[Wasm] Improve stability of wasm import names across compiler runs

Remove code generation for external fake overrides
Fake overrides are resolved to real declaration on call sites
This also removes generation of unused
"equals", "hashCode" and "toString" methods.
Avoid using hashes of IrType in generated code
because they are unstable

Merge-request: KT-MR-8658
Merged-by: Svyatoslav Kuzmich <svyatoslav.kuzmich@jetbrains.com>

compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/ir2wasm/DeclarationGenerator.kt

@@ -53,11 +53,16 @@ class DeclarationGenerator(
         // Type aliases are not material
     }
 
+
+    private val jsCodeCounter = mutableMapOf<String, Int>()
     private fun jsCodeName(declaration: IrFunction): String {
         require(declaration is IrSimpleFunction)
-        val fqName = declaration.fqNameWhenAvailable!!.asString()
-        val hashCode = declaration.wasmSignature(irBuiltIns).hashCode() + declaration.file.path.hashCode()
-        return "${fqName}_$hashCode"
+        val key = declaration.fqNameWhenAvailable.toString()
+        // counter is used to resolve fqName clashes
+        val counterValue = jsCodeCounter.getOrPut(key, defaultValue = { 0 })
+        jsCodeCounter[key] = counterValue + 1
+        val counterSuffix = if (counterValue == 0 && key.lastOrNull()?.isDigit() == false) "" else "_$counterValue"
+        return "$key$counterSuffix"
     }
 
     override fun visitFunction(declaration: IrFunction) {
@@ -79,11 +84,10 @@ class DeclarationGenerator(
                 wasmImportModule
             }
             jsCode != null -> {
-                // TODO: check consistency (currently fails with generated __convertKotlinClosureToJsClosure)
                 // check(declaration.isExternal) { "Non-external fun with @JsFun ${declaration.fqNameWhenAvailable}"}
                 val jsCodeName = jsCodeName(declaration)
                 context.addJsFun(jsCodeName, jsCode)
-                WasmImportDescriptor("js_code", jsCodeName(declaration))
+                WasmImportDescriptor("js_code", jsCodeName)
             }
             else -> {
                 null

compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/lower/ComplexExternalDeclarationsToTopLevelFunctionsLowering.kt

@@ -201,6 +201,10 @@ class ComplexExternalDeclarationsToTopLevelFunctionsLowering(val context: WasmBa
             return
         }
 
+        if (function.isFakeOverride) {
+            return
+        }
+
         val jsFunctionReference = when {
             jsFun != null -> "($jsFun)"
             function.isTopLevelDeclaration -> referenceTopLevelExternalDeclaration(function)

compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/lower/JsInteropFunctionsLowering.kt

@@ -10,6 +10,7 @@ import org.jetbrains.kotlin.backend.common.DeclarationTransformer
 import org.jetbrains.kotlin.backend.common.ir.addDispatchReceiver
 import org.jetbrains.kotlin.backend.common.lower.DeclarationIrBuilder
 import org.jetbrains.kotlin.backend.common.lower.createIrBuilder
+import org.jetbrains.kotlin.backend.common.serialization.cityHash64
 import org.jetbrains.kotlin.backend.wasm.WasmBackendContext
 import org.jetbrains.kotlin.backend.wasm.ir2wasm.isBuiltInWasmRefType
 import org.jetbrains.kotlin.backend.wasm.ir2wasm.isExported
@@ -621,7 +622,8 @@ class JsInteropFunctionsLowering(val context: WasmBackendContext) : DeclarationT
         }
 
         val hashString: String =
-            functionType.hashCode().absoluteValue.toString(Character.MAX_RADIX)
+            // Rendering type to improve hash stability across compiler runs
+            functionType.render().cityHash64().toULong().toString(Character.MAX_RADIX)
 
         val originalParameterTypes: List<IrType> =
             functionType.arguments.dropLast(1).map { (it as IrTypeProjection).type }

js/js.translator/testData/box/native/nestedElements.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND: WASM
 // EXPECTED_REACHABLE_NODES: 1310
 package foo