* [committed] libstdc++: Improve comment on _Power_of_2 helper function
@ 2020-11-09 14:55 Jonathan Wakely
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From: Jonathan Wakely @ 2020-11-09 14:55 UTC (permalink / raw)
To: libstdc++, gcc-patches
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libstdc++-v3/ChangeLog:
* include/bits/uniform_int_dist.h (__detail::_Power_of_2):
Document that true result for zero is intentional.
Tested x86_64-linux. Committed to trunk.
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commit b2b85163731e8647542f2f7561bd4c69ae5f5f2a
Author: Jonathan Wakely <jwakely@redhat.com>
Date: Mon Nov 9 14:32:45 2020
libstdc++: Improve comment on _Power_of_2 helper function
libstdc++-v3/ChangeLog:
* include/bits/uniform_int_dist.h (__detail::_Power_of_2):
Document that true result for zero is intentional.
diff --git a/libstdc++-v3/include/bits/uniform_int_dist.h b/libstdc++-v3/include/bits/uniform_int_dist.h
index 8f02b85c9bb0..4169f705c2af 100644
--- a/libstdc++-v3/include/bits/uniform_int_dist.h
+++ b/libstdc++-v3/include/bits/uniform_int_dist.h
@@ -56,7 +56,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
namespace __detail
{
- /* Determine whether number is a power of 2. */
+ // Determine whether number is a power of two.
+ // This is true for zero, which is OK because we want _Power_of_2(n+1)
+ // to be true if n==numeric_limits<_Tp>::max() and so n+1 wraps around.
template<typename _Tp>
constexpr bool
_Power_of_2(_Tp __x)
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2020-11-09 14:55 [committed] libstdc++: Improve comment on _Power_of_2 helper function Jonathan Wakely
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