abb958ada1
Add assertions to diagnose incorrect uses of valarray masks. The assignment operators of std::mask_array do not have any explicit preconditions in the standard, but the assignment operator valarray<T>::operator=(const mask_array<T>&) requires the lengths to match, so it seems consistent to also require that when the operands are reversed. In support of that interpretation, libstdc++ has undefined behaviour if the right-hand operand has more elements than are selected by the mask, and libc++ has undefined behaviour if it has fewer elements. Our std::mask_array stores the number of selected elements as _M_sz so it's easy to add an assertion that checks it. For the valarray::operator[] that takes a valarray<bool> mask, [valarray.sub] in the standard says: "In each case the selected element(s) shall exist." This makes it undefined to have a mask that refers to out-of-range elements. We can easily check this too. libstdc++-v3/ChangeLog: PR libstdc++/62196 * include/bits/mask_array.h (mask_array): Add assertions to assignment operators. * include/std/valarray (valarray::operator[](valarray<bool>)): Add assertions. * testsuite/26_numerics/valarray/mask-1_neg.cc: New test. * testsuite/26_numerics/valarray/mask-2_neg.cc: New test. * testsuite/26_numerics/valarray/mask-3_neg.cc: New test. * testsuite/26_numerics/valarray/mask-4_neg.cc: New test. * testsuite/26_numerics/valarray/mask-5_neg.cc: New test. * testsuite/26_numerics/valarray/mask-6_neg.cc: New test. * testsuite/26_numerics/valarray/mask-7_neg.cc: New test. * testsuite/26_numerics/valarray/mask-8_neg.cc: New test. * testsuite/26_numerics/valarray/mask.cc: New test.
19 lines
518 B
C++
19 lines
518 B
C++
// { dg-options "-D_GLIBCXX_ASSERTIONS" }
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// { dg-do run { xfail *-*-* } }
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#include <valarray>
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int main()
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{
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using std::valarray;
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using std::mask_array;
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// This is adapted from an example in C++11 [valarray.sub].
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valarray<char> v0("abcdef", 6);
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valarray<char> v1("ABCDEF", 6);
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const bool vb[] = {false, false, true, true, false, true};
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const mask_array<char> m0 = v0[valarray<bool>(vb, 6)];
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const mask_array<char> m1 = v1[valarray<bool>(vb, 5)];
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m0 = m1; // aborts, m0 has more elements than m1
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}
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