[IR SERIALIZATION] Handle UniqId clashes

compiler/ir/serialization.js/src/org/jetbrains/kotlin/ir/backend/js/lower/serialization/ir/JsDeclarationTable.kt

@@ -8,13 +8,30 @@ package org.jetbrains.kotlin.ir.backend.js.lower.serialization.ir
 import org.jetbrains.kotlin.backend.common.serialization.DeclarationTable
 import org.jetbrains.kotlin.backend.common.serialization.DescriptorTable
 import org.jetbrains.kotlin.ir.descriptors.IrBuiltIns
+import org.jetbrains.kotlin.ir.util.render
 
-class JsDeclarationTable(builtIns: IrBuiltIns, descriptorTable: DescriptorTable) : DeclarationTable(builtIns, descriptorTable, JsMangler) {
+class JsUniqIdClashTracker: UniqIdClashTracker {
+    private val commitedUniqIds = mutableMapOf<UniqId, IrDeclaration>()
 
-    override var currentIndex = PUBLIC_LOCAL_UNIQ_ID_EDGE
+    override fun commit(declaration: IrDeclaration, uniqId: UniqId) {
+        if (uniqId.isLocal) return // don't track local ids
 
-    init {
-        loadKnownBuiltins()
-        currentIndex = 0
+        if (uniqId in commitedUniqIds) {
+            val clashedDeclaration = commitedUniqIds[uniqId]!!
+            // TODO: handle clashes properly
+            error("UniqId clash: $uniqId; Existed declaration ${clashedDeclaration.render()} clashed with new ${declaration.render()}")
+        }
+
+        commitedUniqIds[uniqId] = declaration
+    }
+}
+
+class JsGlobalDeclarationTable(builtIns: IrBuiltIns) : GlobalDeclarationTable(JsMangler, JsUniqIdClashTracker()) {
+    private val FUNCTION_INDEX_START: Long = loadKnownBuiltins(builtIns, PUBLIC_LOCAL_UNIQ_ID_EDGE)
+
+    override fun computeUniqIdByDeclaration(declaration: IrDeclaration): UniqId {
+        return if (isBuiltInFunction(declaration)) {
+            UniqId(FUNCTION_INDEX_START + builtInFunctionId(declaration), false)
+        } else super.computeUniqIdByDeclaration(declaration)
     }
 }