[plugins] IJPL-251952 constraint resolver: protect against potential self-dependency coming from provideCompatibilityDependenciesForRemainingCandidates

(cherry picked from commit 7635566925dac4e62778ea4f17c9f9c214dce36b)

GitOrigin-RevId: f7c7e40470eef79bdcf6d8c6de421008944befe4

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

@@ -400,7 +400,10 @@ private class PluginSetConstraintsResolver(
       }
 
       val compatibilityDependencies = initContext.provideCompatibilityDependenciesForRemainingCandidates(descriptor, remainingCandidatesView)
-        .mapNotNullTo(ArrayList()) { remainingCandidatesView.resolveReference(it) }
+        .mapNotNullTo(ArrayList()) { dependencyRef ->
+          remainingCandidatesView.resolveReference(dependencyRef)
+            ?.takeIf { it !== descriptor }
+        }
       if (compatibilityDependencies.isNotEmpty()) {
         contributeDependencies(compatibilityDependencies)
       }
@@ -456,8 +459,11 @@ private class PluginSetConstraintsResolver(
     val descriptorGraph = DFSTBuilder(DescriptorGraphAdapter(remainingCandidates, resolvedDependents))
     if (!descriptorGraph.isAcyclic) {
       for (component in descriptorGraph.components) {
-        if (component.size <= 1) {
-          continue
+        if (component.size == 1) {
+          val selfDependent = component.first() in resolvedDependencies[component.first()].orEmpty()
+          if (!selfDependent) {
+            continue
+          }
         }
         val component = component.sortedWith(compareBy { it.pluginId }) // makes result stable
         val cycleNodesWithDependencies = component.associateWith { ArrayList<IdeaPluginDescriptorImpl>() }
@@ -512,7 +518,7 @@ private class PluginSetConstraintsResolver(
     if (!dfstBuilder.isAcyclic) {
       for (component in dfstBuilder.components) {
         if (component.size <= 1) {
-          continue
+          continue // no self-dependency expected: implied by filtering in dependency list construction above
         }
         val component = component.sortedWith(compareBy { it.representativeModule.pluginId }) // make result stable
         val cycleNodesWithDependencies = component.associateWith { ArrayList<RuntimeModuleGroup>() }

platform/platform-tests/testSrc/com/intellij/ide/plugins/PluginDependenciesTest.kt

@@ -1,6 +1,7 @@
 // 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.ide.plugins
 
+import com.intellij.ide.plugins.PluginDependencyAnalysis.DependencyRef
 import com.intellij.ide.plugins.cl.PluginClassLoader
 import com.intellij.openapi.diagnostic.Logger
 import com.intellij.openapi.extensions.PluginId
@@ -22,6 +23,7 @@ import com.intellij.testFramework.rules.InMemoryFsExtension
 import org.assertj.core.api.Assertions.assertThatThrownBy
 import org.junit.jupiter.api.Nested
 import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.Timeout
 import org.junit.jupiter.api.extension.RegisterExtension
 import java.nio.file.FileVisitResult
 
@@ -856,6 +858,21 @@ internal class PluginDependenciesTest {
 
   @Nested
   inner class ImplicitDependencyAdditionTests {
+    @Test
+    @Timeout(10)
+    fun `soft compatibility dependency on self is ignored`() {
+      plugin("foo") {}.installAt(pluginDirPath)
+      val pluginSet = PluginSetTestBuilder.fromPath(pluginDirPath)
+        .withCompatibilityDependenciesForRemainingCandidatesProvider { descriptor, remainingCandidates ->
+          check(remainingCandidates.resolvePluginId(descriptor.pluginId) === descriptor)
+          sequenceOf(DependencyRef.of(descriptor.pluginId))
+        }
+        .build()
+
+      val foo = pluginSet.getEnabledPlugin("foo")
+      assertThat(pluginSet.resolvedPluginSet?.getDirectResolvedDependencies(foo)).doesNotContain(foo)
+    }
+
     @Test
     fun `legacy plugin gets implicit java dependency when all modules marker is present`() {
       // marker enables implicit dependencies for legacy plugins

platform/pluginSystem/testFramework/src/PluginSetTestBuilder.kt

@@ -2,9 +2,12 @@
 package com.intellij.platform.pluginSystem.testFramework
 
 import com.intellij.ide.plugins.DiscoveredPluginsList
+import com.intellij.ide.plugins.IdeaPluginDescriptorImpl
+import com.intellij.ide.plugins.PluginDependencyAnalysis.DependencyRef
 import com.intellij.ide.plugins.PluginDescriptorLoadingContext
 import com.intellij.ide.plugins.PluginInitContextFactory
 import com.intellij.ide.plugins.PluginInitializationContext
+import com.intellij.ide.plugins.PluginInitializationContext.RemainingCandidatesView
 import com.intellij.ide.plugins.PluginLoadingErrorReportingPolicy
 import com.intellij.ide.plugins.PluginMainDescriptor
 import com.intellij.ide.plugins.PluginManagerCore
@@ -32,6 +35,8 @@ class PluginSetTestBuilder private constructor(
   private var customCoreLoader: UrlClassLoader? = null
   private var productMode: ProductMode = ProductMode.MONOLITH
   private var explicitPluginSubsetToLoad: Set<PluginId>? = null
+  private var compatibilityDependenciesForRemainingCandidatesProvider:
+    ((IdeaPluginDescriptorImpl, RemainingCandidatesView) -> Sequence<DependencyRef>)? = null
 
   companion object {
     @JvmStatic
@@ -75,6 +80,12 @@ class PluginSetTestBuilder private constructor(
     this.explicitPluginSubsetToLoad = pluginsToLoad
   }
 
+  fun withCompatibilityDependenciesForRemainingCandidatesProvider(
+    provider: (IdeaPluginDescriptorImpl, RemainingCandidatesView) -> Sequence<DependencyRef>,
+  ): PluginSetTestBuilder = apply {
+    compatibilityDependenciesForRemainingCandidatesProvider = provider
+  }
+
   var buildNumber: String
     get() = productBuildNumber.toString()
     set(value) {
@@ -92,6 +103,15 @@ class PluginSetTestBuilder private constructor(
       }
       override val explicitPluginSubsetToLoad: Set<PluginId>? = this@PluginSetTestBuilder.explicitPluginSubsetToLoad
       override val currentProductModeId: String = productMode.id
+      override fun provideCompatibilityDependenciesForRemainingCandidates(
+        descriptor: IdeaPluginDescriptorImpl,
+        remainingCandidates: RemainingCandidatesView,
+      ): Sequence<DependencyRef> {
+        compatibilityDependenciesForRemainingCandidatesProvider?.let { provider ->
+          return provider(descriptor, remainingCandidates)
+        }
+        return super.provideCompatibilityDependenciesForRemainingCandidates(descriptor, remainingCandidates)
+      }
     }
   }
 
@@ -120,4 +140,4 @@ class PluginSetTestBuilder private constructor(
   }
 
   fun build(): PluginSet = buildState().pluginSet
-}
+}