[Interop][Metadata] Reuse CCall infrastructure to support global structs

Interop/StubGenerator/src/main/kotlin/org/jetbrains/kotlin/native/interop/gen/CWrapperGenerator.kt

@@ -75,6 +75,14 @@ internal class CWrappersGenerator(private val context: StubIrContext) {
         return CCalleeWrapper(wrapper)
     }
 
+    fun generateCGlobalByPointerGetter(globalDecl: GlobalDecl, symbolName: String): CCalleeWrapper {
+        val wrapperName = generateFunctionWrapperName("${globalDecl.name}_getter")
+        val returnType = "void*"
+        val wrapperBody = "return &${globalDecl.name};"
+        val wrapper = createWrapper(symbolName, wrapperName, returnType, emptyList(), wrapperBody)
+        return CCalleeWrapper(wrapper)
+    }
+
     fun generateCGlobalSetter(globalDecl: GlobalDecl, symbolName: String): CCalleeWrapper {
         val wrapperName = generateFunctionWrapperName("${globalDecl.name}_setter")
         val globalType = globalDecl.type.getStringRepresentation()

Interop/StubGenerator/src/main/kotlin/org/jetbrains/kotlin/native/interop/gen/StubIrBridgeBuilder.kt

@@ -205,7 +205,11 @@ class StubIrBridgeBuilder(
                         val extra = builderResult.wrapperGenerationComponents.getterToWrapperInfo.getValue(accessor)
                         val cCallAnnotation = accessor.annotations.firstIsInstanceOrNull<AnnotationStub.CCall.Symbol>()
                                 ?: error("external getter for ${extra.global.name} wasn't marked with @CCall")
-                        val wrapper = wrapperGenerator.generateCGlobalGetter(extra.global, cCallAnnotation.symbolName)
+                        val wrapper = if (extra.passViaPointer) {
+                            wrapperGenerator.generateCGlobalByPointerGetter(extra.global, cCallAnnotation.symbolName)
+                        } else {
+                            wrapperGenerator.generateCGlobalGetter(extra.global, cCallAnnotation.symbolName)
+                        }
                         simpleBridgeGenerator.insertNativeBridge(accessor, emptyList(), wrapper.lines)
                     }
                 }

Interop/StubGenerator/src/main/kotlin/org/jetbrains/kotlin/native/interop/gen/StubIrBuilder.kt

@@ -66,7 +66,7 @@ class BridgeGenerationComponentsBuilder {
 /**
  * Components that are not passed via StubIr but required for generation of wrappers.
  */
-class WrapperGenerationInfo(val global: GlobalDecl)
+class WrapperGenerationInfo(val global: GlobalDecl, val passViaPointer: Boolean = false)
 
 interface WrapperGenerationComponents {
     val getterToWrapperInfo: Map<PropertyAccessor.Getter.ExternalGetter, WrapperGenerationInfo>

Interop/StubGenerator/src/main/kotlin/org/jetbrains/kotlin/native/interop/gen/StubIrElementBuilders.kt

@@ -649,7 +649,17 @@ internal class GlobalStubBuilder(
                 }
                 is TypeMirror.ByRef -> {
                     kotlinType = mirror.pointedType
-                    val getter = PropertyAccessor.Getter.InterpretPointed(global.name, kotlinType.toStubIrType())
+                    val getter = when (context.generationMode) {
+                        GenerationMode.SOURCE_CODE -> {
+                            PropertyAccessor.Getter.InterpretPointed(global.name, kotlinType.toStubIrType())
+                        }
+                        GenerationMode.METADATA -> {
+                            val cCallAnnotation = AnnotationStub.CCall.Symbol("${context.generateNextUniqueId("knifunptr_")}_${global.name}_getter")
+                            PropertyAccessor.Getter.ExternalGetter(listOf(cCallAnnotation)).also {
+                                context.wrapperComponentsBuilder.getterToWrapperInfo[it] = WrapperGenerationInfo(global, passViaPointer = true)
+                            }
+                        }
+                    }
                     kind = PropertyStub.Kind.Val(getter)
                 }
             }

backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/cgen/CBridgeGen.kt

@@ -820,6 +820,10 @@ private fun KotlinStubs.mapType(
                 ?: reportUnsupportedType("not a structure or too complex"))
     }
 
+    type.classOrNull?.isSubtypeOfClass(symbols.nativePointed) == true -> {
+        TrivialValuePassing(type, CTypes.voidPtr)
+    }
+
     type.isFunction() -> if (variadic){
         reportUnsupportedType("not supported as variadic argument")
     } else {