[build, sbt import] 253 backport: Add a workaround for manually attaching the community/project directory as a source directory to the scalaUltimate-build build module when the Ultimate and Community build definitions are unified under one sbt build instance #SCL-24902

#noport

- This change is an IDEA 2025.3 backport of https://code.jetbrains.team/p/scl/repositories/intellij-scala/revision/05e468ddbf91c3c3fb855d6dd8b42afecabebb0c.
- The commit cannot be cleanly applied because it depends on other changes present in 261.
- Additionally, the code had to be adapted for 253, because it uses both APIs which don't exist in the platform and APIs which we have introduced for replacing deprecated functions in 261.


(cherry picked from commit 8ffad66)

Author: vasilmkd

sbt/sbt-impl/src/org/jetbrains/sbt/project/SbtProjectResolver.scala

@@ -21,8 +21,8 @@ import org.jetbrains.plugins.scala.*
 import org.jetbrains.plugins.scala.build.*
 import org.jetbrains.plugins.scala.compiler.data.CompileOrder
 import org.jetbrains.plugins.scala.extensions.PathExt
-import org.jetbrains.plugins.scala.project.{ReplClasspath, Version}
 import org.jetbrains.plugins.scala.project.external.{JdkByHome, JdkByName, ScalaSdkUtils, SdkReference}
+import org.jetbrains.plugins.scala.project.{ReplClasspath, Version}
 import org.jetbrains.plugins.scala.util.ScalaNotificationGroups
 import org.jetbrains.sbt.SbtUtil.*
 import org.jetbrains.sbt.project.SbtProjectResolver.*
@@ -39,6 +39,7 @@ import org.jetbrains.sbt.{RichBoolean, Sbt, SbtBundle, SbtUtil, SbtVersion, usin
 
 import java.io.FileNotFoundException
 import java.net.URI
+import java.nio.charset.StandardCharsets
 import java.nio.file.{Files, Path}
 import java.util.{Collections, Locale, UUID}
 import scala.collection.{MapView, mutable}
@@ -557,9 +558,8 @@ class SbtProjectResolver extends ExternalSystemProjectResolver[SbtExecutionSetti
    *       }}}<br>
    *       See also https://youtrack.jetbrains.com/issue/SCL-13573/Apply-shared-external-source-directory-logic-for-sbt-build-modules
    */
-  private def configureBuildModuleDependencies(buildModules: Seq[BuildModuleNodeWithBuildBaseDir]): Unit = {
-    if (buildModules.size == 2) {
-      val Seq(module1, module2) = buildModules
+  private def configureBuildModuleDependencies(buildModules: Seq[BuildModuleNodeWithBuildBaseDir]): Unit = buildModules match {
+    case Seq(module1, module2) =>
       if (isChild(module1.buildBaseDir, module2.buildBaseDir)) {
         addModuleDependencyNode(module2.moduleNode, module1.moduleNode, DependencyScope.COMPILE)
       }
@@ -569,7 +569,27 @@ class SbtProjectResolver extends ExternalSystemProjectResolver[SbtExecutionSetti
       else {
         //modules are not hierarchical? Not sure if such case possible but will leave the empty branch here
       }
-    }
+
+    // See https://youtrack.jetbrains.com/issue/SCL-24902/Unify-the-Scala-Ultimate-and-Scala-Community-sbt-builds.
+    // This is an extremely specific workaround for the Scala Plugin for IntelliJ IDEA Ultimate repository.
+    // We set the <root>/community/project directory as a source directory for the "scalaUltimate-build" build module.
+    case Seq(buildModule) if buildModule.moduleNode.getModuleName == "scalaUltimate-build" =>
+      val buildBaseDir = buildModule.buildBaseDir
+      val communityProjectDir = buildBaseDir / "community" / Sbt.ProjectDirectory
+      if (communityProjectDir.exists) { // The community directory exists
+        val buildSbtSourcesPatchFile = buildBaseDir / Sbt.ProjectDirectory / "build.sbt"
+        if (buildSbtSourcesPatchFile.exists) { // <root>/project/build.sbt exists
+          // The suggested optimized eel function does exist in 253, only 261 and later.
+          //noinspection UseOptimizedEelFunctions
+          val contents = Files.readString(buildSbtSourcesPatchFile, StandardCharsets.UTF_8)
+          val containsPatch = contents.contains("""Compile / unmanagedSourceDirectories += baseDirectory.value.getParentFile / "community" / "project"""")
+          if (containsPatch) {
+            buildModule.moduleNode.add(createBuildContentRootForScalaPluginUltimateWorkaround(communityProjectDir))
+          }
+        }
+      }
+
+    case _ =>
   }
 
   private def isChild(child: Path, parentPath: Path): Boolean = {
@@ -1257,6 +1277,13 @@ class SbtProjectResolver extends ExternalSystemProjectResolver[SbtExecutionSetti
     result
   }
 
+  private def createBuildContentRootForScalaPluginUltimateWorkaround(communityProjectDir: Path): ContentRootNode = {
+    val result = new ContentRootNode(communityProjectDir.toCanonicalPath.toString)
+    val sourceDirs = Seq(communityProjectDir.toCanonicalPath.toString)
+    result.storePaths(esProjectData.ExternalSystemSourceType.SOURCE, sourceDirs)
+    result
+  }
+
   private def createSbtBuildModuleData(build: sbtStructure.BuildData, projects: Seq[ProjectData], localCachePath: Option[String]): SbtBuildModuleNode = {
     val buildProjects = projects.filter(p => p.buildURI == build.uri)
     val imports = build.imports.flatMap(_.trim.substring(7).split(", "))