Add project files.

source/tests/UndefinedSymbolFixture/CMakeLists.txt

@@ -0,0 +1,21 @@
+# Hand-written rather than add_lib_module(), same reasoning as
+# HotReloadDemo/PluginV1's CMakeLists.txt: this needs to be a plain,
+# always-rebuildable SHARED library gated on BUILD_TESTS rather than a
+# PRIMARY install target.
+
+if(BUILD_TESTS)
+	add_library(hotreload_tests_undefined_symbol_fixture SHARED src/Fixture.cpp)
+else()
+	add_library(hotreload_tests_undefined_symbol_fixture SHARED EXCLUDE_FROM_ALL src/Fixture.cpp)
+endif()
+
+set_target_properties(hotreload_tests_undefined_symbol_fixture PROPERTIES
+	OUTPUT_NAME "hotreload_tests_undefined_symbol_fixture"
+	WINDOWS_EXPORT_ALL_SYMBOLS ON)
+_set_output_dirs(hotreload_tests_undefined_symbol_fixture
+	"${CMAKE_BINARY_DIR}/${RUNTIME_OUTPUT_SUBDIR}/tests"
+	"${CMAKE_BINARY_DIR}/${LIBRARY_OUTPUT_SUBDIR}/tests")
+_apply_compile_options(hotreload_tests_undefined_symbol_fixture)
+
+_register_module_target(TEST hotreload_tests_undefined_symbol_fixture)
+add_dependencies(all_tests hotreload_tests_undefined_symbol_fixture)

source/tests/UndefinedSymbolFixture/src/Fixture.cpp

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+/* A genuine ODR violation, kept deliberately: a non-inline static
+ * class member that is declared but never given an out-of-class
+ * definition. This compiles cleanly and links cleanly into a shared
+ * library -- a shared library is allowed to keep undefined symbols by
+ * default -- and only fails once something actually calls
+ * trigger_undefined_symbol() below, ODR-using counter for the first
+ * time. See source/HotReload/README.md's "hot_reload_last_error()"
+ * section for the full story; HotReloadTests/Main.cpp loads this
+ * fixture specifically to confirm hot_reload_last_error() reports
+ * something useful for exactly this case, rather than leaving it a
+ * silent "load failed" black box.
+ */
+class HasUndefinedStaticMember
+{
+public:
+	static int useIt()
+	{
+		return counter;
+	}
+
+private:
+	static int counter; // declared, deliberately never defined anywhere
+};
+
+extern "C" int trigger_undefined_symbol()
+{
+	return HasUndefinedStaticMember::useIt();
+}