Fix mapping of jvmStatic functions

#KT-8800 Fixed

compiler/testData/codegen/boxWithStdlib/reflection/mapping/platformStatic/companionObjectFunction.kt

@@ -0,0 +1,33 @@
+import kotlin.platform.platformStatic as static
+import kotlin.reflect.jvm.*
+import kotlin.test.assertEquals
+import kotlin.test.failsWith
+
+class C {
+    companion object {
+        @static fun foo(s: String): Int = s.length()
+    }
+}
+
+fun box(): String {
+    val foo = C.Companion::foo
+
+    val j = foo.javaMethod ?: return "Fail: no Java method found for C::foo"
+    assertEquals(3, j.invoke(C, "abc"))
+
+    val k = j.kotlinFunction ?: return "Fail: no Kotlin function found for Java method C::foo"
+    assertEquals(3, k.call(C, "def"))
+
+
+    val staticMethod = javaClass<C>().getDeclaredMethod("foo", javaClass<String>())
+    val k2 = staticMethod.kotlinFunction ?:
+             return "Fail: no Kotlin function found for static bridge for @jvmStatic method in companion object C::foo"
+    assertEquals(3, k2.call(C, "ghi"))
+
+    failsWith(javaClass<NullPointerException>()) { k2.call(null, "")!! }
+
+    val j2 = k2.javaMethod
+    assertEquals(j, j2)
+
+    return "OK"
+}

compiler/testData/codegen/boxWithStdlib/reflection/mapping/platformStatic/objectFunction.kt

@@ -0,0 +1,19 @@
+import kotlin.platform.platformStatic as static
+import kotlin.reflect.jvm.*
+import kotlin.test.assertEquals
+
+object O {
+    @static fun foo(s: String): Int = s.length()
+}
+
+fun box(): String {
+    val foo = O::foo
+
+    val j = foo.javaMethod ?: return "Fail: no Java method found for O::foo"
+    assertEquals(3, j.invoke(null, "abc"))
+
+    val k = j.kotlinFunction ?: return "Fail: no Kotlin function found for Java method O::foo"
+    assertEquals(3, k.call(O, "def"))
+
+    return "OK"
+}

compiler/tests/org/jetbrains/kotlin/codegen/generated/BlackBoxWithStdlibCodegenTestGenerated.java

@@ -3396,6 +3396,27 @@ public class BlackBoxWithStdlibCodegenTestGenerated extends AbstractBlackBoxCode
                 doTestWithStdlib(fileName);
             }
 
+            @TestMetadata("compiler/testData/codegen/boxWithStdlib/reflection/mapping/platformStatic")
+            @TestDataPath("$PROJECT_ROOT")
+            @RunWith(JUnit3RunnerWithInners.class)
+            public static class PlatformStatic extends AbstractBlackBoxCodegenTest {
+                public void testAllFilesPresentInPlatformStatic() throws Exception {
+                    JetTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("compiler/testData/codegen/boxWithStdlib/reflection/mapping/platformStatic"), Pattern.compile("^(.+)\\.kt$"), true);
+                }
+
+                @TestMetadata("companionObjectFunction.kt")
+                public void testCompanionObjectFunction() throws Exception {
+                    String fileName = JetTestUtils.navigationMetadata("compiler/testData/codegen/boxWithStdlib/reflection/mapping/platformStatic/companionObjectFunction.kt");
+                    doTestWithStdlib(fileName);
+                }
+
+                @TestMetadata("objectFunction.kt")
+                public void testObjectFunction() throws Exception {
+                    String fileName = JetTestUtils.navigationMetadata("compiler/testData/codegen/boxWithStdlib/reflection/mapping/platformStatic/objectFunction.kt");
+                    doTestWithStdlib(fileName);
+                }
+            }
+
             @TestMetadata("compiler/testData/codegen/boxWithStdlib/reflection/mapping/types")
             @TestDataPath("$PROJECT_ROOT")
             @RunWith(JUnit3RunnerWithInners.class)

core/reflection.jvm/src/kotlin/reflect/jvm/mapping.kt

@@ -17,8 +17,12 @@
 package kotlin.reflect.jvm
 
 import java.lang.reflect.*
+import java.util.*
 import kotlin.reflect.*
-import kotlin.reflect.jvm.internal.*
+import kotlin.reflect.jvm.internal.KCallableImpl
+import kotlin.reflect.jvm.internal.KPackageImpl
+import kotlin.reflect.jvm.internal.KPropertyImpl
+import kotlin.reflect.jvm.internal.KTypeImpl
 
 // Kotlin reflection -> Java reflection
 
@@ -115,15 +119,26 @@ public val Field.kotlinProperty: KProperty<*>?
  */
 public val Method.kotlinFunction: KFunction<*>?
     get() {
-        if (isSynthetic()) return null
+        if (isSynthetic) return null
 
-        if (Modifier.isStatic(getModifiers())) {
+        if (Modifier.isStatic(modifiers)) {
-            getDeclaringClass().kotlinPackage?.let { pkg ->
+            val kotlinPackage = declaringClass.kotlinPackage
-                return pkg.functions.firstOrNull { it.javaMethod == this }
+            if (kotlinPackage != null) {
+                return kotlinPackage.functions.firstOrNull { it.javaMethod == this }
+            }
+
+            // For static bridge method generated for a jvmStatic function in the companion object, also try to find the latter
+            val companion = declaringClass.kotlin.companionObject
+            if (companion != null) {
+                companion.functions.firstOrNull {
+                    val m = it.javaMethod
+                    m != null && m.name == this.name &&
+                    Arrays.equals(m.parameterTypes, this.parameterTypes) && m.returnType == this.returnType
+                }?.let { return it }
             }
         }
 
-        return getDeclaringClass().kotlin.functions.firstOrNull { it.javaMethod == this }
+        return declaringClass.kotlin.functions.firstOrNull { it.javaMethod == this }
     }
 
 /**