[sword-devel] SVN 3813 makes compilation of Sword fail

[Jaak Ristioja]

"Added extra cast (int)(size_t) to avoid stupid clang error that doesn't 
like void * being cast (int) directly to an int."

UH-OH!!!

First of all, the build that failed for BibleTime was using GCC not Clang.

Secondly, the compiler is correct to warn, because a pointer does not 
always fit into an int, e.g. for the LLP64 an LP64 data models [1]. So 
it seems that you might be throwing away half of the bits and expect it 
to always work. For those data models it might work if your OS only 
gives you addresses in the range of [0, 2^32) but that is not always 
guaranteed, leading to undefined behavior.

In short, please don't store pointers in integers other than intptr_t 
and uintptr_t and convert them using reinterpret_cast! See also:

   http://eel.is/c++draft/expr.reinterpret.cast#5
   http://eel.is/c++draft/basic.stc.dynamic.safety

Best regards,
J

[1] https://en.wikipedia.org/wiki/64-bit_computing#64-bit_data_models



On 19.10.20 01:23, Troy A. Griffitts wrote:
> Crapola.  Should be fixed.  This was intended to be a call to the new 
> FileMgr::write which hides the OS-specific impl, but I was configured to 
> use CURL instead of FTPLib, so I missed the compilation error.  The 
> Android port uses FTPLib and I just built there successfully with the 
> committed I just pushed.  Thank you Jaak.
> 
> Troy
> 
> 
> On 10/18/20 11:57 PM, Jaak Ristioja wrote:
>> Hello!
>>
>> The commit "A bit more work on making it easier to use SWORD in a 
>> threadsafe manner." makes compilation of Sword fail:
>>
>> src/mgr/ftplibftpt.cpp: In function ‘int 
>> sword::{anonymous}::my_filewriter(netbuf*, void*, size_t, void*)’:
>> src/mgr/ftplibftpt.cpp:52:21: error: cast from ‘void*’ to ‘int’ loses 
>> precision [-fpermissive]
>>    int output = (int)fd;
>>                      ^~
>> src/mgr/ftplibftpt.cpp: In function ‘int 
>> sword::{anonymous}::my_filewriter(netbuf*, void*, size_t, void*)’:
>> src/mgr/ftplibftpt.cpp:52:21: error: cast from ‘void*’ to ‘int’ loses 
>> precision [-fpermissive]
>>    int output = (int)fd;
>>                      ^~
>> src/mgr/ftplibftpt.cpp:53:3: error: ‘write’ was not declared in this 
>> scope
>>    write(output, buffer, size);
>>    ^~~~~
>> src/mgr/ftplibftpt.cpp:53:3: error: ‘write’ was not declared in this 
>> scope
>>    write(output, buffer, size);
>>    ^~~~~
>> src/mgr/ftplibftpt.cpp:53:3: note: suggested alternative: ‘fwrite’
>>    write(output, buffer, size);
>>
>> See https://github.com/bibletime/bibletime/runs/1272250545 for the 
>> failing build run.
>>
>> Commit details in our git mirror of the Sword SVN repository:
>>  https://github.com/bibletime/crosswire-sword-mirror/commit/c52559ecae
>>
>>
>> Best regards,
>> J
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