Re: Bignum speedup patch causes crash at startup

[Andy Moreton]

On Tue 04 Sep 2018, Andy Moreton wrote:

> On Tue 04 Sep 2018, Paul Eggert wrote:
>
>> Andy Moreton wrote:
>>
>>> The recent changes in commit fe042e9d ("Speed up (+ 2 2) by a factor of
>>> 10") cause an immediate crash in 64bit emacs on Windows.
>>
>> Thanks for reporting it. Please try the attached patch, which I installed on 
>> master.
>
> Thanks - that fixes the crash, so Eli's crystal ball is working well.

I now see a strange warning on 64bit Windows (building with gcc 8.2.0
for target x86_64-w64-mingw32):

  CC       data.o
In file included from C:/emacs/git/emacs/master/src/data.c:31:
C:/emacs/git/emacs/master/src/data.c: In function 'arith_driver':
C:/emacs/git/emacs/master/src/lisp.h:2479:34: warning: 'accum' may be used 
uninitialized in this function [-Wmaybe-uninitialized]
   return FIXNUM_OVERFLOW_P (n) ? make_bigint (n) : make_fixnum (n);
                                  ^~~~~~~~~~~~~~~
C:/emacs/git/emacs/master/src/data.c:2962:12: note: 'accum' was declared here
   intmax_t accum = XFIXNUM (val);
            ^~~~~