6 +144,50 @@ class TracerVersionIntegrationTest : VersionPluginsFixture() {
     )
   }
 
+  @Test
+  fun `should increment minor from merged main version tag on feature branch`() {
+    assertTracerVersion(
+      expectedVersion = "1.53.0-SNAPSHOT",
+      beforeGradle = {
+        initGitRepo()
+        exec("git", "tag", "v1.50.0", "-m", "")
+        exec("git", "switch", "-c", "feature")
+        writeFile("feature.txt", "feature")
+        exec("git", "add", "feature.txt")
+        exec("git", "commit", "-m", "Feature commit")
+        exec("git", "switch", "main")
+        writeFile("main.txt", "main")
+        exec("git", "add", "main.txt")
+        exec("git", "commit", "-m", "Main commit")
+        exec("git", "tag", "v1.52.0", "-m", "")
+        exec("git", "switch", "feature")
+        exec("git", "merge", "main", "--no-edit")
+      },
+    )
+  }
+
+  @Test
+  fun `should increment patch from first parent on release branch after main merge`() {
+    assertTracerVersion(
+      expectedVersion = "1.52.1-SNAPSHOT",
+      beforeGradle = {
+        initGitRepo()
+        exec("git", "tag", "v1.52.0", "-m", "")
+        exec("git", "switch", "-c", "release/v1.52.x")
+        writeFile("release.txt", "release")
+        exec("git", "add", "release.txt")
+        exec("git", "commit", "-m", "Release commit")
+        exec("git", "switch", "main")
+        writeFile("main.txt", "main")
+        exec("git", "add", "main.txt")
+        exec("git", "commit", "-m", "Main commit")
+        exec("git", "tag", "v1.53.0", "-m", "")
+        exec("git", "switch", "release/v1.52.x")
+        exec("git", "merge", "main", "--no-edit")
+      },
+    )
+  }
+
   private fun assertTracerVersion(
     expectedVersion: String,
     workingDirectory: File = projectDir,