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[Bug fortran/37930] gfortran error and ICE at automatic type conversion with transfer intrinsic
- From: "dominiq at lps dot ens dot fr" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 31 Oct 2008 12:52:43 -0000
- Subject: [Bug fortran/37930] gfortran error and ICE at automatic type conversion with transfer intrinsic
- References: <bug-37930-8911@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #22 from dominiq at lps dot ens dot fr 2008-10-31 12:52 -------
> One can argue that a NaN real(4)->real(8) conversion is OK or that it is
> invalid - I think one can find arguments for both; in any case NaN can be
> unambiguously converted from one real/complex to another real/complex kind.
I disagree with the last sentence since there in not a single (or dual if you
take into account signaling NaN's) NaN entity, but a whole class of them. So if
you accept the conversion, it should be defined: for instance, for
REAL(4)->REAL(8) copy the mantissa to the upper/lower bits of the mantissa, or
fold all of them to a zero mantissa but for the LSB, ... .
I have never read anything about the reasons for having such a wide class of
NaN's nor seen any use of it (even the use of quiet/signaling NaN's is quite
fuzzy in most compiler implementation).
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37930