Extract platform and feature detection to a separate file and add macro support for a number of C++20/23 features

.github/workflows/build.yml

@@ -4,15 +4,14 @@ on:
   push:
   pull_request:
 
-# TODO: Check different standards?
-
 jobs:
   build-linux:
     runs-on: ubuntu-22.04
     strategy:
       fail-fast: false
       matrix:
         compiler: [g++-10, clang++-14]
+        cxx_version: [ cxx_std_17, cxx_std_20 ]
         target: [Debug, Release]
     steps:
     - uses: actions/checkout@v2
@@ -24,7 +23,8 @@ jobs:
            cd build
            cmake .. \
             -DCMAKE_BUILD_TYPE=${{matrix.target}} \
-            -DCMAKE_CXX_COMPILER=${{matrix.compiler}}
+            -DCMAKE_CXX_COMPILER=${{matrix.compiler}} \
+            -DLIBASSERT_DESIRED_CXX_STANDARD="${{matrix.cxx_version}}"
            make -j
   build-macos:
     runs-on: macos-14
@@ -33,6 +33,7 @@ jobs:
       matrix:
         compiler: [g++-12, clang++]
         c_compiler: [g++-12, clang++]
+        cxx_version: [ cxx_std_17, cxx_std_20 ]
         target: [Debug, Release]
     steps:
     - uses: actions/checkout@v2
@@ -42,14 +43,16 @@ jobs:
            cd build
            cmake .. \
             -DCMAKE_BUILD_TYPE=${{matrix.target}} \
-            -DCMAKE_CXX_COMPILER=${{matrix.compiler}}
+            -DCMAKE_CXX_COMPILER=${{matrix.compiler}} \
+            -DLIBASSERT_DESIRED_CXX_STANDARD="${{matrix.cxx_version}}"
            make -j
   build-windows:
     runs-on: windows-2022
     strategy:
       fail-fast: false
       matrix:
         compiler: [cl, clang++]
+        cxx_version: [ cxx_std_17, cxx_std_20 ]
         target: [Debug, Release]
     steps:
     - uses: actions/checkout@v2
@@ -62,13 +65,15 @@ jobs:
            cmake .. `
             -DCMAKE_BUILD_TYPE=${{matrix.target}} `
             -DCMAKE_CXX_COMPILER=${{matrix.compiler}} `
+            -DLIBASSERT_DESIRED_CXX_STANDARD="${{matrix.cxx_version}}" `
            msbuild .\libassert.sln
   build-mingw:
     runs-on: windows-2022
     strategy:
       fail-fast: false
       matrix:
         compiler: [g++]
+        cxx_version: [ cxx_std_17, cxx_std_20 ]
         target: [Debug, Release]
     steps:
     - uses: actions/checkout@v2
@@ -81,5 +86,6 @@ jobs:
            cmake .. `
             -DCMAKE_BUILD_TYPE=${{matrix.target}} `
             -DCMAKE_CXX_COMPILER=${{matrix.compiler}} `
+            -DLIBASSERT_DESIRED_CXX_STANDARD="${{matrix.cxx_version}}" `
             "-GUnix Makefiles"
            make -j

.gitignore

@@ -1,8 +1,10 @@
 .vs
 .vscode
 .cache
+.idea
 scratch
 build*
+cmake-build-*
 __pycache__
 compile_commands.json
 CMakeUserPresets.json

CMakeLists.txt

@@ -8,6 +8,7 @@ include(cmake/PreventInSourceBuilds.cmake)
 # used to support find_package
 set(package_name "libassert")
 
+
 # create base project
 project(
   libassert
@@ -87,6 +88,7 @@ target_sources(
   ${target_name} PRIVATE
   # include
   include/libassert/assert.hpp
+  include/libassert/platform.hpp
 )
 
 # add /src files to target
@@ -152,11 +154,20 @@ target_include_directories(
   "$<BUILD_INTERFACE:${PROJECT_SOURCE_DIR}/include>"
 )
 
-# require C++17 support
-target_compile_features(
-  ${target_name}
-  PUBLIC cxx_std_17
-)
+# If the user has not defined a C++ standard, default to C++17
+if (NOT DEFINED LIBASSERT_DESIRED_CXX_STANDARD)
+  target_compile_features(
+    ${target_name}
+    PUBLIC cxx_std_17
+  )
+  message(STATUS "libassert: Using cxx_std_17 for target ${target_name}")
+else()
+  target_compile_features(
+    ${target_name}
+    PUBLIC ${LIBASSERT_DESIRED_CXX_STANDARD}
+  )
+  message(STATUS "libassert: Using ${LIBASSERT_DESIRED_CXX_STANDARD} for target ${target_name}")
+endif()
 
 if(LIBASSERT_SANITIZER_BUILD)
   add_compile_options(-fsanitize=address)

include/libassert/assert.hpp

@@ -23,13 +23,9 @@
  #include <expected>
 #endif
 
-#if defined(_MSVC_LANG) && _MSVC_LANG < 201703L
- #error "libassert requires C++17 or newer"
-#elif !defined(_MSVC_LANG) && __cplusplus < 201703L
- #pragma error "libassert requires C++17 or newer"
-#endif
+#include "libassert/platform.hpp"
 
-#if __cplusplus >= 202002L || (defined(_MSVC_LANG) && _MSVC_LANG >= 202002L)
+#if LIBASSERT_STD_VER >= 20
  #include <compare>
 #endif
 
@@ -56,81 +52,6 @@
 // Block comments are used to create some visual separation and try to break the library into more manageable parts.
 // I've tried as much as I can to keep logically connected parts together but there is some bootstrapping necessary.
 
-// =====================================================================================================================
-// || Preprocessor stuff                                                                                              ||
-// =====================================================================================================================
-
-#ifdef _WIN32
-#define LIBASSERT_EXPORT_ATTR __declspec(dllexport)
-#define LIBASSERT_IMPORT_ATTR __declspec(dllimport)
-#else
-#define LIBASSERT_EXPORT_ATTR __attribute__((visibility("default")))
-#define LIBASSERT_IMPORT_ATTR __attribute__((visibility("default")))
-#endif
-
-#ifdef LIBASSERT_STATIC_DEFINE
- #define LIBASSERT_EXPORT
- #define LIBASSERT_NO_EXPORT
-#else
- #ifndef LIBASSERT_EXPORT
-  #ifdef libassert_lib_EXPORTS
-   /* We are building this library */
-   #define LIBASSERT_EXPORT LIBASSERT_EXPORT_ATTR
-  #else
-   /* We are using this library */
-   #define LIBASSERT_EXPORT LIBASSERT_IMPORT_ATTR
-  #endif
- #endif
-#endif
-
-#define LIBASSERT_IS_CLANG 0
-#define LIBASSERT_IS_GCC 0
-#define LIBASSERT_IS_MSVC 0
-
-#if defined(__clang__)
- #undef LIBASSERT_IS_CLANG
- #define LIBASSERT_IS_CLANG 1
-#elif defined(__GNUC__) || defined(__GNUG__)
- #undef LIBASSERT_IS_GCC
- #define LIBASSERT_IS_GCC 1
-#elif defined(_MSC_VER)
- #undef LIBASSERT_IS_MSVC
- #define LIBASSERT_IS_MSVC 1
- #include <iso646.h> // alternative operator tokens are standard but msvc requires the include or /permissive- or /Za
-#else
- #error "Libassert: Unsupported compiler"
-#endif
-
-#if LIBASSERT_IS_CLANG || LIBASSERT_IS_GCC
- #define LIBASSERT_PFUNC __extension__ __PRETTY_FUNCTION__
- #define LIBASSERT_ATTR_COLD     [[gnu::cold]]
- #define LIBASSERT_ATTR_NOINLINE [[gnu::noinline]]
- #define LIBASSERT_UNREACHABLE_CALL __builtin_unreachable()
-#else
- #define LIBASSERT_PFUNC __FUNCSIG__
- #define LIBASSERT_ATTR_COLD
- #define LIBASSERT_ATTR_NOINLINE __declspec(noinline)
- #define LIBASSERT_UNREACHABLE_CALL __assume(false)
-#endif
-
-#if LIBASSERT_IS_MSVC
- #define LIBASSERT_STRONG_EXPECT(expr, value) (expr)
-#elif defined(__clang__) && __clang_major__ >= 11 || __GNUC__ >= 9
- #define LIBASSERT_STRONG_EXPECT(expr, value) __builtin_expect_with_probability((expr), (value), 1)
-#else
- #define LIBASSERT_STRONG_EXPECT(expr, value) __builtin_expect((expr), (value))
-#endif
-
-// deal with gcc shenanigans
-// at one point their std::string's move assignment was not noexcept even in c++17
-// https://gcc.gnu.org/onlinedocs/libstdc++/manual/using_dual_abi.html
-#if defined(_GLIBCXX_USE_CXX11_ABI)
- // NOLINTNEXTLINE(misc-include-cleaner)
- #define LIBASSERT_GCC_ISNT_STUPID _GLIBCXX_USE_CXX11_ABI
-#else
- // assume others target new abi by default - homework
- #define LIBASSERT_GCC_ISNT_STUPID 1
-#endif
 
 // always_false is just convenient to use here
 #define LIBASSERT_PHONY_USE(E) ((void)libassert::detail::always_false<decltype(E)>)
@@ -143,13 +64,6 @@
  #pragma warning(disable: 4251; disable: 4275)
 #endif
 
-#if LIBASSERT_IS_GCC || __cplusplus >= 2020002L
- // __VA_OPT__ needed for GCC, https://gcc.gnu.org/bugzilla/show_bug.cgi?id=44317
- #define LIBASSERT_VA_ARGS(...) __VA_OPT__(,) __VA_ARGS__
-#else
- // clang properly eats the comma with ##__VA_ARGS__
- #define LIBASSERT_VA_ARGS(...) , ##__VA_ARGS__
-#endif
 
 // =====================================================================================================================
 // || Core utilities                                                                                                  ||
@@ -1849,8 +1763,45 @@ namespace libassert {
  #define assert_val(expr, ...) LIBASSERT_INVOKE_VAL(expr, true, true, "assert_val", assertion, , __VA_ARGS__)
 #endif
 
+// Wrapper macro to allow support for C++26's user generated static_assert messages.
+// The backup message version also allows for the user to provide a backup version that will
+// be used if the compiler does not support user generated messages.
+// More info on user generated static_assert's
+// can be found here: https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2023/p2741r1.pdf
+//
+// Currently the functionality works as such. If we are in a C++26 environment, the user generated message will be used.
+// If we are not in a C++26 environment, then either the static_assert will be used without a message or the backup message.
+// TODO: Maybe give these a better name? Ideally one that is shorter and more descriptive?
+// TODO: Maybe add a helper to make passing user generated static_assert messages easier?
+#if defined(__cpp_static_assert) && __cpp_static_assert >= 202306L
+ #ifdef LIBASSERT_LOWERCASE
+  #define libassert_user_static_assert(cond, constant) static_assert(cond, constant)
+  #define libassert_user_static_assert_backup_msg(cond, msg, constant) static_assert(cond, constant)
+  #define user_static_assert(cond, constant) static_assert(cond, constant)
+  #define user_static_assert_backup_msg(cond, msg, constant) static_assert(cond, constant)
+ #else
+  #define LIBASSERT_USER_STATIC_ASSERT(cond, constant) static_assert(cond, constant)
+  #define LIBASSERT_USER_STATIC_ASSERT_BACKUP_MSG(cond, msg, constant) static_assert(cond, constant)
+  #define USER_STATIC_ASSERT(cond, constant) static_assert(cond, constant)
+  #define USER_STATIC_ASSERT_BACKUP_MSG(cond, msg, constant) static_assert(cond, constant)
+ #endif
+#else
+ #ifdef LIBASSERT_LOWERCASE
+  #define libassert_user_static_assert(cond, constant) static_assert(cond)
+  #define libassert_user_static_assert_backup_msg(cond, msg, constant) static_assert(cond, msg)
+  #define user_static_assert(cond, constant) static_assert(cond)
+  #define user_static_assert_backup_msg(cond, msg, constant) static_assert(cond, msg)
+ #else
+  #define LIBASSERT_USER_STATIC_ASSERT(cond, constant) static_assert(cond)
+  #define LIBASSERT_USER_STATIC_ASSERT_BACKUP_MSG(cond, msg, constant) static_assert(cond, msg)
+  #define USER_STATIC_ASSERT(cond, constant) static_assert(cond)
+  #define USER_STATIC_ASSERT_BACKUP_MSG(cond, msg, constant) static_assert(cond, msg)
+ #endif
 #endif
 
+
+#endif // LIBASSERT_HPP
+
 // Intentionally done outside the include guard. Libc++ leaks `assert` (among other things), so the include for
 // assert.hpp should go after other includes when using -DLIBASSERT_LOWERCASE.
 #ifdef LIBASSERT_LOWERCASE