[Octave-bug-tracker] [bug #53650] build: clang-6.0 compiler warnings

[Rik]

Follow-up Comment #7, bug #53650 (project octave):

I'm pretty sure at this point that the clang warning is not to be trusted. 
How would zero make it in to the lambda function other than by capture or
parameter?  According to the documentation for std::count_if
(http://www.cplusplus.com/reference/algorithm/count_if/) the predicate
function test has to be a unary function.  That means zero can't be passed in
via a parameter.  On the other hand, If I remove the capture for zero then gcc
throws an error


./liboctave/array/MDiagArray2.h: In lambda function:
./liboctave/array/MDiagArray2.h:97:56: error: ‘zero’ is not captured
                           [] (T elem) { return elem != zero; });
                                                        ^
./liboctave/array/MDiagArray2.h:97:28: note: the lambda has no
capture-default
                           [] (T elem) { return elem != zero; });
                            ^
./liboctave/array/MDiagArray2.h:94:13: note: ‘const T zero’ declared here
     const T zero = T ();
             ^


I suppose we could drop this entirely and go back to a for loop


  octave_idx_type nnz (void) const
  {
    const T *d = this->data ();

    const octave_idx_type nel = this->length ();

    const T zero = T ();

    octave_idx_type nnz = 0;
    for (octave_idx_type i = 0; i < nel; i++) 
      {
        if (*d != zero)
          nnz++;
        d++;
      }

   return nnz;
  }




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