be515b4ce0
* g++.dg/*.C: Use target c++17 instead of explicit dg-options. * lib/g++-dg.exp: Don't test C++11 by default. Add C++17 to the list of default stds to test. From-SVN: r265343
30 lines
1.0 KiB
C
30 lines
1.0 KiB
C
// Testcase from P0170R1
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// { dg-do compile { target c++17 } }
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auto monoid = [](auto v) { return [=] { return v; }; };
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auto add = [](auto m1) constexpr {
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auto ret = m1();
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return [=](auto m2) mutable {
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auto m1val = m1();
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auto plus = [=] (auto m2val) mutable constexpr
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{ return m1val += m2val; };
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ret = plus(m2());
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return monoid(ret);
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};
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};
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int main()
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{
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constexpr auto zero = monoid(0);
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constexpr auto one = monoid(1);
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static_assert(add(one)(zero)() == one()); // OK
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// Since 'two' below is not declared constexpr, an evaluation of its constexpr
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// member function call operator can not perform an lvalue-to-rvalue conversion
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// on one of its subobjects (that represents its capture) in a constant
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// expression.
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auto two = monoid(2);
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if (!(two() == 2)) __builtin_abort(); // OK, not a constant expression.
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static_assert(add(one)(one)() == two()); // { dg-error "|in .constexpr. expansion of " } two() is not a constant expression
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static_assert(add(one)(one)() == monoid(2)()); // OK
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}
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