[Blitz-support] Stencil behaves differently for const and non-const Arrays

[Andreas R. <and...@we...>]

Hello.

If I define a stencil operator like described in the docu:

BZ_DECLARE_STENCIL_OPERATOR1(IsLocalMaximum2D, A)
    return (A(0,0) > A( 0, 1) &&
	    A(0,0) > A( 1, 0) &&
 	    A(0,0) > A( 1, 1) &&
	    A(0,0) > A( 0,-1) &&
	    A(0,0) > A(-1, 0) &&
 	    A(0,0) > A(-1,-1) &&
 	    A(0,0) > A(-1, 1) &&
 	    A(0,0) > A( 1,-1)
	    ? 1 : 0);
BZ_END_STENCIL_OPERATOR

and use it like shown below (in getPeaks(...)),
it compiles, but crashes if the following code line is omitted.
In array/stencil-et.h I found the same for Laplacian2D:

BZ_ET_STENCIL(IsLocalMaximum2D, P_numtype)


The follwing code compiles without warnings and runs without problems
(as long as we do not use const modifier for the Array):

Array<float, 2> getPeaks(Array<float, 2> last_observed) {
	// ...
	Array<float, 2> is_local_maximum( IsLocalMaximum2D(last_observed) );
	// ...
}

#define printVar(x) std::cout << #x << "="; std::cout << "`" << x << "'\n"

If const Array<float, 2> or const Array<float, 2>& is used,
we get a warning and a failure:

Array<float, 2> getPeaks(const Array<float, 2>& last_observed) {
	// ...
	printVar(last_observed.shape());
	Array<float, 2> is_local_maximum( IsLocalMaximum2D(last_observed) ); // <=
line 516
	printVar(is_local_maximum.shape());
	// ...
}

The following warning message is printed during compilation:

StencilsPrice.cpp: In member function `blitz::Array<float, 2>
   PriceDefectMarker2DStencilWrapper::getPeaks(const blitz::Array<float, 2>&)':
StencilsPrice.cpp:516: warning: passing `float' for converting 1 of `
   blitz::Array<T, N>::Array(int, blitz::GeneralArrayStorage<N_rank>) [with
   P_numtype = float, int N_rank = 2]'


And when the program runs (in the code without const they have the same size):
last_observed.shape()=`2 [        258       258 ]'
is_local_maximum.shape()=`2 [          0         0 ]'

So, for some reason the stencil behaves differently for const and non-const
arrays.

Is it Blitz, gcc, or am I doing something wrong?

Blitz version: 0.9.
gcc (GCC) 3.3.6 (Gentoo 3.3.6, ssp-3.3.6-1.0, pie-8.7.8)

Regards,
  Andreas R.