[glibc/azanella/clang] dirent: Remove variable lenght array structure for tst-getdents64.c

[Adhemerval Zanella]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=9c4af6e72887b35516e3b864af196ddf8971f9b8

commit 9c4af6e72887b35516e3b864af196ddf8971f9b8
Author: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Date:   Fri Mar 25 09:03:03 2022 -0300

    dirent: Remove variable lenght array structure for tst-getdents64.c
    
    Clang emits the following warnings:
    
      ../sysdeps/unix/sysv/linux/tst-getdents64.c:111:18: error: fields must
      have a constant size: 'variable length array in structure' extension
      will never be supported
                  char buffer[buffer_size];
                       ^

Diff:
---
 sysdeps/unix/sysv/linux/tst-getdents64.c | 16 +++++-----------
 1 file changed, 5 insertions(+), 11 deletions(-)

diff --git a/sysdeps/unix/sysv/linux/tst-getdents64.c b/sysdeps/unix/sysv/linux/tst-getdents64.c
index 39cf34cd4d..b177956ca6 100644
--- a/sysdeps/unix/sysv/linux/tst-getdents64.c
+++ b/sysdeps/unix/sysv/linux/tst-getdents64.c
@@ -96,6 +96,8 @@ do_test_by_size (size_t buffer_size)
   int fd = xopen (".", O_RDONLY | O_DIRECTORY, 0);
   TEST_VERIFY (fd >= 0);
 
+  char *data = xposix_memalign (_Alignof (struct dirent64), buffer_size);
+
   /* Perform two passes, with a rewind operating between passes.  */
   for (int pass = 0; pass < 2; ++pass)
     {
@@ -104,23 +106,15 @@ do_test_by_size (size_t buffer_size)
 
       while (true)
         {
-          /* Simple way to make sure that the memcpy below does not read
-             non-existing data.  */
-          struct
-          {
-            char buffer[buffer_size];
-            struct dirent64 pad;
-          } data;
-
-          ssize_t ret = getdents64 (fd, &data.buffer, sizeof (data.buffer));
+          ssize_t ret = getdents64 (fd, data, buffer_size);
           if (ret < 0)
             FAIL_EXIT1 ("getdents64: %m");
           if (ret == 0)
             break;
           ++read_count;
 
-          char *current = data.buffer;
-          char *end = data.buffer + ret;
+          char *current = data;
+          char *end = data + ret;
           while (current != end)
             {
               struct dirent64 entry;