[PATCH 2/2] libgfortran: Avoid undefined shift in caf_shmem

When building gcc 16 for 32-bit Windows, I noticed this warning:

gcc/libgfortran/caf/shmem/shared_memory.c: In function 'shared_memory_init':
gcc/libgfortran/caf/shmem/shared_memory.c:173:35: warning: right shift count >= width of type [-Wshift-count-overflow]
173 |                              size >> (sizeof (DWORD) * 8),
    |                                   ^~

CreateFileMapping takes the maximum mapping size split into high and low
DWORDs.  Cast size through uint64_t before computing the high DWORD so 32-bit
Windows targets do not shift a 32-bit size_t by 32 bits.

libgfortran/ChangeLog:

	* caf/shmem/shared_memory.c: Include stdint.h.
	(shared_memory_init): Cast size through uint64_t before computing the
	high-order CreateFileMapping size DWORD.
---
Resubmitting without changes from the last time.

 libgfortran/caf/shmem/shared_memory.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/libgfortran/caf/shmem/shared_memory.c b/libgfortran/caf/shmem/shared_memory.c
index a2520a89cc7..168906b0dc0 100644
--- a/libgfortran/caf/shmem/shared_memory.c
+++ b/libgfortran/caf/shmem/shared_memory.c
@@ -35,6 +35,7 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 #include <fcntl.h>
 #include <stdlib.h>
 #include <string.h>
+#include <stdint.h>
 #ifdef HAVE_SYS_MMAN_H
 #include <sys/mman.h>
 #elif defined(WIN32)
@@ -170,8 +171,8 @@ shared_memory_init (shared_memory_act *mem, size_t size)
 #elif defined(WIN32)
       mem->shm_fd
 	= CreateFileMapping (INVALID_HANDLE_VALUE, NULL, PAGE_READWRITE,
-			     size >> (sizeof (DWORD) * 8),
-			     (DWORD) (size & ~((DWORD) 0)), shm_name);
+			     (DWORD) ((uint64_t) size >> 32),
+			     (DWORD) size, shm_name);
       if (mem->shm_fd == NULL)
 	{
 	  LPVOID lpMsgBuf;
-- 
2.54.0