Address philnik777's comments

Author: winner245

libcxx/include/bitset

@@ -80,7 +80,7 @@ public:
     constexpr bool operator[](size_t pos) const;
     reference operator[](size_t pos);            // constexpr since C++23
     unsigned long to_ulong() const;              // constexpr since C++23
-    unsigned long long to_ullong() const;        // since C++11, constexpr since C++23
+    unsigned long long to_ullong() const;        // constexpr since C++23
     template <class charT, class traits, class Allocator> // constexpr since C++23
         basic_string<charT, traits, Allocator> to_string(charT zero = charT('0'), charT one = charT('1')) const;
     template <class charT, class traits> // constexpr since C++23
@@ -226,30 +226,19 @@ protected:
 
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 void flip() _NOEXCEPT;
 
-  // unsigned long spans only one word
-  template <typename _StorageType                                             = __storage_type,
-            __enable_if_t<sizeof(_StorageType) >= sizeof(unsigned long), int> = 0>
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 unsigned long __to_ulong() const {
+    static_assert(sizeof(__storage_type) >= sizeof(unsigned long),
+                  "libc++ only supports platforms where sizeof(size_t) >= sizeof(unsigned long), such as 32-bit and "
+                  "64-bit platforms. If you're interested in supporting a platform where that is not the case, please "
+                  "contact the libc++ developers.");
     return static_cast<unsigned long>(__first_[0]);
   }
 
-  // unsigned long may span multiple words which are concatenated to form the result
-  template <typename _StorageType                                            = __storage_type,
-            __enable_if_t<sizeof(_StorageType) < sizeof(unsigned long), int> = 0>
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 unsigned long __to_ulong() const {
-    const size_t __ul_words = (sizeof(unsigned long) - 1) / sizeof(__storage_type) + 1;
-    const size_t __n_words  = _N_words < __ul_words ? _N_words : __ul_words;
-    unsigned long __r       = static_cast<unsigned long>(__first_[0]);
-    for (size_t __i = 1; __i < __n_words; ++__i)
-      __r |= static_cast<unsigned long>(__first_[__i]) << (__bits_per_word * __i);
-    return __r;
-  }
-
   // _Bit_size > sizeof(unsigned long) * CHAR_BIT: overflow check needed
   template <size_t _Bit_size = _Size, __enable_if_t<(_Bit_size > sizeof(unsigned long) * CHAR_BIT), int> = 0>
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 unsigned long to_ulong() const {
     if (auto __e = __make_iter(_Bit_size); std::find(__make_iter(sizeof(unsigned long) * CHAR_BIT), __e, true) != __e)
-      std::__throw_overflow_error("__bitset<_N_words, _Size>::__to_ulong overflow error");
+      std::__throw_overflow_error("__bitset<_N_words, _Size>::to_ulong overflow error");
 
     return __to_ulong();
   }
@@ -265,7 +254,7 @@ protected:
     if _LIBCPP_CONSTEXPR (_Size > sizeof(unsigned long long) * CHAR_BIT) {
       if (auto __e = __make_iter(_Size);
           std::find(__make_iter(sizeof(unsigned long long) * CHAR_BIT), __e, true) != __e)
-        std::__throw_overflow_error("__bitset<_N_words, _Size>::__to_ullong overflow error");
+        std::__throw_overflow_error("__bitset<_N_words, _Size>::to_ullong overflow error");
     }
 
     // At this point, the effective bitset size (excluding leading zeros) fits in unsigned long long
@@ -527,9 +516,9 @@ inline _LIBCPP_CONSTEXPR __bitset<1, _Size>::__bitset() _NOEXCEPT : __first_(0)
 
 template <size_t _Size>
 inline _LIBCPP_CONSTEXPR __bitset<1, _Size>::__bitset(unsigned long long __v) _NOEXCEPT
-    // TODO: This is a workaround for a gdb test failure (gdb_pretty_printer_test.sh.cpp) in
-    // stage1 CI (generic-gcc, gcc-14, g++-14), due to the __bits_per_word name lookup failure
-    // if not referenced in the constructor initializer list.
+    // TODO: We must refer to __bits_per_word in order to work around an issue with the GDB pretty-printers.
+    //       Without it, the pretty-printers complain about a missing __bits_per_word member. This needs to
+    //       be investigated further.
     // See: https://github.com/llvm/llvm-project/actions/runs/15071518915/job/42368867929?pr=121348#logs
     : __first_(_Size == __bits_per_word ? static_cast<__storage_type>(__v) : static_cast<__storage_type>(__v)) {}
 
@@ -617,8 +606,8 @@ protected:
 
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 void flip() _NOEXCEPT {}
 
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 unsigned long to_ulong() const { return 0UL; }
-  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 unsigned long long to_ullong() const { return 0ULL; }
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 unsigned long to_ulong() const { return 0; }
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 unsigned long long to_ullong() const { return 0; }
 
   template <bool _Sparse, class _CharT, class _Traits, class _Allocator>
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 basic_string<_CharT, _Traits, _Allocator>

libcxx/test/std/utilities/template.bitset/bitset.members/to_ullong.pass.cpp

@@ -6,8 +6,6 @@
 //
 //===----------------------------------------------------------------------===//
 
-// UNSUPPORTED: no-exceptions
-
 // unsigned long long to_ullong() const; // constexpr since C++23
 
 #include <bitset>
@@ -59,6 +57,7 @@ TEST_CONSTEXPR_CXX23 bool test() {
   test_to_ullong<65>();
   test_to_ullong<1000>();
 
+#ifndef TEST_HAS_NO_EXCEPTIONS
   if (!TEST_IS_CONSTANT_EVALUATED) {
     // bitset has true bits beyond the size of unsigned long long
     std::bitset<std::numeric_limits<unsigned long long>::digits + 1> q(0);
@@ -72,6 +71,7 @@ TEST_CONSTEXPR_CXX23 bool test() {
       assert(false);
     }
   }
+#endif // TEST_HAS_NO_EXCEPTIONS
 
   return true;
 }

libcxx/test/std/utilities/template.bitset/bitset.members/to_ulong.pass.cpp

@@ -6,8 +6,6 @@
 //
 //===----------------------------------------------------------------------===//
 
-// UNSUPPORTED: no-exceptions
-
 // unsigned long to_ulong() const; // constexpr since C++23
 
 #include <bitset>
@@ -59,6 +57,7 @@ TEST_CONSTEXPR_CXX23 bool test() {
   test_to_ulong<65>();
   test_to_ulong<1000>();
 
+#ifndef TEST_HAS_NO_EXCEPTIONS
   if (!TEST_IS_CONSTANT_EVALUATED) {
     // bitset has true bits beyond the size of unsigned long
     std::bitset<std::numeric_limits<unsigned long>::digits + 1> q(0);
@@ -72,6 +71,7 @@ TEST_CONSTEXPR_CXX23 bool test() {
       assert(false);
     }
   }
+#endif // TEST_HAS_NO_EXCEPTIONS
 
   return true;
 }