Re: libstdc++/3247

[Peter Schmid <schmid at snake dot iap dot physik dot tu-darmstadt dot de>]

This is a known (IMHO mis-) "feature" of the slice or
gslice interface of the ISO standard. This is because the C++ standard
library does not specify that valarray subsets provide the same
operations as valarrays. Therefore, some ugly casts to the valarray
type are needed. Please confer page 554 of "The C++ Standard Library"
by Josuttis. For example, the following code does indeed compile. To get a
working program, you have to dimension the (val)arrays, though.

Hope this helps,

Peter Schmid

Source code tbkoz.C
#include <cstddef>
#include <valarray>

template <typename T1, typename Param1, class Param2> 
void gnu_operator(T1, Param1 p1, Param2 p2)
{ std::operator*<T1>(p1, p2); }

int main()
{
    double dvar = 1.0;
    std::valarray<double> val_d;
    std::slice slc;
    std::gslice gslc;
    std::valarray<bool> val_b;
    std::valarray<std::size_t> val_sizet;

    gnu_operator(dvar, val_d, val_d);
    gnu_operator(dvar, val_d, static_cast<std::valarray<double> > (val_d[slc]));
    gnu_operator(dvar, val_d, static_cast<std::valarray<double> > (val_d[gslc]) ); 
    gnu_operator(dvar, val_d, static_cast<std::valarray<double> > (val_d[val_b]));
    gnu_operator(dvar, val_d, static_cast<std::valarray<double> > (val_d[val_sizet]));

        // and so on...
    gnu_operator(dvar, static_cast<std::valarray<double> > (val_d[slc]), static_cast<std::valarray<double> > (val_d[slc]));

    return 0;
};

Compiling tbkoz.C

g++ -v tbkoz.C -W -Wall
Reading specs from /usr/local/lib/gcc-lib/i686-pc-linux-gnu/3.0/specs
Configured with: ../gcc/configure --enable-shared --disable-nls --enable-threads=posix --enable-languages=c,c++,f77,objc
Thread model: posix
gcc version 3.0 20010615 (prerelease)
 /usr/local/lib/gcc-lib/i686-pc-linux-gnu/3.0/cc1plus -v -D__GNUC__=3 -D__GNUC_MINOR__=0 -D__GNUC_PATCHLEVEL__=0 -D__ELF__ -Dunix -Dlinux -D__ELF__ -D__unix__ -D__linux__ -D__unix -D__linux -Asystem=posix -D__NO_INLINE__ -D__STDC_HOSTED__=1 -W -Wall -D_GNU_SOURCE -Acpu=i386 -Amachine=i386 -Di386 -D__i386 -D__i386__ -D__tune_i686__ -D__tune_pentiumpro__ tbkoz.C -D__GNUG__=3 -D__GXX_DEPRECATED -D__EXCEPTIONS -D__GXX_ABI_VERSION=100 -quiet -dumpbase tbkoz.C -W -Wall -version -o /tmp/cc6nIa8N.s
GNU CPP version 3.0 20010615 (prerelease) (cpplib) (i386 Linux/ELF)
GNU C++ version 3.0 20010615 (prerelease) (i686-pc-linux-gnu)
	compiled by GNU C version 3.0 20010615 (prerelease).
ignoring nonexistent directory "/usr/local/i686-pc-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:
 /usr/local/include/g++-v3
 /usr/local/include/g++-v3/i686-pc-linux-gnu
 /usr/local/include/g++-v3/backward
 /usr/local/include
 /usr/local/lib/gcc-lib/i686-pc-linux-gnu/3.0/include
 /usr/include
End of search list.
 /usr/local/lib/gcc-lib/i686-pc-linux-gnu/3.0/../../../../i686-pc-linux-gnu/bin/as -V -Qy -o /tmp/ccNiYQFr.o /tmp/cc6nIa8N.s
GNU assembler version 2.11.90.0.15 (i686-pc-linux-gnu) using BFD version 2.11.90.0.15
 /usr/local/lib/gcc-lib/i686-pc-linux-gnu/3.0/collect2 -m elf_i386 -dynamic-linker /lib/ld-linux.so.2 /usr/lib/crt1.o /usr/lib/crti.o /usr/local/lib/gcc-lib/i686-pc-linux-gnu/3.0/crtbegin.o -L/usr/local/lib/gcc-lib/i686-pc-linux-gnu/3.0 -L/usr/local/lib/gcc-lib/i686-pc-linux-gnu/3.0/../../../../i686-pc-linux-gnu/lib -L/usr/local/lib/gcc-lib/i686-pc-linux-gnu/3.0/../../.. /tmp/ccNiYQFr.o -lstdc++ -lm -lgcc_s -lgcc -lc -lgcc_s -lgcc /usr/local/lib/gcc-lib/i686-pc-linux-gnu/3.0/crtend.o /usr/lib/crtn.o