OpenE2K
/
gcc
2
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

libstdc++: Replace incorrect static assertion in std::reduce [PR95833] 

The standard does not require the iterator's value type to be
convertible to the result type, it only requires that the result of
dereferencing the iterator can be passed to the binary function.

libstdc++-v3/ChangeLog:

	PR libstdc++/95833
	* include/std/numeric (reduce(Iter, Iter, T, BinaryOp)): Replace
	incorrect static_assert with ones matching the 'Mandates'
	conditions in the standard.
	* testsuite/26_numerics/reduce/95833.cc: New test.

(cherry picked from commit 0532452dcd)
This commit is contained in:
Jonathan Wakely 2021-06-18 14:46:58 +01:00
parent 3c805829c9
commit ae17634d5f
2 changed files with 20 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
libstdc++-v3/include/std/numeric
View File

@ -261,9 +261,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
reduce(_InputIterator __first, _InputIterator __last, _Tp __init,
_BinaryOperation __binary_op)
{
using value_type = typename iterator_traits<_InputIterator>::value_type;
using __ref = typename iterator_traits<_InputIterator>::reference;
static_assert(is_invocable_r_v<_Tp, _BinaryOperation&, _Tp&, __ref>);
static_assert(is_invocable_r_v<_Tp, _BinaryOperation&, __ref, _Tp&>);
static_assert(is_invocable_r_v<_Tp, _BinaryOperation&, _Tp&, _Tp&>);
static_assert(is_convertible_v<value_type, _Tp>);
static_assert(is_invocable_r_v<_Tp, _BinaryOperation&, __ref, __ref>);
if constexpr (__is_random_access_iter<_InputIterator>::value)
{
while ((__last - __first) >= 4)

16
libstdc++-v3/testsuite/26_numerics/reduce/95833.cc Normal file
View File

@ -0,0 +1,16 @@
// { dg-do compile { target c++17 } }
// PR libstdc++/95833 - Incorrect static_assert in std::reduce overload
#include <numeric>
struct A { };
struct B { };
struct binop
{
template<typename T, typename U>
A operator()(T&&, U&&) const { return A{}; }
};
B b;
A a = std::reduce(&b, &b + 1, A{}, binop{});