Merge pull request #10229 from igfoo/igfoo/singleOrNullSubType

Kotlin: Implement and use singleOrNullSubType

Author: igfoo

java/kotlin-extractor/src/main/kotlin/KotlinUsesExtractor.kt

@@ -1169,7 +1169,7 @@ open class KotlinUsesExtractor(
         "kotlin.Boolean", "kotlin.Byte", "kotlin.Char", "kotlin.Double", "kotlin.Float", "kotlin.Int", "kotlin.Long", "kotlin.Number", "kotlin.Short"
     )
 
-    private fun kotlinFunctionToJavaEquivalent(f: IrFunction, noReplace: Boolean) =
+    private fun kotlinFunctionToJavaEquivalent(f: IrFunction, noReplace: Boolean): IrFunction =
         if (noReplace)
             f
         else
@@ -1186,8 +1186,7 @@ open class KotlinUsesExtractor(
                             decl.valueParameters.zip(f.valueParameters).all { p -> p.first.type.classifierOrNull == p.second.type.classifierOrNull }
                         } ?:
                         // Or if there is none, look for the only viable overload
-                        javaClass.declarations.singleOrNull { decl ->
-                            decl is IrFunction &&
+                        javaClass.declarations.singleOrNullSubType<IrFunction> { decl ->
                             decl.name == f.name &&
                             decl.valueParameters.size == f.valueParameters.size
                         } ?:
@@ -1213,7 +1212,7 @@ open class KotlinUsesExtractor(
                     else
                         null
                 }
-            } as IrFunction? ?: f
+            } ?: f
 
     fun <T: DbCallable> useFunction(f: IrFunction, classTypeArgsIncludingOuterClasses: List<IrTypeArgument>? = null, noReplace: Boolean = false): Label<out T> {
         return useFunction(f, null, classTypeArgsIncludingOuterClasses, noReplace)

java/kotlin-extractor/src/main/kotlin/utils/Iterable.kt

@@ -13,3 +13,14 @@ inline fun <reified S: IrDeclaration> Iterable<IrDeclaration>.findSubType(
     return this.find { it is S && predicate(it) } as S?
 }
 
+/**
+ * This behaves the same as Iterable<IrDeclaration>.singleOrNull, but
+ * requires that the value found is of the subtype S, and it casts
+ * the result for you appropriately.
+ */
+inline fun <reified S: IrDeclaration> Iterable<IrDeclaration>.singleOrNullSubType(
+    predicate: (S) -> Boolean
+): S? {
+    return this.singleOrNull { it is S && predicate(it) } as S?
+}
+