44 lines
1.7 KiB
Diff
44 lines
1.7 KiB
Diff
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From https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87822
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Author: Jonathan Wakely <jwakely@redhat.com>
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Date: Wed Oct 31 13:03:25 2018 +0000
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PR libstdc++/87822 fix layout change for nested std::pair
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The introduction of the empty __pair_base base class for PR 86751
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changed the layout of std::pair<std::pair<...>, ...>. The outer pair and
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its first member both have a base class of the same type, which cannot
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exist at the same address. This causes the first member to be at a
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non-zero offset.
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The solution is to make the base class depend on the template
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parameters, so that each pair type has a different base class type,
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which allows the base classes of the outer pair and its first member to
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have the same address.
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PR libstdc++/87822
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* include/bits/stl_pair.h (__pair_base): Change to class template.
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(pair): Make base class type depend on template parameters.
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diff --git a/libstdc++-v3/include/bits/stl_pair.h b/libstdc++-v3/include/bits/stl_pair.h
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index a30b630b4fd..5a4823ab018 100644
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--- a/libstdc++-v3/include/bits/stl_pair.h
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+++ b/libstdc++-v3/include/bits/stl_pair.h
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@@ -183,7 +183,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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};
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#endif // C++11
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- class __pair_base
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+ template<typename _U1, typename _U2> class __pair_base
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{
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#if __cplusplus >= 201103L
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template<typename _T1, typename _T2> friend struct pair;
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@@ -202,7 +202,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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*/
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template<typename _T1, typename _T2>
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struct pair
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- : private __pair_base
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+ : private __pair_base<_T1, _T2>
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{
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typedef _T1 first_type; /// @c first_type is the first bound type
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typedef _T2 second_type; /// @c second_type is the second bound type
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