[Python-checkins] CVS: python/dist/src/Objects complexobject.c,2.53.4.1,2.53.4.2

[Michael Hudson]

Update of /cvsroot/python/python/dist/src/Objects
In directory usw-pr-cvs1:/tmp/cvs-serv4722

Modified Files:
      Tag: release22-maint
	complexobject.c 
Log Message:
backport tim_one's checkin of
    revision 2.55 of complexobject.c

SF bug 533198:  Complex power underflow raises exception.
Konrad was too kind.  Not only did it raise an exception, the specific
exception it raised made no sense.  These are old bugs in complex_pow()
and friends:

1. Raising 0 to a negative power isn't a range error, it's a domain
   error, so changed c_pow() to set errno to EDOM in that case instead
   of ERANGE.

2. Changed complex_pow() to:

A. Used the Py_ADJUST_ERANGE2 macro to try to clear errno of a spurious
   ERANGE error due to underflow in the libm pow() called by c_pow().

B. Produced different exceptions depending on the errno value:
   i) For errno==EDOM, raise ZeroDivisionError instead of ValueError.
      This is for consistency with the non-complex cases 0.0**-2 and
      0**-2 and 0L**-2.
   ii) For errno==ERANGE, raise OverflowError.

Bugfix candidate.


Index: complexobject.c
===================================================================
RCS file: /cvsroot/python/python/dist/src/Objects/complexobject.c,v
retrieving revision 2.53.4.1
retrieving revision 2.53.4.2
diff -C2 -d -r2.53.4.1 -r2.53.4.2
*** complexobject.c	22 Feb 2002 13:23:33 -0000	2.53.4.1
--- complexobject.c	25 Mar 2002 13:21:41 -0000	2.53.4.2
***************
*** 132,136 ****
  	else if (a.real == 0. && a.imag == 0.) {
  		if (b.imag != 0. || b.real < 0.)
! 			errno = ERANGE;
  		r.real = 0.;
  		r.imag = 0.;
--- 132,136 ----
  	else if (a.real == 0. && a.imag == 0.) {
  		if (b.imag != 0. || b.real < 0.)
! 			errno = EDOM;
  		r.real = 0.;
  		r.imag = 0.;
***************
*** 457,463 ****
  
  	PyFPE_END_PROTECT(p)
! 	if (errno == ERANGE) {
! 		PyErr_SetString(PyExc_ValueError,
  				"0.0 to a negative or complex power");
  		return NULL;
  	}
--- 457,469 ----
  
  	PyFPE_END_PROTECT(p)
! 	Py_ADJUST_ERANGE2(p.real, p.imag);
! 	if (errno == EDOM) {
! 		PyErr_SetString(PyExc_ZeroDivisionError,
  				"0.0 to a negative or complex power");
+ 		return NULL;
+ 	}
+ 	else if (errno == ERANGE) {
+ 		PyErr_SetString(PyExc_OverflowError,
+ 				"complex exponentiaion");
  		return NULL;
  	}