FIR: Optimize supertypes scope structure

compiler/fir/java/src/org/jetbrains/kotlin/fir/java/JavaSymbolProvider.kt

@@ -121,7 +121,7 @@ class JavaSymbolProvider(
                     }
             JavaClassUseSiteMemberScope(
                 regularClass, useSiteSession,
-                FirSuperTypeScope(
+                FirSuperTypeScope.prepareSupertypeScope(
                     useSiteSession,
                     JavaOverrideChecker(
                         useSiteSession, if (regularClass is FirJavaClass) regularClass

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/FirSymbolProvider.kt

@@ -18,7 +18,9 @@ import org.jetbrains.kotlin.fir.scopes.impl.FirStandardOverrideChecker
 import org.jetbrains.kotlin.fir.scopes.impl.FirSuperTypeScope
 import org.jetbrains.kotlin.fir.scopes.impl.declaredMemberScope
 import org.jetbrains.kotlin.fir.scopes.jvm.JvmMappedScope
-import org.jetbrains.kotlin.fir.symbols.*
+import org.jetbrains.kotlin.fir.symbols.ConeClassLikeLookupTag
+import org.jetbrains.kotlin.fir.symbols.ConeClassifierLookupTag
+import org.jetbrains.kotlin.fir.symbols.ConeClassifierLookupTagWithFixedSymbol
 import org.jetbrains.kotlin.fir.symbols.impl.*
 import org.jetbrains.kotlin.fir.types.ConeClassErrorType
 import org.jetbrains.kotlin.fir.types.ConeClassLikeType
@@ -110,7 +112,7 @@ abstract class FirSymbolProvider : FirSessionComponent {
                 }
             FirClassUseSiteMemberScope(
                 useSiteSession,
-                FirSuperTypeScope(useSiteSession, FirStandardOverrideChecker(useSiteSession), scopes),
+                FirSuperTypeScope.prepareSupertypeScope(useSiteSession, FirStandardOverrideChecker(useSiteSession), scopes),
                 wrappedDeclaredScope
             )
         }

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/scopes/impl/FirSuperTypeScope.kt

@@ -14,7 +14,7 @@ import org.jetbrains.kotlin.fir.symbols.impl.FirClassifierSymbol
 import org.jetbrains.kotlin.fir.symbols.impl.FirFunctionSymbol
 import org.jetbrains.kotlin.name.Name
 
-class FirSuperTypeScope(
+class FirSuperTypeScope private constructor(
     session: FirSession,
     overrideChecker: FirOverrideChecker,
     val scopes: List<FirScope>
@@ -112,4 +112,16 @@ class FirSuperTypeScope(
         }
         return super.processClassifiersByName(name, processor)
     }
-}
+
+    companion object {
+        fun prepareSupertypeScope(
+            session: FirSession,
+            overrideChecker: FirOverrideChecker,
+            scopes: List<FirScope>
+        ): FirScope {
+            scopes.singleOrNull()?.let { return it }
+
+            return FirSuperTypeScope(session, overrideChecker, scopes)
+        }
+    }
+}