smart_library correct constructors from shared_library (#114)

include/boost/dll/smart_library.hpp

@@ -151,23 +151,26 @@ public:
       *
       * \throw Nothing.
       */
-      explicit smart_library(const shared_library & lib) noexcept
-          : lib_(lib)
-      {
-          storage_.load(lib.location());
-      }
-     /*!
-     * Construct from a shared_library object.
-     *
-     * \param lib A shared_library to move from.
-     *
-     * \throw Nothing.
-     */
-     explicit smart_library(shared_library&& lib) noexcept
-         : lib_(std::move(lib))
-     {
-         storage_.load(lib.location());
-     }
+    explicit smart_library(const shared_library & lib) noexcept
+        : lib_(lib) {
+        if (lib_.is_loaded()) {
+            storage_.load(lib_.location());
+        }
+    }
+    /*!
+    * Construct from a shared_library object.
+    *
+    * \param lib A shared_library to move from.
+    *
+    * \throw Nothing.
+    */
+    explicit smart_library(shared_library&& lib) noexcept
+        : lib_(std::move(lib))
+    {
+        if (lib_.is_loaded()) {
+            storage_.load(lib_.location());
+        }
+    }
 
     /*!
     * Destroys the smart_library.

test/CMakeLists.txt

@@ -116,6 +116,7 @@ boost_dll_add_test(dll_test_cpp_mangle cpp_mangle_test.cpp #[[export_symbols=]]
 target_link_libraries(dll_test_cpp_mangle PRIVATE Boost::variant)
 boost_dll_add_test(dll_test_cpp_load cpp_load_test.cpp #[[export_symbols=]] FALSE dll_cpp_plugin)
 target_link_libraries(dll_test_cpp_load PRIVATE Boost::variant)
+boost_dll_add_test(dll_test_smart_library smart_library_test.cpp #[[export_symbols=]] FALSE dll_cpp_plugin)
 boost_dll_add_test(dll_test_cpp_import cpp_import_test.cpp #[[export_symbols=]] FALSE dll_cpp_plugin)
 target_link_libraries(dll_test_cpp_import PRIVATE Boost::variant)
 if(LINUX)

test/Jamfile.v2

@@ -105,6 +105,7 @@ project
         [ run cpp_mangling.cpp ]
         [ compile-fail cpp_mangling1_cf.cpp ]
         [ run cpp_load_test.cpp   : : cpp_plugin ]
+        [ run smart_library_test.cpp   : : cpp_plugin ]
         [ run cpp_import_test.cpp   : : cpp_plugin ]
         [ run template_method_linux_test.cpp : : cpp_plugin ]
         # TODO: uncomment (fails on some MSVCs and Clang-5)

test/smart_library_test.cpp

@@ -0,0 +1,70 @@
+// Copyright 2026 Roman Savchenko
+//
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt
+// or copy at http://www.boost.org/LICENSE_1_0.txt)
+
+// For more information, see http://www.boost.org
+
+#include <boost/config.hpp>
+#include <boost/predef.h>
+
+#include "../example/b2_workarounds.hpp"
+
+#include <boost/core/lightweight_test.hpp>
+#include <boost/filesystem.hpp>
+
+#include <iostream>
+
+#include <boost/dll/smart_library.hpp>
+
+// Test for smart_library construction from empty/unloaded shared_library objects.
+int main(int argc, char* argv[])
+{
+    using namespace boost::dll;
+    using namespace boost::dll::experimental;
+    boost::dll::fs::path pt = b2_workarounds::first_lib_from_argv(argc, argv);
+
+    BOOST_TEST(!pt.empty());
+    std::cout << "Library: " << pt << std::endl;
+
+    {
+        shared_library empty_lib;
+        BOOST_TEST(!empty_lib.is_loaded());
+
+        // Should not access location() for an unloaded library.
+        smart_library sm(empty_lib);
+        BOOST_TEST(!sm.is_loaded());
+    }
+
+    {
+        shared_library lib(pt);
+        BOOST_TEST(lib.is_loaded());
+
+        shared_library moved_to  = std::move(lib);
+        BOOST_TEST(!lib.is_loaded());
+        BOOST_TEST(moved_to.is_loaded());
+
+        // Should not access location() for a moved-from library.
+        smart_library sm(std::move(lib));
+        BOOST_TEST(!sm.is_loaded());
+    }
+
+    {
+        shared_library lib(pt);
+        BOOST_TEST(lib.is_loaded());
+
+        smart_library sm(lib);
+        BOOST_TEST(sm.is_loaded());
+    }
+
+    {
+        shared_library lib(pt);
+        BOOST_TEST(lib.is_loaded());
+
+        smart_library sm(std::move(lib));
+        BOOST_TEST(sm.is_loaded());
+    }
+
+    return boost::report_errors();
+}