Fix incorrect deallocation from PMR when memory was not aligned

include/jsoncons/utility/heap_string.hpp

@@ -177,7 +177,7 @@ namespace utility {
 
                 std::size_t mem_size = ptr->align_pad_ + aligned_size(ptr->length_*sizeof(char_type));
                 byte_allocator_type byte_alloc(ptr->get_allocator());
-                byte_alloc.deallocate(p,mem_size + ptr->offset_);
+                byte_alloc.deallocate(p,mem_size);
             }
         }
     };

test/corelib/src/utility/heap_string_tests.cpp

@@ -31,14 +31,45 @@ TEST_CASE("heap_string test")
 #if defined(JSONCONS_HAS_POLYMORPHIC_ALLOCATOR) && JSONCONS_HAS_POLYMORPHIC_ALLOCATOR == 1
 #include <memory_resource> 
 
+class checked_resource : public std::pmr::memory_resource
+{
+public:
+   explicit checked_resource(std::pmr::memory_resource* upstream = std::pmr::get_default_resource())
+      : upstream_(upstream)
+   {
+   }
+
+   std::make_signed<size_t>::type allocated = 0;
+
+protected:
+   void* do_allocate(std::size_t bytes, std::size_t alignment) override
+   {
+      allocated += bytes;
+      return upstream_->allocate(bytes, alignment);
+   }
+
+   void do_deallocate(void* p, std::size_t bytes, std::size_t alignment) override
+   {
+      allocated -= bytes;
+      upstream_->deallocate(p, bytes, alignment);
+   }
+
+   bool do_is_equal(const memory_resource& other) const noexcept override { return this == &other; }
+
+private:
+   std::pmr::memory_resource* upstream_;
+};
+
+
 TEST_CASE("heap_string with polymorphic allocator test")
 {
     using heap_string_factory_type = jsoncons::utility::heap_string_factory<char, null_type, std::pmr::polymorphic_allocator<char>>;
     using pointer = typename heap_string_factory_type::pointer;
 
     char buffer[1024] = {}; // a small buffer on the stack
     std::pmr::monotonic_buffer_resource pool1{ std::data(buffer), std::size(buffer) };
-    std::pmr::polymorphic_allocator<char> alloc(&pool1);
+    checked_resource checked(&pool1);
+    std::pmr::polymorphic_allocator<char> alloc(&checked);
 
     std::string s1("Hello World 1");
     pointer ptr1 = heap_string_factory_type::create(s1.data(), s1.length(), null_type(), alloc);
@@ -52,6 +83,8 @@ TEST_CASE("heap_string with polymorphic allocator test")
 
     heap_string_factory_type::destroy(ptr1);
     heap_string_factory_type::destroy(ptr2);
+
+    CHECK(checked.allocated == 0);
 }