[CMake] Delete HAVE_ISATTY

[MaskRay]

Summary

unistd.h provides isatty. It is provided by 4.3BSD and SVR4, and is
required by POSIX.1-2001. If an old commercial UNIX indeed screw it up,
its libc must lack enough utilities to build LLVM. We should not support
such an ancient system.

[probinson]

isatty() is not supported on the PS4 console OS. We'd like to be able to run some LLVM libraries there, e.g., to support symbolization in compiler-rt on the device. D75278 is a step toward that goal, which I don't think is too unreasonable.
I wonder if other small/embedded devices would have similar restrictions e.g. a watch. Add @aprantl for an opinion.

I'd rather you did not do this.

[aprantl]

While I don't think that this is a concern for Darwin-based systems, since the PS4 is a supported LLVM target, that should be enough reason to keep it in, right?

[aprantl]

And we could comment that it is needed for the PS4 target specifically to avoid this coming up in the future :-)

[MaskRay]

Abandoning. See my comment at https://reviews.llvm.org/D75278#1910158

llvm/cmake/config-ix.cmake

if(C_SUPPORTS_WERROR_UNGUARDED_AVAILABILITY_NEW)
   set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -Werror=unguarded-availability-new")
 endif()
 
 check_symbol_exists(_Unwind_Backtrace "unwind.h" HAVE__UNWIND_BACKTRACE)
 check_symbol_exists(getpagesize unistd.h HAVE_GETPAGESIZE)
 check_symbol_exists(sysconf unistd.h HAVE_SYSCONF)
 check_symbol_exists(getrusage sys/resource.h HAVE_GETRUSAGE)
 check_symbol_exists(setrlimit sys/resource.h HAVE_SETRLIMIT)
-check_symbol_exists(isatty unistd.h HAVE_ISATTY)
 check_symbol_exists(futimens sys/stat.h HAVE_FUTIMENS)
 check_symbol_exists(futimes sys/time.h HAVE_FUTIMES)
 check_symbol_exists(posix_fallocate fcntl.h HAVE_POSIX_FALLOCATE)
 # AddressSanitizer conflicts with lib/Support/Unix/Signals.inc
 # Avoid sigaltstack on Apple platforms, where backtrace() cannot handle it
 # (rdar://7089625) and _Unwind_Backtrace is unusable because it cannot unwind
 # past the signal handler after an assertion failure (rdar://29866587).
 if( HAVE_SIGNAL_H AND NOT LLVM_USE_SANITIZER MATCHES ".*Address.*" AND NOT APPLE )

llvm/include/llvm/Config/config.h.cmake

 #cmakedefine HAVE_GETPAGESIZE ${HAVE_GETPAGESIZE}
 
 /* Define to 1 if you have the `getrlimit' function. */
 #cmakedefine HAVE_GETRLIMIT ${HAVE_GETRLIMIT}
 
 /* Define to 1 if you have the `getrusage' function. */
 #cmakedefine HAVE_GETRUSAGE ${HAVE_GETRUSAGE}
 
-/* Define to 1 if you have the `isatty' function. */
-#cmakedefine HAVE_ISATTY 1
-
 /* Define to 1 if you have the `edit' library (-ledit). */
 #cmakedefine HAVE_LIBEDIT ${HAVE_LIBEDIT}
 
 /* Define to 1 if you have the `pfm' library (-lpfm). */
 #cmakedefine HAVE_LIBPFM ${HAVE_LIBPFM}
 
 /* Define to 1 if you have the `psapi' library (-lpsapi). */
 #cmakedefine HAVE_LIBPSAPI ${HAVE_LIBPSAPI}

llvm/lib/Support/Unix/Process.inc

bool Process::StandardOutIsDisplayed() {
   return FileDescriptorIsDisplayed(STDOUT_FILENO);
 }
 
 bool Process::StandardErrIsDisplayed() {
   return FileDescriptorIsDisplayed(STDERR_FILENO);
 }
 
 bool Process::FileDescriptorIsDisplayed(int fd) {
-#if HAVE_ISATTY
   return isatty(fd);
-#else
-  // If we don't have isatty, just return false.
-  return false;
-#endif
 }
 
 static unsigned getColumns(int FileID) {
   // If COLUMNS is defined in the environment, wrap to that many columns.
   if (const char *ColumnsStr = std::getenv("COLUMNS")) {
     int Columns = std::atoi(ColumnsStr);
     if (Columns > 0)
       return Columns;

llvm/utils/gn/secondary/llvm/include/llvm/Config/BUILD.gn

if (current_os == "win") {
     values += [
       "HAVE_DECL_STRERROR_S=1",
       "HAVE_DLFCN_H=",
       "HAVE_DLOPEN=",
       "HAVE_FUTIMES=",
       "HAVE_GETPAGESIZE=",
       "HAVE_GETRLIMIT=",
       "HAVE_GETRUSAGE=",
-      "HAVE_ISATTY=",
       "HAVE_LIBPTHREAD=",
       "HAVE_PTHREAD_SETNAME_NP=",
       "HAVE_LIBZ=",
       "HAVE_PREAD=",
       "HAVE_PTHREAD_GETSPECIFIC=",
       "HAVE_PTHREAD_H=",
       "HAVE_PTHREAD_MUTEX_LOCK=",
       "HAVE_PTHREAD_RWLOCK_INIT=",
if (current_os == "win") {
     values += [
       "HAVE_DECL_STRERROR_S=",
       "HAVE_DLFCN_H=1",
       "HAVE_DLOPEN=1",
       "HAVE_FUTIMES=1",
       "HAVE_GETPAGESIZE=1",
       "HAVE_GETRLIMIT=1",
       "HAVE_GETRUSAGE=1",
-      "HAVE_ISATTY=1",
       "HAVE_LIBPTHREAD=1",
       "HAVE_PTHREAD_SETNAME_NP=1",
       "HAVE_LIBZ=1",
       "HAVE_PREAD=1",
       "HAVE_PTHREAD_GETSPECIFIC=1",
       "HAVE_PTHREAD_H=1",
       "HAVE_PTHREAD_MUTEX_LOCK=1",
       "HAVE_PTHREAD_RWLOCK_INIT=1",