[libcxx-commits] [PATCH] D120444: [libc++] [LWG3656] Update the return type of std::bit_width

[Arthur O'Dwyer via Phabricator via libcxx-commits]

This revision was landed with ongoing or failed builds.
This revision was automatically updated to reflect the committed changes.
Closed by commit rG3347e7d40fd8: [libc++] [LWG3656] Update the return type of std::bit_width. (authored by arthur.j.odwyer).

Changed prior to commit:
  https://reviews.llvm.org/D120444?vs=410979&id=413145#toc

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D120444/new/

https://reviews.llvm.org/D120444

Files:
  libcxx/docs/Status/Cxx2bIssues.csv
  libcxx/include/bit
  libcxx/test/std/numerics/bit/bit.pow.two/bit_width.pass.cpp


Index: libcxx/test/std/numerics/bit/bit.pow.two/bit_width.pass.cpp
===================================================================
--- libcxx/test/std/numerics/bit/bit.pow.two/bit_width.pass.cpp
+++ libcxx/test/std/numerics/bit/bit.pow.two/bit_width.pass.cpp
@@ -9,7 +9,7 @@
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 
 // template <class T>
-//   constexpr T bit_width(T x) noexcept;
+//   constexpr int bit_width(T x) noexcept;
 
 // Constraints: T is an unsigned integer type
 // Returns: If x == 0, 0; otherwise one plus the base-2 logarithm of x, with any fractional part discarded.
@@ -29,28 +29,28 @@
 template <class T>
 constexpr bool test()
 {
-    ASSERT_SAME_TYPE(decltype(std::bit_width(T())), T);
+    ASSERT_SAME_TYPE(decltype(std::bit_width(T())), int);
     ASSERT_NOEXCEPT(std::bit_width(T()));
     T max = std::numeric_limits<T>::max();
 
-    assert(std::bit_width(T(0)) == T(0));
-    assert(std::bit_width(T(1)) == T(1));
-    assert(std::bit_width(T(2)) == T(2));
-    assert(std::bit_width(T(3)) == T(2));
-    assert(std::bit_width(T(4)) == T(3));
-    assert(std::bit_width(T(5)) == T(3));
-    assert(std::bit_width(T(6)) == T(3));
-    assert(std::bit_width(T(7)) == T(3));
-    assert(std::bit_width(T(8)) == T(4));
-    assert(std::bit_width(T(9)) == T(4));
-    assert(std::bit_width(T(125)) == T(7));
-    assert(std::bit_width(T(126)) == T(7));
-    assert(std::bit_width(T(127)) == T(7));
-    assert(std::bit_width(T(128)) == T(8));
-    assert(std::bit_width(T(129)) == T(8));
-    assert(std::bit_width(T(130)) == T(8));
-    assert(std::bit_width(T(max - 1)) == T(std::numeric_limits<T>::digits));
-    assert(std::bit_width(max) == T(std::numeric_limits<T>::digits));
+    assert(std::bit_width(T(0)) == 0);
+    assert(std::bit_width(T(1)) == 1);
+    assert(std::bit_width(T(2)) == 2);
+    assert(std::bit_width(T(3)) == 2);
+    assert(std::bit_width(T(4)) == 3);
+    assert(std::bit_width(T(5)) == 3);
+    assert(std::bit_width(T(6)) == 3);
+    assert(std::bit_width(T(7)) == 3);
+    assert(std::bit_width(T(8)) == 4);
+    assert(std::bit_width(T(9)) == 4);
+    assert(std::bit_width(T(125)) == 7);
+    assert(std::bit_width(T(126)) == 7);
+    assert(std::bit_width(T(127)) == 7);
+    assert(std::bit_width(T(128)) == 8);
+    assert(std::bit_width(T(129)) == 8);
+    assert(std::bit_width(T(130)) == 8);
+    assert(std::bit_width(T(max - 1)) == std::numeric_limits<T>::digits);
+    assert(std::bit_width(max) == std::numeric_limits<T>::digits);
 
 #ifndef TEST_HAS_NO_INT128
     if constexpr (std::is_same_v<T, __uint128_t>) {
Index: libcxx/include/bit
===================================================================
--- libcxx/include/bit
+++ libcxx/include/bit
@@ -30,7 +30,7 @@
   template <class T>
     constexpr T bit_floor(T x) noexcept;         // C++20
   template <class T>
-    constexpr T bit_width(T x) noexcept;         // C++20
+    constexpr int bit_width(T x) noexcept;       // C++20
 
   // [bit.rotate], rotating
   template<class T>
@@ -322,7 +322,7 @@
 
 template <class _Tp>
 _LIBCPP_INLINE_VISIBILITY constexpr
-enable_if_t<__libcpp_is_unsigned_integer<_Tp>::value, _Tp>
+enable_if_t<__libcpp_is_unsigned_integer<_Tp>::value, int>
 bit_width(_Tp __t) noexcept
 {
     return __t == 0 ? 0 : __bit_log2(__t) + 1;
Index: libcxx/docs/Status/Cxx2bIssues.csv
===================================================================
--- libcxx/docs/Status/Cxx2bIssues.csv
+++ libcxx/docs/Status/Cxx2bIssues.csv
@@ -157,7 +157,8 @@
 "`3654 <https://wg21.link/LWG3654>`__","``basic_format_context::arg(size_t)`` should be ``noexcept`` ","February 2022","|Complete|","15.0","|format|"
 "`3657 <https://wg21.link/LWG3657>`__","``std::hash<std::filesystem::path>`` is not enabled","February 2022","",""
 "`3660 <https://wg21.link/LWG3660>`__","``iterator_traits<common_iterator>::pointer`` should conform to §[iterator.traits]","February 2022","|Complete|","14.0"
-"`3661 <https://wg21.link/LWG3661>`__","``constinit atomic<shared_ptr<T>> a (nullptr);`` should work","February 2022","",""
+"`3661 <https://wg21.link/LWG3661>`__","``constinit atomic<shared_ptr<T>> a(nullptr);`` should work","February 2022","",""
 "","","","",""
-`3645 <https://wg21.link/LWG3645>`__,"``resize_and_overwrite`` is overspecified to call its callback with lvalues", "Not voted in","|Complete|","14.0",""
+"`3645 <https://wg21.link/LWG3645>`__","``resize_and_overwrite`` is overspecified to call its callback with lvalues","Not voted in","|Complete|","14.0",""
+"`3656 <https://wg21.link/LWG3656>`__","Inconsistent bit operations returning a count","Not voted in","|Complete|","15.0",""
 "","","","",""


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