On 7 Nov, Peter Kovacs wrote:
> Hi there,
>
>
> so I tried all solutions from Dennis E. Hammilton From 2.1.2017:
>
>> Try a couple of things:
>>
>> 1. Put spaces in the "=~" to be something like " = ~" in the definition of
>> bit_mask.
>>
>> 2. If that makes no difference, try
>>
>> bit_mask = ~ ((value_type)(~0 << bits_per_pixel))
>>
>> and if that doesn't work, see if
>>
>> bit_mask = ~ ((int)(~0 << bits_per_pixel))
>>
>> or even
>>
>> bit_mask = (int) (~(~0 << bits_per_pixel))
>>
>> get the job done.
>>
>> It seems strange for an enum being used this way. It is a clumsy way to
>> define two numeric constants that are not involved in an enumeration at all.
>>
>>> };
> All failed now. The Compiler is allways complaining on on the << part,
> ignoring the casts.
> Patricia suggested that I work with a "wrong" configuration back then. This
> is definitly true. My distro enables C++17 (Letest shit yadada ;) )
> And I do not know how to switch it off. So it could well be that over time
> the Code broke.
>
> One possibility could be to switch all modern Standards off. But maybe we
> should simply consider to write this part of the code again, with the goal
> that it works with the old and new ones.
> So I think I will try this. It does not make any differences if I can compile
> anyhow.
>
> Opinions?
>
>
> On 07.11.2017 10:23, Peter Kovacs wrote:
>> Hi all,
>>
>>
>> 1)
>>
>> I have a build error on latest trunk while building
>>
>> /usr/bin/ld: cannot find -luno_salhelpergcc3
>>
>> I worked around it with build --from salhelper
>>
>>
>> Maybe some dependency is missing in registry module?
>>
>>
>> 2)
>>
>> Have a build error in registry
>>
>> '../unxlngx6.pro/slo/bitmapdevice.obj'
>>
>> /home/legine/workspace/ApacheOpenOffice/git/main/basebmp/source/bitmapdevice.cxx:2060:1:
>>
>> required from here
>> ../inc/basebmp/packedpixeliterator.hxx:54:19: warning: left shift of
>> negative value [-Wshift-negative-value]
>> return ((~(~0 << bits_per_pixel)) << bits_per_pixel*(MsbFirst ?
>>
>> ../inc/basebmp/packedpixeliterator.hxx:86:23: error: left operand of
>> shift expression '(-1 << 4)' is negative [-fpermissive]
>> ../inc/basebmp/packedpixeliterator.hxx:80:10: error: enumerator value
>> for 'bit_mask' is not an integer constant
>> enum {
>> ^
>>
>> Maybe this is about my compiler. (I use gcc 7.2.0 :P ) I will check
>> tonight. However if someone has an idea. Help is apreciated.
On a two-complement machine, ~0 evaluates to -1, and in C, the result of
shifting a negative value is undefined. Most machines will do an
arithmetic shift, but some machines (powerpc?) don't have arithmetic
shift hardware and will do a logical shift. Try changing ~0 to ~0u so
that it is treated as an unsigned value, which is probably what is
intended here. It shouldn't make a difference for -1, but it does make
a difference for other negative values.
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