| # =========================================================================== |
| # 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> |
| # |
| # 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 10 |
| |
| 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], [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 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 |
| ) |
| |
| 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++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 |
| |
| #error "This is not a C++11 compiler" |
| |
| #else |
| |
| namespace 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 void f() {} |
| }; |
| |
| struct Derived : public Base |
| { |
| 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++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 |
| |
| #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_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++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 |
| |
| #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 |
| |
| ]]) |