From 381af2d089d206de009b167b18e7bcacc1bb26cf Mon Sep 17 00:00:00 2001 From: Moritz Bunkus Date: Wed, 24 Apr 2024 09:16:22 +0200 Subject: [PATCH] require a C++20 compatible compiler --- NEWS.md | 2 + README.md | 9 ++- ac/c++-features.m4 | 189 +-------------------------------------------- 3 files changed, 11 insertions(+), 189 deletions(-) diff --git a/NEWS.md b/NEWS.md index 835bdfa72..3d01aef72 100644 --- a/NEWS.md +++ b/NEWS.md @@ -26,6 +26,8 @@ * Release v8.0.0 of the `fmt` library is now required. If not found, the bundled copy will be used. +* A C++20 compatible compiler is now required for several but certainly not + all C++20 features. g++ v10 & clang++ v10 should suffice. # Version 83.0 "Circle Of Friends" 2024-03-10 diff --git a/README.md b/README.md index 545643710..b05e79347 100644 --- a/README.md +++ b/README.md @@ -81,15 +81,16 @@ In order to compile MKVToolNix, you need a couple of libraries. Most of them should be available pre-compiled for your distribution. The programs and libraries you absolutely need are: -- A C++ compiler that supports several features of the C++11, C++14 - and C++17 standards: initializer lists, range-based `for` loops, +- A C++ compiler that supports several features of the C++11, C++14, + C++17 & C++20 standards: initializer lists, range-based `for` loops, right angle brackets, the `auto` keyword, lambda functions, the `nullptr` keyword, tuples, alias declarations, `std::make_unique()`, digit separators, binary literals, generic lambdas, user-defined literals for `std::string`, `[[maybe_unused]]` attribute, nested namespace definition, structured bindings, `std::optional`, - `std::regex`. Others may be needed, too. For GCC this means at least - v8; for clang v7 or later. + designated initializers, concepts, three-way comparison + operators. Others may be needed, too. For GCC this means at least + v10; for clang v10 or later. - [libOgg](http://downloads.xiph.org/releases/ogg/) and [libVorbis](http://downloads.xiph.org/releases/vorbis/) for access to Ogg/OGM diff --git a/ac/c++-features.m4 b/ac/c++-features.m4 index cec376f99..74b3852f1 100644 --- a/ac/c++-features.m4 +++ b/ac/c++-features.m4 @@ -1,10 +1,10 @@ AC_DEFUN([AX_CXX_STD_CXX_FLAG],[ - AC_CACHE_CHECK([for support for the "-std=c++20" or "-std=c++17" flag], [ax_cv_std_cxx_flag],[ + AC_CACHE_CHECK([for support for the "-std=c++20" flag], [ax_cv_std_cxx_flag],[ AC_LANG_PUSH(C++) CXXFLAGS_SAVED="$CXXFLAGS" - for flag in c++20 c++17; do + for flag in c++20; do CXXFLAGS="$CXXFLAGS_SAVED -std=$flag" AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[]], [[true;]])],[ax_cv_std_cxx_flag="-std=$flag"],[ax_cv_std_cxx_flag="undecided"]) @@ -24,158 +24,13 @@ AC_DEFUN([AX_CXX_STD_CXX_FLAG],[ STD_CXX="" if test x"$ax_cv_std_cxx_flag" != xno ; then STD_CXX=$ax_cv_std_cxx_flag + else + AC_MSG_ERROR([compiler does not support the -std=c++20 flag]) fi AC_SUBST(STD_CXX) ]) -AC_DEFUN([AX_CXX17_ATTRIBUTE_MAYBE_UNUSED],[ - AC_CACHE_CHECK([for support for C++17 feature "attribute 'maybe_unused'"], [ax_cv_cxx17_attribute_maybe_unused],[ - - CXXFLAGS_SAVED=$CXXFLAGS - CXXFLAGS="$CXXFLAGS $STD_CXX" - export CXXFLAGS - - AC_LANG_PUSH(C++) - AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[ -int testme([[maybe_unused]] int the_var) { - return 42; -} - ]], [[return testme(54);]])], - [ax_cv_cxx17_attribute_maybe_unused="yes"], - [ax_cv_cxx17_attribute_maybe_unused="no"]) - AC_LANG_POP - - CXXFLAGS="$CXXFLAGS_SAVED" - ]) - - if ! test x"$ax_cv_cxx17_attribute_maybe_unused" = xyes ; then - missing_cxx_features="$missing_cxx_features\n * attribute 'maybe_unused' (C++17)" - fi -]) - -AC_DEFUN([AX_CXX17_STRUCTURED_BINDINGS],[ - AC_CACHE_CHECK([for support for C++17 feature "structured bindings"], [ax_cv_cxx17_structured_bindings],[ - - CXXFLAGS_SAVED=$CXXFLAGS - CXXFLAGS="$CXXFLAGS $STD_CXX" - export CXXFLAGS - - AC_LANG_PUSH(C++) - AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[ -#include -std::pair testme() { - return std::make_pair(42, '!'); -} - ]], [[ -auto const &[the_int, the_char] = testme(); -return the_int; - ]])], - [ax_cv_cxx17_structured_bindings="yes"], - [ax_cv_cxx17_structured_bindings="no"]) - AC_LANG_POP - - CXXFLAGS="$CXXFLAGS_SAVED" - ]) - - if ! test x"$ax_cv_cxx17_structured_bindings" = xyes ; then - missing_cxx_features="$missing_cxx_features\n * structured bindings (C++17)" - fi -]) - -AC_DEFUN([AX_CXX17_NESTED_NAMESPACE_DEFINITION],[ - AC_CACHE_CHECK([for support for C++17 feature "nested namespace definition"], [ax_cv_cxx17_nested_namespace_definition],[ - - CXXFLAGS_SAVED=$CXXFLAGS - CXXFLAGS="$CXXFLAGS $STD_CXX" - export CXXFLAGS - - AC_LANG_PUSH(C++) - AC_COMPILE_IFELSE([AC_LANG_PROGRAM( - [[namespace A::B::C { int d; }]], - [[A::B::C::d = 1; return A::B::C::d;]])], - [ax_cv_cxx17_nested_namespace_definition="yes"], - [ax_cv_cxx17_nested_namespace_definition="no"]) - AC_LANG_POP - - CXXFLAGS="$CXXFLAGS_SAVED" - ]) - - if ! test x"$ax_cv_cxx17_nested_namespace_definition" = xyes ; then - missing_cxx_features="$missing_cxx_features\n * nested namespace definition (C++17)" - fi -]) - -AC_DEFUN([AX_CXX17_STD_OPTIONAL],[ - AC_CACHE_CHECK([for support for C++17 feature "std::optional"], [ax_cv_cxx17_std_optional],[ - - CXXFLAGS_SAVED=$CXXFLAGS - CXXFLAGS="$CXXFLAGS $STD_CXX" - export CXXFLAGS - - AC_LANG_PUSH(C++) - AC_COMPILE_IFELSE([AC_LANG_PROGRAM( - [[#include ]], [[ - std::optional moo; - moo = 42; - return moo ? moo.value() : moo.value_or(54); - ]])], - [ax_cv_cxx17_std_optional="yes"], - [ax_cv_cxx17_std_optional="no"]) - AC_LANG_POP - - CXXFLAGS="$CXXFLAGS_SAVED" - ]) - - if ! test x"$ax_cv_cxx17_std_optional" = xyes ; then - missing_cxx_features="$missing_cxx_features\n * std::optional (C++17)" - fi -]) - -AC_DEFUN([AX_CXX17_STD_GCD],[ - AC_CACHE_CHECK([for support for C++17 feature "std::gcd"], [ax_cv_cxx17_std_gcd],[ - - CXXFLAGS_SAVED=$CXXFLAGS - CXXFLAGS="$CXXFLAGS $STD_CXX" - export CXXFLAGS - - AC_LANG_PUSH(C++) - AC_COMPILE_IFELSE([AC_LANG_PROGRAM( - [[#include ]], - [[return std::gcd(42, 54);]])], - [ax_cv_cxx17_std_gcd="yes"], - [ax_cv_cxx17_std_gcd="no"]) - AC_LANG_POP - - CXXFLAGS="$CXXFLAGS_SAVED" - ]) - - if ! test x"$ax_cv_cxx17_std_gcd" = xyes ; then - missing_cxx_features="$missing_cxx_features\n * std::gcd (C++17)" - fi -]) - -AC_DEFUN([AX_CXX17_CONSTEXPR_IF],[ - AC_CACHE_CHECK([for support for C++17 feature "constexpr if"], [ax_cv_cxx17_constexpr_if],[ - - CXXFLAGS_SAVED=$CXXFLAGS - CXXFLAGS="$CXXFLAGS $STD_CXX" - export CXXFLAGS - - AC_LANG_PUSH(C++) - AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[]], [[if constexpr (true) return 42; else return 54;]])], - [ax_cv_cxx17_constexpr_if="yes"], - [ax_cv_cxx17_constexpr_if="no"]) - AC_LANG_POP - - CXXFLAGS="$CXXFLAGS_SAVED" - ]) - - if ! test x"$ax_cv_cxx17_constexpr_if" = xyes ; then - missing_cxx_features="$missing_cxx_features\n * constexpr if (C++17)" - fi -]) - AC_DEFUN([AX_CXX17_LIBSTDCPPFS],[ AC_CACHE_CHECK([for libraries to link against for the file system library], [ax_cv_cxx17_libstdcppfs],[ @@ -202,41 +57,5 @@ AC_DEFUN([AX_CXX17_LIBSTDCPPFS],[ AC_SUBST(STDCPPFS_LIBS) ]) -dnl AC_DEFUN([AX_CXX17_DEF_NAME],[ -dnl AC_CACHE_CHECK([for support for C++17 feature "human"], [ax_cv_cxx17_def_name],[ -dnl -dnl CXXFLAGS_SAVED=$CXXFLAGS -dnl CXXFLAGS="$CXXFLAGS $STD_CXX" -dnl export CXXFLAGS -dnl -dnl AC_LANG_PUSH(C++) -dnl AC_COMPILE_IFELSE([AC_LANG_PROGRAM( -dnl [[#include <…>]], -dnl [[code("…");]])], -dnl [ax_cv_cxx17_def_name="yes"], -dnl [ax_cv_cxx17_def_name="no"]) -dnl AC_LANG_POP -dnl -dnl CXXFLAGS="$CXXFLAGS_SAVED" -dnl ]) -dnl -dnl if ! test x"$ax_cv_cxx17_def_name" = xyes ; then -dnl missing_cxx_features="$missing_cxx_features\n * human (C++17)" -dnl fi -dnl ]) - AX_CXX_STD_CXX_FLAG -AX_CXX17_ATTRIBUTE_MAYBE_UNUSED -AX_CXX17_NESTED_NAMESPACE_DEFINITION -AX_CXX17_STRUCTURED_BINDINGS -AX_CXX17_STD_OPTIONAL -AX_CXX17_STD_GCD -AX_CXX17_CONSTEXPR_IF AX_CXX17_LIBSTDCPPFS - -if test x"$missing_cxx_features" != x ; then - printf "The following features of the C++17 standards are not supported by $CXX:$missing_cxx_features\n" - printf "If you are using the GNU C compiler collection (gcc), you need\n" - printf "at least v8; for clang v7 and newer should work.\n" - AC_MSG_ERROR([support for required C++17 features incomplete]) -fi