git / moonbite-core / build-aux/m4/ax_cxx_compile_stdcxx.m4 · raw
# ===========================================================================# 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).## 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.## 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 <bkoz@redhat.com># Copyright (c) 2012 Zack Weinberg <zackw@panix.com># Copyright (c) 2013 Roy Stogner <roystgnr@ices.utexas.edu># Copyright (c) 2014, 2015 Google Inc.; contributed by Alexey Sokolov <sokolov@google.com># Copyright (c) 2015 Paul Norman <penorman@mac.com># Copyright (c) 2015 Moritz Klammler <moritz@klammler.eu># Copyright (c) 2016, 2018 Krzesimir Nowak <qdlacz@gmail.com># Copyright (c) 2019 Enji Cooper <yaneurabeya@gmail.com>## 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 11dnl This macro is based on the code from the AX_CXX_COMPILE_STDCXX_11 macrodnl (serial version number 13).AC_DEFUN([AX_CXX_COMPILE_STDCXX], [dnl 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"], [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 m4_if([$2], [noext], [], [dnl if test x$ac_success = xno; then 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 $switch" if test -n "$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 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 supportm4_define([_AX_CXX_COMPILE_STDCXX_testbody_11], _AX_CXX_COMPILE_STDCXX_testbody_new_in_11)dnl Test body for checking C++14 supportm4_define([_AX_CXX_COMPILE_STDCXX_testbody_14], _AX_CXX_COMPILE_STDCXX_testbody_new_in_11 _AX_CXX_COMPILE_STDCXX_testbody_new_in_14)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 Tests for new features in C++11m4_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#error "This is not a C++11 compiler"#elsenamespace cxx11{ namespace test_static_assert { template <typename T> 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<void> single_type; typedef check<check<void>> double_type; typedef check<check<check<void>>> triple_type; typedef check<check<check<check<void>>>> 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<T, T> { 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<int, decltype(0)>::value == true, ""); static_assert(is_same<int, decltype(c)>::value == false, ""); static_assert(is_same<int, decltype(v)>::value == false, ""); auto ac = c; auto av = v; auto sumi = ac + av + 'x'; auto sumf = ac + av + 1.0; static_assert(is_same<int, decltype(ac)>::value == true, ""); static_assert(is_same<int, decltype(av)>::value == true, ""); static_assert(is_same<int, decltype(sumi)>::value == true, ""); static_assert(is_same<int, decltype(sumf)>::value == false, ""); static_assert(is_same<int, decltype(add(c, v))>::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 <int...> struct sum; template <int N0, int... N1toN> struct sum<N0, N1toN...> { static constexpr auto value = N0 + sum<N1toN...>::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<typename T> using member = typename T::member_type; template<typename T> void func(...) {} template<typename T> void func(member<T>*) {} void test(); void test() { func<foo>(0); } }} // namespace cxx11#endif // __cplusplus >= 201103L]])dnl Tests for new features in C++14m4_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#error "This is not a C++14 compiler"#elsenamespace 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_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<T, T> { static constexpr auto value = true; }; int test() { auto x = 0; static_assert(is_same<int, decltype(f(x))>::value, ""); static_assert(is_same<int&, decltype(g(x))>::value, ""); return x; } }} // namespace cxx14#endif // __cplusplus >= 201402L]])dnl Tests for new features in C++17m4_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#error "This is not a C++17 compiler"#else#include <initializer_list>#include <utility>#include <type_traits>namespace cxx17{ namespace test_constexpr_lambdas { constexpr int foo = [](){return 42;}(); } namespace test::nested_namespace::definitions { } namespace test_fold_expression { template<typename... Args> int multiply(Args... args) { return (args * ... * 1); } template<typename... Args> 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<std::initializer_list<int>, decltype(foo)>::value); static_assert(std::is_same<int, decltype(bar)>::value); } namespace test_typename_in_template_template_parameter { template<template<typename> 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 <bool cond> 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 <typename T1, typename T2> 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 <auto n> struct B {}; B<5> b1; B<'a'> b2; } namespace test_structured_bindings { int arr[2] = { 1, 2 }; std::pair<int, int> pr = { 1, 2 }; auto f1() -> int(&)[2] { return arr; } auto f2() -> std::pair<int, int>& { 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<typename T> Bad f(T*, T*); template<typename T1, typename T2> Good f(T1*, T2*); static_assert (std::is_same_v<Good, decltype(f(g1, g2))>); } namespace test_inline_variables { template<class T> void f(T) {} template<class T> inline T g(T) { return T{}; } template<> inline void f<>(int) {} template<> int g<>(int) { return 5; } }} // namespace cxx17#endif // __cplusplus < 201703L]])