MSVC: Warn about unused formal parameters

Provide _U_ macro definition for Visual Studio.

Change the way _U_ macro is ifdefed for some targets to allow Visual
Studio to recognize it.

Ping-Bug: 15832
Change-Id: Ic7ce145cbe9e8aa751d64c9c09ce8ba6c1bbbd30
Reviewed-on: https://code.wireshark.org/review/34530
Tested-by: Petri Dish Buildbot
Petri-Dish: Peter Wu <peter@lekensteyn.nl>
Reviewed-by: Peter Wu <peter@lekensteyn.nl>

CMakeLists.txt

@@ -427,10 +427,11 @@ if( CMAKE_C_COMPILER_ID MATCHES "MSVC")
 	# Additional compiler warnings to be treated as "Level 3"
 	# when compiling Wireshark sources. (Selected from "level 4" warnings).
 	## 4295: array is too small to include a terminating null character
+	## 4100: unreferenced formal parameter
 	## 4189: local variable is initialized but not referenced
 	# Disable warnings about about use of flexible array members:
 	## 4200: nonstandard extension used : zero-sized array in struct/union
-	list(APPEND LOCAL_CFLAGS /w34295 /w34189 /wd4200)
+	list(APPEND LOCAL_CFLAGS /w34295 /w34100 /w34189 /wd4200)
 
 	# We've matched these to specific compiler versions using the
 	# checks above. There's no need to pass them to check_c_compiler_flag

caputils/capture-pcap-util.c

@@ -823,12 +823,13 @@ linktype_name_to_val(const char *linktype)
  * rest-of-the-universe libpcap.
  */
 int
-get_pcap_datalink(pcap_t *pch, const char *devicename
-#ifndef _AIX
-    _U_)
+get_pcap_datalink(pcap_t *pch,
+#ifdef _AIX
+    const char* devicename
 #else
-    )
+    const char* devicename _U_
 #endif
+    )
 {
 	int datalink;
 #ifdef _AIX
@@ -1257,11 +1258,11 @@ get_if_capabilities_pcap_create(interface_options *interface_opts,
 }
 
 pcap_t *
-open_capture_device_pcap_create(capture_options *capture_opts
+open_capture_device_pcap_create(
 #if defined(HAVE_PCAP_SET_TSTAMP_PRECISION) || defined (HAVE_PCAP_SET_TSTAMP_TYPE)
-    ,
+    capture_options* capture_opts,
 #else
-    _U_,
+    capture_options* capture_opts _U_,
 #endif
     interface_options *interface_opts, int timeout,
     cap_device_open_err *open_err,

dumpcap.c

@@ -591,9 +591,10 @@ relinquish_all_capabilities(void)
 
 static const char *
 get_pcap_failure_secondary_error_message(cap_device_open_err open_err,
+#ifdef __hpux
                                          const char *open_err_str
-#ifndef __hpux
-                                                                  _U_
+#else
+                                         const char* open_err_str _U_
 #endif
                                          )
 {

ui/win32/file_dlg_win32.c

@@ -1477,7 +1477,7 @@ save_as_file_hook_proc(HWND sf_hwnd, UINT msg, WPARAM w_param, LPARAM l_param) {
 }
 
 static UINT_PTR CALLBACK
-save_as_statstree_hook_proc(HWND sf_hwnd, UINT msg, WPARAM w_param, LPARAM l_param) {
+save_as_statstree_hook_proc(HWND sf_hwnd, UINT msg, WPARAM w_param _U_, LPARAM l_param _U_) {
 
     switch(msg) {
         case WM_INITDIALOG:

ws_attributes.h

@@ -27,6 +27,8 @@ extern "C" {
 #if defined(__GNUC__)
   /* This includes clang */
   #define _U_ __attribute__((unused))
+#elif defined(_MSC_VER)
+  #define _U_ __pragma(warning(suppress:4100))
 #else
   #define _U_
 #endif

wsutil/file_util.c

@@ -57,6 +57,7 @@
 #include <stdlib.h>
 
 #include "file_util.h"
+#include "ws_attributes.h"
 
 static gchar *program_path = NULL;
 static gchar *system_path = NULL;
@@ -189,7 +190,7 @@ ws_stdio_rename (const gchar *oldfilename, const gchar *newfilename)
  * Since: 2.6
  */
 int
-ws_stdio_mkdir (const gchar *filename, int mode)
+ws_stdio_mkdir (const gchar *filename, int mode _U_)
 {
     wchar_t *wfilename = g_utf8_to_utf16 (filename, -1, NULL, NULL, NULL);
     int retval;

wsutil/filesystem.c

@@ -469,9 +469,11 @@ get_executable_path(void)
  * g_mallocated string containing an error on failure.
  */
 char *
-init_progfile_dir(const char *arg0
+init_progfile_dir(
 #ifdef _WIN32
-    _U_
+    const char* arg0 _U_
+#else
+    const char* arg0
 #endif
 )
 {

wsutil/getopt_long.c

@@ -19,6 +19,7 @@
 #endif
 
 #include "config.h"
+#include "ws_attributes.h"
 
 #include <stdio.h>
 
@@ -271,7 +272,13 @@ exchange (char **argv, struct _getopt_data *d)
 /* Initialize the internal data when the first call is made.  */
 
 static const char *
-_getopt_initialize (int argc, char *const *argv, const char *optstring,
+_getopt_initialize (
+#if defined _LIBC && defined USE_NONOPTION_FLAGS
+                    int argc, char *const *argv,
+#else
+                    int argc _U_, char *const *argv _U_,
+#endif
+                    const char *optstring,
                     struct _getopt_data *d, int posixly_correct)
 {
   /* Start processing options with ARGV-element 1 (since ARGV-element 0