[erlang-patches] [PATCH] correct conversion of MIN_SMALL numeral to fixnum

[Mikael Pettersson]

Jesper Louis Andersen writes:
 > I would definitely add test cases for this to the test suite. It warrants
 > one on the evil corner case numbers to make sure they are right in the
 > future.

Ok, I'm adding some test cases.


 > 
 > 
 > On Wed, Aug 20, 2014 at 9:53 AM, Mikael Pettersson <mikpelinux@REDACTED>
 > wrote:
 > 
 > > Conversion of MIN_SMALL as a numeral to an Erlang integer, via
 > > binary_to_integer/1 or list_to_integer/1, succeeds but creates
 > > the integer as a negative bignum.  This is incorrect as (a) the
 > > value fits in a fixnum, and (b) the VM expects values that fit
 > > in fixnums to also be fixnums.  The bug is that the numeral is
 > > converted first as a non-negative number, and then finally
 > > negated if prefixed by a unary minus sign.  MIN_SMALL without
 > > the sign is MAX_SMALL+1, which doesn't fit in a fixnum, so the
 > > value before the negation is a bignum.  To correct the
 > > representation after the negation call big_plus_small with zero,
 > > as already done in other places.
 > >
 > > Tested with the emulator testsuite on Linux/x86_64, no regressions.
 > >
 > > Thanks to Jesper Louis Andersen for the report to erlang-bugs.
 > >
 > > Signed-off-by: Mikael Pettersson <mikpelinux@REDACTED>
 > >
 > > Links:
 > >
 > > git fetch git://github.com/mikpe/otp.git MIN_SMALL-to-integer
 > >
 > > https://github.com/mikpe/otp/compare/erlang:maint...MIN_SMALL-to-integer
 > >
 > > https://github.com/mikpe/otp/compare/erlang:maint...MIN_SMALL-to-integer.patch
 > >
 > > https://github.com/erlang/otp/pull/452
 > > _______________________________________________
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 > > erlang-patches@REDACTED
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 > >
 > 
 > 
 > 
 > -- 
 > J.

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