[WIP] Enable leaks tracking

This is part 1 of many to enable leaks tracking in the unit test suite.
 To compile with leak tracking enabled run

swift/utils/build-script -- --swift-runtime-enable-leak-checker

Author: CodaFi

stdlib/private/StdlibUnittest/CMakeLists.txt

@@ -5,6 +5,10 @@ set(swift_stdlib_unittest_framework_depends)
 set(swift_stdlib_unittest_compile_flags
   "-Xfrontend" "-disable-objc-attr-requires-foundation-module")
 
+if (SWIFT_RUNTIME_ENABLE_LEAK_CHECKER)
+  list(APPEND swift_stdlib_unittest_compile_flags "-DSWIFT_RUNTIME_ENABLE_LEAK_CHECKER")
+endif()
+
 if(SWIFT_HOST_VARIANT MATCHES "${SWIFT_DARWIN_VARIANTS}")
   list(APPEND swift_stdlib_unittest_platform_sources
     GetOSVersion.mm)

stdlib/private/StdlibUnittest/StdlibUnittest.swift.gyb

@@ -1167,6 +1167,15 @@ public func runAllTests() {
   }
 }
 
+#if SWIFT_RUNTIME_ENABLE_LEAK_CHECKER
+
+@_silgen_name("swift_leaks_startTrackingObjects")
+func startTrackingObjects(_: UnsafePointer<CChar>)
+@_silgen_name("swift_leaks_stopTrackingObjects")
+func stopTrackingObjects(_: UnsafePointer<CChar>) -> Int
+
+#endif
+
 public final class TestSuite {
   public init(_ name: String) {
     self.name = name
@@ -1225,6 +1234,11 @@ public final class TestSuite {
       f()
     }
     let test = _testByName(testName)
+
+#if SWIFT_RUNTIME_ENABLE_LEAK_CHECKER
+    startTrackingObjects(name)
+#endif
+
     switch test.code {
     case .single(let code):
       precondition(
@@ -1234,6 +1248,11 @@ public final class TestSuite {
     case .parameterized(code: let code, _):
       code(parameter!)
     }
+
+#if SWIFT_RUNTIME_ENABLE_LEAK_CHECKER
+    _ = stopTrackingObjects(name)
+#endif
+
     if let f = _testTearDownCode {
       f()
     }

test/1_stdlib/Leak.swift

@@ -0,0 +1,30 @@
+// RUN: %target-run-simple-swift | FileCheck %s
+// REQUIRES: leak-checker
+
+import StdlibUnittest
+
+class VictimObject {
+  var field1, field2: String
+  var block: () -> () = {}
+
+  init(field1: String, field2: String) {
+    self.field1 = field1
+    self.field2 = field2
+    self.block = {
+      self.field1 = self.field1 + self.field2
+      self.field2 = self.field2 + self.field1
+    }
+  }
+}
+
+let LeaksTests = TestSuite("Leaks")
+
+// CHECK: [ RUN      ] Leaks.Known leak
+// CHECK: {"name":"Leaks", "swift_count": 2, "objc_count": 0, "swift_objects": [{"type": "nominal", "name": "C4main12VictimObject", "kind": "Class"},{"type": "unknown", "kind": "HeapLocalVariable"}], "objc_objects": []}
+// CHECK: [       OK ] Leaks.Known leak
+LeaksTests.test("Known leak") {
+  _ = VictimObject(field1: "Leak", field2: "Checker")
+}
+
+runAllTests()
+

test/lit.site.cfg.in

@@ -40,6 +40,9 @@ if "@SWIFT_ASAN_BUILD@" == "TRUE":
 else:
     config.available_features.add('no_asan')
 
+if "@SWIFT_RUNTIME_ENABLE_LEAK_CHECKER@" == "TRUE":
+    config.available_features.add('leak-checker')
+
 if '@SWIFT_TOOLS_ENABLE_LTO@'.lower() in ['full', 'thin']:
     config.available_features.add('lto')
 else: