KT-64931: add convertion of kotlin top-lvl functions into swift static functions

Merge-request: KT-MR-13878
Merged-by: Artem Olkov <artem.olkov@jetbrains.com>

plugins/swift-export/swift-export.backend/src/org/jetbrains/kotlin/swiftexport/SwiftExportExtension.kt

@@ -164,7 +164,7 @@ class SwiftExportExtension(
             }
 
             override fun visitFunction(function: SirFunction) {
-                val fqName = (function.origin as? SirKotlinOrigin.Function)?.fqName
+                val fqName = (function.origin as? SirKotlinOrigin.Function)?.path
                     ?: return
                 val fqNameForBridge = if (fqName.count() == 1) {
                     listOf("__root__", fqName.first()) // todo: should be changed with correct mangling KT-64970

plugins/swift-export/testData/simple.golden.h

@@ -5,3 +5,5 @@ int32_t namespace1_main_foobar(int32_t param);
 int32_t namespace1_foo();
 
 int32_t namespace2_bar();
+
+int32_t __root___foo();

plugins/swift-export/testData/simple.golden.kt

@@ -17,3 +17,9 @@ public fun namespace2_bar(): Int {
     val result = namespace2.bar()
     return result
 }
+
+@ExportedBridge("__root___foo")
+public fun __root___foo(): Int {
+    val result = foo()
+    return result
+}

plugins/swift-export/testData/simple.golden.swift

@@ -1,18 +1,22 @@
 enum namespace1 {
     enum main {
-        public func foobar(
+        public static func foobar(
             param: Swift.Int32
         ) -> Swift.Int32 {
             return namespace1_main_foobar(param)
         }
     }
-    public func foo() -> Swift.Int32 {
+    public static func foo() -> Swift.Int32 {
         return namespace1_foo()
     }
 }
 
 enum namespace2 {
-    public func bar() -> Swift.Int32 {
+    public static func bar() -> Swift.Int32 {
         return namespace2_bar()
     }
 }
+
+public func foo() -> Swift.Int32 {
+    return __root___foo()
+}

plugins/swift-export/testData/simple.kt

@@ -1,5 +1,8 @@
 // WITH_STDLIB
 
+// FILE: no_package.kt
+fun foo(): Int = 123
+
 // FILE: foo.kt
 package namespace1
 fun foo(): Int = 123