[PD-dev] how to cast printed pointers? (commit c019784b83 throwing warnings)

Fri Dec 3 17:33:20 CET 2021

Don't suppress the warnings, let's keep them as a reminder - either on 
Linux or Windows :-)

I would suggest to look for a general solution to the object ID problem 
after Pd 0.52. The GitHub issue 
https://github.com/pure-data/pure-data/issues/1474 already contains a 
couple of ideas.

Christof

On 03.12.2021 17:27, Miller Puckette wrote:
> Or better yet - perhaps just silence the warning in the windows compiler.
> (I already have to silence a bunch of them that complain when I convert
> double to float and whatnot).
>
> cheers
> M
>
> On Fri, Dec 03, 2021 at 08:23:54AM -0800, Miller Puckette via Pd-dev wrote:
>> So... here's no solution that makes all compilers happy and doesn't get
>> Tcl in a snit... I guess the only way is to make a compiler-dependent macro
>> like #define ptr_to_tag(x) ((unsigned long)(x)) (for gcc) and whatever it is
>> now for windows... I'm OK with punting this for 0.52 and will keep it your way
>> to make sure I keep seeing the problem :)
>>
>> cheers
>> Miller
>>
>> On Fri, Dec 03, 2021 at 11:06:54AM +0100, Christof Ressi wrote:
>>> IOhannes has the answer: the resulting string might not be valid Tcl
>>> variable name.
>>>
>>> For further discussion see: https://urldefense.proofpoint.com/v2/url?u=https-3A__github.com_pure-2Ddata_pure-2Ddata_issues_1474-23issuecomment-2D985386181&d=DwIDaQ&c=-35OiAkTchMrZOngvJPOeA&r=XprZV3Fxus2L1LCw80hE4Q&m=Ly2D1_om-E67IEJJOaq_Tvdcw4H3tteqvJoJ694Qt4qva9dc1gnt7U9n5zj2mQdr&s=O47fgmtoAjHX-uNksFBQntYsj9gjWQApnXNjGVqAeFY&e=
>>>
>>> On 03.12.2021 10:39, Christof Ressi wrote:
>>>>> NOTE: although %p would be the obvious choice, we can't use it,
>>>>> because the result is platform/compiler dependent. This is not a
>>>>> problem most of the time but it can break in the case of a remote
>>>>> GUI! We really want the pointer ID to look the same on all
>>>>> platforms!
>>>> Hmmm... on a second thought I forgot why this would be a problem... the
>>>> IDs are only generated in the core and GUI app shouldn't care.
>>>>
>>>> So Albert is right, why don't we use %p everywhere?
>>>>
>>>> Christof
>>>>
>>>> On 03.12.2021 10:34, Christof Ressi wrote:
>>>>>> I presume there's a good reason to change the code (what if
>>>>>> "long" is the wrong
>>>>>> size?) but I'd like to figure out a way to do it that doesn't
>>>>>> throw warnings.
>>>>> Ok, now I understand the reason for those few (unsigned long) casts.
>>>>> It's because the printf() family functions will check the format
>>>>> specifier, but the sys_vgui() function, which is used most of the
>>>>> time, does not.
>>>>>
>>>>> However, casting a pointer to (unsigned long) will give a warning on
>>>>> 64-bit Windows, so one of us will always get warnings either way :-)
>>>>>
>>>>> See here for a discussion how to actually fix the problem: https://urldefense.proofpoint.com/v2/url?u=https-3A__github.com_pure-2Ddata_pure-2Ddata_issues_1474&d=DwIDaQ&c=-35OiAkTchMrZOngvJPOeA&r=XprZV3Fxus2L1LCw80hE4Q&m=Ly2D1_om-E67IEJJOaq_Tvdcw4H3tteqvJoJ694Qt4qva9dc1gnt7U9n5zj2mQdr&s=qz6BmoJd22aBui-mpwgjsk4nBCSyIK3o0BZYGdczUZM&e=
>>>>>
>>>>> NOTE: although %p would be the obvious choice, we can't use it,
>>>>> because the result is platform/compiler dependent. This is not a
>>>>> problem most of the time but it can break in the case of a remote
>>>>> GUI! We really want the pointer ID to look the same on all
>>>>> platforms!
>>>>>
>>>>> Christof
>>>>>
>>>>> On 03.12.2021 09:51, Albert Rafetseder wrote:
>>>>>>> After merging commit c019784b83 (get rid of a 3 more bogus
>>>>>>> (unsigned long) casts)
>>>>>> (Link to commit for reference: [0] )
>>>>>>
>>>>>>> I'm now getting compiler warnings like this:
>>>>>>>
>>>>>>> g_editor.c:1884:73: warning: format ‘%lx’ expects argument
>>>>>>> of type ‘long unsigned int’, but argument 4 has type ‘struct
>>>>>>> _glist *’ [-Wformat=]
>>>>>>>    1884 |             snprintf(cbuf, MAXPDSTRING - 2,
>>>>>>> "pdtk_canvas_setparents .x%lx", c);
>>>>>>> | ~~^   ~
>>>>>>> | |   |
>>>>>>> | |   struct _glist *
>>>>>>> | long unsigned int
>>>>>>>
>>>>>>>
>>>>>>> ..
>>>>>>> I presume there's a good reason to change the code (what if
>>>>>>> "long" is the wrong
>>>>>>> size?) but I'd like to figure out a way to do it that
>>>>>>> doesn't throw warnings.
>>>>>> My C has oxidized substantially over time, but I think the p conversion
>>>>>> specifier might be the correct thing to use -- if you can live with the
>>>>>> additional leading "0x" that is caused by its implied "alternate form"
>>>>>> flag, `#`.
>>>>>>
>>>>>>   From `man snprintf` on Linux / OS X:
>>>>>>
>>>>>> """
>>>>>> p       The void * pointer argument is printed in hexadecimal (as if by
>>>>>>                `%#x' or `%#lx').
>>>>>> """
>>>>>>
>>>>>> Trying with the current master [1] which includes the commit above, the
>>>>>> change from `%lx` to `%p` in lines 1884 and 1891 in `g_editor.c` fixes
>>>>>> the warning. (Other warnings/errors remain, and I wouldn't have a clue
>>>>>> what to test to check the outcome anyway.)
>>>>>>
>>>>>> Best,
>>>>>>     Albert.
>>>>>>
>>>>>> [0]
>>>>>> https://urldefense.proofpoint.com/v2/url?u=https-3A__github.com_pure-2Ddata_pure-2Ddata_commit_c019784b83f6638a1c4090ce27e6a0036b6bacaa&d=DwIDaQ&c=-35OiAkTchMrZOngvJPOeA&r=XprZV3Fxus2L1LCw80hE4Q&m=Ly2D1_om-E67IEJJOaq_Tvdcw4H3tteqvJoJ694Qt4qva9dc1gnt7U9n5zj2mQdr&s=wOhwmkw5E0QkQVRHbkg0nFY02pwbmk6IMrwB4VTmC3k&e=
>>>>>>
>>>>>> [1]
>>>>>> https://urldefense.proofpoint.com/v2/url?u=https-3A__github.com_pure-2Ddata_pure-2Ddata_commit_364d859aa29c1d42be1d42ad81c74bc2fbc76cca&d=DwIDaQ&c=-35OiAkTchMrZOngvJPOeA&r=XprZV3Fxus2L1LCw80hE4Q&m=Ly2D1_om-E67IEJJOaq_Tvdcw4H3tteqvJoJ694Qt4qva9dc1gnt7U9n5zj2mQdr&s=ZJ4rcgiT37GYVCA4p1DalWp46xU1aJzf-WNRI4dUSNU&e=
>>>>>>
>>>>>>
>>>>>>
>>>>>>
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