Use Abseil's implementation of absl::rotl and absl::rotr for libc++

prior to 18.0 to workaround libc++ having the wrong signature for
these functions.

Upstream issue: https://github.com/llvm/llvm-project/issues/64544

The preprocessor conditions were inverted for readability as the
conditions became more complex.

PiperOrigin-RevId: 557559472
Change-Id: Ibf7a2651e13a0d2a91846bc0d72ba3a44f56747b

1 files changed, 40 insertions, 18 deletions

diff --git a/absl/numeric/bits.h b/absl/numeric/bits.h
index 5ed36f52..4b90d3fa 100644
--- a/absl/numeric/bits.h
+++ b/absl/numeric/bits.h
@@ -49,9 +49,22 @@
 
 namespace absl {
 ABSL_NAMESPACE_BEGIN
-#if !(defined(__cpp_lib_bitops) && __cpp_lib_bitops >= 201907L)
 
-// rotating
+// https://github.com/llvm/llvm-project/issues/64544
+// libc++ had the wrong signature for std::rotl and std::rotr
+// prior to libc++ 18.0.
+//
+// b/289016048 requires a workaround for _LIBCPP_GOOGLE3.
+#if (defined(__cpp_lib_bitops) && __cpp_lib_bitops >= 201907L) && \
+    (!defined(_LIBCPP_VERSION) || _LIBCPP_VERSION >= 180000) &&   \
+    !defined(_LIBCPP_GOOGLE3)
+
+using std::rotl;
+using std::rotr;
+
+#else
+
+// Rotating functions
 template <class T>
 ABSL_MUST_USE_RESULT constexpr
     typename std::enable_if<std::is_unsigned<T>::value, T>::type
@@ -66,6 +79,20 @@ ABSL_MUST_USE_RESULT constexpr
   return numeric_internal::RotateRight(x, s);
 }
 
+#endif
+
+// b/289016048 requires a workaround for _LIBCPP_GOOGLE3.
+#if (defined(__cpp_lib_bitops) && __cpp_lib_bitops >= 201907L) && \
+    !defined(_LIBCPP_GOOGLE3)
+
+using std::countl_one;
+using std::countl_zero;
+using std::countr_one;
+using std::countr_zero;
+using std::popcount;
+
+#else
+
 // Counting functions
 //
 // While these functions are typically constexpr, on some platforms, they may
@@ -107,19 +134,20 @@ ABSL_INTERNAL_CONSTEXPR_POPCOUNT inline
     popcount(T x) noexcept {
   return numeric_internal::Popcount(x);
 }
-#else  // defined(__cpp_lib_bitops) && __cpp_lib_bitops >= 201907L
-
-using std::countl_one;
-using std::countl_zero;
-using std::countr_one;
-using std::countr_zero;
-using std::popcount;
-using std::rotl;
-using std::rotr;
 
 #endif
 
-#if !(defined(__cpp_lib_int_pow2) && __cpp_lib_int_pow2 >= 202002L)
+// b/289016048 requires a workaround for _LIBCPP_GOOGLE3.
+#if (defined(__cpp_lib_int_pow2) && __cpp_lib_int_pow2 >= 202002L) && \
+    !defined(_LIBCPP_GOOGLE3)
+
+using std::bit_ceil;
+using std::bit_floor;
+using std::bit_width;
+using std::has_single_bit;
+
+#else
+
 // Returns: true if x is an integral power of two; false otherwise.
 template <class T>
 constexpr inline typename std::enable_if<std::is_unsigned<T>::value, bool>::type
@@ -162,12 +190,6 @@ ABSL_INTERNAL_CONSTEXPR_CLZ inline
   return has_single_bit(x) ? T{1} << (bit_width(x) - 1)
                            : numeric_internal::BitCeilNonPowerOf2(x);
 }
-#else  // defined(__cpp_lib_int_pow2) && __cpp_lib_int_pow2 >= 202002L
-
-using std::bit_ceil;
-using std::bit_floor;
-using std::bit_width;
-using std::has_single_bit;
 
 #endif