Re: [Bug-apl] cast from pointer to smaller type 'int'

Wed, 20 Sep 2017 13:01:50 -0700

Hi Xiao-Yong,

with reinterpret_cast<size_t> I am getting (gcc 4.8)  this:

Thread_context.cc: In member function ‘void Thread_context::print(std::ostream&) const’:
Thread_context.cc:73:42: error: invalid cast from type ‘pthread_t {aka long unsigned int}’ to type ‘size_t {aka unsigned int}’
        << reinterpret_cast<size_t>(thread)
                                          ^
make[1]: *** [apl-Thread_context.o] Error 1

It seems a little ridiculous to me that replacing a good old C-style cast that worked fine for the
last 10 years cannot be replaced by one of the 3 members of the C++ zoo of casts in a portable way?

Maybe some intermediate cast to const void * can be done on your machine?

Best Regards,
Jürgen


On 09/19/2017 11:44 PM, Xiao-Yong Jin wrote:
Should have got back to you sooner, but static_cast is not allowed between pointer types and non-pointer types.

Thread_context.cc:73:11: error: static_cast from 'pthread_t' (aka '_opaque_pthread_t *') to 'int' is not allowed
       << static_cast<int>(thread)
          ^~~~~~~~~~~~~~~~~~~~~~~~

I need reinterpret_cast<size_t> here.  I cannot reinterpret_cast<int> either, because of the difference in size.


On Sep 11, 2017, at 3:01 PM, Juergen Sauermann <[email protected]> wrote:

Hi Xiao-Yong,

I see. In this particular case the pthread_t is only used to identify a thread and
to distinguish it from other threads for debugging purposes. So as long as the
compiler does not complain about the cast everything is fine. Cast to void * instead of
int would also be an option.

/// Jürgen
 

On 09/11/2017 08:38 PM, Xiao-Yong Jin wrote:

I don't think there is a portable way of printing a variable of type pthread_t.  It could be a struct, depending on the implementation.  static_cast<int> is alright, but may not be useful in the future.



On Sep 11, 2017, at 1:08 PM, Juergen Sauermann <[email protected]>
 wrote:

Hi Xiao-Yong,

thanks, maybe fixed in SVN 1011.
Problem with that error is that the casted type is not a pointer, at least on my machine.

/// Jürgen


On 09/11/2017 06:55 PM, Xiao-Yong Jin wrote:


At revision 1010

Thread_context.cc:72:65: error: cast from pointer to smaller type 'int' loses information
   out << "thread #"     << setw(2) << N << ":" << setw(16)  << int(thread)







        

        

      

      



    

    

  
























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