We need to be explicit about narrowing conversions from uint128_t since,
on targets that lack __int128, this type is defined as an integer-class
type that is only _explicitly_ convertible to the builtin integer types.
This issue was latent until r12-7563-ge32869a17b788b made the frontend
correctly reject explicit conversion functions during (dependent)
copy-initialization.
Tested on x86_64-pc-linux-gnu using both possible definitions of uint128
(as an alias for unsigned __int128 and as the integer-class type), committed to
trunk as obvious.
PR libstdc++/104859
libstdc++-v3/ChangeLog:
* src/c++17/floating_to_chars.cc (__floating_to_chars_hex):
Be explicit when narrowing the shifted effective_mantissa,
since it may have an integer-class type.
---
libstdc++-v3/src/c++17/floating_to_chars.cc | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/libstdc++-v3/src/c++17/floating_to_chars.cc
b/libstdc++-v3/src/c++17/floating_to_chars.cc
index 5825e661bf4..66bd457cbe2 100644
--- a/libstdc++-v3/src/c++17/floating_to_chars.cc
+++ b/libstdc++-v3/src/c++17/floating_to_chars.cc
@@ -801,14 +801,14 @@ template<typename T>
char leading_hexit;
if constexpr (has_implicit_leading_bit)
{
- const unsigned nibble = effective_mantissa >> rounded_mantissa_bits;
+ const auto nibble = unsigned(effective_mantissa >>
rounded_mantissa_bits);
__glibcxx_assert(nibble <= 2);
leading_hexit = '0' + nibble;
effective_mantissa &= ~(mantissa_t{0b11} << rounded_mantissa_bits);
}
else
{
- const unsigned nibble = effective_mantissa >> (rounded_mantissa_bits-4);
+ const auto nibble = unsigned(effective_mantissa >>
(rounded_mantissa_bits-4));
__glibcxx_assert(nibble < 16);
leading_hexit = "0123456789abcdef"[nibble];
effective_mantissa &= ~(mantissa_t{0b1111} <<
(rounded_mantissa_bits-4));
@@ -853,7 +853,7 @@ template<typename T>
while (effective_mantissa != 0)
{
nibble_offset -= 4;
- const unsigned nibble = effective_mantissa >> nibble_offset;
+ const auto nibble = unsigned(effective_mantissa >> nibble_offset);
__glibcxx_assert(nibble < 16);
*first++ = "0123456789abcdef"[nibble];
++written_hexits;
--
2.35.1.415.gc2162907e9
