CMake: use check_symbol_exists also for inet_pton

It doesn't make much sense to only check if the function can be linked
when it's not declared in any header and that is treated as an error.
With the correct target Windows version set, the function is declared
in ws2tcpip.h and the comment above the modified block is invalid.

Also, move the definition of `_WIN32_WINNT` up to before all symbol
availability checks so that we don't have to care which ones must be
done after it.

Tested with Visual Studio 2019 and current MinGW-w64.

Closes https://github.com/curl/curl/pull/4808

diff --git a/CMakeLists.txt b/CMakeLists.txt
index a8be8a332fb62dd6eab554ba4fe4cbbd0d4e5360..649db52a649cbb1875b6f27210dbdc4e031954a3 100644 (file)
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -858,6 +858,16 @@ elseif(HAVE_LIBSOCKET)
   set(CMAKE_REQUIRED_LIBRARIES socket)
 endif()
 
+if(WIN32)
+  if(ENABLE_INET_PTON)
+    # _WIN32_WINNT_VISTA (0x0600)
+    add_definitions(-D_WIN32_WINNT=0x0600)
+  else()
+    # _WIN32_WINNT_WINXP (0x0501)
+    add_definitions(-D_WIN32_WINNT=0x0501)
+  endif()
+endif()
+
 check_symbol_exists(basename      "${CURL_INCLUDES}" HAVE_BASENAME)
 check_symbol_exists(socket        "${CURL_INCLUDES}" HAVE_SOCKET)
 check_symbol_exists(select        "${CURL_INCLUDES}" HAVE_SELECT)
@@ -929,20 +939,7 @@ check_symbol_exists(fcntl          "${CURL_INCLUDES}" HAVE_FCNTL)
 check_symbol_exists(ioctl          "${CURL_INCLUDES}" HAVE_IOCTL)
 check_symbol_exists(setsockopt     "${CURL_INCLUDES}" HAVE_SETSOCKOPT)
 check_function_exists(mach_absolute_time HAVE_MACH_ABSOLUTE_TIME)
-
-# symbol exists in win32, but function does not.
-if(WIN32)
-  if(ENABLE_INET_PTON)
-    check_function_exists(inet_pton HAVE_INET_PTON)
-    # _WIN32_WINNT_VISTA (0x0600)
-    add_definitions(-D_WIN32_WINNT=0x0600)
-  else()
-    # _WIN32_WINNT_WINXP (0x0501)
-    add_definitions(-D_WIN32_WINNT=0x0501)
-  endif()
-else()
-  check_function_exists(inet_pton HAVE_INET_PTON)
-endif()
+check_symbol_exists(inet_pton      "${CURL_INCLUDES}" HAVE_INET_PTON)
 
 check_symbol_exists(fsetxattr "${CURL_INCLUDES}" HAVE_FSETXATTR)
 if(HAVE_FSETXATTR)