From: Jonathan Wakely <jwakely@redhat.com>
Date: Thu, 13 Feb 2025 09:40:44 +0000 (+0000)
Subject: libstdc++: Fix invalid signed arguments to <bit> functions
X-Git-Tag: basepoints/gcc-16~1906
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=r15-7647-g32457bc25fea80;p=thirdparty%2Fgcc.git

libstdc++: Fix invalid signed arguments to <bit> functions

These should have been unsigned, but the static assertions are only in
the public std::bit_ceil and std::bit_width functions, not the internal
__bit_ceil and __bit_width ones.

libstdc++-v3/ChangeLog:

	* include/experimental/bits/simd.h (__find_next_valid_abi): Cast
	__bit_ceil argument to unsigned.
	* src/c++17/floating_from_chars.cc (__floating_from_chars_hex):
	Cast __bit_ceil argument to unsigned.
	* src/c++17/memory_resource.cc (big_block): Cast __bit_width
	argument to unsigned.
---

diff --git a/libstdc++-v3/include/experimental/bits/simd.h b/libstdc++-v3/include/experimental/bits/simd.h
index 500c1781ae54..f0cb101aaa82 100644
--- a/libstdc++-v3/include/experimental/bits/simd.h
+++ b/libstdc++-v3/include/experimental/bits/simd.h
@@ -4634,7 +4634,7 @@ template <template <int> class _Abi, int _Bytes, typename _Tp>
     static constexpr auto
     _S_choose()
     {
-      constexpr int _NextBytes = std::__bit_ceil(_Bytes) / 2;
+      constexpr int _NextBytes = std::__bit_ceil((unsigned)_Bytes) / 2;
       using _NextAbi = _Abi<_NextBytes>;
       if constexpr (_NextBytes < sizeof(_Tp) * 2) // break recursion
 	return _Abi<_Bytes>();
diff --git a/libstdc++-v3/src/c++17/floating_from_chars.cc b/libstdc++-v3/src/c++17/floating_from_chars.cc
index f8b1e23937d2..d48f1c0d4545 100644
--- a/libstdc++-v3/src/c++17/floating_from_chars.cc
+++ b/libstdc++-v3/src/c++17/floating_from_chars.cc
@@ -1102,8 +1102,9 @@ namespace
       {
 	// If the leading hexit is not '1', shift MANTISSA to make it so.
 	// This normalizes input like "4.08p0" into "1.02p2".
-	const int leading_hexit = mantissa >> mantissa_bits;
-	const int leading_hexit_width = __bit_width(leading_hexit); // FIXME: optimize?
+	const unsigned leading_hexit = mantissa >> mantissa_bits;
+	const int leading_hexit_width
+	  = __bit_width((unsigned)leading_hexit); // FIXME: optimize?
 	__glibcxx_assert(leading_hexit_width >= 1 && leading_hexit_width <= 4);
 	shift_mantissa(leading_hexit_width - 1);
 	// After this adjustment, we can assume the leading hexit is '1'.
diff --git a/libstdc++-v3/src/c++17/memory_resource.cc b/libstdc++-v3/src/c++17/memory_resource.cc
index 0e984f27b827..fac4c782c5f7 100644
--- a/libstdc++-v3/src/c++17/memory_resource.cc
+++ b/libstdc++-v3/src/c++17/memory_resource.cc
@@ -591,7 +591,8 @@ namespace pmr
     // The minimum size of a big block.
     // All big_block allocations will be a multiple of this value.
     // Use bit_ceil to get a power of two even for e.g. 20-bit size_t.
-    static constexpr size_t min = __bit_ceil(numeric_limits<size_t>::digits);
+    static constexpr size_t min
+      = __bit_ceil((unsigned)numeric_limits<size_t>::digits);
 
     constexpr
     big_block(size_t bytes, size_t alignment)