Skip C overloads (#3821)

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

@@ -123,6 +123,8 @@ interface StubsBuildingContext {
     fun getKotlinClassFor(objCClassOrProtocol: ObjCClassOrProtocol, isMeta: Boolean = false): Classifier
 
     fun getKotlinClassForPointed(structDecl: StructDecl): Classifier
+
+    fun isOverloading(func: FunctionDecl): Boolean
 }
 
 /**
@@ -146,6 +148,9 @@ class StubsBuildingContextImpl(
 
     private var theCounter = 0
 
+    private val uniqFunctions = mutableSetOf<String>()
+    override fun isOverloading(func: FunctionDecl) = !uniqFunctions.add(func.name) // TODO: params & return type.
+
     override fun generateNextUniqueId(prefix: String) =
             prefix + pkgName.replace('.', '_') + theCounter++
 
@@ -358,7 +363,7 @@ class StubIrBuilder(private val context: StubIrContext) {
 
     private fun generateStubsForFunction(func: FunctionDecl) {
         try {
-            addStubs(FunctionStubBuilder(buildingContext, func).build())
+            addStubs(FunctionStubBuilder(buildingContext, func, skipOverloads = true).build())
         } catch (e: Throwable) {
             context.log("Warning: cannot generate stubs for function ${func.name}")
         }

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

@@ -454,8 +454,10 @@ internal class EnumStubBuilder(
 
 internal class FunctionStubBuilder(
         override val context: StubsBuildingContext,
-        private val func: FunctionDecl
+        private val func: FunctionDecl,
+        private val skipOverloads: Boolean = false
 ) : StubElementBuilder {
+
     override fun build(): List<StubIrElement> {
         val platform = context.platform
         val parameters = mutableListOf<FunctionParameterStub>()
@@ -508,6 +510,8 @@ internal class FunctionStubBuilder(
             context.mirror(func.returnType).argType
         }.toStubIrType()
 
+        if (skipOverloads && context.isOverloading(func))
+            return emptyList()
 
         val annotations: List<AnnotationStub>
         val mustBeExternal: Boolean