[plugin model] provide replacement for com.intellij.platform.experimental.* plugin aliases (IJPL-177155)

This introduces 'intellij.platform.backend' as a content module, and dependencies on 'intellij.platform.backend' and 'intellij.platform.frontend' can be used instead of com.intellij.platform.experimental.* plugin aliases. PluginSetBuilder automatically disabled modules which aren't compatible with the current product mode.

GitOrigin-RevId: 5c0a82d256dd7abe1720a77cd94ee38efed6b6d6

platform/backend/intellij.platform.backend.iml

@@ -2,7 +2,9 @@
 <module type="JAVA_MODULE" version="4">
   <component name="NewModuleRootManager" inherit-compiler-output="true">
     <exclude-output />
-    <content url="file://$MODULE_DIR$" />
+    <content url="file://$MODULE_DIR$">
+      <sourceFolder url="file://$MODULE_DIR$/resources" type="java-resource" />
+    </content>
     <orderEntry type="inheritedJdk" />
     <orderEntry type="sourceFolder" forTests="false" />
   </component>

platform/backend/resources/intellij.platform.backend.xml

@@ -0,0 +1,2 @@
+<idea-plugin>
+</idea-plugin>

platform/core-impl/src/com/intellij/ide/plugins/IdeaPluginDescriptorImpl.kt

@@ -279,22 +279,11 @@ class IdeaPluginDescriptorImpl(
    * This is done to support running without the module-based loader (from sources and in dev mode),
    * where all modules are available, but only some of them need to be loaded.
    *
-   * Module dependencies must be satisfied, module dependencies determine whether a module will be loaded.
-   * If a module declares a special dependency, the dependency might be not satisfied in some produce mode,
-   * and the module will not be loaded in that mode.
-   * This function determines which dependencies are satisfiable by the current product mode.
-   *
-   * There are three product modes:
-   * 1. Split frontend (JetBrains Client)
-   * 2. Monolith, or regular local IDE
-   * 3. Split backend (Remote Dev Host) or CWM plugin installed in monolith
-   *
-   * If a module needs to be loaded in some mode(-s), declare the following dependency(-ies):
-   * - in 1 or 2: `com.intellij.platform.experimental.frontend`
-   * - in 2 or 3: `com.intellij.platform.experimental.backend`
-   * - only in 2: both `com.intellij.platform.experimental.frontend` and `com.intellij.platform.experimental.backend`
-   * - in 1 or 2 or 3: no dependency needed
+   * This method is left for compatibility only. 
+   * Now dependencies on 'intellij.platform.frontend' and 'intellij.platform.backend' should be used instead. 
+   * These modules are automatically disabled if they aren't relevant to the product mode, see [PluginSetBuilder.getModuleIncompatibleWithCurrentProductMode].
    */
+  @ApiStatus.Obsolete
   private fun productModeAliasesForCorePlugin(): List<PluginId> = buildList {
     if (!AppMode.isRemoteDevHost()) {
       // This alias is available in monolith and frontend.

platform/core-impl/src/com/intellij/ide/plugins/PluginSetBuilder.kt

@@ -92,6 +92,7 @@ class PluginSetBuilder(@JvmField val unsortedPlugins: Set<IdeaPluginDescriptorIm
     val loadingErrors = ArrayList<PluginLoadingError>()
     val enabledRequiredContentModules = HashMap<String, IdeaPluginDescriptorImpl>()
     val disabledModuleToProblematicPlugin = HashMap<String, PluginId>()
+    val moduleIncompatibleWithCurrentMode = getModuleIncompatibleWithCurrentProductMode()
 
     fun registerLoadingError(plugin: IdeaPluginDescriptorImpl, disabledModule: PluginContentDescriptor.ModuleItem) {
       loadingErrors.add(createCannotLoadError(
@@ -102,6 +103,12 @@ class PluginSetBuilder(@JvmField val unsortedPlugins: Set<IdeaPluginDescriptorIm
     }
 
     m@ for (module in sortedModulesWithDependencies.modules) {
+      if (module.moduleName == moduleIncompatibleWithCurrentMode) {
+        module.isEnabled = false
+        logMessages.add("Module ${module.moduleName} is disabled because it is not compatible with the current product mode")
+        continue
+      }
+      
       if (module.isUseIdeaClassLoader && !canExtendIdeaClassLoader) {
         module.isEnabled = false
         logMessages.add("Module ${module.moduleName ?: module.pluginId} is not enabled because it uses deprecated `use-idea-classloader` attribute but PathClassLoader is disabled")
@@ -188,6 +195,20 @@ class PluginSetBuilder(@JvmField val unsortedPlugins: Set<IdeaPluginDescriptorIm
     return loadingErrors
   }
 
+  /**
+   * Returns a module which should be disabled because it's not relevant to the current com.intellij.platform.runtime.product.ProductMode.
+   * All modules that depend on the specified module will be automatically disabled as well.
+   */
+  private fun getModuleIncompatibleWithCurrentProductMode(): String? {
+    return when (ProductLoadingStrategy.strategy.currentModeId) {
+      /** intellij.platform.backend.split is currently available in 'monolith' mode because it's used as a backend in CodeWithMe */
+      "monolith" -> "intellij.platform.frontend.split"
+      "backend" -> "intellij.platform.frontend"
+      "frontend" -> "intellij.platform.backend"
+      else -> null
+    }
+  }
+
   private fun markModuleAsEnabled(moduleName: String, moduleDescriptor: IdeaPluginDescriptorImpl) {
     enabledModuleV2Ids.put(moduleName, moduleDescriptor)
     for (pluginAlias in moduleDescriptor.pluginAliases) {

platform/platform-frontend/resources/intellij.platform.frontend.xml

@@ -1,5 +1,2 @@
 <idea-plugin package="com.intellij.platform.frontend">
-  <dependencies>
-    <plugin id="com.intellij.platform.experimental.frontend"/>
-  </dependencies>
 </idea-plugin>

platform/platform-resources/src/META-INF/essential-modules.xml

@@ -4,6 +4,7 @@
     <module name="intellij.libraries.ktor.client"/>
     <module name="intellij.libraries.ktor.client.cio"/>
 
+    <module name="intellij.platform.backend"/>
     <module name="intellij.platform.rpc.backend"/>
     <module name="intellij.platform.kernel.backend"/>
     <module name="intellij.platform.project.backend"/>