add option to store the .idea directory outside the project root (#191, #202)

Author: DetachHead

platform/configuration-store-impl/src/NestedProjectStorePathManager.kt

@@ -2,8 +2,10 @@
 package com.intellij.configurationStore
 
 import com.intellij.diagnostic.PluginException
+import com.intellij.ide.GeneralSettings
 import com.intellij.ide.highlighter.ProjectFileType
 import com.intellij.openapi.application.ApplicationManager
+import com.intellij.openapi.application.PathManager
 import com.intellij.openapi.components.PersistentStateComponent
 import com.intellij.openapi.components.State
 import com.intellij.openapi.components.StateSplitterEx
@@ -23,12 +25,15 @@ import com.intellij.openapi.vfs.LocalFileSystem
 import com.intellij.openapi.vfs.VirtualFile
 import com.intellij.util.PathUtil
 import com.intellij.util.PathUtilRt
+import com.intellij.util.system.OS
 import org.jdom.Element
 import org.jetbrains.annotations.VisibleForTesting
 import org.jetbrains.jps.util.JpsPathUtil
 import java.nio.file.AccessDeniedException
 import java.nio.file.Files
 import java.nio.file.Path
+import java.nio.file.Paths
+import kotlin.io.path.div
 
 private val EP_NAME: ExtensionPointName<ProjectStorePathCustomizer> = ExtensionPointName("com.intellij.projectStorePathCustomizer")
 private val DEPRECATED_PROJECT_FILE_STORAGE_ANNOTATION = FileStorageAnnotation(StoragePathMacros.PROJECT_FILE, true)
@@ -93,14 +98,35 @@ internal class NestedProjectStorePathManager : ProjectStorePathManager {
   }
 }
 
+/**
+ * used for embedding an absolute into another path, for example a path `/home/user/projects/foo` gets converted to `home/user/projects/foo`
+ * and eventually becomes `/home/user/.config/detachhead/rebased/home/user/projects/foo` where `/home/user/.config/detachhead/rebased`
+ * is the global IDE config directory.
+ *
+ * we do it this way so that projects can have their settings stored in a single spot outside their own root directory, and with predictable
+ * locations.
+ */
+private fun Path.toRelativeWithNoDriveLetterSyntax(): Path {
+  val pathString = this.toString()
+  return Paths.get(
+    if (OS.CURRENT == OS.Windows)
+      pathString.replaceFirst(':', '\\')
+    else
+      pathString.replaceFirst("/", ""))
+}
+
 private class DotIdeaProjectStoreDescriptor(
   override val projectIdentityFile: Path,
   override val historicalProjectBasePath: Path,
 ) : ProjectStoreDescriptor {
   private var lastSavedProjectName: String? = null
 
 
-  override val dotIdea: Path = projectIdentityFile.resolve(Project.DIRECTORY_STORE_FOLDER)
+  override val dotIdea: Path =
+    if (GeneralSettings.getInstance().storeProjectSettingsInProjectRoot)
+      projectIdentityFile.resolve(Project.DIRECTORY_STORE_FOLDER)
+    else
+      (PathManager.getConfigDir() / Project.DIRECTORY_STORE_FOLDER).resolve(projectIdentityFile.toRelativeWithNoDriveLetterSyntax())
 
   override fun getJpsBridgeAwareStorageSpec(filePath: String, project: Project): Storage {
     return doGetJpsBridgeAwareStorageSpec(filePath, project)

platform/configuration-store-impl/testSrc/DefaultProjectStoreTest.kt

@@ -1,16 +1,19 @@
 // Copyright 2000-2025 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
 package com.intellij.configurationStore
 
+import com.intellij.ide.GeneralSettings
 import com.intellij.ide.highlighter.ProjectFileType
 import com.intellij.openapi.application.ApplicationManager
 import com.intellij.openapi.application.EDT
+import com.intellij.openapi.application.PathManager
 import com.intellij.openapi.application.ex.PathManagerEx
 import com.intellij.openapi.components.Service
 import com.intellij.openapi.components.impl.stores.stateStore
 import com.intellij.openapi.components.service
 import com.intellij.openapi.project.Project
 import com.intellij.openapi.project.ProjectManager
 import com.intellij.openapi.project.ex.ProjectManagerEx
+import com.intellij.openapi.project.impl.ProjectImpl
 import com.intellij.openapi.project.impl.ProjectManagerImpl
 import com.intellij.openapi.util.JDOMUtil
 import com.intellij.testFramework.ProjectRule
@@ -56,6 +59,13 @@ class DefaultProjectStoreTest {
     }
   }
 
+  @Test
+  fun `project settings stored outside project root`(): Unit = runBlocking(Dispatchers.Default) {
+    GeneralSettings.getInstance().storeProjectSettingsInProjectRoot = false
+    val project = openAsNewProjectAndUseDefaultSettings(fsRule.fs.getPath("/test"))
+    assertThat(project is ProjectImpl && project.componentStore.storeDescriptor.dotIdea!!.startsWith(PathManager.getConfigDir())).isTrue
+  }
+
   @Test
   fun `save default project configuration changes`() {
     runBlocking {

platform/external-system-impl/resources/META-INF/ExternalSystemExtensions.xml

@@ -118,7 +118,7 @@
     <!--Execution-->
     <programRunner implementation="com.intellij.openapi.externalSystem.service.execution.ExternalSystemTaskRunner"/>
 
-    <streamProviderFactory implementation="com.intellij.openapi.externalSystem.configurationStore.ExternalSystemStreamProviderFactory"/>
+    <!--<streamProviderFactory implementation="com.intellij.openapi.externalSystem.configurationStore.ExternalSystemStreamProviderFactory"/>-->
 
     <moduleService serviceInterface="com.intellij.openapi.externalSystem.ExternalSystemModulePropertyManager"
                    serviceImplementation="com.intellij.openapi.externalSystem.service.project.ExternalSystemModulePropertyManagerBridge"/>

platform/ide-core/src/com/intellij/ide/GeneralSettings.kt

@@ -134,6 +134,15 @@ class GeneralSettings : PersistentStateComponent<GeneralSettingsState> {
       state.processCloseConfirmation = value
     }
 
+  // TODO: figure out why this doesn't work. it doesn't save the setting when changed for some reason
+  // var storeProjectSettingsInProjectRoot by state::storeProjectSettingsInProjectRoot
+
+  var storeProjectSettingsInProjectRoot: Boolean
+    get() = state.storeProjectSettingsInProjectRoot
+    set(value) {
+      state.storeProjectSettingsInProjectRoot = value
+    }
+
   init {
     val app = ApplicationManager.getApplication()
     if (app != null && !app.isHeadlessEnvironment &&
@@ -254,7 +263,9 @@ data class GeneralSettingsState(
   @JvmField
   var inactiveTimeout: Int = 15,
   @JvmField
-  var supportScreenReaders: Boolean = false
+  var supportScreenReaders: Boolean = false,
+  @JvmField
+  var storeProjectSettingsInProjectRoot: Boolean = true
 )
 
 enum class ProcessCloseConfirmation {

platform/platform-api/resources/messages/IdeBundle.properties

@@ -3285,3 +3285,7 @@ badge.text.new=New
 badge.text.alpha=Alpha
 badge.text.beta=Beta
 badge.text.trial=Trial
+
+# rebased-exclusive strings:
+checkbox.store.project.settings.in.project.root=Store project settings in the project root directory
+tooltip.store.project.settings.in.project.root=Disable this if you don''t want {0} to generate or respect <code>.idea</code> directories in the root of your projects.

platform/platform-impl/src/com/intellij/ide/GeneralSettingsConfigurable.kt

@@ -3,7 +3,9 @@ package com.intellij.ide
 
 import com.intellij.application.options.editor.CheckboxDescriptor
 import com.intellij.application.options.editor.checkBox
+import com.intellij.ide.IdeBundle.message
 import com.intellij.ide.ui.search.BooleanOptionDescription
+import com.intellij.openapi.application.ApplicationNamesInfo
 import com.intellij.openapi.extensions.ExtensionPointName
 import com.intellij.openapi.fileChooser.FileChooserDescriptorFactory
 import com.intellij.openapi.fileChooser.PathChooserDialog
@@ -29,6 +31,7 @@ import com.intellij.ui.dsl.builder.panel
 import com.intellij.ui.dsl.builder.selected
 import com.intellij.util.PlatformUtils
 import com.intellij.util.io.TrashBin
+import com.intellij.util.ui.RestartDialogImpl
 
 private val model: GeneralSettings
   get() = GeneralSettings.getInstance()
@@ -49,6 +52,8 @@ private val myChkAutoSaveIfInactive
   get() = CheckboxDescriptor(IdeBundle.message("checkbox.save.files.automatically"), model::isAutoSaveIfInactive)
 private val myChkUseSafeWrite
   get() = CheckboxDescriptor(IdeBundle.message("checkbox.safe.write"), model::isUseSafeWrite)
+private val myChkStoreProjectSettingsInProjectRoot
+  get() = CheckboxDescriptor(message("checkbox.store.project.settings.in.project.root"), model::storeProjectSettingsInProjectRoot)
 
 internal val allOptionDescriptors: List<BooleanOptionDescription>
   get() =
@@ -60,7 +65,8 @@ internal val allOptionDescriptors: List<BooleanOptionDescription>
       myChkSyncInBackground,
       myChkSaveOnFrameDeactivation,
       myChkAutoSaveIfInactive,
-      myChkUseSafeWrite
+      myChkUseSafeWrite,
+      myChkStoreProjectSettingsInProjectRoot
     )
     .map(CheckboxDescriptor::asUiOptionDescriptor)
 
@@ -126,6 +132,11 @@ internal class GeneralSettingsConfigurable :
             .columns(COLUMNS_MEDIUM)
             .comment(IdeBundle.message("settings.general.directory.preselected"), 80)
         }
+        row {
+          checkBox(myChkStoreProjectSettingsInProjectRoot)
+            .comment(message("ide.restart.required.comment"))
+            .contextHelp(message("tooltip.store.project.settings.in.project.root", ApplicationNamesInfo.getInstance().productName))
+        }
       }
 
       group(IdeBundle.message("settings.general.files")) {
@@ -170,6 +181,14 @@ internal class GeneralSettingsConfigurable :
       }
     }
 
+  override fun apply() {
+    val previousValue = model.storeProjectSettingsInProjectRoot
+    super.apply()
+    if (previousValue !=  model.storeProjectSettingsInProjectRoot) {
+      RestartDialogImpl.showRestartRequired()
+    }
+  }
+
   override fun getId(): String = helpTopic!!
 
   override fun createConfigurables(): List<SearchableConfigurable> = ConfigurableWrapper.createConfigurables(EP_NAME)