[K/N][tests] Added a test on stack allocated string

kotlin-native/backend.native/tests/build.gradle

@@ -3305,6 +3305,14 @@ standaloneTest("codegen_escapeAnalysis_stackAllocated") {
     source = "codegen/escapeAnalysis/stackAllocated.kt"
 }
 
+standaloneTest("codegen_escapeAnalysis_string") {
+    disabled = (cacheTesting != null) || // Cache is not compatible with -opt.
+        project.globalTestArgs.contains('-g') || // -g and -opt are incompatible
+        !isExperimentalMM // strings are frozen in legacy GC
+    flags = ['-opt', '-tr', '-opt-in=kotlin.native.internal.InternalForKotlinNative']
+    source = "codegen/escapeAnalysis/string.kt"
+}
+
 task memory_var1(type: KonanLocalTest) {
     source = "runtime/memory/var1.kt"
 }

kotlin-native/backend.native/tests/codegen/escapeAnalysis/string.kt

@@ -0,0 +1,14 @@
+/*
+ * Copyright 2010-2021 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the LICENSE file.
+ */
+
+package codegen.escapeAnalysis.string
+
+import kotlin.test.*
+import kotlin.native.internal.*
+
+@Test fun runTest() {
+    val s = String()
+    assertTrue(s.isLocal())
+}