Relax type parameter constraint for Closeable.use and AutoCloseable.use to allow nullable receiver.

#KT-12894 Fixed

libraries/stdlib/jre7/src/kotlin/Standard.kt

@@ -3,17 +3,17 @@ package kotlin
 
 @Suppress("INVISIBLE_REFERENCE", "INVISIBLE_MEMBER")
 @kotlin.internal.InlineOnly
-public inline fun <T : AutoCloseable, R> T.use(block: (T) -> R): R {
+public inline fun <T : AutoCloseable?, R> T.use(block: (T) -> R): R {
     var closed = false
     try {
         return block(this)
     } catch (e: Throwable) {
         closed = true
         @Suppress("NON_PUBLIC_CALL_FROM_PUBLIC_INLINE")
-        closeSuppressed(e)
+        this?.closeSuppressed(e)
         throw e
     } finally {
-        if (!closed) {
+        if (this != null && !closed) {
             close()
         }
     }

libraries/stdlib/jre7/test/TryWithResourcesAutoCloseableTest.kt

@@ -2,11 +2,14 @@ package kotlin.jdk7.test
 
 import java.io.*
 import org.junit.Test
+import java.util.*
 import kotlin.test.*
 
 
 class TryWithResourcesAutoCloseableTest {
 
+    @Suppress("HasPlatformType") fun <T> platformNull() = Collections.singletonList(null as T).first()
+
     class Resource(val faultyClose: Boolean = false) : AutoCloseable {
 
         var isClosed = false
@@ -80,7 +83,31 @@ class TryWithResourcesAutoCloseableTest {
             assertEquals("nonLocal", result)
             assertTrue(resource.isClosed)
         }
+    }
 
+
+    @Test fun nullableResourceSuccess() {
+        val resource: Resource? = null
+        val result = resource.use { "ok" }
+        assertEquals("ok", result)
+    }
+
+    @Test fun nullableResourceOpFails() {
+        val resource: Resource? = null
+        val e = assertFails {
+            resource.use { requireNotNull(it) }
+        }
+        assertTrue(e is IllegalArgumentException)
+        assertTrue(e.suppressed.isEmpty())
+    }
+
+    @Test fun platformResourceOpFails() {
+        val resource = platformNull<Resource>()
+        val e = assertFails {
+            resource.use { requireNotNull(it) }
+        }
+        assertTrue(e is IllegalArgumentException)
+        assertTrue(e.suppressed.isEmpty())
     }
 
 }

libraries/stdlib/jre7/test/TryWithResourcesCloseableTest.kt

@@ -2,10 +2,13 @@ package kotlin.jdk7.test
 
 import java.io.*
 import org.junit.Test
+import java.util.*
 import kotlin.test.*
 
 class TryWithResourcesCloseableTest {
 
+    @Suppress("HasPlatformType") fun <T> platformNull() = Collections.singletonList(null as T).first()
+
     class Resource(val faultyClose: Boolean = false) : Closeable {
 
         var isClosed = false
@@ -81,4 +84,27 @@ class TryWithResourcesCloseableTest {
 
     }
 
+    @Test fun nullableResourceSuccess() {
+        val resource: Resource? = null
+        val result = resource.use { "ok" }
+        assertEquals("ok", result)
+    }
+
+    @Test fun nullableResourceOpFails() {
+        val resource: Resource? = null
+        val e = assertFails {
+            resource.use { requireNotNull(it) }
+        }
+        assertTrue(e is IllegalArgumentException)
+        assertTrue(e.suppressed.isEmpty())
+    }
+
+    @Test fun platformResourceOpFails() {
+        val resource = platformNull<Resource>()
+        val e = assertFails {
+            resource.use { requireNotNull(it) }
+        }
+        assertTrue(e is IllegalArgumentException)
+        assertTrue(e.suppressed.isEmpty())
+    }
 }

libraries/stdlib/src/kotlin/io/ReadWrite.kt

@@ -152,17 +152,17 @@ public fun URL.readBytes(): ByteArray = openStream().use { it.readBytes() }
  * @return the result of [block] function on this closable resource.
  */
 @kotlin.internal.InlineOnly
-public inline fun <T : Closeable, R> T.use(block: (T) -> R): R {
+public inline fun <T : Closeable?, R> T.use(block: (T) -> R): R {
     var closed = false
     try {
         return block(this)
     } catch (e: Throwable) {
         closed = true
         @Suppress("NON_PUBLIC_CALL_FROM_PUBLIC_INLINE")
-        platformCloseSuppressed(this, e)
+        if (this != null) platformCloseSuppressed(this, e)
         throw e
     } finally {
-        if (!closed) {
+        if (this != null && !closed) {
             close()
         }
     }

libraries/stdlib/test/io/ReadWrite.kt

@@ -141,6 +141,15 @@ class ReadWriteTest {
         assertEquals(arrayListOf("Hello", "World"), list)
     }
 
+    @test fun testPlatformNullUse() {
+        fun <T> platformNull() = java.util.Collections.singleton(null as T).first()
+        val resource = platformNull<java.io.Closeable>()
+        val result = resource.use {
+            "ok"
+        }
+        assertEquals("ok", result)
+    }
+
     @test fun testURL() {
         val url = URL("http://kotlinlang.org")
         val text = url.readText()