msvc fixes

ext/base64/CMakeLists.txt

@@ -1,6 +1,7 @@
 add_library(base64
 	base64.cpp base64.h)
 add_library(base64::base64 ALIAS base64)
-set_target_properties(base64 PROPERTIES CXX_STANDARD 17)
+set_target_properties(base64 PROPERTIES CXX_STANDARD 17 CXX_STANDARD_REQUIRED ON)
+target_compile_options(base64 PUBLIC $<$<CXX_COMPILER_ID:MSVC>:/Zc:__cplusplus>)
 target_include_directories(base64
 	PUBLIC ${CMAKE_CURRENT_SOURCE_DIR})

src/CMakeLists.txt

@@ -15,7 +15,9 @@ configure_file(config.h.in config.h @ONLY)
 target_sources(tmx2gba PRIVATE ${CMAKE_CURRENT_BINARY_DIR}/config.h)
 target_include_directories(tmx2gba PRIVATE ${CMAKE_CURRENT_BINARY_DIR})
 
-set_target_properties(tmx2gba PROPERTIES CXX_STANDARD 20)
+set_target_properties(tmx2gba PROPERTIES
+	CXX_STANDARD 20
+	CXX_STANDARD_REQUIRED ON)
 
 target_compile_definitions(${PROJECT_NAME} PRIVATE
 	$<$<BOOL:${MSVC}>:_CRT_SECURE_NO_WARNINGS>  # disable msvc warning

src/tmxmap.cpp

@@ -13,6 +13,7 @@
 #include <limits>
 #include <cerrno>
 #include <optional>
+#include <algorithm>
 
 
 template <typename T>