Ensure that there are no references to atomicfu in classes

* Updated to 0.12.7 version of atmoicfu with fixes.
* Added test that that is no references to atomicfu in any of the
  resulting class files.

Fixes #1155

Author: elizarov

binary-compatibility-validator/test/PublicApiTest.kt

@@ -43,14 +43,18 @@ class PublicApiTest(
     @Test
     fun testApi() {
         val libsDir = File("../$rootDir/$moduleName/build/libs").absoluteFile.normalize()
-        val jarFile = getJarPath(libsDir)
+        val jarPath = getJarPath(libsDir)
         val kotlinJvmMappingsFiles = listOf(libsDir.resolve("../visibilities.json"))
         val visibilities =
                 kotlinJvmMappingsFiles
                         .map { readKotlinVisibilities(it) }
                         .reduce { m1, m2 -> m1 + m2 }
-        val api = getBinaryAPI(JarFile(jarFile), visibilities).filterOutNonPublic(nonPublicPackages)
-        api.dumpAndCompareWith(File("reference-public-api").resolve("$moduleName.txt"))
+        JarFile(jarPath).use { jarFile ->
+            val api = getBinaryAPI(jarFile, visibilities).filterOutNonPublic(nonPublicPackages)
+            api.dumpAndCompareWith(File("reference-public-api").resolve("$moduleName.txt"))
+            // check for atomicfu leaks
+            jarFile.checkForAtomicFu()
+        }
     }
 
     private fun getJarPath(libsDir: File): File {
@@ -68,3 +72,25 @@ class PublicApiTest(
             error("No single file matching $regex in $libsDir:\n${files.joinToString("\n")}")
     }
 }
+
+private val ATOMIC_FU_REF = "Lkotlinx/atomicfu/".toByteArray()
+
+private fun JarFile.checkForAtomicFu() {
+    val foundClasses = mutableListOf<String>()
+    for (e in entries()) {
+        if (!e.name.endsWith(".class")) continue
+        val bytes = getInputStream(e).use { it.readBytes() }
+        loop@for (i in 0 until bytes.size - ATOMIC_FU_REF.size) {
+            for (j in 0 until ATOMIC_FU_REF.size) {
+                if (bytes[i + j] != ATOMIC_FU_REF[j]) continue@loop
+            }
+            foundClasses += e.name // report error at the end with all class names
+            break@loop
+        }
+    }
+    if (foundClasses.isNotEmpty()) {
+        error("Found references to atomicfu in jar file $name in the following class files: ${
+            foundClasses.joinToString("") { "\n\t\t" + it }
+        }")
+    }
+}

gradle.properties

@@ -5,7 +5,7 @@ kotlin_version=1.3.30
 
 # Dependencies
 junit_version=4.12
-atomicfu_version=0.12.5
+atomicfu_version=0.12.7
 html_version=0.6.8
 lincheck_version=2.0
 dokka_version=0.9.16-rdev-2-mpp-hacks