[FIR] Fix infinite loop in attribute substitution

#KT-65318 Fixed

compiler/fir/providers/src/org/jetbrains/kotlin/fir/resolve/substitution/Substitutors.kt

@@ -89,7 +89,17 @@ abstract class AbstractConeSubstitutor(protected val typeContext: ConeTypeContex
         }
 
         val substitutedType = newType ?: type.substituteRecursive()
-        val substitutedAttributes = (substitutedType ?: type).attributes.transformTypesWith(this::substituteOrNull)
+
+        // Don't substitute attributes of flexible types because their bounds will be processed individually.
+        val substitutedAttributesOfUnsubstitutedType = runIf(type !is ConeFlexibleType) {
+            type.attributes.transformTypesWith(this::substituteOrNull)
+        }
+        val substitutedAttributes = substitutedAttributesOfUnsubstitutedType?.let {
+            // ConeAttribute.add is typically implemented to favor the RHS if both are not-null, so we use the substituted attributes as RHS.
+            // We can't do `(substitutedType ?: type).attributes.transformTypesWith(this::substituteOrNull)` because it could lead to an
+            // infinite loop in a situation like `{E -> Attr(E) Foo}` applied to `E`.
+            substitutedType?.attributes?.add(it) ?: it
+        }
 
         return if (substitutedType != null || substitutedAttributes != null) {
             var result = substitutedType ?: type