From a7772f2ed881c19a778f6128e90a409da36570d7 Mon Sep 17 00:00:00 2001
From: Alexey Kuznetsov <alexey.kuznetsov@datadoghq.com>
Date: Fri, 15 May 2026 17:28:29 -0400
Subject: [PATCH] Calculate version using 'first-parent' only for release
 branches. For PRs calculate on latest released version.

---
 .../plugin/version/TracerVersionPlugin.kt     | 21 +++++++--
 .../version/TracerVersionIntegrationTest.kt   | 46 +++++++++++++++++++
 2 files changed, 63 insertions(+), 4 deletions(-)

diff --git a/buildSrc/src/main/kotlin/datadog/gradle/plugin/version/TracerVersionPlugin.kt b/buildSrc/src/main/kotlin/datadog/gradle/plugin/version/TracerVersionPlugin.kt
index 5255cbf5328..4cd8669c389 100644
--- a/buildSrc/src/main/kotlin/datadog/gradle/plugin/version/TracerVersionPlugin.kt
+++ b/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")
       }
diff --git a/buildSrc/src/test/kotlin/datadog/gradle/plugin/version/TracerVersionIntegrationTest.kt b/buildSrc/src/test/kotlin/datadog/gradle/plugin/version/TracerVersionIntegrationTest.kt
index 4f253b41633..69b10e15dc6 100644
--- a/buildSrc/src/test/kotlin/datadog/gradle/plugin/version/TracerVersionIntegrationTest.kt
+++ b/buildSrc/src/test/kotlin/datadog/gradle/plugin/version/TracerVersionIntegrationTest.kt
@@ -89,6 +89,29 @@ class TracerVersionIntegrationTest {
     )
   }
 
+  @Test
+  fun `should increment minor from merged main version tag on feature branch`(@TempDir projectDir: File) {
+    val fixture = VersionPluginsFixture(projectDir)
+    fixture.assertTracerVersion(
+      expectedVersion = "1.53.0-SNAPSHOT",
+      beforeGradle = {
+        fixture.initGitRepo()
+        fixture.exec("git", "tag", "v1.50.0", "-m", "")
+        fixture.exec("git", "switch", "-c", "feature")
+        File(projectDir, "feature.txt").writeText("feature")
+        fixture.exec("git", "add", "feature.txt")
+        fixture.exec("git", "commit", "-m", "Feature commit")
+        fixture.exec("git", "switch", "main")
+        File(projectDir, "main.txt").writeText("main")
+        fixture.exec("git", "add", "main.txt")
+        fixture.exec("git", "commit", "-m", "Main commit")
+        fixture.exec("git", "tag", "v1.52.0", "-m", "")
+        fixture.exec("git", "switch", "feature")
+        fixture.exec("git", "merge", "main", "--no-edit")
+      },
+    )
+  }
+
   @Test
   fun `should increment minor with snapshot and dirtiness with added commits after version tag and dirty`(@TempDir projectDir: File) {
     val fixture = VersionPluginsFixture(projectDir)
@@ -106,6 +129,29 @@ class TracerVersionIntegrationTest {
     )
   }
 
+  @Test
+  fun `should increment patch from first parent on release branch after main merge`(@TempDir projectDir: File) {
+    val fixture = VersionPluginsFixture(projectDir)
+    fixture.assertTracerVersion(
+      expectedVersion = "1.52.1-SNAPSHOT",
+      beforeGradle = {
+        fixture.initGitRepo()
+        fixture.exec("git", "tag", "v1.52.0", "-m", "")
+        fixture.exec("git", "switch", "-c", "release/v1.52.x")
+        File(projectDir, "release.txt").writeText("release")
+        fixture.exec("git", "add", "release.txt")
+        fixture.exec("git", "commit", "-m", "Release commit")
+        fixture.exec("git", "switch", "main")
+        File(projectDir, "main.txt").writeText("main")
+        fixture.exec("git", "add", "main.txt")
+        fixture.exec("git", "commit", "-m", "Main commit")
+        fixture.exec("git", "tag", "v1.53.0", "-m", "")
+        fixture.exec("git", "switch", "release/v1.52.x")
+        fixture.exec("git", "merge", "main", "--no-edit")
+      },
+    )
+  }
+
   @Test
   fun `should increment patch on release branch and no patch release tag`(@TempDir projectDir: File) {
     val fixture = VersionPluginsFixture(projectDir)