[Bug fortran/113412] ATAN(Y,X) does not check arguments and generates wrong error message.

[kargl at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113412

--- Comment #1 from kargl at gcc dot gnu.org ---
Ugh.  This seems to be by design.

The error message 
  Error: Too many arguments in call to ‘atan’ at (1)
is queued by intrinsic.cc(sort_actual) and appears to take
precedence over an error queued by check.cc(gfc_check_atan2).
For a robust error message, if looks like we'll need to 
special case the one versus to argument atan(), atand(),
and atanpi() cases intrinsic.cc(sort_actual).  In pseudocode,
change

whoops:
  gfc_error ("Too many arguments in call to %qs at %L", name, where);
  return false;

to

whoops:
  if (name == "atan")
     check for two arguments and issue error
  else
     above gfc_error() 

  return false;