Descriptor renderer: add option to render function without return type

core/descriptors/src/org/jetbrains/kotlin/renderer/DescriptorRenderer.kt

@@ -156,6 +156,7 @@ public interface DescriptorRendererOptions {
     public var classWithPrimaryConstructor: Boolean
     public var verbose: Boolean
     public var unitReturnType: Boolean
+    public var withoutReturnType: Boolean
     public var normalizedVisibilities: Boolean
     public var showInternalKeyword: Boolean
     public var prettyFunctionTypes: Boolean

core/descriptors/src/org/jetbrains/kotlin/renderer/DescriptorRendererImpl.kt

@@ -543,7 +543,7 @@ internal class DescriptorRendererImpl(
         renderReceiverAfterName(function, builder)
 
         val returnType = function.getReturnType()
-        if (unitReturnType || (returnType == null || !KotlinBuiltIns.isUnit(returnType))) {
+        if (!withoutReturnType && (unitReturnType || (returnType == null || !KotlinBuiltIns.isUnit(returnType)))) {
             builder.append(": ").append(if (returnType == null) "[NULL]" else escape(renderType(returnType)))
         }
 

core/descriptors/src/org/jetbrains/kotlin/renderer/DescriptorRendererOptionsImpl.kt

@@ -67,6 +67,7 @@ internal class DescriptorRendererOptionsImpl : DescriptorRendererOptions {
     override var classWithPrimaryConstructor by property(false)
     override var verbose by property(false)
     override var unitReturnType by property(true)
+    override var withoutReturnType by property(false)
     override var normalizedVisibilities by property(false)
     override var showInternalKeyword by property(true)
     override var prettyFunctionTypes by property(true)