Thread: BUG #17424: Build failed on disabled GNUC in Clang environment CFLAGS= -O2 -fgnuc-version=0

The following bug has been logged on the website:

Bug reference:      17424
Logged by:          arjun shetty
Email address:      arjunshetty955@gmail.com
PostgreSQL version: 14.2
Operating system:   RHEL8.3
Description:

PostgreSQLv14.2 source compiled with build command 
CC=clang CXX=clang++ ../configure --prefix=<install path> CFLAGS='-O2
-fgnuc-version=0' CXXFLAGS='-O2 -fno-builtin -fgnuc-version=0'
And observed build errors like:
/postgresql-14.2/build/../src/include/nodes/execnodes.h:1596:2: error:
unknown type name 'slock_t'; did you mean 'clock_t'?
        slock_t         mutex;
        ^~~~~~~
        clock_t
/usr/include/x86_64-linux-gnu/bits/types/clock_t.h:7:19: note: 'clock_t'
declared here
typedef __clock_t clock_t;
postgresql-14.2/build/../src/backend/access/brin/brin.c:24

-fgnuc-version flag used to disable __builtin_xx functions in
PotgreSQLv14.2
Example :/postgresql14.2/contrib/cube/cubeparse.c +385


if defined YYCOPY_NEEDED && YYCOPY_NEEDED
/* Copy COUNT objects from SRC to DST.  The source and destination do
   not overlap.  */
# ifndef YYCOPY
#  if defined __GNUC__ && 1 < __GNUC__
#   define YYCOPY(Dst, Src, Count) \
      __builtin_memcpy (Dst, Src, (Count) * sizeof (*(Src)))  /
#  else
#   define YYCOPY(Dst, Src, Count)              \
      do                                        \
        {                                       \
          YYSIZE_T yyi;                         \
          for (yyi = 0; yyi < (Count); yyi++)   \
            (Dst)[yyi] = (Src)[yyi];            \
        }                                       \
      while (0)
#  endif
# endif
#endif /*

please let me know  how to disable __builtin__xxx functions in
PostgreSQLv14.2an build source  code.

PG Bug reporting form <noreply@postgresql.org> writes:
> -fgnuc-version flag used to disable __builtin_xx functions in
> PotgreSQLv14.2

We do not support that, and I don't see any very good reason why
we should.  If you want to use some other compiler, then do so,
but if you're on gcc then what's wrong with using its builtins?

            regards, tom lane