[Wasm] WasmExport implementation

compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/dce/Dce.kt

@@ -6,6 +6,8 @@
 package org.jetbrains.kotlin.backend.wasm.dce
 
 import org.jetbrains.kotlin.backend.wasm.WasmBackendContext
+import org.jetbrains.kotlin.backend.wasm.ir2wasm.isExported
+import org.jetbrains.kotlin.backend.wasm.utils.getWasmExportNameIfWasmExport
 import org.jetbrains.kotlin.ir.IrElement
 import org.jetbrains.kotlin.ir.backend.js.dce.DceDumpNameCache
 import org.jetbrains.kotlin.ir.backend.js.utils.*
@@ -51,7 +53,7 @@ private fun buildRoots(modules: List<IrModuleFragment>, context: WasmBackendCont
 
     modules.onAllFiles {
         declarations.forEach { declaration ->
-            if (declaration.isJsExport()) {
+            if (declaration is IrFunction && declaration.isExported()) {
                 declaration.acceptVoid(declarationsCollector)
             }
         }

compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/dce/WasmUsefulDeclarationProcessor.kt

@@ -207,5 +207,5 @@ internal class WasmUsefulDeclarationProcessor(
         }
     }
 
-    override fun isExported(declaration: IrDeclaration): Boolean = declaration.isJsExport()
+    override fun isExported(declaration: IrDeclaration): Boolean = (declaration is IrFunction && declaration.isExported())
 }

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

@@ -23,6 +23,7 @@ import org.jetbrains.kotlin.ir.types.getClass
 import org.jetbrains.kotlin.ir.util.*
 import org.jetbrains.kotlin.ir.visitors.IrElementVisitorVoid
 import org.jetbrains.kotlin.ir.visitors.acceptVoid
+import org.jetbrains.kotlin.name.FqName
 import org.jetbrains.kotlin.name.parentOrNull
 import org.jetbrains.kotlin.wasm.ir.*
 import org.jetbrains.kotlin.wasm.ir.source.location.SourceLocation
@@ -182,11 +183,16 @@ class DeclarationGenerator(
         if (initPriority != null)
             context.registerInitFunction(function, initPriority)
 
-        if (declaration.isExported()) {
+        val nameIfExported = when {
+            declaration.isJsExport() -> declaration.getJsNameOrKotlinName().identifier
+            else -> declaration.getWasmExportNameIfWasmExport()
+        }
+
+        if (nameIfExported != null) {
             context.addExport(
                 WasmExport.Function(
                     field = function,
-                    name = declaration.getJsNameOrKotlinName().identifier
+                    name = nameIfExported
                 )
             )
         }
@@ -500,8 +506,7 @@ fun IrFunction.getEffectiveValueParameters(): List<IrValueParameter> {
 }
 
 fun IrFunction.isExported(): Boolean =
-    isJsExport()
-
+    isJsExport() || getWasmExportNameIfWasmExport() != null
 
 fun generateConstExpression(
     expression: IrConst<*>,

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

@@ -12,13 +12,13 @@ import org.jetbrains.kotlin.backend.common.lower.DeclarationIrBuilder
 import org.jetbrains.kotlin.backend.common.lower.createIrBuilder
 import org.jetbrains.kotlin.backend.wasm.WasmBackendContext
 import org.jetbrains.kotlin.backend.wasm.ir2wasm.isBuiltInWasmRefType
-import org.jetbrains.kotlin.backend.wasm.ir2wasm.isExported
 import org.jetbrains.kotlin.backend.wasm.ir2wasm.isExternalType
 import org.jetbrains.kotlin.backend.wasm.ir2wasm.toJsStringLiteral
 import org.jetbrains.kotlin.backend.wasm.utils.getJsFunAnnotation
 import org.jetbrains.kotlin.backend.wasm.utils.getWasmImportDescriptor
 import org.jetbrains.kotlin.descriptors.DescriptorVisibilities
 import org.jetbrains.kotlin.ir.backend.js.utils.getJsNameOrKotlinName
+import org.jetbrains.kotlin.ir.backend.js.utils.isJsExport
 import org.jetbrains.kotlin.ir.builders.*
 import org.jetbrains.kotlin.ir.builders.declarations.*
 import org.jetbrains.kotlin.ir.declarations.*
@@ -49,7 +49,7 @@ class JsInteropFunctionsLowering(val context: WasmBackendContext) : DeclarationT
     override fun transformFlat(declaration: IrDeclaration): List<IrDeclaration>? {
         if (declaration.isFakeOverride) return null
         if (declaration !is IrSimpleFunction) return null
-        val isExported = declaration.isExported()
+        val isExported = declaration.isJsExport()
         val isExternal = declaration.isExternal || declaration.getJsFunAnnotation() != null
         if (declaration.isPropertyAccessor) return null
         if (declaration.parent !is IrPackageFragment) return null

compiler/ir/backend.wasm/src/org/jetbrains/kotlin/backend/wasm/utils/Annotations.kt

@@ -61,3 +61,10 @@ fun IrAnnotationContainer.getJsFunAnnotation(): String? =
 
 fun IrAnnotationContainer.getJsPrimitiveType(): String? =
     getAnnotation(FqName("kotlin.wasm.internal.JsPrimitive"))?.getSingleConstStringArgument()
+
+@Suppress("UNCHECKED_CAST")
+fun IrFunction.getWasmExportNameIfWasmExport(): String? {
+    val annotation = getAnnotation(FqName("kotlin.wasm.WasmExport")) ?: return null
+    if (annotation.valueArgumentsCount == 0) return name.identifier
+    return (annotation.getValueArgument(0) as? IrConst<String>)?.value ?: name.identifier
+}

compiler/testData/codegen/boxWasmJsInterop/wasmExport.kt

@@ -0,0 +1,19 @@
+// TARGET_BACKEND: WASM
+
+import kotlin.wasm.WasmExport
+
+@WasmExport
+fun exportDefaultName(): String = "some string"
+
+fun checkDefaultName(): Int = js("typeof wasmExports.exportDefaultName() === 'object'")
+
+@WasmExport("exportOverriddenName")
+fun exportWithName(): String = "some string"
+
+fun checkOverriddenName(): Int = js("typeof wasmExports.exportOverriddenName() === 'object'")
+
+fun box(): String {
+    if (checkDefaultName() != 1) return "checkDefaultName fail"
+    if (checkOverriddenName() != 1) return "checkOverriddenName fail"
+    return "OK"
+}

compiler/testData/diagnostics/wasmTests/wasmInterop/wasmExport.kt

@@ -0,0 +1,23 @@
+import kotlin.wasm.WasmExport
+
+<!WASM_EXPORT_ON_EXTERNAL_DECLARATION!>@WasmExport("a")
+external fun foo0(): Unit<!>
+
+<!WASM_EXPORT_ON_EXTERNAL_DECLARATION!>@WasmExport("a")
+fun foo1(): Int = js("42")<!>
+
+class C() {
+    <!NESTED_WASM_EXPORT!>@WasmExport("a")
+    fun foo2(): Int = 42<!>
+}
+
+@WasmExport("a")
+fun foo3(): Int = 42
+
+@WasmExport()
+fun foo4(): Int = 42
+
+<!JS_AND_WASM_EXPORTS_ON_SAME_DECLARATION!>@OptIn(kotlin.js.ExperimentalJsExport::class)
+@JsExport()
+@WasmExport()
+fun foo6(): Int = 42<!>