* [committed] libstdc++: Make variant_npos conversions explicit [PR 96766]
@ 2020-08-24 15:16 Jonathan Wakely
0 siblings, 0 replies; only message in thread
From: Jonathan Wakely @ 2020-08-24 15:16 UTC (permalink / raw)
To: libstdc++, gcc-patches
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libstdc++-v3/ChangeLog:
PR libstdc++/96766
* include/std/variant (_Variant_storage): Replace implicit
conversions from size_t to __index_type with explicit casts.
This fixes a silly Clang UBsan warning from its silly
unsigned-integer-overflow sanitizer which complains about perfectly
valid code doing exactly what it's intended to. How silly.
Tested powerpc64le-linux, and with Clang. Committed to trunk.
I'll backport this to the branches, because people use clang's silly
sanitizer with the branches too.
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commit 074436cf8cdd2a9ce75cadd36deb8301f00e55b9
Author: Jonathan Wakely <jwakely@redhat.com>
Date: Mon Aug 24 16:10:07 2020
libstdc++: Make variant_npos conversions explicit [PR 96766]
libstdc++-v3/ChangeLog:
PR libstdc++/96766
* include/std/variant (_Variant_storage): Replace implicit
conversions from size_t to __index_type with explicit casts.
diff --git a/libstdc++-v3/include/std/variant b/libstdc++-v3/include/std/variant
index eb3d6779205..dd8847cf829 100644
--- a/libstdc++-v3/include/std/variant
+++ b/libstdc++-v3/include/std/variant
@@ -385,12 +385,16 @@ namespace __variant
template<typename... _Types>
struct _Variant_storage<false, _Types...>
{
- constexpr _Variant_storage() : _M_index(variant_npos) { }
+ constexpr
+ _Variant_storage()
+ : _M_index(static_cast<__index_type>(variant_npos))
+ { }
template<size_t _Np, typename... _Args>
- constexpr _Variant_storage(in_place_index_t<_Np>, _Args&&... __args)
+ constexpr
+ _Variant_storage(in_place_index_t<_Np>, _Args&&... __args)
: _M_u(in_place_index<_Np>, std::forward<_Args>(__args)...),
- _M_index(_Np)
+ _M_index{_Np}
{ }
void _M_reset()
@@ -403,7 +407,7 @@ namespace __variant
std::_Destroy(std::__addressof(__this_mem));
}, __variant_cast<_Types...>(*this));
- _M_index = variant_npos;
+ _M_index = static_cast<__index_type>(variant_npos);
}
~_Variant_storage()
@@ -432,16 +436,20 @@ namespace __variant
template<typename... _Types>
struct _Variant_storage<true, _Types...>
{
- constexpr _Variant_storage() : _M_index(variant_npos) { }
+ constexpr
+ _Variant_storage()
+ : _M_index(static_cast<__index_type>(variant_npos))
+ { }
template<size_t _Np, typename... _Args>
- constexpr _Variant_storage(in_place_index_t<_Np>, _Args&&... __args)
+ constexpr
+ _Variant_storage(in_place_index_t<_Np>, _Args&&... __args)
: _M_u(in_place_index<_Np>, std::forward<_Args>(__args)...),
- _M_index(_Np)
+ _M_index{_Np}
{ }
void _M_reset() noexcept
- { _M_index = variant_npos; }
+ { _M_index = static_cast<__index_type>(variant_npos); }
void*
_M_storage() const noexcept
@@ -455,7 +463,7 @@ namespace __variant
{
if constexpr (__variant::__never_valueless<_Types...>())
return true;
- return this->_M_index != __index_type(variant_npos);
+ return this->_M_index != static_cast<__index_type>(variant_npos);
}
_Variadic_union<_Types...> _M_u;
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2020-08-24 15:16 [committed] libstdc++: Make variant_npos conversions explicit [PR 96766] Jonathan Wakely
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