Re: New warnings on emacs-26 branch with gcc 8.2.0

[Bruno Haible <bruno@clisp.org>]

Eli Zaretskii wrote:
> There's also this additional option:
> 
>   5) Cast through (void *).  Like this:
> 
>       GetSystemTimePreciseAsFileTimeFunc =
>         (GetSystemTimePreciseAsFileTimeFuncType) (void (*) (void)) GetProcAddress (kernel32, "GetSystemTimePreciseAsFileTime");

Indeed, casting through (void *) or (void (*) (void)) avoids the
warning. I'm going to test this patch:


2018-08-18  Bruno Haible  <bruno@clisp.org>

	Avoid -Wcast-function-type warnings from casts after GetProcAddress.
	Reported by Andy Moreton <andrewjmoreton@gmail.com> in
	<https://lists.gnu.org/archive/html/emacs-devel/2018-08/msg00468.html>.
	Solution proposed by Eli Zaretskii.
	* lib/getaddrinfo.c (GetProcAddress): Cast result to 'void *' first.
	* lib/gettimeofday.c (GetProcAddress): Likewise.
	* lib/link.c (GetProcAddress): Likewise.
	* lib/physmem.c (GetProcAddress): Likewise.
	* lib/poll.c (GetProcAddress): Likewise.
	* lib/select.c (GetProcAddress): Likewise.
	* lib/stat-w32.c (GetProcAddress): Likewise.

diff --git a/lib/getaddrinfo.c b/lib/getaddrinfo.c
index 756c31b..7bf38e8 100644
--- a/lib/getaddrinfo.c
+++ b/lib/getaddrinfo.c
@@ -62,6 +62,11 @@
 #include "sockets.h"
 
 #ifdef WINDOWS_NATIVE
+
+/* Avoid warnings from gcc -Wcast-function-type.  */
+# define GetProcAddress \
+   (void *) GetProcAddress
+
 typedef int (WSAAPI *getaddrinfo_func) (const char*, const char*,
                                         const struct addrinfo*,
                                         struct addrinfo**);
diff --git a/lib/gettimeofday.c b/lib/gettimeofday.c
index bff40d7..36b5074 100644
--- a/lib/gettimeofday.c
+++ b/lib/gettimeofday.c
@@ -33,6 +33,10 @@
 
 #ifdef WINDOWS_NATIVE
 
+/* Avoid warnings from gcc -Wcast-function-type.  */
+# define GetProcAddress \
+   (void *) GetProcAddress
+
 /* GetSystemTimePreciseAsFileTime was introduced only in Windows 8.  */
 typedef void (WINAPI * GetSystemTimePreciseAsFileTimeFuncType) (FILETIME *lpTime);
 static GetSystemTimePreciseAsFileTimeFuncType GetSystemTimePreciseAsFileTimeFunc = NULL;
diff --git a/lib/link.c b/lib/link.c
index bf0b344..cff54a2 100644
--- a/lib/link.c
+++ b/lib/link.c
@@ -30,6 +30,10 @@
 #  define WIN32_LEAN_AND_MEAN
 #  include <windows.h>
 
+/* Avoid warnings from gcc -Wcast-function-type.  */
+#  define GetProcAddress \
+    (void *) GetProcAddress
+
 /* CreateHardLink was introduced only in Windows 2000.  */
 typedef BOOL (WINAPI * CreateHardLinkFuncType) (LPCTSTR lpFileName,
                                                 LPCTSTR lpExistingFileName,
diff --git a/lib/physmem.c b/lib/physmem.c
index cbb33ac..c89c0f0 100644
--- a/lib/physmem.c
+++ b/lib/physmem.c
@@ -59,8 +59,14 @@
 #endif
 
 #ifdef _WIN32
+
 # define WIN32_LEAN_AND_MEAN
 # include <windows.h>
+
+/* Avoid warnings from gcc -Wcast-function-type.  */
+# define GetProcAddress \
+   (void *) GetProcAddress
+
 /*  MEMORYSTATUSEX is missing from older windows headers, so define
     a local replacement.  */
 typedef struct
@@ -76,6 +82,7 @@ typedef struct
   DWORDLONG ullAvailExtendedVirtual;
 } lMEMORYSTATUSEX;
 typedef WINBOOL (WINAPI *PFN_MS_EX) (lMEMORYSTATUSEX*);
+
 #endif
 
 #define ARRAY_SIZE(a) (sizeof (a) / sizeof ((a)[0]))
diff --git a/lib/poll.c b/lib/poll.c
index 26f7f12..576ec9f 100644
--- a/lib/poll.c
+++ b/lib/poll.c
@@ -84,6 +84,10 @@
    of SOCKETs, not bit masks of FDs.  */
 # undef select
 
+/* Avoid warnings from gcc -Wcast-function-type.  */
+# define GetProcAddress \
+   (void *) GetProcAddress
+
 static BOOL IsConsoleHandle (HANDLE h)
 {
   DWORD mode;
diff --git a/lib/select.c b/lib/select.c
index 3659cb5..ffb58ee 100644
--- a/lib/select.c
+++ b/lib/select.c
@@ -47,6 +47,10 @@
 
 #undef select
 
+/* Avoid warnings from gcc -Wcast-function-type.  */
+#define GetProcAddress \
+  (void *) GetProcAddress
+
 struct bitset {
   unsigned char in[FD_SETSIZE / CHAR_BIT];
   unsigned char out[FD_SETSIZE / CHAR_BIT];
diff --git a/lib/stat-w32.c b/lib/stat-w32.c
index 802b38a..c7a53f9 100644
--- a/lib/stat-w32.c
+++ b/lib/stat-w32.c
@@ -38,6 +38,10 @@
 #include "pathmax.h"
 #include "verify.h"
 
+/* Avoid warnings from gcc -Wcast-function-type.  */
+#define GetProcAddress \
+  (void *) GetProcAddress
+
 #if _GL_WINDOWS_STAT_INODES == 2
 /* GetFileInformationByHandleEx was introduced only in Windows Vista.  */
 typedef DWORD (WINAPI * GetFileInformationByHandleExFuncType) (HANDLE hFile,