[LL] Fix computeIfAbsent contract violation during dangling file session creation

- To avoid recursive updates, we can create sessions which cannot be
  created in isolation outside `computeIfAbsent`. Note that this is the
  current behavior of the default implementation of
  `ConcurrentMap.computeIfAbsent`, which will be replaced soon with
  the stricter behavior of `CleanableSoftValueCache` (see KT-61222).

^KT-65683 fixed

analysis/low-level-api-fir/src/org/jetbrains/kotlin/analysis/low/level/api/fir/sessions/LLFirSessionCache.kt

@@ -88,9 +88,18 @@ class LLFirSessionCache(private val project: Project) {
     private fun <T : KtModule> getCachedSession(module: T, storage: SessionStorage, factory: (T) -> LLFirSession): LLFirSession {
         checkCanceled()
 
-        val session = storage.computeIfAbsent(module) { factory(module) }
-        checkSessionValidity(session)
+        val session = if (module.supportsIsolatedSessionCreation) {
+            storage.computeIfAbsent(module) { factory(module) }
+        } else {
+            // Non-isolated session creation may need to access other sessions, so we should create the session outside `computeIfAbsent` to
+            // avoid recursive update exceptions.
+            storage[module] ?: run {
+                val danglingSession = factory(module)
+                storage.computeIfAbsent(module) { danglingSession }
+            }
+        }
 
+        checkSessionValidity(session)
         return session
     }
 
@@ -199,6 +208,13 @@ class LLFirSessionCache(private val project: Project) {
         }
     }
 
+    /**
+     * Whether the session for [module] can be created without getting other sessions from the cache. Should be kept in sync with
+     * [createSession].
+     */
+    private val KtModule.supportsIsolatedSessionCreation: Boolean
+        get() = this !is KtDanglingFileModule
+
     private fun createSession(module: KtModule): LLFirSession {
         val sessionFactory = createPlatformAwareSessionFactory(module)
         return when (module) {