Added ARM jobs in GitHub Actions.

This reduces the likelihood of spurious CI failures caused by DDoS filters
being triggered by massive numbers of concurrent CI jobs.

.drone.jsonnet

@@ -124,7 +124,7 @@ local windows_pipeline(name, image, environment, arch = "amd64") =
     linux_pipeline(
         "Linux 16.04 GCC 4.8 32/64",
         "cppalliance/droneubuntu1604:1",
-        { TOOLSET: 'gcc', COMPILER: 'g++', CXXSTD: '03,11', ADDRMD: '32,64' },
+        { TOOLSET: 'gcc', COMPILER: 'g++-4.8', CXXSTD: '03,11', ADDRMD: '32,64' },
         "g++-4.8-multilib",
     ),
 

.github/workflows/ci.yml

@@ -1,5 +1,5 @@
 # Copyright 2020-2021 Peter Dimov
-# Copyright 2021-2024 Andrey Semashev
+# Copyright 2021-2025 Andrey Semashev
 #
 # Distributed under the Boost Software License, Version 1.0.
 # (See accompanying file LICENSE_1_0.txt or copy at http://boost.org/LICENSE_1_0.txt)
@@ -100,13 +100,13 @@ jobs:
           - toolset: gcc-9
             cxxstd: "03,11,14,17,2a"
             address-model: 32,64
-            os: ubuntu-20.04
+            os: ubuntu-24.04
             install:
               - g++-9-multilib
           - toolset: gcc-10
             cxxstd: "03,11,14,17,20"
             address-model: 32,64
-            os: ubuntu-20.04
+            os: ubuntu-24.04
             install:
               - g++-10-multilib
           - toolset: gcc-11
@@ -125,7 +125,7 @@ jobs:
             cxxstd: "03,11,14,17,20,23"
             address-model: 32,64
             os: ubuntu-latest
-            container: ubuntu:23.04
+            container: ubuntu:24.04
             install:
               - g++-13-multilib
           - toolset: gcc-14
@@ -135,6 +135,13 @@ jobs:
             container: ubuntu:24.04
             install:
               - g++-14-multilib
+          - toolset: gcc-15
+            cxxstd: "03,11,14,17,20,23,2c"
+            address-model: 32,64
+            os: ubuntu-latest
+            container: ubuntu:25.04
+            install:
+              - g++-15-multilib
           - name: UBSAN
             toolset: gcc-12
             cxxstd: "03,11,14,17,20,23"
@@ -220,13 +227,15 @@ jobs:
           - toolset: clang
             compiler: clang++-9
             cxxstd: "03,11,14,17,2a"
-            os: ubuntu-20.04
+            os: ubuntu-latest
+            container: ubuntu:20.04
             install:
               - clang-9
           - toolset: clang
             compiler: clang++-10
             cxxstd: "03,11,14,17,20"
-            os: ubuntu-20.04
+            os: ubuntu-latest
+            container: ubuntu:20.04
             install:
               - clang-10
           - toolset: clang
@@ -283,7 +292,7 @@ jobs:
             compiler: clang++-16
             cxxstd: "03,11,14,17,20,2b"
             os: ubuntu-latest
-            container: ubuntu:23.04
+            container: ubuntu:24.04
             install:
               - clang-16
               - libc++-16-dev
@@ -294,7 +303,7 @@ jobs:
             compiler: clang++-17
             cxxstd: "03,11,14,17,20,2b"
             os: ubuntu-latest
-            container: ubuntu:23.10
+            container: ubuntu:24.04
             install:
               - clang-17
               - libc++-17-dev
@@ -312,6 +321,28 @@ jobs:
               - libc++abi-18-dev
             cxxflags: -stdlib=libc++
             linkflags: -stdlib=libc++
+          - toolset: clang
+            compiler: clang++-19
+            cxxstd: "03,11,14,17,20,2b"
+            os: ubuntu-latest
+            container: ubuntu:24.04
+            install:
+              - clang-19
+              - libc++-19-dev
+              - libc++abi-19-dev
+            cxxflags: -stdlib=libc++
+            linkflags: -stdlib=libc++
+          - toolset: clang
+            compiler: clang++-20
+            cxxstd: "03,11,14,17,20,2b,2c"
+            os: ubuntu-latest
+            container: ubuntu:25.04
+            install:
+              - clang-20
+              - libc++-20-dev
+              - libc++abi-20-dev
+            cxxflags: -stdlib=libc++
+            linkflags: -stdlib=libc++
           - name: UBSAN
             toolset: clang
             compiler: clang++-15
@@ -325,6 +356,14 @@ jobs:
               - libc++-15-dev
               - libc++abi-15-dev
 
+          - name: ARM
+            toolset: gcc-13
+            cxxstd: "03-gnu,11-gnu,14-gnu,17-gnu,20-gnu,23-gnu"
+            os: ubuntu-24.04-arm
+            container: ubuntu:24.04
+            install:
+              - g++-13
+
           - toolset: clang
             cxxstd: "03,11,14,17,20,2b"
             os: macos-13
@@ -352,6 +391,22 @@ jobs:
                 echo "GHA_CONTAINER=${{matrix.container}}" >> $GITHUB_ENV
                 if [ -f "/etc/debian_version" ]
                 then
+                    # Use Azure APT mirrors in containers to avoid HTTP errors due to DDoS filters triggered by lots of CI jobs launching concurrently.
+                    # Note that not all Ubuntu versions support "mirror+file:..." URIs in APT sources, so just use Azure mirrors exclusively.
+                    # Note also that on recent Ubuntu versions DEB822 format is used for source files.
+                    APT_SOURCES=()
+                    if [ -d "/etc/apt/sources.list.d" ]
+                    then
+                        readarray -t APT_SOURCES < <(find "/etc/apt/sources.list.d" -type f -name '*.sources' -print)
+                    fi
+                    if [ -f "/etc/apt/sources.list" ]
+                    then
+                        APT_SOURCES+=("/etc/apt/sources.list")
+                    fi
+                    if [ "${#APT_SOURCES[@]}" -gt 0 ]
+                    then
+                        sed -i -E -e 's!([^ ]+) (http|https)://(archive|security)\.ubuntu\.com/ubuntu[^ ]*(.*)!\1 http://azure.archive.ubuntu.com/ubuntu/\4!' "${APT_SOURCES[@]}"
+                    fi
                     apt-get -o Acquire::Retries=$NET_RETRY_COUNT update
                     if [ "$(apt-cache search "^python-is-python3$" | wc -l)" -ne 0 ]
                     then
@@ -552,14 +607,6 @@ jobs:
       fail-fast: false
       matrix:
         include:
-          - toolset: msvc-14.0
-            cxxstd: "14"
-            addrmd: 32,64
-            os: windows-2019
-          - toolset: msvc-14.2
-            cxxstd: "14,17,20,latest"
-            addrmd: 32,64
-            os: windows-2019
           - toolset: msvc-14.3
             cxxstd: "14,17,20,latest"
             addrmd: 32,64
@@ -571,7 +618,14 @@ jobs:
           - toolset: gcc
             cxxstd: "03,11,14,17,2a"
             addrmd: 64
-            os: windows-2019
+            os: windows-2022
+
+          # Windows SDK 32-bit ARM libs not installed in this image
+          - name: ARM
+            toolset: msvc-14.3
+            cxxstd: "14,17,20,latest"
+            addrmd: 64
+            os: windows-11-arm
 
     runs-on: ${{matrix.os}}
     timeout-minutes: 45
@@ -624,7 +678,6 @@ jobs:
       fail-fast: false
       matrix:
         include:
-          - os: ubuntu-20.04
           - os: ubuntu-22.04
           - os: ubuntu-24.04
           - os: macos-13
@@ -692,7 +745,6 @@ jobs:
       fail-fast: false
       matrix:
         include:
-          - os: ubuntu-20.04
           - os: ubuntu-22.04
           - os: ubuntu-24.04
           - os: macos-13
@@ -770,7 +822,6 @@ jobs:
       fail-fast: false
       matrix:
         include:
-          - os: ubuntu-20.04
           - os: ubuntu-22.04
           - os: ubuntu-24.04
           - os: macos-13
@@ -852,8 +903,8 @@ jobs:
       fail-fast: false
       matrix:
         include:
-          - os: windows-2019
           - os: windows-2022
+          - os: windows-2025
 
     runs-on: ${{matrix.os}}
     timeout-minutes: 10
@@ -914,8 +965,8 @@ jobs:
       fail-fast: false
       matrix:
         include:
-          - os: windows-2019
           - os: windows-2022
+          - os: windows-2025
 
     runs-on: ${{matrix.os}}
     timeout-minutes: 10
@@ -994,8 +1045,8 @@ jobs:
       fail-fast: false
       matrix:
         include:
-          - os: windows-2019
           - os: windows-2022
+          - os: windows-2025
 
     runs-on: ${{matrix.os}}
     timeout-minutes: 20

doc/span.qbk

@@ -38,7 +38,7 @@ and return type use spans.
 
 ```
 auto sha1(boost::span<const unsigned char> input,
-    boost::span<unsigned char, SHA_DIGEST_LENGTH> ouput)
+    boost::span<unsigned char, SHA_DIGEST_LENGTH> output)
 {
     SHA_CTX context;
     SHA1_Init(&context);

include/boost/core/bit.hpp

@@ -28,7 +28,7 @@
 # pragma intrinsic(_BitScanForward)
 # pragma intrinsic(_BitScanReverse)
 
-# if defined(_M_X64)
+# if defined(_M_X64) || defined(_M_ARM64)
 #  pragma intrinsic(_BitScanForward64)
 #  pragma intrinsic(_BitScanReverse64)
 # endif
@@ -230,7 +230,7 @@ inline int countl_impl( boost::uint16_t x ) BOOST_NOEXCEPT
 
 #endif
 
-#if defined(_MSC_VER) && defined(_M_X64) && defined(BOOST_CORE_HAS_BUILTIN_ISCONSTEVAL)
+#if defined(_MSC_VER) && (defined(_M_X64) || defined(_M_ARM64)) && defined(BOOST_CORE_HAS_BUILTIN_ISCONSTEVAL)
 
 BOOST_CXX14_CONSTEXPR inline int countl_impl( boost::uint64_t x ) BOOST_NOEXCEPT
 {
@@ -255,7 +255,7 @@ BOOST_CXX14_CONSTEXPR inline int countl_impl( boost::uint64_t x ) BOOST_NOEXCEPT
     }
 }
 
-#elif defined(_MSC_VER) && defined(_M_X64)
+#elif defined(_MSC_VER) && (defined(_M_X64) || defined(_M_ARM64))
 
 inline int countl_impl( boost::uint64_t x ) BOOST_NOEXCEPT
 {
@@ -455,7 +455,7 @@ inline int countr_impl( boost::uint16_t x ) BOOST_NOEXCEPT
 
 #endif
 
-#if defined(_MSC_VER) && defined(_M_X64) && defined(BOOST_CORE_HAS_BUILTIN_ISCONSTEVAL)
+#if defined(_MSC_VER) && (defined(_M_X64) || defined(_M_ARM64)) && defined(BOOST_CORE_HAS_BUILTIN_ISCONSTEVAL)
 
 BOOST_CXX14_CONSTEXPR inline int countr_impl( boost::uint64_t x ) BOOST_NOEXCEPT
 {
@@ -480,7 +480,7 @@ BOOST_CXX14_CONSTEXPR inline int countr_impl( boost::uint64_t x ) BOOST_NOEXCEPT
     }
 }
 
-#elif defined(_MSC_VER) && defined(_M_X64)
+#elif defined(_MSC_VER) && (defined(_M_X64) || defined(_M_ARM64))
 
 inline int countr_impl( boost::uint64_t x ) BOOST_NOEXCEPT
 {
@@ -703,7 +703,7 @@ BOOST_CXX14_CONSTEXPR inline boost::uint32_t bit_ceil_impl( boost::uint32_t x )
 {
     if( x == 0 )
     {
-        return 0;
+        return 1;
     }
 
     --x;
@@ -723,7 +723,7 @@ BOOST_CXX14_CONSTEXPR inline boost::uint64_t bit_ceil_impl( boost::uint64_t x )
 {
     if( x == 0 )
     {
-        return 0;
+        return 1;
     }
 
     --x;

include/boost/core/default_allocator.hpp

@@ -10,6 +10,7 @@ Distributed under the Boost Software License, Version 1.0.
 
 #include <boost/config.hpp>
 #include <new>
+#include <cstddef>
 
 namespace boost {
 

include/boost/core/demangle.hpp

@@ -30,7 +30,7 @@
 
 #if defined( BOOST_CORE_HAS_CXXABI_H )
 # include <cxxabi.h>
-// For some archtectures (mips, mips64, x86, x86_64) cxxabi.h in Android NDK is implemented by gabi++ library
+// For some architectures (mips, mips64, x86, x86_64) cxxabi.h in Android NDK is implemented by gabi++ library
 // (https://android.googlesource.com/platform/ndk/+/master/sources/cxx-stl/gabi++/), which does not implement
 // abi::__cxa_demangle(). We detect this implementation by checking the include guard here.
 # if defined( __GABIXX_CXXABI_H__ )

include/boost/core/detail/assert.hpp

@@ -0,0 +1,18 @@
+/*
+Copyright 2025 Glen Joseph Fernandes
+(glenjofe@gmail.com)
+
+Distributed under the Boost Software License, Version 1.0.
+(http://www.boost.org/LICENSE_1_0.txt)
+*/
+#undef BOOST_CORE_DETAIL_ASSERT
+
+#if !defined(__clang__) && \
+    !defined(__INTEL_COMPILER) && \
+    defined(__GNUC__) && \
+    (__GNUC__ < 5)
+#define BOOST_CORE_DETAIL_ASSERT(expr) void(0)
+#else
+#include <boost/assert.hpp>
+#define BOOST_CORE_DETAIL_ASSERT(expr) BOOST_ASSERT(expr)
+#endif

include/boost/core/detail/sp_thread_sleep.hpp

@@ -67,7 +67,7 @@ namespace core
 
 inline void sp_thread_sleep() BOOST_NOEXCEPT
 {
-#if defined(BOOST_HAS_PTHREADS) && !defined(__ANDROID__)
+#if defined(BOOST_HAS_PTHREADS) && !defined(__ANDROID__) && !defined(__OHOS__)
 
     int oldst;
     pthread_setcancelstate( PTHREAD_CANCEL_DISABLE, &oldst );
@@ -85,7 +85,7 @@ inline void sp_thread_sleep() BOOST_NOEXCEPT
 
     nanosleep( &rqtp, 0 );
 
-#if defined(BOOST_HAS_PTHREADS) && !defined(__ANDROID__)
+#if defined(BOOST_HAS_PTHREADS) && !defined(__ANDROID__) && !defined(__OHOS__)
 
     pthread_setcancelstate( oldst, &oldst );
 

include/boost/core/detail/string_view.hpp

@@ -378,7 +378,7 @@ public:
     }
 
     template<class End> BOOST_CXX14_CONSTEXPR basic_string_view( Ch const* first, End last,
-        typename boost::enable_if<boost::core::detail::is_same<End, Ch const*> >::type* = 0 ) BOOST_NOEXCEPT: p_( first ), n_( static_cast<size_type>( last - first ) )
+        typename boost::enable_if<boost::core::detail::is_same<End, Ch const*>, int >::type = 0 ) BOOST_NOEXCEPT: p_( first ), n_( static_cast<size_type>( last - first ) )
     {
         BOOST_ASSERT( last - first >= 0 );
     }
@@ -396,7 +396,7 @@ public:
 #endif
 
     template<class Ch2> basic_string_view( boost::basic_string_view<Ch2, std::char_traits<Ch2> > const& str,
-        typename boost::enable_if<boost::core::detail::is_same<Ch, Ch2> >::type* = 0 ) BOOST_NOEXCEPT: p_( str.data() ), n_( str.size() )
+        typename boost::enable_if<boost::core::detail::is_same<Ch, Ch2>, int >::type = 0 ) BOOST_NOEXCEPT: p_( str.data() ), n_( str.size() )
     {
     }
 

include/boost/core/scoped_enum.hpp

@@ -37,7 +37,7 @@ namespace boost
   /**
    * Casts a scoped enum to its underlying type.
    *
-   * This function is useful when working with scoped enum classes, which doens't implicitly convert to the underlying type.
+   * This function is useful when working with scoped enum classes, which doesn't implicitly convert to the underlying type.
    * @param v A scoped enum.
    * @returns The underlying type.
    * @throws No-throws.

include/boost/core/span.hpp

@@ -8,6 +8,7 @@ Distributed under the Boost Software License, Version 1.0.
 #ifndef BOOST_CORE_SPAN_HPP
 #define BOOST_CORE_SPAN_HPP
 
+#include <boost/core/detail/assert.hpp>
 #include <boost/core/data.hpp>
 #include <array>
 #include <iterator>
@@ -274,17 +275,21 @@ public:
     }
 
     constexpr span<T, dynamic_extent> first(size_type c) const {
-        return span<T, dynamic_extent>(s_.p, c);
+        return BOOST_CORE_DETAIL_ASSERT(c <= size()),
+            span<T, dynamic_extent>(s_.p, c);
     }
 
     constexpr span<T, dynamic_extent> last(size_type c) const {
-        return span<T, dynamic_extent>(s_.p + (s_.n - c), c);
+        return BOOST_CORE_DETAIL_ASSERT(c <= size()),
+            span<T, dynamic_extent>(s_.p + (s_.n - c), c);
     }
 
     constexpr span<T, dynamic_extent> subspan(size_type o,
         size_type c = dynamic_extent) const {
-        return span<T, dynamic_extent>(s_.p + o,
-            c == dynamic_extent ? s_.n - o : c);
+        return BOOST_CORE_DETAIL_ASSERT(o <= size() &&
+                (c == dynamic_extent || c + o <= size())),
+            span<T, dynamic_extent>(s_.p + o,
+                c == dynamic_extent ? s_.n - o : c);
     }
 
     constexpr size_type size() const noexcept {
@@ -300,15 +305,15 @@ public:
     }
 
     constexpr reference operator[](size_type i) const {
-        return s_.p[i];
+        return BOOST_CORE_DETAIL_ASSERT(i < size()), s_.p[i];
     }
 
     constexpr reference front() const {
-        return *s_.p;
+        return BOOST_CORE_DETAIL_ASSERT(!empty()), *s_.p;
     }
 
     constexpr reference back() const {
-        return s_.p[s_.n - 1];
+        return BOOST_CORE_DETAIL_ASSERT(!empty()), s_.p[s_.n - 1];
     }
 
     constexpr pointer data() const noexcept {

test/Jamfile.v2

@@ -409,6 +409,7 @@ run span_test.cpp ;
 run span_types_test.cpp ;
 run span_constructible_test.cpp ;
 run span_deduction_guide_test.cpp ;
+run span_constexpr_test.cpp ;
 run as_bytes_test.cpp ;
 run as_writable_bytes_test.cpp ;
 compile span_boost_begin_test.cpp ;

test/bit_ceil_test.cpp

@@ -19,14 +19,15 @@ template<class T> void test_bit_ceil( T x )
 
     T y = boost::core::bit_ceil( x );
 
+    BOOST_TEST( boost::core::has_single_bit( y ) );
+    BOOST_TEST_GE( +y, +x );
+
     if( x == 0 )
     {
-        BOOST_TEST_EQ( y, 0 );
+        BOOST_TEST_EQ( y, 1 );
     }
     else
     {
-        BOOST_TEST( boost::core::has_single_bit( y ) );
-        BOOST_TEST_GE( +y, +x );
         BOOST_TEST_LT( y >> 1, +x );
     }
 }

test/detail_iterator_test.cpp

@@ -31,7 +31,7 @@ using std::distance;
 
 */
 
-// struct C {} doesn't wotk with libc++.
+// struct C {} doesn't work with libc++.
 typedef std::forward_iterator_tag C;
 
 struct T

test/span_constexpr_test.cpp

@@ -0,0 +1,72 @@
+/*
+Copyright 2025 Glen Joseph Fernandes
+(glenjofe@gmail.com)
+
+Distributed under the Boost Software License, Version 1.0.
+(http://www.boost.org/LICENSE_1_0.txt)
+*/
+#include <boost/config.hpp>
+#if !defined(BOOST_NO_CXX11_CONSTEXPR)
+#include <boost/core/span.hpp>
+#include <boost/core/lightweight_test.hpp>
+
+constexpr const int array[4]{ 5, 10, 15, 20 };
+
+void test_first()
+{
+    constexpr boost::span<const int> s =
+        boost::span<const int>(array, 4).first(2);
+    BOOST_TEST_EQ(s.data(), &array[0]);
+    BOOST_TEST_EQ(s.size(), 2);
+}
+
+void test_last()
+{
+    constexpr boost::span<const int> s =
+        boost::span<const int>(array, 4).last(2);
+    BOOST_TEST_EQ(s.data(), &array[2]);
+    BOOST_TEST_EQ(s.size(), 2);
+}
+
+void test_subspan()
+{
+    constexpr boost::span<const int> s =
+        boost::span<const int>(array, 4).subspan(1, 2);
+    BOOST_TEST_EQ(s.data(), &array[1]);
+    BOOST_TEST_EQ(s.size(), 2);
+}
+
+void test_index()
+{
+    constexpr const int i = boost::span<const int>(array, 4)[1];
+    BOOST_TEST_EQ(i, 10);
+}
+
+void test_front()
+{
+    constexpr const int i = boost::span<const int>(array, 4).front();
+    BOOST_TEST_EQ(i, 5);
+}
+
+void test_back()
+{
+    constexpr const int i = boost::span<const int>(array, 4).back();
+    BOOST_TEST_EQ(i, 20);
+}
+
+int main()
+{
+    test_first();
+    test_last();
+    test_subspan();
+    test_index();
+    test_front();
+    test_back();
+    return boost::report_errors();
+}
+#else
+int main()
+{
+    return 0;
+}
+#endif

test/swap/swap_no_ambiguity_in_boost.cpp

@@ -9,7 +9,7 @@
 // objects to be swapped would themselves be from the boost namespace.
 // If so, boost::core::invoke_swap itself might be found by argument dependent lookup.
 // The implementation of boost::core::invoke_swap resolves this issue by giving
-// boost::core::invoke_swap two template argumetns, thereby making it less specialized
+// boost::core::invoke_swap two template arguments, thereby making it less specialized
 // than std::swap.
 
 #include <boost/core/invoke_swap.hpp>

test/swap/swap_specialized_in_global.cpp

@@ -12,7 +12,7 @@
 //Put test class in the global namespace
 #include "./swap_test_class.hpp"
 
-//Provide swap function in gloabl namespace
+//Provide swap function in global namespace
 void swap(swap_test_class& left, swap_test_class& right)
 {
   left.swap(right);