diff --git a/m4/ax_cxx_compile_stdcxx.m4 b/m4/ax_cxx_compile_stdcxx.m4 index 8f45b67b..a3d964c6 100644 --- a/m4/ax_cxx_compile_stdcxx.m4 +++ b/m4/ax_cxx_compile_stdcxx.m4 @@ -1,558 +1,1009 @@ # =========================================================================== -# https://www.gnu.org/software/autoconf-archive/ax_cxx_compile_stdcxx.html +# https://www.gnu.org/software/autoconf-archive/ax_cxx_compile_stdcxx.html # =========================================================================== # # SYNOPSIS # # AX_CXX_COMPILE_STDCXX(VERSION, [ext|noext], [mandatory|optional]) # # DESCRIPTION # # Check for baseline language coverage in the compiler for the specified # version of the C++ standard. If necessary, add switches to CXX and -# CXXCPP to enable support. VERSION may be '11' (for the C++11 standard) -# or '14' (for the C++14 standard). +# CXXCPP to enable support. VERSION may be '11', '14', '17', or '20' for +# the respective C++ standard version. # # The second argument, if specified, indicates whether you insist on an # extended mode (e.g. -std=gnu++11) or a strict conformance mode (e.g. # -std=c++11). If neither is specified, you get whatever works, with -# preference for an extended mode. +# preference for no added switch, and then for an extended mode. # # The third argument, if specified 'mandatory' or if left unspecified, # indicates that baseline support for the specified C++ standard is # required and that the macro should error out if no mode with that # support is found. If specified 'optional', then configuration proceeds # regardless, after defining HAVE_CXX${VERSION} if and only if a # supporting mode is found. # # LICENSE # # Copyright (c) 2008 Benjamin Kosnik # Copyright (c) 2012 Zack Weinberg # Copyright (c) 2013 Roy Stogner # Copyright (c) 2014, 2015 Google Inc.; contributed by Alexey Sokolov # Copyright (c) 2015 Paul Norman # Copyright (c) 2015 Moritz Klammler +# Copyright (c) 2016, 2018 Krzesimir Nowak +# Copyright (c) 2019 Enji Cooper +# Copyright (c) 2020 Jason Merrill +# Copyright (c) 2021 Jörn Heusipp # # Copying and distribution of this file, with or without modification, are # permitted in any medium without royalty provided the copyright notice # and this notice are preserved. This file is offered as-is, without any # warranty. -#serial 4 +#serial 15 dnl This macro is based on the code from the AX_CXX_COMPILE_STDCXX_11 macro dnl (serial version number 13). AC_DEFUN([AX_CXX_COMPILE_STDCXX], [dnl - m4_if([$1], [11], [], - [$1], [14], [], - [$1], [17], [m4_fatal([support for C++17 not yet implemented in AX_CXX_COMPILE_STDCXX])], + m4_if([$1], [11], [ax_cxx_compile_alternatives="11 0x"], + [$1], [14], [ax_cxx_compile_alternatives="14 1y"], + [$1], [17], [ax_cxx_compile_alternatives="17 1z"], + [$1], [20], [ax_cxx_compile_alternatives="20"], [m4_fatal([invalid first argument `$1' to AX_CXX_COMPILE_STDCXX])])dnl m4_if([$2], [], [], [$2], [ext], [], [$2], [noext], [], [m4_fatal([invalid second argument `$2' to AX_CXX_COMPILE_STDCXX])])dnl m4_if([$3], [], [ax_cxx_compile_cxx$1_required=true], [$3], [mandatory], [ax_cxx_compile_cxx$1_required=true], [$3], [optional], [ax_cxx_compile_cxx$1_required=false], [m4_fatal([invalid third argument `$3' to AX_CXX_COMPILE_STDCXX])]) AC_LANG_PUSH([C++])dnl ac_success=no - AC_CACHE_CHECK(whether $CXX supports C++$1 features by default, - ax_cv_cxx_compile_cxx$1, - [AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_testbody_$1])], - [ax_cv_cxx_compile_cxx$1=yes], - [ax_cv_cxx_compile_cxx$1=no])]) - if test x$ax_cv_cxx_compile_cxx$1 = xyes; then - ac_success=yes - fi + + m4_if([$2], [], [dnl + AC_CACHE_CHECK(whether $CXX supports C++$1 features by default, + ax_cv_cxx_compile_cxx$1, + [AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_testbody_$1])], + [ax_cv_cxx_compile_cxx$1=yes], + [ax_cv_cxx_compile_cxx$1=no])]) + if test x$ax_cv_cxx_compile_cxx$1 = xyes; then + ac_success=yes + fi]) m4_if([$2], [noext], [], [dnl if test x$ac_success = xno; then - for switch in -std=gnu++$1 -std=gnu++0x; do + for alternative in ${ax_cxx_compile_alternatives}; do + switch="-std=gnu++${alternative}" cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx$1_$switch]) AC_CACHE_CHECK(whether $CXX supports C++$1 features with $switch, $cachevar, [ac_save_CXX="$CXX" CXX="$CXX $switch" AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_testbody_$1])], [eval $cachevar=yes], [eval $cachevar=no]) CXX="$ac_save_CXX"]) if eval test x\$$cachevar = xyes; then CXX="$CXX $switch" - CXXCPP="$CXXCPP $switch" + if test -n "$CXXCPP" ; then + CXXCPP="$CXXCPP $switch" + fi ac_success=yes break fi done fi]) m4_if([$2], [ext], [], [dnl if test x$ac_success = xno; then dnl HP's aCC needs +std=c++11 according to: dnl http://h21007.www2.hp.com/portal/download/files/unprot/aCxx/PDF_Release_Notes/769149-001.pdf dnl Cray's crayCC needs "-h std=c++11" - for switch in -std=c++$1 -std=c++0x +std=c++$1 "-h std=c++$1"; do - cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx$1_$switch]) - AC_CACHE_CHECK(whether $CXX supports C++$1 features with $switch, - $cachevar, - [ac_save_CXX="$CXX" - CXX="$CXX $switch" - AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_testbody_$1])], - [eval $cachevar=yes], - [eval $cachevar=no]) - CXX="$ac_save_CXX"]) - if eval test x\$$cachevar = xyes; then - CXX="$CXX $switch" - CXXCPP="$CXXCPP $switch" - ac_success=yes + for alternative in ${ax_cxx_compile_alternatives}; do + for switch in -std=c++${alternative} +std=c++${alternative} "-h std=c++${alternative}"; do + cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx$1_$switch]) + AC_CACHE_CHECK(whether $CXX supports C++$1 features with $switch, + $cachevar, + [ac_save_CXX="$CXX" + CXX="$CXX $switch" + AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_testbody_$1])], + [eval $cachevar=yes], + [eval $cachevar=no]) + CXX="$ac_save_CXX"]) + if eval test x\$$cachevar = xyes; then + CXX="$CXX $switch" + if test -n "$CXXCPP" ; then + CXXCPP="$CXXCPP $switch" + fi + ac_success=yes + break + fi + done + if test x$ac_success = xyes; then break fi done fi]) AC_LANG_POP([C++]) if test x$ax_cxx_compile_cxx$1_required = xtrue; then if test x$ac_success = xno; then AC_MSG_ERROR([*** A compiler with support for C++$1 language features is required.]) fi fi if test x$ac_success = xno; then HAVE_CXX$1=0 AC_MSG_NOTICE([No compiler with C++$1 support was found]) else HAVE_CXX$1=1 AC_DEFINE(HAVE_CXX$1,1, [define if the compiler supports basic C++$1 syntax]) fi AC_SUBST(HAVE_CXX$1) ]) dnl Test body for checking C++11 support m4_define([_AX_CXX_COMPILE_STDCXX_testbody_11], _AX_CXX_COMPILE_STDCXX_testbody_new_in_11 ) - dnl Test body for checking C++14 support m4_define([_AX_CXX_COMPILE_STDCXX_testbody_14], _AX_CXX_COMPILE_STDCXX_testbody_new_in_11 _AX_CXX_COMPILE_STDCXX_testbody_new_in_14 ) +dnl Test body for checking C++17 support + +m4_define([_AX_CXX_COMPILE_STDCXX_testbody_17], + _AX_CXX_COMPILE_STDCXX_testbody_new_in_11 + _AX_CXX_COMPILE_STDCXX_testbody_new_in_14 + _AX_CXX_COMPILE_STDCXX_testbody_new_in_17 +) + +dnl Test body for checking C++20 support + +m4_define([_AX_CXX_COMPILE_STDCXX_testbody_20], + _AX_CXX_COMPILE_STDCXX_testbody_new_in_11 + _AX_CXX_COMPILE_STDCXX_testbody_new_in_14 + _AX_CXX_COMPILE_STDCXX_testbody_new_in_17 + _AX_CXX_COMPILE_STDCXX_testbody_new_in_20 +) + dnl Tests for new features in C++11 m4_define([_AX_CXX_COMPILE_STDCXX_testbody_new_in_11], [[ // If the compiler admits that it is not ready for C++11, why torture it? // Hopefully, this will speed up the test. #ifndef __cplusplus #error "This is not a C++ compiler" -#elif __cplusplus < 201103L +// MSVC always sets __cplusplus to 199711L in older versions; newer versions +// only set it correctly if /Zc:__cplusplus is specified as well as a +// /std:c++NN switch: +// https://devblogs.microsoft.com/cppblog/msvc-now-correctly-reports-__cplusplus/ +#elif __cplusplus < 201103L && !defined _MSC_VER #error "This is not a C++11 compiler" #else namespace cxx11 { namespace test_static_assert { template struct check { static_assert(sizeof(int) <= sizeof(T), "not big enough"); }; } namespace test_final_override { struct Base { + virtual ~Base() {} virtual void f() {} }; struct Derived : public Base { + virtual ~Derived() override {} virtual void f() override {} }; } namespace test_double_right_angle_brackets { template < typename T > struct check {}; typedef check single_type; typedef check> double_type; typedef check>> triple_type; typedef check>>> quadruple_type; } namespace test_decltype { int f() { int a = 1; decltype(a) b = 2; return a + b; } } namespace test_type_deduction { template < typename T1, typename T2 > struct is_same { static const bool value = false; }; template < typename T > struct is_same { static const bool value = true; }; template < typename T1, typename T2 > auto add(T1 a1, T2 a2) -> decltype(a1 + a2) { return a1 + a2; } int test(const int c, volatile int v) { static_assert(is_same::value == true, ""); static_assert(is_same::value == false, ""); static_assert(is_same::value == false, ""); auto ac = c; auto av = v; auto sumi = ac + av + 'x'; auto sumf = ac + av + 1.0; static_assert(is_same::value == true, ""); static_assert(is_same::value == true, ""); static_assert(is_same::value == true, ""); static_assert(is_same::value == false, ""); static_assert(is_same::value == true, ""); return (sumf > 0.0) ? sumi : add(c, v); } } namespace test_noexcept { int f() { return 0; } int g() noexcept { return 0; } static_assert(noexcept(f()) == false, ""); static_assert(noexcept(g()) == true, ""); } namespace test_constexpr { template < typename CharT > unsigned long constexpr strlen_c_r(const CharT *const s, const unsigned long acc) noexcept { return *s ? strlen_c_r(s + 1, acc + 1) : acc; } template < typename CharT > unsigned long constexpr strlen_c(const CharT *const s) noexcept { return strlen_c_r(s, 0UL); } static_assert(strlen_c("") == 0UL, ""); static_assert(strlen_c("1") == 1UL, ""); static_assert(strlen_c("example") == 7UL, ""); static_assert(strlen_c("another\0example") == 7UL, ""); } namespace test_rvalue_references { template < int N > struct answer { static constexpr int value = N; }; answer<1> f(int&) { return answer<1>(); } answer<2> f(const int&) { return answer<2>(); } answer<3> f(int&&) { return answer<3>(); } void test() { int i = 0; const int c = 0; static_assert(decltype(f(i))::value == 1, ""); static_assert(decltype(f(c))::value == 2, ""); static_assert(decltype(f(0))::value == 3, ""); } } namespace test_uniform_initialization { struct test { static const int zero {}; static const int one {1}; }; static_assert(test::zero == 0, ""); static_assert(test::one == 1, ""); } namespace test_lambdas { void test1() { auto lambda1 = [](){}; auto lambda2 = lambda1; lambda1(); lambda2(); } int test2() { auto a = [](int i, int j){ return i + j; }(1, 2); auto b = []() -> int { return '0'; }(); auto c = [=](){ return a + b; }(); auto d = [&](){ return c; }(); auto e = [a, &b](int x) mutable { const auto identity = [](int y){ return y; }; for (auto i = 0; i < a; ++i) a += b--; return x + identity(a + b); }(0); return a + b + c + d + e; } int test3() { const auto nullary = [](){ return 0; }; const auto unary = [](int x){ return x; }; using nullary_t = decltype(nullary); using unary_t = decltype(unary); const auto higher1st = [](nullary_t f){ return f(); }; const auto higher2nd = [unary](nullary_t f1){ return [unary, f1](unary_t f2){ return f2(unary(f1())); }; }; return higher1st(nullary) + higher2nd(nullary)(unary); } } namespace test_variadic_templates { template struct sum; template struct sum { static constexpr auto value = N0 + sum::value; }; template <> struct sum<> { static constexpr auto value = 0; }; static_assert(sum<>::value == 0, ""); static_assert(sum<1>::value == 1, ""); static_assert(sum<23>::value == 23, ""); static_assert(sum<1, 2>::value == 3, ""); static_assert(sum<5, 5, 11>::value == 21, ""); static_assert(sum<2, 3, 5, 7, 11, 13>::value == 41, ""); } // http://stackoverflow.com/questions/13728184/template-aliases-and-sfinae // Clang 3.1 fails with headers of libstd++ 4.8.3 when using std::function // because of this. namespace test_template_alias_sfinae { struct foo {}; template using member = typename T::member_type; template void func(...) {} template void func(member*) {} void test(); void test() { func(0); } } } // namespace cxx11 #endif // __cplusplus >= 201103L ]]) dnl Tests for new features in C++14 m4_define([_AX_CXX_COMPILE_STDCXX_testbody_new_in_14], [[ // If the compiler admits that it is not ready for C++14, why torture it? // Hopefully, this will speed up the test. #ifndef __cplusplus #error "This is not a C++ compiler" -#elif __cplusplus < 201402L +#elif __cplusplus < 201402L && !defined _MSC_VER #error "This is not a C++14 compiler" #else namespace cxx14 { namespace test_polymorphic_lambdas { int test() { const auto lambda = [](auto&&... args){ const auto istiny = [](auto x){ return (sizeof(x) == 1UL) ? 1 : 0; }; const int aretiny[] = { istiny(args)... }; return aretiny[0]; }; return lambda(1, 1L, 1.0f, '1'); } } namespace test_binary_literals { constexpr auto ivii = 0b0000000000101010; static_assert(ivii == 42, "wrong value"); } namespace test_generalized_constexpr { template < typename CharT > constexpr unsigned long strlen_c(const CharT *const s) noexcept { auto length = 0UL; for (auto p = s; *p; ++p) ++length; return length; } static_assert(strlen_c("") == 0UL, ""); static_assert(strlen_c("x") == 1UL, ""); static_assert(strlen_c("test") == 4UL, ""); static_assert(strlen_c("another\0test") == 7UL, ""); } namespace test_lambda_init_capture { int test() { auto x = 0; const auto lambda1 = [a = x](int b){ return a + b; }; const auto lambda2 = [a = lambda1(x)](){ return a; }; return lambda2(); } } - namespace test_digit_seperators + namespace test_digit_separators { constexpr auto ten_million = 100'000'000; static_assert(ten_million == 100000000, ""); } namespace test_return_type_deduction { auto f(int& x) { return x; } decltype(auto) g(int& x) { return x; } template < typename T1, typename T2 > struct is_same { static constexpr auto value = false; }; template < typename T > struct is_same { static constexpr auto value = true; }; int test() { auto x = 0; static_assert(is_same::value, ""); static_assert(is_same::value, ""); return x; } } } // namespace cxx14 #endif // __cplusplus >= 201402L ]]) + + +dnl Tests for new features in C++17 + +m4_define([_AX_CXX_COMPILE_STDCXX_testbody_new_in_17], [[ + +// If the compiler admits that it is not ready for C++17, why torture it? +// Hopefully, this will speed up the test. + +#ifndef __cplusplus + +#error "This is not a C++ compiler" + +#elif __cplusplus < 201703L && !defined _MSC_VER + +#error "This is not a C++17 compiler" + +#else + +#include +#include +#include + +namespace cxx17 +{ + + namespace test_constexpr_lambdas + { + + constexpr int foo = [](){return 42;}(); + + } + + namespace test::nested_namespace::definitions + { + + } + + namespace test_fold_expression + { + + template + int multiply(Args... args) + { + return (args * ... * 1); + } + + template + bool all(Args... args) + { + return (args && ...); + } + + } + + namespace test_extended_static_assert + { + + static_assert (true); + + } + + namespace test_auto_brace_init_list + { + + auto foo = {5}; + auto bar {5}; + + static_assert(std::is_same, decltype(foo)>::value); + static_assert(std::is_same::value); + } + + namespace test_typename_in_template_template_parameter + { + + template typename X> struct D; + + } + + namespace test_fallthrough_nodiscard_maybe_unused_attributes + { + + int f1() + { + return 42; + } + + [[nodiscard]] int f2() + { + [[maybe_unused]] auto unused = f1(); + + switch (f1()) + { + case 17: + f1(); + [[fallthrough]]; + case 42: + f1(); + } + return f1(); + } + + } + + namespace test_extended_aggregate_initialization + { + + struct base1 + { + int b1, b2 = 42; + }; + + struct base2 + { + base2() { + b3 = 42; + } + int b3; + }; + + struct derived : base1, base2 + { + int d; + }; + + derived d1 {{1, 2}, {}, 4}; // full initialization + derived d2 {{}, {}, 4}; // value-initialized bases + + } + + namespace test_general_range_based_for_loop + { + + struct iter + { + int i; + + int& operator* () + { + return i; + } + + const int& operator* () const + { + return i; + } + + iter& operator++() + { + ++i; + return *this; + } + }; + + struct sentinel + { + int i; + }; + + bool operator== (const iter& i, const sentinel& s) + { + return i.i == s.i; + } + + bool operator!= (const iter& i, const sentinel& s) + { + return !(i == s); + } + + struct range + { + iter begin() const + { + return {0}; + } + + sentinel end() const + { + return {5}; + } + }; + + void f() + { + range r {}; + + for (auto i : r) + { + [[maybe_unused]] auto v = i; + } + } + + } + + namespace test_lambda_capture_asterisk_this_by_value + { + + struct t + { + int i; + int foo() + { + return [*this]() + { + return i; + }(); + } + }; + + } + + namespace test_enum_class_construction + { + + enum class byte : unsigned char + {}; + + byte foo {42}; + + } + + namespace test_constexpr_if + { + + template + int f () + { + if constexpr(cond) + { + return 13; + } + else + { + return 42; + } + } + + } + + namespace test_selection_statement_with_initializer + { + + int f() + { + return 13; + } + + int f2() + { + if (auto i = f(); i > 0) + { + return 3; + } + + switch (auto i = f(); i + 4) + { + case 17: + return 2; + + default: + return 1; + } + } + + } + + namespace test_template_argument_deduction_for_class_templates + { + + template + struct pair + { + pair (T1 p1, T2 p2) + : m1 {p1}, + m2 {p2} + {} + + T1 m1; + T2 m2; + }; + + void f() + { + [[maybe_unused]] auto p = pair{13, 42u}; + } + + } + + namespace test_non_type_auto_template_parameters + { + + template + struct B + {}; + + B<5> b1; + B<'a'> b2; + + } + + namespace test_structured_bindings + { + + int arr[2] = { 1, 2 }; + std::pair pr = { 1, 2 }; + + auto f1() -> int(&)[2] + { + return arr; + } + + auto f2() -> std::pair& + { + return pr; + } + + struct S + { + int x1 : 2; + volatile double y1; + }; + + S f3() + { + return {}; + } + + auto [ x1, y1 ] = f1(); + auto& [ xr1, yr1 ] = f1(); + auto [ x2, y2 ] = f2(); + auto& [ xr2, yr2 ] = f2(); + const auto [ x3, y3 ] = f3(); + + } + + namespace test_exception_spec_type_system + { + + struct Good {}; + struct Bad {}; + + void g1() noexcept; + void g2(); + + template + Bad + f(T*, T*); + + template + Good + f(T1*, T2*); + + static_assert (std::is_same_v); + + } + + namespace test_inline_variables + { + + template void f(T) + {} + + template inline T g(T) + { + return T{}; + } + + template<> inline void f<>(int) + {} + + template<> int g<>(int) + { + return 5; + } + + } + +} // namespace cxx17 + +#endif // __cplusplus < 201703L && !defined _MSC_VER + +]]) + + +dnl Tests for new features in C++20 + +m4_define([_AX_CXX_COMPILE_STDCXX_testbody_new_in_20], [[ + +#ifndef __cplusplus + +#error "This is not a C++ compiler" + +#elif __cplusplus < 202002L && !defined _MSC_VER + +#error "This is not a C++20 compiler" + +#else + +#include + +namespace cxx20 +{ + +// As C++20 supports feature test macros in the standard, there is no +// immediate need to actually test for feature availability on the +// Autoconf side. + +} // namespace cxx20 + +#endif // __cplusplus < 202002L && !defined _MSC_VER + +]])