Add test for variant_CONFIG_OVERRIDE_BAD_VARIANT_ACCESS, variant_CONFIG_OVERRIDE_MONOSTATE

Author: martinmoene

README.md

@@ -484,6 +484,7 @@ variant_alternative_t<>: Allows to select type by index (C++11)
 variant_alternative_T(): Allows to select type by index (non-standard: macro)
 std::hash<>: Allows to obtain hash (C++11)
 tweak header: reads tweak header if supported [tweak]
+bad_variant_access: Allows to override nonstd::bad_variant_access via variant_CONFIG_OVERRIDE_MONOSTATE
 ```
 
 </p>

test/t.bat

@@ -24,11 +24,12 @@ set unit_config=
 
 set msvc_defines=^
     -D_CRT_SECURE_NO_WARNINGS ^
-    -D_SCL_SECURE_NO_WARNINGS
+    -D_SCL_SECURE_NO_WARNINGS ^
+    -D_SILENCE_CXX23_ALIGNED_STORAGE_DEPRECATION_WARNING
 
 set CppCoreCheckInclude=%VCINSTALLDIR%\Auxiliary\VS\include
 
-cl -nologo -W3 -EHsc %std% %unit_select% %unit_config% %msvc_defines% -I"%CppCoreCheckInclude%" -Ilest -I../include -I. %unit%-main.t.cpp %unit%.t.cpp && %unit%-main.t.exe
+cl -nologo -W3 -EHsc %std% %unit_select% %unit_config% %msvc_defines% -I"%CppCoreCheckInclude%" -Ilest -I../include -I. %unit%-main.t.cpp %unit%.t.cpp %unit%-override.t.cpp && %unit%-main.t.exe
 endlocal & goto :EOF
 
 :: subroutines:

test/tg-all.bat

@@ -1,3 +1,3 @@
-@for %%s in ( c++98 c++03 c++11 c++14 c++17 ) do (
+@for %%s in ( c++98 c++03 c++11 c++14 c++17 c++23 ) do (
     call tg.bat %%s
 )

test/tg.bat

@@ -29,7 +29,7 @@ rem -flto / -fwhole-program
 set  optflags=-O2
 set warnflags=-Wall -Wextra -Wpedantic -Wconversion -Wsign-conversion -Wno-padded -Wno-missing-noreturn
 
-%gpp% -std=%std% %optflags% %warnflags% %unit_select% %unit_config% -o %unit%-main.t.exe -isystem lest -I../include -I. %unit%-main.t.cpp %unit%.t.cpp && %unit%-main.t.exe
+%gpp% -std=%std% %optflags% %warnflags% %unit_select% %unit_config% -o %unit%-main.t.exe -isystem lest -I../include -I. %unit%-main.t.cpp %unit%.t.cpp %unit%-override.t.cpp && %unit%-main.t.exe
 
 endlocal & goto :EOF
 

test/variant-override.t.cpp

@@ -0,0 +1,85 @@
+// Copyright 2016-2025 by Martin Moene
+//
+// https://github.com/martinmoene/variant-lite
+//
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+
+// mix C++17 std::monostate and std::bad_variant_access with nonstd::variant with configurable such types.
+// msvc: dumpbin /symbols variant-override.t.obj |grep -i bad_variant_access: std::bad_variant_access
+// msvc: dumpbin /symbols variant.t.obj          |grep -i bad_variant_access: nonstd::variants::bad_variant_access
+
+// make sure to only override with std::monostate for C++17 and later:
+
+#ifndef   variant_ovr_CPLUSPLUS
+# if defined(_MSVC_LANG ) && !defined(__clang__)
+#  define variant_ovr_CPLUSPLUS  (_MSC_VER == 1900 ? 201103L : _MSVC_LANG )
+# else
+#  define variant_ovr_CPLUSPLUS  __cplusplus
+# endif
+#endif
+
+// Requires C++17:
+
+#if variant_ovr_CPLUSPLUS >= 201703L
+
+#define variant_CONFIG_SELECT_VARIANT               variant_VARIANT_NONSTD
+#define variant_CONFIG_OVERRIDE_MONOSTATE           std::monostate
+#define variant_CONFIG_OVERRIDE_BAD_VARIANT_ACCESS  std::bad_variant_access
+
+#include <string>
+#include <utility>      // std::monostate
+#include <variant>
+
+#include "variant-main.t.hpp"
+
+namespace std_compat
+{
+    using std::monostate;
+    using std::bad_variant_access;
+}
+
+namespace std_compat
+{
+    template <class... Types>
+    using variant = nonstd::variant<Types...>;
+
+    // using nonstd::bad_variant_access;
+    // using nonstd::monostate;
+    using nonstd::in_place_type_t;
+    using nonstd::in_place_type;
+    using nonstd::in_place_index_t;
+    using nonstd::in_place_index;
+    using nonstd::get;
+    using nonstd::get_if;
+    using nonstd::holds_alternative;
+    using nonstd::visit;
+    using nonstd::variant_npos;
+    using nonstd::variant_size;
+    using nonstd::variant_size_v;
+    using nonstd::variant_alternative;
+    using nonstd::variant_alternative_t;
+}
+
+#else // variant_ovr_CPLUSPLUS >= 201703L
+
+// configuration without override of monostate, bad_variant access:
+#include "variant-main.t.hpp"
+
+#endif // variant_ovr_CPLUSPLUS >= 201703L
+
+CASE("bad_variant_access: Allows to override nonstd::bad_variant_access via variant_CONFIG_OVERRIDE_MONOSTATE")
+{
+#if variant_ovr_CPLUSPLUS >= 201703L
+    // using namespace std_compat;
+    // use namespace std_compat explicitly, as to avoid 'invisible' parameter type-dependent (koenig) lookup
+
+    auto var = std_compat::variant<int, std::string>(std_compat::in_place_type<std::string>, std::string("std::variant") );
+
+    EXPECT_THROWS_AS(std_compat::get<int>(var), std_compat::bad_variant_access);
+#else
+    EXPECT("bad_variant_access: no override using std::bad_variant_access (no C++17)");
+#endif // variant_ovr_CPLUSPLUS >= 201703L
+}
+
+// end of file