Check existence of inet_pton for win32 in CMakeLists.txt (fixes #5019) (#5159)

* check existence of inet_pton for win32 in CMakeLists.txt (fix #5019)

* remove extra spaces

* add check for inet_pton in configure.win

* Update CMakeLists.txt
Co-authored-by: Nikita Titov <nekit94-08@mail.ru>

* Update src/network/socket_wrapper.hpp
Co-authored-by: Nikita Titov <nekit94-08@mail.ru>

* Update src/network/socket_wrapper.hpp
Co-authored-by: Nikita Titov <nekit94-08@mail.ru>

* Update CMakeLists.txt
Co-authored-by: Nikita Titov <nekit94-08@mail.ru>

* Update R-package/configure.win
Co-authored-by: Nikita Titov <nekit94-08@mail.ru>

* Update CMakeLists.txt
Co-authored-by: James Lamb <jaylamb20@gmail.com>

* fix comments in CMakeLists.txt

* include check for WIN64

* remove WIN64 flag checks

* fix #ifdef

* Update R-package/configure.win
Co-authored-by: Nikita Titov <nekit94-08@mail.ru>
Co-authored-by: Nikita Titov <nekit94-08@mail.ru>
Co-authored-by: James Lamb <jaylamb20@gmail.com>

CMakeLists.txt

@@ -324,6 +324,18 @@ if(WIN32 AND MINGW)
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -static-libstdc++")
 endif()
 
+# Check if inet_pton is already available, to avoid conflicts with the implementation in LightGBM.
+# As of 2022, MinGW started including a definition of inet_pton.
+if(WIN32)
+  include(CheckSymbolExists)
+  list(APPEND CMAKE_REQUIRED_LIBRARIES "ws2_32")
+  check_symbol_exists(inet_pton "ws2tcpip.h" WIN_INET_PTON_FOUND)
+  if(WIN_INET_PTON_FOUND)
+    add_definitions(-DWIN_HAS_INET_PTON)
+  endif()
+  list(REMOVE_ITEM CMAKE_REQUIRED_LIBRARIES "ws2_32")
+endif()
+
 if(MSVC)
     set(
       variables

R-package/configure.win

@@ -70,6 +70,30 @@ then
     LGB_CPPFLAGS="${LGB_CPPFLAGS} -DMM_MALLOC=1"
 fi
 
+#############
+# INET_PTON #
+#############
+
+ac_inet_pton="no"
+
+cat > conftest.cpp <<EOL
+#include <ws2tcpip.h>
+int main() {
+  void* p = inet_pton;
+  return 0;
+}
+EOL
+
+${CXX} ${CXXFLAGS} ${CPPFLAGS} -o conftest conftest.cpp 2>/dev/null && ./conftest && ac_inet_pton="yes"
+rm -f ./conftest
+rm -f ./conftest.cpp
+echo "checking whether INET_PTON works...${ac_inet_pton}"
+
+if test "${ac_inet_pton}" = "yes";
+then
+    LGB_CPPFLAGS="${LGB_CPPFLAGS} -DWIN_HAS_INET_PTON=1"
+fi
+
 # Generate Makevars.win from Makevars.win.in
 sed -e \
     "s/@LGB_CPPFLAGS@/$LGB_CPPFLAGS/" \

src/network/socket_wrapper.hpp

@@ -55,11 +55,8 @@ const int INVALID_SOCKET = -1;
 #endif
 
 #ifdef _WIN32
-#ifndef _UCRT
-// Recent MinGW has inet_pton, which then causes compiler error in
-// combination with this replacement.
-#ifndef _MSC_VER
-// not using visual studio in windows
+// existence of inet_pton is checked in CMakeLists.txt and configure.win, then stored in WIN_HAS_INET_PTON
+#ifndef WIN_HAS_INET_PTON
 inline int inet_pton(int af, const char *src, void *dst) {
   struct sockaddr_storage ss;
   int size = sizeof(ss);
@@ -84,7 +81,6 @@ inline int inet_pton(int af, const char *src, void *dst) {
 }
 #endif
 #endif
-#endif
 
 #define MALLOC(x) HeapAlloc(GetProcessHeap(), 0, (x))
 #define FREE(x) HeapFree(GetProcessHeap(), 0, (x))