Fix simulator runtime availability checking on older Xcode/macOS.

build-tools/src/main/kotlin/org/jetbrains/kotlin/FrameworkTest.kt

@@ -102,14 +102,17 @@ open class FrameworkTest : DefaultTask() {
             KonanTarget.MACOS_X64 -> "macosx"
             else -> throw IllegalStateException("Test target $target is not supported")
         }
-        return when (target) {
+        val simulatorPath = when (target) {
             KonanTarget.TVOS_X64,
             KonanTarget.IOS_X64,
-            KonanTarget.WATCHOS_X64 -> Xcode.current.getLatestSimulatorRuntimeFor(target, configs.osVersionMin)?.let {
-                "${it.bundlePath}/Contents/Resources/RuntimeRoot/usr/lib/swift"
-            } ?: error("Simulator runtime for $target ${configs.osVersionMin} is not available")
-            else -> configs.absoluteTargetToolchain + "/usr/lib/swift/$swiftPlatform"
+            KonanTarget.WATCHOS_X64 -> Xcode.current.getLatestSimulatorRuntimeFor(target, configs.osVersionMin)?.bundlePath?.let {
+                "$it/Contents/Resources/RuntimeRoot/usr/lib/swift"
+            }
+            else -> null
         }
+        // Use default path from toolchain if we cannot get `bundlePath` for target.
+        // It may be the case for simulators if Xcode/macOS is old.
+        return simulatorPath ?: configs.absoluteTargetToolchain + "/usr/lib/swift/$swiftPlatform"
     }
 
     private fun buildEnvironment(): Map<String, String> {

build-tools/src/main/kotlin/org/jetbrains/kotlin/XcRunRuntimeUtils.kt

@@ -38,7 +38,7 @@ fun Xcode.getLatestSimulatorRuntimeFor(target: KonanTarget, osMinVersion: String
         else -> error("Unexpected simulator target: $target")
     }
     return getSimulatorRuntimeDescriptors().firstOrNull {
-        it.isAvailable && it.name.startsWith(osName) && compareStringsAsVersions(it.version, osMinVersion) >= 0
+        it.checkAvailability() && it.name.startsWith(osName) && compareStringsAsVersions(it.version, osMinVersion) >= 0
     }
 }
 
@@ -51,9 +51,21 @@ data class ListRuntimesReport(
 @Serializable
 data class SimulatorRuntimeDescriptor(
         val version: String,
-        val bundlePath: String,
-        val isAvailable: Boolean,
+        // bundlePath field may not exist in the old Xcode (prior to 10.3).
+        val bundlePath: String? = null,
+        val isAvailable: Boolean? = null,
+        val availability: String? = null,
         val name: String,
         val identifier: String,
         val buildversion: String
-)
+) {
+    /**
+     * Different Xcode/macOS combinations give different fields that checks
+     * runtime availability. This method is an umbrella for these fields.
+     */
+    fun checkAvailability(): Boolean {
+        if (isAvailable == true) return true
+        if (availability?.contains("unavailable") == true) return false
+        return false
+    }
+}