[Bug bootstrap/25002] New: build breaks if no `NAN'

["gcc-bugzilla at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>]

This gcc version always requires that system have at least one
floating value that is usable as `NAN' - in its own headers or
specified in build configuration.  In this system with this compiler
it is not the case.  Can not obtain `NAN' value at all.  When trying
to compute it dynamically, the process just gets <Floating point
exception> signal, so can not even obtain the value in it and copy
into `NAN' definition.

Environment:
System: OSF1 . V5.1 2650 alpha

Machine:
        Using native `CC=cc', `CFLAGS='-pthread -g''.
host: alpha-dec-osf5.1b
build: alpha-dec-osf5.1b
target: alpha-dec-osf5.1b
configured with: ../gcc-4.0.2/configure --disable-nls --disable-libgcj
--enable-languages=c,c++,objc

How-To-Repeat:
gmake[1]: Entering directory `gcc-4.0.2-e/build-alpha-dec-osf5.1b/libiberty'
        make bootstrap
cc -c -DHAVE_CONFIG_H -pthread -g  -I.
-I../../../gcc-4.0.2/libiberty/../include  
../../../gcc-4.0.2/libiberty/floatformat.c -o floatformat.o
cc: Error: ../../../gcc-4.0.2/libiberty/floatformat.c, line 319: In this
statement, the libraries on this platform do not yet support compile-time
evaluation of the constant expression "0.0/0.0". (constfoldns)
        dto = NAN;
--------------^
gmake[1]: *** [floatformat.o] Error 1

The preprocessed line 319 is as follows.

        dto =  ( 0.0 / 0.0 ) ;


------- Comment #1 from gin at mo dot msk dot ru  2005-11-23 15:02 -------
Fix:

Do not have patch currently.  Most likely gcc has to check whether
`NAN' value exists, and compile some code in `floatformat.c' only if
it is the case.  Or at least allow to disable compiling that code in
build configuration.


-- 
           Summary: build breaks if no `NAN'
           Product: gcc
           Version: 4.0.2
            Status: UNCONFIRMED
          Severity: critical
          Priority: P2
         Component: bootstrap
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: gin at mo dot msk dot ru
 GCC build triplet: alpha-dec-osf5.1b
  GCC host triplet: alpha-dec-osf5.1b
GCC target triplet: alpha-dec-osf5.1b


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25002