[libcxx-commits] [PATCH] D118902: [libc++] Fix chrono::duration constructor constraint

[Tiago Macarios via Phabricator via libcxx-commits]

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As per [time.duration.cons]/1 the constructor constraint should be on
const Rep2&. As it is now the code will fail to compile in certain
cases, ex:

https://godbolt.org/z/c7fPrcTYM

struct S{
operator int() const&& noexcept = delete;
operator int() const& noexcept;
};

const S &fun();

auto k = std::chrono::microseconds{fun()};


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D118902

Files:
  libcxx/include/__chrono/duration.h


Index: libcxx/include/__chrono/duration.h
===================================================================
--- libcxx/include/__chrono/duration.h
+++ libcxx/include/__chrono/duration.h
@@ -251,7 +251,7 @@
         explicit duration(const _Rep2& __r,
             typename enable_if
             <
-               is_convertible<_Rep2, rep>::value &&
+               is_convertible<const _Rep2&, rep>::value &&
                (treat_as_floating_point<rep>::value ||
                !treat_as_floating_point<_Rep2>::value)
             >::type* = nullptr)


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