Update .drone.jsonnet

The macos-13 image is retierd.

Also, clang on macos-15 supports C++23.

.drone.jsonnet

@@ -382,26 +382,33 @@ local windows_pipeline(name, image, environment, arch = "amd64") =
     ),
 
     linux_pipeline(
-        "Linux 24.04 Clang 19 UBSAN",
+        "Linux 24.04 Clang 19",
         "cppalliance/droneubuntu2404:1",
-        { TOOLSET: 'clang', COMPILER: 'clang++-19', CXXSTD: '03,11,14,17,20,2b' } + ubsan,
+        { TOOLSET: 'clang', COMPILER: 'clang++-19', CXXSTD: '03,11,14,17,20,2b' },
         "clang-19",
     ),
 
     linux_pipeline(
-        "Linux 24.04 Clang 19 ASAN",
+        "Linux 24.04 Clang 20 UBSAN",
         "cppalliance/droneubuntu2404:1",
-        { TOOLSET: 'clang', COMPILER: 'clang++-19', CXXSTD: '03,11,14,17,20,2b' } + asan,
-        "clang-19",
-    ),
-
-    linux_pipeline(
-        "Linux 25.04 Clang 20",
-        "cppalliance/droneubuntu2504:1",
-        { TOOLSET: 'clang', COMPILER: 'clang++-20', CXXSTD: '03,11,14,17,20,23,2c' },
+        { TOOLSET: 'clang', COMPILER: 'clang++-20', CXXSTD: '03,11,14,17,20,23,2c' } + ubsan,
         "clang-20",
     ),
 
+    linux_pipeline(
+        "Linux 24.04 Clang 20 ASAN",
+        "cppalliance/droneubuntu2404:1",
+        { TOOLSET: 'clang', COMPILER: 'clang++-20', CXXSTD: '03,11,14,17,20,23,2c' } + asan,
+        "clang-20",
+    ),
+
+    linux_pipeline(
+        "Linux 25.10 Clang 21",
+        "cppalliance/droneubuntu2510:1",
+        { TOOLSET: 'clang', COMPILER: 'clang++-21', CXXSTD: '03,11,14,17,20,23,2c' },
+        "clang-21",
+    ),
+
     macos_pipeline(
         "MacOS 10.15 Xcode 12.2 UBSAN",
         { TOOLSET: 'clang', COMPILER: 'clang++', CXXSTD: '03,11,14,1z' } + ubsan,

.github/workflows/ci.yml

@@ -151,20 +151,6 @@ jobs:
               - g++-12
 
           # Linux, clang
-          - toolset: clang
-            compiler: clang++-3.5
-            cxxstd: "03,11"
-            os: ubuntu-latest
-            container: ubuntu:16.04
-            install:
-              - clang-3.5
-          - toolset: clang
-            compiler: clang++-3.6
-            cxxstd: "03,11,14"
-            os: ubuntu-latest
-            container: ubuntu:16.04
-            install:
-              - clang-3.6
           - toolset: clang
             compiler: clang++-3.7
             cxxstd: "03,11,14"
@@ -334,15 +320,26 @@ jobs:
             linkflags: -stdlib=libc++
           - toolset: clang
             compiler: clang++-20
-            cxxstd: "03,11,14,17,20,2b,2c"
+            cxxstd: "03,11,14,17,20,23,2c"
             os: ubuntu-latest
-            container: ubuntu:25.04
+            container: ubuntu:24.04
             install:
               - clang-20
               - libc++-20-dev
               - libc++abi-20-dev
             cxxflags: -stdlib=libc++
             linkflags: -stdlib=libc++
+          - toolset: clang
+            compiler: clang++-21
+            cxxstd: "03,11,14,17,20,23,2c"
+            os: ubuntu-latest
+            container: ubuntu:25.10
+            install:
+              - clang-21
+              - libc++-21-dev
+              - libc++abi-21-dev
+            cxxflags: -stdlib=libc++
+            linkflags: -stdlib=libc++
           - name: UBSAN
             toolset: clang
             compiler: clang++-15
@@ -365,14 +362,14 @@ jobs:
               - g++-13
 
           - toolset: clang
-            cxxstd: "03,11,14,17,20,2b"
-            os: macos-13
-          - toolset: clang
-            cxxstd: "03,11,14,17,20,2b"
             os: macos-14
-          - toolset: clang
             cxxstd: "03,11,14,17,20,2b"
+          - toolset: clang
             os: macos-15
+            cxxstd: "03,11,14,17,20,23,2c"
+          - toolset: clang
+            os: macos-26
+            cxxstd: "03,11,14,17,20,23,2c"
 
     timeout-minutes: 45
     runs-on: ${{matrix.os}}
@@ -628,7 +625,7 @@ jobs:
             os: windows-11-arm
 
     runs-on: ${{matrix.os}}
-    timeout-minutes: 45
+    timeout-minutes: 60
 
     steps:
       - name: Setup Boost
@@ -680,9 +677,9 @@ jobs:
         include:
           - os: ubuntu-22.04
           - os: ubuntu-24.04
-          - os: macos-13
           - os: macos-14
           - os: macos-15
+          - os: macos-26
 
     runs-on: ${{matrix.os}}
     timeout-minutes: 10
@@ -747,9 +744,9 @@ jobs:
         include:
           - os: ubuntu-22.04
           - os: ubuntu-24.04
-          - os: macos-13
           - os: macos-14
           - os: macos-15
+          - os: macos-26
 
     runs-on: ${{matrix.os}}
     timeout-minutes: 10
@@ -824,9 +821,9 @@ jobs:
         include:
           - os: ubuntu-22.04
           - os: ubuntu-24.04
-          - os: macos-13
           - os: macos-14
           - os: macos-15
+          - os: macos-26
 
     runs-on: ${{matrix.os}}
     timeout-minutes: 20

CMakeLists.txt

@@ -16,7 +16,6 @@ target_link_libraries(boost_core
   INTERFACE
     Boost::assert
     Boost::config
-    Boost::static_assert
     Boost::throw_exception
 )
 

README.md

@@ -6,14 +6,14 @@ The criteria for inclusion is that the utility component be:
 
 * simple,
 * used by other Boost libraries, and
-* not dependent on any other Boost modules except Core itself, Config, Assert, Static Assert, or Predef.
+* not dependent on any other Boost modules except Core itself, Config, Assert, or ThrowException.
 
 ### Build Status
 
 Branch   | GitHub Actions | AppVeyor | Test Matrix | Dependencies |
 ---------|----------------|--------- | ----------- | ------------ |
-Develop  | [![GitHub Actions](https://github.com/boostorg/core/actions/workflows/ci.yml/badge.svg?branch=develop)](https://github.com/boostorg/filesystem/actions?query=branch%3Adevelop) | [![AppVeyor](https://ci.appveyor.com/api/projects/status/github/boostorg/core?branch=develop&svg=true)](https://ci.appveyor.com/project/pdimov/core) | [![Tests](https://img.shields.io/badge/matrix-develop-brightgreen.svg)](https://regression.boost.io/develop/developer/core.html) | [![Dependencies](https://img.shields.io/badge/deps-develop-brightgreen.svg)](https://pdimov.github.io/boostdep-report/develop/core.html)
-Master   | [![GitHub Actions](https://github.com/boostorg/core/actions/workflows/ci.yml/badge.svg?branch=master)](https://github.com/boostorg/filesystem/actions?query=branch%3Amaster) | [![AppVeyor](https://ci.appveyor.com/api/projects/status/github/boostorg/core?branch=master&svg=true)](https://ci.appveyor.com/project/pdimov/core) | [![Tests](https://img.shields.io/badge/matrix-master-brightgreen.svg)](https://regression.boost.io/master/developer/core.html) | [![Dependencies](https://img.shields.io/badge/deps-master-brightgreen.svg)](https://pdimov.github.io/boostdep-report/master/core.html)
+Develop  | [![GitHub Actions](https://github.com/boostorg/core/actions/workflows/ci.yml/badge.svg?branch=develop)](https://github.com/boostorg/core/actions?query=branch%3Adevelop) | [![AppVeyor](https://ci.appveyor.com/api/projects/status/75arrvfh5ibryd0p/branch/develop?svg=true)](https://ci.appveyor.com/project/cppalliance/core) | [![Tests](https://img.shields.io/badge/matrix-develop-brightgreen.svg)](https://regression.boost.io/develop/developer/core.html) | [![Dependencies](https://img.shields.io/badge/deps-develop-brightgreen.svg)](https://pdimov.github.io/boostdep-report/develop/core.html)
+Master   | [![GitHub Actions](https://github.com/boostorg/core/actions/workflows/ci.yml/badge.svg?branch=master)](https://github.com/boostorg/core/actions?query=branch%3Amaster) | [![AppVeyor](https://ci.appveyor.com/api/projects/status/75arrvfh5ibryd0p/branch/master?svg=true)](https://ci.appveyor.com/project/cppalliance/core) | [![Tests](https://img.shields.io/badge/matrix-master-brightgreen.svg)](https://regression.boost.io/master/developer/core.html) | [![Dependencies](https://img.shields.io/badge/deps-master-brightgreen.svg)](https://pdimov.github.io/boostdep-report/master/core.html)
 
 ### Directories
 
@@ -24,8 +24,8 @@ Master   | [![GitHub Actions](https://github.com/boostorg/core/actions/workflows
 ### More information
 
 * [Documentation](https://boost.org/libs/core)
-* [Report bugs](https://svn.boost.org/trac/boost/newticket?component=core;version=Boost%20Release%20Branch). Be sure to mention Boost version, platform and compiler you're using. A small compilable code sample to reproduce the problem is always good as well.
-* Submit your patches as pull requests against **develop** branch. Note that by submitting patches you agree to license your modifications under the [Boost Software License, Version 1.0](https://www.boost.org/LICENSE_1_0.txt).
+* Report bugs by opening issues in this repository. Be sure to mention Boost version, platform and compiler you're using. A small compilable code sample to reproduce the problem is always good as well.
+* Submit your patches as pull requests against the **develop** branch. Note that by submitting patches you agree to license your modifications under the [Boost Software License, Version 1.0](https://www.boost.org/LICENSE_1_0.txt).
 
 ### License
 

appveyor.yml

@@ -27,17 +27,15 @@ environment:
       ADDRMD: 32,64
       CXXSTD: 14,17
 
-    # clang-win 32 bit fails to link with "unable to load mspdbcore.dll (error code: 126)"
-
-    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
+    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2019
       TOOLSET: clang-win
       ADDRMD: 64
-      CXXSTD: 14,17,latest
+      CXXSTD: 14,17
 
     - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2019
       TOOLSET: clang-win
       ADDRMD: 64
-      CXXSTD: 14,17,latest
+      CXXSTD: 20,latest
 
     - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
       ADDPATH: C:\cygwin\bin;

benchmark/Jamfile

@@ -0,0 +1,8 @@
+# Copyright 2020, 2025 Peter Dimov
+# Distributed under the Boost Software License, Version 1.0.
+
+project : default-build release <link>static <cxxstd>17
+    : requirements <library>/boost/core//boost_core ;
+
+exe sv_find_first_of : sv_find_first_of.cpp ;
+exe sv_find_first_not_of : sv_find_first_not_of.cpp ;

benchmark/sv_find_first_not_of.cpp

@@ -0,0 +1,277 @@
+// Copyright 2021, 2025 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/utility/string_view.hpp>
+#include <boost/core/detail/string_view.hpp>
+#include <boost/core/lightweight_test.hpp>
+#include <boost/core/type_name.hpp>
+#include <boost/cstdint.hpp>
+#include <string_view>
+#include <chrono>
+#include <iostream>
+
+using namespace std::chrono_literals;
+
+template<class Sv> void test()
+{
+    constexpr char const* q1 = "{";
+    constexpr char const* q2 = "<(";
+    constexpr char const* q3 = " :=";
+    constexpr char const* q4 = " \t\r\n";
+    constexpr char const* q6 = " \t\r\n\f\v";
+    constexpr char const* q10 = "0123456789";
+    constexpr char const* q52 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
+
+    constexpr std::size_t npos = static_cast<std::size_t>( -1 );
+
+    constexpr std::size_t N = 1'000'000'000;
+
+    std::cout << boost::core::type_name<Sv>() << ":\n\n";
+
+    auto t0 = std::chrono::steady_clock::now();
+
+    {
+        constexpr char const* q = q1;
+
+        std::string s1( 1'000'000, q[ std::strlen( q ) - 1 ] );
+        std::string s2( 100, q[ std::strlen( q ) - 1 ] );
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s1.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s1 ).find_first_not_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_not_of( sv, \"" << q << "\" ) in " << s1.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s2.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s2 ).find_first_not_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_not_of( sv, \"" << q << "\" ) in " << s2.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+    }
+
+    {
+        constexpr char const* q = q2;
+
+        std::string s1( 1'000'000, q[ std::strlen( q ) - 1 ] );
+        std::string s2( 100, q[ std::strlen( q ) - 1 ] );
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s1.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s1 ).find_first_not_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_not_of( sv, \"" << q << "\" ) in " << s1.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s2.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s2 ).find_first_not_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_not_of( sv, \"" << q << "\" ) in " << s2.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+    }
+
+    {
+        constexpr char const* q = q3;
+
+        std::string s1( 1'000'000, q[ std::strlen( q ) - 1 ] );
+        std::string s2( 100, q[ std::strlen( q ) - 1 ] );
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s1.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s1 ).find_first_not_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_not_of( sv, \"" << q << "\" ) in " << s1.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s2.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s2 ).find_first_not_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_not_of( sv, \"" << q << "\" ) in " << s2.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+    }
+
+    {
+        constexpr char const* q = q4;
+
+        std::string s1( 1'000'000, q[ std::strlen( q ) - 1 ] );
+        std::string s2( 100, q[ std::strlen( q ) - 1 ] );
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s1.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s1 ).find_first_not_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_not_of( sv, \"" << q << "\" ) in " << s1.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s2.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s2 ).find_first_not_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_not_of( sv, \"" << q << "\" ) in " << s2.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+    }
+
+    {
+        constexpr char const* q = q6;
+
+        std::string s1( 1'000'000, q[ std::strlen( q ) - 1 ] );
+        std::string s2( 100, q[ std::strlen( q ) - 1 ] );
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s1.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s1 ).find_first_not_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_not_of( sv, \"" << q << "\" ) in " << s1.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s2.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s2 ).find_first_not_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_not_of( sv, \"" << q << "\" ) in " << s2.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+    }
+
+    {
+        constexpr char const* q = q10;
+
+        std::string s1( 1'000'000, q[ std::strlen( q ) - 1 ] );
+        std::string s2( 100, q[ std::strlen( q ) - 1 ] );
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s1.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s1 ).find_first_not_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_not_of( sv, \"" << q << "\" ) in " << s1.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s2.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s2 ).find_first_not_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_not_of( sv, \"" << q << "\" ) in " << s2.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+    }
+
+    {
+        constexpr char const* q = q52;
+
+        std::string s1( 1'000'000, q[ std::strlen( q ) - 1 ] );
+        std::string s2( 100, q[ std::strlen( q ) - 1 ] );
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s1.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s1 ).find_first_not_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_not_of( sv, \"" << q << "\" ) in " << s1.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s2.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s2 ).find_first_not_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_not_of( sv, \"" << q << "\" ) in " << s2.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+    }
+
+    auto tn = std::chrono::steady_clock::now();
+
+    std::cout << "\nTotal for " << boost::core::type_name<Sv>() << ": " << ( tn - t0 ) / 1ms << " ms\n\n";
+}
+
+int main()
+{
+    test<std::string_view>();
+    test<boost::string_view>();
+    test<boost::core::string_view>();
+
+    return boost::report_errors();
+}

benchmark/sv_find_first_of.cpp

@@ -0,0 +1,259 @@
+// Copyright 2021, 2025 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/utility/string_view.hpp>
+#include <boost/core/detail/string_view.hpp>
+#include <boost/core/lightweight_test.hpp>
+#include <boost/core/type_name.hpp>
+#include <boost/cstdint.hpp>
+#include <string_view>
+#include <chrono>
+#include <iostream>
+
+using namespace std::chrono_literals;
+
+template<class Sv> void test()
+{
+    std::string s1( 1'000'000, '\x00' );
+    std::string s2( 100, '\x00' );
+
+    constexpr char const* q1 = "{";
+    constexpr char const* q2 = "<(";
+    constexpr char const* q3 = " :=";
+    constexpr char const* q4 = " \t\r\n";
+    constexpr char const* q6 = " \t\r\n\f\v";
+    constexpr char const* q10 = "0123456789";
+    constexpr char const* q52 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
+
+    constexpr std::size_t npos = static_cast<std::size_t>( -1 );
+
+    constexpr std::size_t N = 1'000'000'000;
+
+    std::cout << boost::core::type_name<Sv>() << ":\n\n";
+
+    auto t0 = std::chrono::steady_clock::now();
+
+    {
+        constexpr char const* q = q1;
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s1.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s1 ).find_first_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_of( sv, \"" << q << "\" ) in " << s1.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s2.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s2 ).find_first_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_of( sv, \"" << q << "\" ) in " << s2.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+    }
+
+    {
+        constexpr char const* q = q2;
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s1.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s1 ).find_first_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_of( sv, \"" << q << "\" ) in " << s1.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s2.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s2 ).find_first_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_of( sv, \"" << q << "\" ) in " << s2.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+    }
+
+    {
+        constexpr char const* q = q3;
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s1.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s1 ).find_first_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_of( sv, \"" << q << "\" ) in " << s1.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s2.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s2 ).find_first_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_of( sv, \"" << q << "\" ) in " << s2.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+    }
+
+    {
+        constexpr char const* q = q4;
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s1.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s1 ).find_first_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_of( sv, \"" << q << "\" ) in " << s1.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s2.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s2 ).find_first_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_of( sv, \"" << q << "\" ) in " << s2.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+    }
+
+    {
+        constexpr char const* q = q6;
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s1.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s1 ).find_first_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_of( sv, \"" << q << "\" ) in " << s1.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s2.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s2 ).find_first_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_of( sv, \"" << q << "\" ) in " << s2.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+    }
+
+    {
+        constexpr char const* q = q10;
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s1.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s1 ).find_first_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_of( sv, \"" << q << "\" ) in " << s1.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s2.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s2 ).find_first_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_of( sv, \"" << q << "\" ) in " << s2.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+    }
+
+    {
+        constexpr char const* q = q52;
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s1.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s1 ).find_first_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_of( sv, \"" << q << "\" ) in " << s1.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+
+        {
+            auto t1 = std::chrono::steady_clock::now();
+
+            for( std::size_t i = 0; i < N / s2.size(); ++i )
+            {
+                BOOST_TEST_EQ( Sv( s2 ).find_first_of( q ), npos );
+            }
+
+            auto t2 = std::chrono::steady_clock::now();
+
+            std::cout << "find_first_of( sv, \"" << q << "\" ) in " << s2.size() << " bytes: " << ( t2 - t1 ) / 1ms << " ms\n";
+        }
+    }
+
+    auto tn = std::chrono::steady_clock::now();
+
+    std::cout << "\nTotal for " << boost::core::type_name<Sv>() << ": " << ( tn - t0 ) / 1ms << " ms\n\n";
+}
+
+int main()
+{
+    test<std::string_view>();
+    test<boost::string_view>();
+    test<boost::core::string_view>();
+
+    return boost::report_errors();
+}

build.jam

@@ -8,7 +8,6 @@ require-b2 5.2 ;
 constant boost_dependencies :
     /boost/assert//boost_assert
     /boost/config//boost_config
-    /boost/static_assert//boost_static_assert
     /boost/throw_exception//boost_throw_exception
     ;
 

doc/core.qbk

@@ -37,7 +37,7 @@ criteria for inclusion is that the utility component be:
 * simple,
 * used by other Boost libraries, and
 * not dependent on any other Boost modules except Core
-  itself, Config, Assert, StaticAssert, or ThrowException.
+  itself, Config, Assert, or ThrowException.
 
 [endsect]
 

doc/null_deleter.qbk

@@ -18,7 +18,7 @@
 The header `<boost/core/null_deleter.hpp>` defines the `boost::null_deleter` function object,
 which can be used as a deleter with smart pointers such as `unique_ptr` or `shared_ptr`. The
 deleter doesn't do anything with the pointer provided upon deallocation, which makes it useful
-when the pointed object is deallocated elsewhere.
+when the pointed object doesn't need to be deallocated or is deallocated elsewhere.
 
 [section Example]
 ``

include/boost/core/bit.hpp

@@ -15,8 +15,8 @@
 // Distributed under the Boost Software License, Version 1.0.
 // https://www.boost.org/LICENSE_1_0.txt
 
+#include <boost/core/detail/static_assert.hpp>
 #include <boost/config.hpp>
-#include <boost/static_assert.hpp>
 #include <boost/cstdint.hpp>
 #include <limits>
 #include <cstring>
@@ -80,7 +80,7 @@ BOOST_CONSTEXPR To bit_cast( From const & from ) BOOST_NOEXCEPT
 template<class To, class From>
 To bit_cast( From const & from ) BOOST_NOEXCEPT
 {
-    BOOST_STATIC_ASSERT( sizeof(To) == sizeof(From) );
+    BOOST_CORE_STATIC_ASSERT( sizeof(To) == sizeof(From) );
 
     To to;
     std::memcpy( &to, &from, sizeof(To) );
@@ -126,7 +126,7 @@ BOOST_CONSTEXPR inline int countl_impl( boost::ulong_long_type x ) BOOST_NOEXCEP
 template<class T>
 BOOST_CONSTEXPR int countl_zero( T x ) BOOST_NOEXCEPT
 {
-    BOOST_STATIC_ASSERT( std::numeric_limits<T>::is_integer && !std::numeric_limits<T>::is_signed );
+    BOOST_CORE_STATIC_ASSERT( std::numeric_limits<T>::is_integer && !std::numeric_limits<T>::is_signed );
 
     return boost::core::detail::countl_impl( x );
 }
@@ -296,9 +296,9 @@ inline int countl_impl( boost::uint64_t x ) BOOST_NOEXCEPT
 template<class T>
 BOOST_CXX14_CONSTEXPR int countl_zero( T x ) BOOST_NOEXCEPT
 {
-    BOOST_STATIC_ASSERT( std::numeric_limits<T>::is_integer && !std::numeric_limits<T>::is_signed );
+    BOOST_CORE_STATIC_ASSERT( std::numeric_limits<T>::is_integer && !std::numeric_limits<T>::is_signed );
 
-    BOOST_STATIC_ASSERT( sizeof(T) == sizeof(boost::uint8_t) || sizeof(T) == sizeof(boost::uint16_t) || sizeof(T) == sizeof(boost::uint32_t) || sizeof(T) == sizeof(boost::uint64_t) );
+    BOOST_CORE_STATIC_ASSERT( sizeof(T) == sizeof(boost::uint8_t) || sizeof(T) == sizeof(boost::uint16_t) || sizeof(T) == sizeof(boost::uint32_t) || sizeof(T) == sizeof(boost::uint64_t) );
 
     BOOST_IF_CONSTEXPR ( sizeof(T) == sizeof(boost::uint8_t) )
     {
@@ -323,7 +323,7 @@ BOOST_CXX14_CONSTEXPR int countl_zero( T x ) BOOST_NOEXCEPT
 template<class T>
 BOOST_CONSTEXPR int countl_one( T x ) BOOST_NOEXCEPT
 {
-    BOOST_STATIC_ASSERT( std::numeric_limits<T>::is_integer && !std::numeric_limits<T>::is_signed );
+    BOOST_CORE_STATIC_ASSERT( std::numeric_limits<T>::is_integer && !std::numeric_limits<T>::is_signed );
 
     return boost::core::countl_zero( static_cast<T>( ~x ) );
 }
@@ -365,7 +365,7 @@ BOOST_CONSTEXPR inline int countr_impl( boost::ulong_long_type x ) BOOST_NOEXCEP
 template<class T>
 BOOST_CONSTEXPR int countr_zero( T x ) BOOST_NOEXCEPT
 {
-    BOOST_STATIC_ASSERT( std::numeric_limits<T>::is_integer && !std::numeric_limits<T>::is_signed );
+    BOOST_CORE_STATIC_ASSERT( std::numeric_limits<T>::is_integer && !std::numeric_limits<T>::is_signed );
 
     return boost::core::detail::countr_impl( x );
 }
@@ -521,9 +521,9 @@ inline int countr_impl( boost::uint64_t x ) BOOST_NOEXCEPT
 template<class T>
 BOOST_CXX14_CONSTEXPR int countr_zero( T x ) BOOST_NOEXCEPT
 {
-    BOOST_STATIC_ASSERT( std::numeric_limits<T>::is_integer && !std::numeric_limits<T>::is_signed );
+    BOOST_CORE_STATIC_ASSERT( std::numeric_limits<T>::is_integer && !std::numeric_limits<T>::is_signed );
 
-    BOOST_STATIC_ASSERT( sizeof(T) == sizeof(boost::uint8_t) || sizeof(T) == sizeof(boost::uint16_t) || sizeof(T) == sizeof(boost::uint32_t) || sizeof(T) == sizeof(boost::uint64_t) );
+    BOOST_CORE_STATIC_ASSERT( sizeof(T) == sizeof(boost::uint8_t) || sizeof(T) == sizeof(boost::uint16_t) || sizeof(T) == sizeof(boost::uint32_t) || sizeof(T) == sizeof(boost::uint64_t) );
 
     BOOST_IF_CONSTEXPR ( sizeof(T) == sizeof(boost::uint8_t) )
     {
@@ -548,7 +548,7 @@ BOOST_CXX14_CONSTEXPR int countr_zero( T x ) BOOST_NOEXCEPT
 template<class T>
 BOOST_CONSTEXPR int countr_one( T x ) BOOST_NOEXCEPT
 {
-    BOOST_STATIC_ASSERT( std::numeric_limits<T>::is_integer && !std::numeric_limits<T>::is_signed );
+    BOOST_CORE_STATIC_ASSERT( std::numeric_limits<T>::is_integer && !std::numeric_limits<T>::is_signed );
 
     return boost::core::countr_zero( static_cast<T>( ~x ) );
 }
@@ -598,7 +598,7 @@ BOOST_CORE_POPCOUNT_CONSTEXPR inline int popcount_impl( boost::ulong_long_type x
 template<class T>
 BOOST_CONSTEXPR int popcount( T x ) BOOST_NOEXCEPT
 {
-    BOOST_STATIC_ASSERT( std::numeric_limits<T>::is_integer && !std::numeric_limits<T>::is_signed );
+    BOOST_CORE_STATIC_ASSERT( std::numeric_limits<T>::is_integer && !std::numeric_limits<T>::is_signed );
 
     return boost::core::detail::popcount_impl( x );
 }
@@ -631,9 +631,9 @@ BOOST_CXX14_CONSTEXPR inline int popcount_impl( boost::uint64_t x ) BOOST_NOEXCE
 template<class T>
 BOOST_CXX14_CONSTEXPR int popcount( T x ) BOOST_NOEXCEPT
 {
-    BOOST_STATIC_ASSERT( std::numeric_limits<T>::is_integer && !std::numeric_limits<T>::is_signed );
+    BOOST_CORE_STATIC_ASSERT( std::numeric_limits<T>::is_integer && !std::numeric_limits<T>::is_signed );
 
-    BOOST_STATIC_ASSERT( sizeof(T) <= sizeof(boost::uint64_t) );
+    BOOST_CORE_STATIC_ASSERT( sizeof(T) <= sizeof(boost::uint64_t) );
 
     BOOST_IF_CONSTEXPR ( sizeof(T) <= sizeof(boost::uint32_t) )
     {
@@ -652,7 +652,7 @@ BOOST_CXX14_CONSTEXPR int popcount( T x ) BOOST_NOEXCEPT
 template<class T>
 BOOST_CXX14_CONSTEXPR T rotl( T x, int s ) BOOST_NOEXCEPT
 {
-    BOOST_STATIC_ASSERT( std::numeric_limits<T>::is_integer && !std::numeric_limits<T>::is_signed );
+    BOOST_CORE_STATIC_ASSERT( std::numeric_limits<T>::is_integer && !std::numeric_limits<T>::is_signed );
 
     unsigned const mask = std::numeric_limits<T>::digits - 1;
     return static_cast<T>( x << (static_cast<unsigned>( s ) & mask) | x >> (static_cast<unsigned>( -s ) & mask) );
@@ -661,7 +661,7 @@ BOOST_CXX14_CONSTEXPR T rotl( T x, int s ) BOOST_NOEXCEPT
 template<class T>
 BOOST_CXX14_CONSTEXPR T rotr( T x, int s ) BOOST_NOEXCEPT
 {
-    BOOST_STATIC_ASSERT( std::numeric_limits<T>::is_integer && !std::numeric_limits<T>::is_signed );
+    BOOST_CORE_STATIC_ASSERT( std::numeric_limits<T>::is_integer && !std::numeric_limits<T>::is_signed );
 
     unsigned const mask = std::numeric_limits<T>::digits - 1;
     return static_cast<T>( x >> (static_cast<unsigned>( s ) & mask) | x << (static_cast<unsigned>( -s ) & mask) );
@@ -672,7 +672,7 @@ BOOST_CXX14_CONSTEXPR T rotr( T x, int s ) BOOST_NOEXCEPT
 template<class T>
 BOOST_CONSTEXPR bool has_single_bit( T x ) BOOST_NOEXCEPT
 {
-    BOOST_STATIC_ASSERT( std::numeric_limits<T>::is_integer && !std::numeric_limits<T>::is_signed );
+    BOOST_CORE_STATIC_ASSERT( std::numeric_limits<T>::is_integer && !std::numeric_limits<T>::is_signed );
 
     return x != 0 && ( x & ( x - 1 ) ) == 0;
 }
@@ -683,7 +683,7 @@ BOOST_CONSTEXPR bool has_single_bit( T x ) BOOST_NOEXCEPT
 template<class T>
 BOOST_CONSTEXPR int bit_width( T x ) BOOST_NOEXCEPT
 {
-    BOOST_STATIC_ASSERT( std::numeric_limits<T>::is_integer && !std::numeric_limits<T>::is_signed );
+    BOOST_CORE_STATIC_ASSERT( std::numeric_limits<T>::is_integer && !std::numeric_limits<T>::is_signed );
 
     return std::numeric_limits<T>::digits - boost::core::countl_zero( x );
 }
@@ -691,7 +691,7 @@ BOOST_CONSTEXPR int bit_width( T x ) BOOST_NOEXCEPT
 template<class T>
 BOOST_CONSTEXPR T bit_floor( T x ) BOOST_NOEXCEPT
 {
-    BOOST_STATIC_ASSERT( std::numeric_limits<T>::is_integer && !std::numeric_limits<T>::is_signed );
+    BOOST_CORE_STATIC_ASSERT( std::numeric_limits<T>::is_integer && !std::numeric_limits<T>::is_signed );
 
     return x == 0? T(0): static_cast<T>( T(1) << ( boost::core::bit_width( x ) - 1 ) );
 }
@@ -745,9 +745,9 @@ BOOST_CXX14_CONSTEXPR inline boost::uint64_t bit_ceil_impl( boost::uint64_t x )
 template<class T>
 BOOST_CXX14_CONSTEXPR T bit_ceil( T x ) BOOST_NOEXCEPT
 {
-    BOOST_STATIC_ASSERT( std::numeric_limits<T>::is_integer && !std::numeric_limits<T>::is_signed );
+    BOOST_CORE_STATIC_ASSERT( std::numeric_limits<T>::is_integer && !std::numeric_limits<T>::is_signed );
 
-    BOOST_STATIC_ASSERT( sizeof(T) <= sizeof(boost::uint64_t) );
+    BOOST_CORE_STATIC_ASSERT( sizeof(T) <= sizeof(boost::uint64_t) );
 
     BOOST_IF_CONSTEXPR ( sizeof(T) <= sizeof(boost::uint32_t) )
     {
@@ -922,9 +922,9 @@ BOOST_CXX14_CONSTEXPR inline boost::uint64_t byteswap_impl( boost::uint64_t x )
 
 template<class T> BOOST_CXX14_CONSTEXPR T byteswap( T x ) BOOST_NOEXCEPT
 {
-    BOOST_STATIC_ASSERT( std::numeric_limits<T>::is_integer );
+    BOOST_CORE_STATIC_ASSERT( std::numeric_limits<T>::is_integer );
 
-    BOOST_STATIC_ASSERT( sizeof(T) == sizeof(boost::uint8_t) || sizeof(T) == sizeof(boost::uint16_t) || sizeof(T) == sizeof(boost::uint32_t) || sizeof(T) == sizeof(boost::uint64_t) );
+    BOOST_CORE_STATIC_ASSERT( sizeof(T) == sizeof(boost::uint8_t) || sizeof(T) == sizeof(boost::uint16_t) || sizeof(T) == sizeof(boost::uint32_t) || sizeof(T) == sizeof(boost::uint64_t) );
 
     BOOST_IF_CONSTEXPR ( sizeof(T) == sizeof(boost::uint8_t) )
     {

include/boost/core/cmath.hpp

@@ -20,8 +20,8 @@
 
 #if defined(BOOST_CORE_USE_GENERIC_CMATH) || (!defined(_MSC_VER) && !defined(FP_SUBNORMAL))
 
+#include <boost/core/detail/static_assert.hpp>
 #include <boost/cstdint.hpp>
-#include <boost/static_assert.hpp>
 #include <limits>
 #include <cstring>
 
@@ -81,7 +81,7 @@ inline bool signbit( float x )
 {
     boost::int32_t y;
 
-    BOOST_STATIC_ASSERT( sizeof( x ) == sizeof( y ) );
+    BOOST_CORE_STATIC_ASSERT( sizeof( x ) == sizeof( y ) );
 
     std::memcpy( &y, &x, sizeof( y ) );
 
@@ -92,7 +92,7 @@ inline bool signbit( double x )
 {
     boost::int64_t y;
 
-    BOOST_STATIC_ASSERT( sizeof( x ) == sizeof( y ) );
+    BOOST_CORE_STATIC_ASSERT( sizeof( x ) == sizeof( y ) );
 
     std::memcpy( &y, &x, sizeof( y ) );
 

include/boost/core/detail/static_assert.hpp

@@ -0,0 +1,42 @@
+#ifndef BOOST_CORE_DETAIL_STATIC_ASSERT_HPP_INCLUDED
+#define BOOST_CORE_DETAIL_STATIC_ASSERT_HPP_INCLUDED
+
+// Copyright 2025 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#if defined(__cpp_static_assert) && __cpp_static_assert >= 200410L
+
+#define BOOST_CORE_STATIC_ASSERT(...) static_assert(__VA_ARGS__, #__VA_ARGS__)
+
+#else
+
+#include <boost/config.hpp>
+#include <cstddef>
+
+namespace boost
+{
+namespace core
+{
+
+template<bool> struct STATIC_ASSERTION_FAILURE;
+
+template<> struct STATIC_ASSERTION_FAILURE<true>
+{
+};
+
+template<std::size_t> struct static_assert_test
+{
+};
+
+} // namespace core
+} // namespace boost
+
+#define BOOST_CORE_STATIC_ASSERT(expr) \
+    typedef ::boost::core::static_assert_test< \
+        sizeof( ::boost::core::STATIC_ASSERTION_FAILURE<(expr)? true: false> ) \
+    > BOOST_JOIN(boost_static_assert_typedef_,__LINE__) BOOST_ATTRIBUTE_UNUSED
+
+#endif
+
+#endif  // #ifndef BOOST_CORE_DETAIL_STATIC_ASSERT_HPP_INCLUDED

include/boost/core/lightweight_test.hpp

@@ -156,18 +156,15 @@ inline void no_throw_failed_impl(const char* expr, const char* what, const char*
 # pragma GCC diagnostic ignored "-Wsign-conversion"
 #endif
 
-// specialize test output for char pointers to avoid printing as cstring
-template <class T> inline const T& test_output_impl(const T& v) { return v; }
-inline const void* test_output_impl(const char* v) { return v; }
-inline const void* test_output_impl(const unsigned char* v) { return v; }
-inline const void* test_output_impl(const signed char* v) { return v; }
-inline const void* test_output_impl(char* v) { return v; }
-inline const void* test_output_impl(unsigned char* v) { return v; }
-inline const void* test_output_impl(signed char* v) { return v; }
-template<class T> inline const void* test_output_impl(T volatile* v) { return const_cast<T*>(v); }
+// specialize test output for pointers to avoid printing as cstring
+
+template<class T> inline T const& test_output_impl( T const& v ) { return v; }
+
+template<class T> inline void const* test_output_impl( T* const& v ) { return v; }
+template<class T> inline void const* test_output_impl( T volatile* const& v ) { return const_cast<T*>(v); }
 
 #if !defined( BOOST_NO_CXX11_NULLPTR )
-inline const void* test_output_impl(std::nullptr_t) { return nullptr; }
+inline const void* test_output_impl( std::nullptr_t ) { return nullptr; }
 #endif
 
 // print chars as numeric
@@ -551,22 +548,15 @@ inline void lwt_init()
 #define BOOST_TEST_ALL_EQ(begin1, end1, begin2, end2) ( ::boost::detail::test_all_eq_impl(BOOST_LIGHTWEIGHT_TEST_OSTREAM, __FILE__, __LINE__, BOOST_CURRENT_FUNCTION, begin1, end1, begin2, end2) )
 #define BOOST_TEST_ALL_WITH(begin1, end1, begin2, end2, predicate) ( ::boost::detail::test_all_with_impl(BOOST_LIGHTWEIGHT_TEST_OSTREAM, __FILE__, __LINE__, BOOST_CURRENT_FUNCTION, begin1, end1, begin2, end2, predicate) )
 
-#if !defined(BOOST_MSVC) || (BOOST_MSVC >= 1900)
-// The usual idiom for multiline macros. But disabled for MSVC versions
-// prior to 2015, which would emit a "conditional expression is constant"
-// warning that we could not silence with a _Pragma, despite this being
-// the same thing described here:
-//
-// <https://learn.microsoft.com/en-us/cpp/preprocessor/pragma-directives-and-the-pragma-keyword?view=msvc-140>.
-//
-   #define BOOST_LWT_DETAIL_DO_WHILE_FALSE( x ) do { x } while (false)
+#if defined(BOOST_MSVC) && BOOST_MSVC < 1900
+# define BOOST_LWT_DETAIL_WHILE_FALSE __pragma(warning(push)) __pragma(warning(disable:4127)) while(false) __pragma(warning(pop))
 #else
-   #define BOOST_LWT_DETAIL_DO_WHILE_FALSE( x ) x
+# define BOOST_LWT_DETAIL_WHILE_FALSE while(false)
 #endif
 
 #ifndef BOOST_NO_EXCEPTIONS
    #define BOOST_TEST_THROWS( EXPR, EXCEP )                              \
-      BOOST_LWT_DETAIL_DO_WHILE_FALSE(                                   \
+      do {                                                               \
          try {                                                           \
             EXPR;                                                        \
             ::boost::detail::throw_failed_impl                           \
@@ -579,15 +569,14 @@ inline void lwt_init()
             ::boost::detail::throw_failed_impl                           \
             (#EXPR, #EXCEP, __FILE__, __LINE__, BOOST_CURRENT_FUNCTION); \
          }                                                               \
-      )
-   //
+      } BOOST_LWT_DETAIL_WHILE_FALSE
 #else
-   #define BOOST_TEST_THROWS( EXPR, EXCEP ) BOOST_LWT_DETAIL_DO_WHILE_FALSE((void)0;)
+   #define BOOST_TEST_THROWS( EXPR, EXCEP ) do {} BOOST_LWT_DETAIL_WHILE_FALSE
 #endif
 
 #ifndef BOOST_NO_EXCEPTIONS
 #  define BOOST_TEST_NO_THROW(EXPR)                                        \
-     BOOST_LWT_DETAIL_DO_WHILE_FALSE(                                      \
+    do {                                                                   \
         try {                                                              \
             EXPR;                                                          \
         } catch (const std::exception& e) {                                \
@@ -597,10 +586,9 @@ inline void lwt_init()
             ::boost::detail::no_throw_failed_impl                          \
             (#EXPR, __FILE__, __LINE__, BOOST_CURRENT_FUNCTION);           \
         }                                                                  \
-    )
-    //
+    } BOOST_LWT_DETAIL_WHILE_FALSE
 #else
-#  define BOOST_TEST_NO_THROW(EXPR) BOOST_LWT_DETAIL_DO_WHILE_FALSE(EXPR;)
+#  define BOOST_TEST_NO_THROW(EXPR) do { EXPR; } BOOST_LWT_DETAIL_WHILE_FALSE
 #endif
 
 #endif // #ifndef BOOST_CORE_LIGHTWEIGHT_TEST_HPP

include/boost/core/span.hpp

@@ -23,9 +23,15 @@ class span;
 
 namespace detail {
 
-template<class U, class T>
+template<class U, class T, class = void>
 struct span_convertible {
-    static constexpr bool value = std::is_convertible<U(*)[], T(*)[]>::value;
+    static constexpr bool value = false;
+};
+
+template<class U, class T>
+struct span_convertible<U, T, typename
+    std::enable_if<std::is_convertible<U(*)[], T(*)[]>::value>::type> {
+    static constexpr bool value = true;
 };
 
 template<std::size_t E, std::size_t N>

test/Jamfile.v2

@@ -14,6 +14,7 @@ import testing ;
 
 project : requirements
   <library>/boost/core//boost_core
+  <library>/boost/static_assert//boost_static_assert
   <library>/boost/type_traits//boost_type_traits
   <warnings>extra
   <toolset>msvc:<warnings-as-errors>on
@@ -176,6 +177,9 @@ run lightweight_test_with_test.cpp
   : : : $(pedantic-errors) ;
 run-fail lightweight_test_with_fail.cpp ;
 
+run lightweight_test_eq_ptr.cpp
+  : : : $(pedantic-errors) ;
+
 run is_same_test.cpp ;
 
 run typeinfo_test.cpp ;
@@ -469,3 +473,12 @@ run minstd_rand_test.cpp
 
 use-project /boost/core/swap : ./swap ;
 build-project ./swap ;
+
+compile static_assert_test.cpp ;
+compile static_assert_test2.cpp ;
+compile static_assert_test3.cpp ;
+
+compile-fail static_assert_fail.cpp ;
+compile-fail static_assert_fail2.cpp ;
+compile-fail static_assert_fail3.cpp ;
+compile-fail static_assert_fail4.cpp ;

test/cmake_subdir_test/CMakeLists.txt

@@ -9,7 +9,6 @@ project(cmake_subdir_test LANGUAGES CXX)
 add_subdirectory(../.. boostorg/core)
 add_subdirectory(../../../assert boostorg/assert)
 add_subdirectory(../../../config boostorg/config)
-add_subdirectory(../../../static_assert boostorg/static_assert)
 add_subdirectory(../../../throw_exception boostorg/throw_exception)
 
 add_executable(quick ../quick.cpp)

test/lightweight_test_eq_ptr.cpp

@@ -0,0 +1,106 @@
+// Copyright 2025 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/core/lightweight_test.hpp>
+#include <boost/config.hpp>
+
+int main()
+{
+    {
+        char const* p = "12";
+
+        BOOST_TEST_EQ( p, p );
+        BOOST_TEST_NE( p, p + 1 );
+    }
+
+    {
+        wchar_t const* p = L"12";
+
+        BOOST_TEST_EQ( p, p );
+        BOOST_TEST_NE( p, p + 1 );
+    }
+
+#if !defined( BOOST_NO_CXX11_CHAR16_T )
+
+    {
+        char16_t const* p = u"12";
+
+        BOOST_TEST_EQ( p, p );
+        BOOST_TEST_NE( p, p + 1 );
+    }
+
+#endif
+
+#if !defined( BOOST_NO_CXX11_CHAR32_T )
+
+    {
+        char32_t const* p = U"12";
+
+        BOOST_TEST_EQ( p, p );
+        BOOST_TEST_NE( p, p + 1 );
+    }
+
+#endif
+
+#if defined(__cpp_char8_t) && __cpp_char8_t >= 201811L
+
+    {
+        char8_t const* p = u8"12";
+
+        BOOST_TEST_EQ( p, p );
+        BOOST_TEST_NE( p, p + 1 );
+    }
+
+#endif
+
+    {
+        int v;
+        int volatile* p = &v;
+
+        BOOST_TEST_EQ( p, p );
+        BOOST_TEST_NE( p, p + 1 );
+    }
+
+    {
+        int v;
+        int const volatile* p = &v;
+
+        BOOST_TEST_EQ( p, p );
+        BOOST_TEST_NE( p, p + 1 );
+    }
+
+    {
+        char v;
+        char volatile* p = &v;
+
+        BOOST_TEST_EQ( p, p );
+        BOOST_TEST_NE( p, p + 1 );
+    }
+
+    {
+        char v;
+        char const volatile* p = &v;
+
+        BOOST_TEST_EQ( p, p );
+        BOOST_TEST_NE( p, p + 1 );
+    }
+
+    {
+        wchar_t v;
+        wchar_t volatile* p = &v;
+
+        BOOST_TEST_EQ( p, p );
+        BOOST_TEST_NE( p, p + 1 );
+    }
+
+    {
+        wchar_t v;
+        wchar_t const volatile* p = &v;
+
+        BOOST_TEST_EQ( p, p );
+        BOOST_TEST_NE( p, p + 1 );
+    }
+
+    return boost::report_errors();
+}

test/span_constructible_test.cpp

@@ -25,6 +25,20 @@ struct range {
     }
 };
 
+struct buffer {
+    void* data() {
+        return 0;
+    }
+
+    const void* data() const {
+        return 0;
+    }
+
+    std::size_t size() const {
+        return 0;
+    }
+};
+
 struct base { };
 
 struct derived
@@ -138,6 +152,10 @@ void test_range()
         const range<int>&>));
     BOOST_TEST_TRAIT_FALSE((std::is_constructible<boost::span<base>,
         range<derived>&>));
+    BOOST_TEST_TRAIT_FALSE((std::is_constructible<boost::span<int>,
+        buffer>));
+    BOOST_TEST_TRAIT_FALSE((std::is_constructible<boost::span<int>,
+        const buffer&>));
 }
 
 void test_initializer_list()

test/static_assert_fail.cpp

@@ -0,0 +1,11 @@
+// Copyright 2025 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/core/detail/static_assert.hpp>
+
+BOOST_CORE_STATIC_ASSERT( sizeof(char[1]) != 1 );
+
+int main()
+{
+}

test/static_assert_fail2.cpp

@@ -0,0 +1,14 @@
+// Copyright 2025 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/core/detail/static_assert.hpp>
+
+struct X
+{
+    BOOST_CORE_STATIC_ASSERT( sizeof(char[2]) != 2 );
+};
+
+int main()
+{
+}

test/static_assert_fail3.cpp

@@ -0,0 +1,10 @@
+// Copyright 2025 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/core/detail/static_assert.hpp>
+
+int main()
+{
+    BOOST_CORE_STATIC_ASSERT( sizeof(char[3]) != 3 );
+}

test/static_assert_fail4.cpp

@@ -0,0 +1,16 @@
+// Copyright 2025 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/core/detail/static_assert.hpp>
+
+template<int C> struct X
+{
+    BOOST_CORE_STATIC_ASSERT( C >= 0 );
+};
+
+int main()
+{
+    X< -4 > x;
+    (void)x;
+}

test/static_assert_test.cpp

@@ -0,0 +1,17 @@
+// Copyright 2025 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/core/detail/static_assert.hpp>
+
+BOOST_CORE_STATIC_ASSERT( sizeof(char[1]) == 1 );
+
+struct X
+{
+    BOOST_CORE_STATIC_ASSERT( sizeof(char[2]) == 2 );
+};
+
+int main()
+{
+    BOOST_CORE_STATIC_ASSERT( sizeof(char[3]) == 3 );
+}

test/static_assert_test2.cpp

@@ -0,0 +1,25 @@
+// Copyright 2025 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/core/detail/static_assert.hpp>
+
+template<int A, int B> struct plus
+{
+    static const int value = A + B;
+};
+
+BOOST_CORE_STATIC_ASSERT((plus<1, 2>::value == 3));
+
+template<int C> struct X
+{
+    BOOST_CORE_STATIC_ASSERT((plus<C, 1>::value == C + 1));
+};
+
+int main()
+{
+    BOOST_CORE_STATIC_ASSERT((plus<3, 4>::value == 7));
+
+    X<4> x;
+    (void)x;
+}

test/static_assert_test3.cpp

@@ -0,0 +1,16 @@
+// Copyright 2025 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/core/detail/static_assert.hpp>
+
+template<int C> struct X
+{
+    BOOST_CORE_STATIC_ASSERT( C >= 0 );
+};
+
+int main()
+{
+    X<4> x;
+    (void)x;
+}