Add contract for action/block

okio/build.gradle.kts

@@ -59,6 +59,8 @@ kotlin {
       languageSettings.apply {
         // Required for CPointer etc. since Kotlin 1.9.
         optIn("kotlinx.cinterop.ExperimentalForeignApi")
+        // Required for Contract API. since Kotlin 1.3.
+        optIn("kotlin.contracts.ExperimentalContracts")
       }
     }
 
@@ -141,12 +143,20 @@ kotlin {
         .also { nativeMain ->
           nativeMain.dependsOn(zlibMain)
           nativeMain.dependsOn(systemFileSystemMain)
-          createSourceSet("mingwMain", parent = nativeMain, children = mingwTargets).also { mingwMain ->
+          createSourceSet(
+              "mingwMain",
+              parent = nativeMain,
+              children = mingwTargets,
+          ).also { mingwMain ->
             mingwMain.dependsOn(nonAppleMain)
           }
           createSourceSet("unixMain", parent = nativeMain)
             .also { unixMain ->
-              createSourceSet("linuxMain", parent = unixMain, children = linuxTargets).also { linuxMain ->
+              createSourceSet(
+                  "linuxMain",
+                  parent = unixMain,
+                  children = linuxTargets,
+              ).also { linuxMain ->
                 linuxMain.dependsOn(nonAppleMain)
               }
               createSourceSet("appleMain", parent = unixMain, children = appleTargets)

okio/src/commonMain/kotlin/okio/Okio.kt

@@ -20,6 +20,8 @@
 
 package okio
 
+import kotlin.contracts.InvocationKind
+import kotlin.contracts.contract
 import kotlin.jvm.JvmMultifileClass
 import kotlin.jvm.JvmName
 
@@ -49,6 +51,10 @@ private class BlackholeSink : Sink {
 
 /** Execute [block] then close this. This will be closed even if [block] throws. */
 inline fun <T : Closeable?, R> T.use(block: (T) -> R): R {
+  contract {
+    callsInPlace(block, InvocationKind.EXACTLY_ONCE)
+  }
+
   var thrown: Throwable? = null
 
   val result = try {

okio/src/jsMain/kotlin/okio/FileSystem.kt

@@ -15,6 +15,8 @@
  */
 package okio
 
+import kotlin.contracts.InvocationKind
+import kotlin.contracts.contract
 import okio.Path.Companion.toPath
 import okio.internal.commonCopy
 import okio.internal.commonCreateDirectories
@@ -50,6 +52,10 @@ actual abstract class FileSystem : Closeable {
   actual abstract fun source(file: Path): Source
 
   actual inline fun <T> read(file: Path, readerAction: BufferedSource.() -> T): T {
+    contract {
+      callsInPlace(readerAction, InvocationKind.EXACTLY_ONCE)
+    }
+
     return source(file).buffer().use {
       it.readerAction()
     }
@@ -62,6 +68,10 @@ actual abstract class FileSystem : Closeable {
     mustCreate: Boolean,
     writerAction: BufferedSink.() -> T,
   ): T {
+    contract {
+      callsInPlace(writerAction, InvocationKind.EXACTLY_ONCE)
+    }
+
     return sink(file, mustCreate).buffer().use {
       it.writerAction()
     }
@@ -71,7 +81,8 @@ actual abstract class FileSystem : Closeable {
 
   actual abstract fun createDirectory(dir: Path, mustCreate: Boolean)
 
-  actual fun createDirectories(dir: Path, mustCreate: Boolean): Unit = commonCreateDirectories(dir, mustCreate)
+  actual fun createDirectories(dir: Path, mustCreate: Boolean): Unit =
+    commonCreateDirectories(dir, mustCreate)
 
   actual abstract fun atomicMove(source: Path, target: Path)
 

okio/src/jvmMain/kotlin/okio/-JvmPlatform.kt

@@ -18,6 +18,8 @@ package okio
 
 import java.util.concurrent.locks.ReentrantLock
 import kotlin.concurrent.withLock as jvmWithLock
+import kotlin.contracts.InvocationKind
+import kotlin.contracts.contract
 
 internal actual fun ByteArray.toUtf8String(): String = String(this, Charsets.UTF_8)
 
@@ -30,7 +32,13 @@ actual typealias Lock = ReentrantLock
 
 internal actual fun newLock(): Lock = ReentrantLock()
 
-actual inline fun <T> Lock.withLock(action: () -> T): T = jvmWithLock(action)
+actual inline fun <T> Lock.withLock(action: () -> T): T {
+  contract {
+    callsInPlace(action, InvocationKind.EXACTLY_ONCE)
+  }
+
+  return jvmWithLock(action)
+}
 
 actual typealias IOException = java.io.IOException
 

okio/src/jvmMain/kotlin/okio/FileSystem.kt

@@ -16,6 +16,8 @@
 package okio
 
 import java.nio.file.FileSystem as JavaNioFileSystem
+import kotlin.contracts.InvocationKind
+import kotlin.contracts.contract
 import okio.Path.Companion.toPath
 import okio.internal.ResourceFileSystem
 import okio.internal.commonCopy
@@ -64,6 +66,10 @@ actual abstract class FileSystem : Closeable {
   @Throws(IOException::class)
   @JvmName("-read")
   actual inline fun <T> read(file: Path, readerAction: BufferedSource.() -> T): T {
+    contract {
+      callsInPlace(readerAction, InvocationKind.EXACTLY_ONCE)
+    }
+
     return source(file).buffer().use {
       it.readerAction()
     }
@@ -77,7 +83,15 @@ actual abstract class FileSystem : Closeable {
 
   @Throws(IOException::class)
   @JvmName("-write")
-  actual inline fun <T> write(file: Path, mustCreate: Boolean, writerAction: BufferedSink.() -> T): T {
+  actual inline fun <T> write(
+    file: Path,
+    mustCreate: Boolean,
+    writerAction: BufferedSink.() -> T,
+  ): T {
+    contract {
+      callsInPlace(writerAction, InvocationKind.EXACTLY_ONCE)
+    }
+
     return sink(file, mustCreate = mustCreate).buffer().use {
       it.writerAction()
     }

okio/src/nativeMain/kotlin/okio/FileSystem.kt

@@ -15,6 +15,8 @@
  */
 package okio
 
+import kotlin.contracts.InvocationKind
+import kotlin.contracts.contract
 import okio.internal.commonCopy
 import okio.internal.commonCreateDirectories
 import okio.internal.commonDeleteRecursively
@@ -58,6 +60,10 @@ actual abstract class FileSystem : Closeable {
 
   @Throws(IOException::class)
   actual inline fun <T> read(file: Path, readerAction: BufferedSource.() -> T): T {
+    contract {
+      callsInPlace(readerAction, InvocationKind.EXACTLY_ONCE)
+    }
+
     return source(file).buffer().use {
       it.readerAction()
     }
@@ -72,6 +78,10 @@ actual abstract class FileSystem : Closeable {
     mustCreate: Boolean,
     writerAction: BufferedSink.() -> T,
   ): T {
+    contract {
+      callsInPlace(writerAction, InvocationKind.EXACTLY_ONCE)
+    }
+
     return sink(file, mustCreate).buffer().use {
       it.writerAction()
     }
@@ -84,7 +94,8 @@ actual abstract class FileSystem : Closeable {
   actual abstract fun createDirectory(dir: Path, mustCreate: Boolean)
 
   @Throws(IOException::class)
-  actual fun createDirectories(dir: Path, mustCreate: Boolean): Unit = commonCreateDirectories(dir, mustCreate)
+  actual fun createDirectories(dir: Path, mustCreate: Boolean): Unit =
+    commonCreateDirectories(dir, mustCreate)
 
   @Throws(IOException::class)
   actual abstract fun atomicMove(source: Path, target: Path)

okio/src/nonJvmMain/kotlin/okio/NonJvmPlatform.kt

@@ -16,6 +16,8 @@
 
 package okio
 
+import kotlin.contracts.InvocationKind
+import kotlin.contracts.contract
 import okio.internal.commonAsUtf8ToByteArray
 import okio.internal.commonToUtf8String
 
@@ -37,7 +39,13 @@ actual class Lock {
 
 internal actual fun newLock(): Lock = Lock.instance
 
-actual inline fun <T> Lock.withLock(action: () -> T): T = action()
+actual inline fun <T> Lock.withLock(action: () -> T): T {
+  contract {
+    callsInPlace(action, InvocationKind.EXACTLY_ONCE)
+  }
+
+  return action()
+}
 
 actual open class IOException actual constructor(
   message: String?,

okio/src/wasmMain/kotlin/okio/FileSystem.kt

@@ -15,6 +15,9 @@
  */
 package okio
 
+import kotlin.contracts.ExperimentalContracts
+import kotlin.contracts.InvocationKind
+import kotlin.contracts.contract
 import okio.Path.Companion.toPath
 import okio.internal.commonCopy
 import okio.internal.commonCreateDirectories
@@ -23,6 +26,7 @@ import okio.internal.commonExists
 import okio.internal.commonListRecursively
 import okio.internal.commonMetadata
 
+@OptIn(ExperimentalContracts::class)
 actual abstract class FileSystem : Closeable {
   actual abstract fun canonicalize(path: Path): Path
 
@@ -50,6 +54,10 @@ actual abstract class FileSystem : Closeable {
   actual abstract fun source(file: Path): Source
 
   actual inline fun <T> read(file: Path, readerAction: BufferedSource.() -> T): T {
+    contract {
+      callsInPlace(readerAction, InvocationKind.EXACTLY_ONCE)
+    }
+
     return source(file).buffer().use {
       it.readerAction()
     }
@@ -62,6 +70,10 @@ actual abstract class FileSystem : Closeable {
     mustCreate: Boolean,
     writerAction: BufferedSink.() -> T,
   ): T {
+    contract {
+      callsInPlace(writerAction, InvocationKind.EXACTLY_ONCE)
+    }
+
     return sink(file, mustCreate).buffer().use {
       it.writerAction()
     }