Add script to sychronize stdlib sources

project/scripts/syncStdLib.scala

@@ -0,0 +1,154 @@
+//> using scala 3.7
+//> using toolkit default
+
+import scala.util.matching.Regex
+
+import scala.util.CommandLineParser.FromString
+
+given FromString[os.Path] with
+  def fromString(s: String) = os.Path(s, os.pwd)
+
+/** Sync standard library changes from scala/scala to scala/scala3.
+  *
+  * Usage: scala run syncStdLib.scala -- <scala2-repo-path> <from-tag> <to-tag>
+  *
+  * Example: scala syncStdLib.scala -- ../scala2 v2.13.17 v2.13.18
+  */
+@main def syncStdLib(
+    scala2RepoPath: os.Path,
+    fromTag: String,
+    toTag: String
+): Unit =
+  val scala2Path = os.Path(scala2RepoPath, os.pwd)
+  val scala3Path = os.pwd
+
+  val workDir = scala3Path / "stdlib-sync-work"
+  val patchDir = workDir / "patches"
+
+  println(s"Scala 2 repo: $scala2Path")
+  println(s"Scala 3 repo: $scala3Path")
+  println(s"Syncing: $fromTag..$toTag")
+  println()
+
+  // Clean up and create directories
+  os.remove.all(workDir)
+  os.makeDir.all(patchDir)
+
+  // -------------------------
+  // 1) Fetch latest changes in scala2 repo
+  // -------------------------
+  println(s"Fetching tags $fromTag and $toTag from scala2...")
+  os.proc("git", "fetch", "--tags", "origin", fromTag, toTag)
+    .call(cwd = scala2Path, stdout = os.Inherit, stderr = os.Inherit)
+
+  // Show what will be synced
+  println(s"\nCommits to sync ($fromTag..$toTag):")
+  val logResult = os
+    .proc("git", "log", "--oneline", s"$fromTag..$toTag", "--", "src/library")
+    .call(cwd = scala2Path)
+  logResult.out.lines().foreach(println)
+  println()
+
+  // -------------------------
+  // 2) Create patch series for src/library only, paths relative to src/library/
+  // -------------------------
+  println("Creating patches...")
+  os.proc(
+    "git",
+    "format-patch",
+    "--output-directory",
+    patchDir.toString,
+    "--relative=src/library",
+    "--no-signature",
+    s"$fromTag..$toTag",
+    "--",
+    "src/library"
+  ).call(cwd = scala2Path, stdout = os.Inherit, stderr = os.Inherit)
+
+  val patchFiles = os.list(patchDir).filter(_.ext == "patch").sorted
+  println(s"Created ${patchFiles.size} patches")
+
+  // -------------------------
+  // 3) Rewrite patches:
+  //    - qualify #NNNN -> scala/scala#NNNN
+  //    - add footer: "Upstream: scala/scala@<sha>"
+  // -------------------------
+  println("\nRewriting patches...")
+  rewritePatches(patchDir)
+
+  // -------------------------
+  // 4) Apply onto scala3
+  // -------------------------
+  val branchName = s"stdlib-sync/${toTag.stripPrefix("v")}"
+  println(s"\nCreating branch $branchName...")
+
+  os.proc("git", "checkout", "-b", branchName, "origin/main")
+    .call(cwd = scala3Path, stdout = os.Inherit, stderr = os.Inherit)
+
+  println(s"Applying ${patchFiles.size} patches...")
+
+  val patches = os.list(patchDir).filter(_.ext == "patch").sorted
+  val amResult = os
+    .proc("git", "am", "--3way", "--directory=library/src", patches)
+    .call(
+      cwd = scala3Path,
+      check = false,
+      stdout = os.Inherit,
+      stderr = os.Inherit
+    )
+
+  if amResult.exitCode != 0 then
+    println()
+    println("Conflicts occurred.")
+    println("Resolve, then run: git am --continue")
+    println("Abort with:        git am --abort")
+    sys.exit(1)
+
+  println("\nPatches applied successfully!")
+  os.remove.all(workDir)
+
+  println(s"\nTo push the branch, run:")
+  println(s"  git push -u origin $branchName")
+end syncStdLib
+
+/** Rewrite patches to:
+  *   - Qualify GitHub issue refs: #NNNN -> scala/scala#NNNN
+  *   - Add footer: "Upstream: scala/scala@<sha>"
+  */
+def rewritePatches(patchDir: os.Path): Unit =
+  val patchFiles = os.list(patchDir).filter(_.ext == "patch").sorted
+  val issueRefPattern = """(?<!\w)#(\d+)""".r
+  val fromLinePattern = """^From ([0-9a-f]{40}) """.r
+
+  var rewrittenCount = 0
+
+  for patch <- patchFiles do
+    val raw = os.read(patch)
+
+    // Extract upstream commit SHA from the "From <sha> ..." line
+    val upstream = fromLinePattern.findFirstMatchIn(raw).map(_.group(1))
+
+    // Qualify github refs in the patch (commit message is inside)
+    var rewritten = issueRefPattern.replaceAllIn(raw, "scala/scala#$1")
+
+    // Insert "Upstream: ..." footer into the commit message.
+    // In format-patch output, commit message ends just before "\n---\n"
+    upstream.foreach { sha =>
+      val footer = s"Upstream: scala/scala@$sha"
+      if !rewritten.contains(footer) then
+        rewritten.split("\n---\n", 2) match
+          case Array(msg, rest) =>
+            var newMsg = msg
+            if !newMsg.endsWith("\n") then newMsg += "\n"
+            if !newMsg.endsWith("\n\n") then newMsg += "\n"
+            newMsg += s"$footer\n"
+            rewritten = newMsg + "\n---\n" + rest
+          case _ => // No split point found, leave as is
+    }
+
+    if rewritten != raw then
+      os.write.over(patch, rewritten)
+      rewrittenCount += 1
+
+  println(s"Rewrote $rewrittenCount patches")
+end rewritePatches