Invoke now correctly returns a LocalString for rank 1 jstring.

Previously this returned a `jobject` which triggered an incorrect lifecycle<jobject> to be used.

Thrash test.

Author: jwhpryor

implementation/local_string.h

@@ -48,6 +48,11 @@ class LocalString : public LocalStringImpl {
   using Base = LocalStringImpl;
   using Base::Base;
 
+  ~LocalString()
+  {
+      printf("~LocalString\n");
+  }
+
   LocalString(LocalObject<kJavaLangString>&& obj)
       : Base(AdoptLocal{}, static_cast<jstring>(obj.Release())) {}
 

implementation/overload_ref.h

@@ -60,6 +60,22 @@ struct OverloadRefUniqueId {
   }
 };
 
+  template <typename T>
+constexpr std::string_view type_name() {
+#ifdef __clang__
+    std::string_view p = __PRETTY_FUNCTION__;
+    return std::string_view(p.data() + 31, p.size() - 31 - 1);
+#elif defined(__GNUC__)
+    std::string_view p = __PRETTY_FUNCTION__;
+    return std::string_view(p.data() + 46, p.size() - 46 - 1);
+#elif defined(_MSC_VER)
+    std::string_view p = __FUNCSIG__;
+    return std::string_view(p.data() + 38, p.size() - 38 - 7);
+#else
+#error Unsupported compiler
+#endif
+  }
+
 template <typename IdT_, IdType kReturnIDType>
 struct OverloadRef {
   using IdT = IdT_;
@@ -93,7 +109,7 @@ struct OverloadRef {
   }
 
   template <typename... Params>
-  static ReturnProxied Invoke(jclass clazz, jobject object,
+  static auto Invoke(jclass clazz, jobject object,
                               Params&&... params) {
     constexpr std::size_t kRank = ReturnIdT::kRank;
     constexpr bool kStatic = ReturnIdT::kIsStatic;
@@ -104,11 +120,38 @@ struct OverloadRef {
           object, clazz, mthd,
           Proxy_t<Params>::ProxyAsArg(std::forward<Params>(params))...);
     } else if constexpr (IdT::kIsConstructor) {
-      return ReturnProxied{
+      if constexpr (std::is_same_v<typename IdT::_JniT::SpanType, jstring> && IdT::kRank == 0)
+      {
+        //printf("jif return proxied %s ", type_name<ReturnProxied>().data());
+
+          /*
+        auto a =
+            ReturnProxied{
+                AdoptLocal{},
+                LifecycleHelper<jobject, LifecycleType::LOCAL>::Construct(
+                    clazz, mthd,
+                    Proxy_t<Params>::ProxyAsArg(std::forward<Params>(params))...)
+            };
+            */
+
+        return LocalString{
+          AdoptLocal{},
+              Proxy_t<Params>::ProxyAsArg(std::forward<Params>(params))...
+        };
+          /*
+          return LocalString{
+              AdoptLocal{},
+              a.Release() };
+              */
+
+      } else
+      {
+        return ReturnProxied{
           AdoptLocal{},
           LifecycleHelper<jobject, LifecycleType::LOCAL>::Construct(
               clazz, mthd,
               Proxy_t<Params>::ProxyAsArg(std::forward<Params>(params))...)};
+      }
     } else {
       if constexpr (std::is_base_of_v<RefBaseBase, ReturnProxied>) {
         return ReturnProxied{

implementation/string_ref_test.cc

@@ -235,4 +235,49 @@ TEST_F(JniTest, GlobalString_AllowsRValueGlobalString) {
   obj.Call<"TakesStrParam">(GlobalString{"abcde"});
 }
 
+TEST_F(JniTest, AllocationThrash)
+{
+  int i = 0;
+  //while (true)
+  for (int i = 0; i < 1; i++)
+  {
+    //for (int j = 0; j < 10000; j++)
+    for (int j = 0; j < 1; j++)
+    {
+      /*
+      LocalString str = "akdfajslkfaskflj"
+      "alkdsjklafjkldsajklfasdjldasfjklasdfkjdlasfkjdsafljafs"
+      "alkdsjklafjkldsajklfasdjldasfjklasdfkjdlasfkjdsafljafs"
+      "alkdsjklafjkldsajklfasdjldasfjklasdfkjdlasfkjdsafljafs"
+      "alkdsjklafjkldsajklfasdjldasfjklasdfkjdlasfkjdsafljafs"
+      "alkdsjklafjkldsajklfasdjldasfjklasdfkjdlasfkjdsafljafs"
+      "alkdsjklafjkldsajklfasdjldasfjklasdfkjdlasfkjdsafljafs"
+      "alkdsjklafjkldsajklfasdjldasfjklasdfkjdlasfkjdsafljafs"
+      "alkdsjklafjkldsajklfasdjldasfjklasdfkjdlasfkjdsafljafs"
+      "alkdsjklafjkldsajklfasdjldasfjklasdfkjdlasfkjdsafljafs"
+      "alkdsjklafjkldsajklfasdjldasfjklasdfkjdlasfkjdsafljafs"
+      "alkdsjklafjkldsajklfasdjldasfjklasdfkjdlasfkjdsafljafs"
+      "alkdsjklafjkldsajklfasdjldasfjklasdfkjdlasfkjdsafljafs"
+      "alkdsjklafjkldsajklfasdjldasfjklasdfkjdlasfkjdsafljafs"
+      "alkdsjklafjkldsajklfasdjldasfjklasdfkjdlasfkjdsafljafs"
+      "alkdsjklafjkldsajklfasdjldasfjklasdfkjdlasfkjdsafljafs"
+      "alkdsjklafjkldsajklfasdjldasfjklasdfkjdlasfkjdsafljafs"
+      "alkdsjklafjkldsajklfasdjldasfjklasdfkjdlasfkjdsafljafs"
+      "alkdsjklafjkldsajklfasdjldasfjklasdfkjdlasfkjdsafljafs"
+      "alkdsjklafjkldsajklfasdjldasfjklasdfkjdlasfkjdsafljafs"
+      "alkdsjklafjkldsajklfasdjldasfjklasdfkjdlasfkjdsafljafs"
+      "alkdsjklafjkldsajklfasdjldasfjklasdfkjdlasfkjdsafljafs";
+      */
+      LocalString str { "akdfajslkfaskflj" };
+    }
+
+    i++;
+    if (i % 100 == 0)
+    {
+      std::cout << "Iteration: " << i << std::endl;
+      // I even tried to manually call gc, but it has no effect in this case.
+    }
+  }
+}
+
 }  // namespace

javatests/com/jnibind/test/StringTest.java

@@ -146,4 +146,11 @@ public void nullStringTests() {
   public void globalReturnsCorrectlyOverJniBoundary() {
     jniReturnsAGlobalString();
   }
+
+  native void nativeAllocationThrash();
+
+  @Test
+  public void allocationThrash() {
+    nativeAllocationThrash();
+  }
 }