[vlc-commits] [Git][videolan/vlc][master] switch C++ support to C++17
Thomas Guillem (@tguillem)
gitlab at videolan.org
Fri Jan 26 10:59:11 UTC 2024
Thomas Guillem pushed to branch master at VideoLAN / VLC
Commits:
5dcc5ff8 by Steve Lhomme at 2024-01-26T10:42:23+00:00
switch C++ support to C++17
As contribs keep being updated with newer versions of the language, we need to
support a more modern version of C++ going forward.
Setting -std=c++17 should not break existing contribs that are built with C++11 or C++14.
In fact we already support the mix of versions between 11 and 14 without problem.
Modern C++ compilers are designed to take care of this [1].
When switching to a new C++ version there might however be some slight differences on how the
code is interpreted. These differences [2] might trigger some build errors for removed parts.
[1] https://stackoverflow.com/questions/46746878/is-it-safe-to-link-c17-c14-and-c11-objects
[2] https://www.open-std.org/JTC1/SC22/WG21/docs/papers/2018/p0636r3.html
- - - - -
6 changed files:
- configure.ac
- m4/Makefile.am
- + m4/ax_cxx_compile_stdcxx.m4
- + m4/ax_cxx_compile_stdcxx_17.m4
- − m4/stdcxx_14.m4
- meson.build
Changes:
=====================================
configure.ac
=====================================
@@ -73,7 +73,7 @@ AC_C_CONST
AC_C_INLINE
AC_C_RESTRICT
AC_LANG_PUSH([C++])
-AX_CXX_COMPILE_STDCXX_14([noext], [mandatory])
+AX_CXX_COMPILE_STDCXX_17([noext], [mandatory])
AX_CXX_TYPEOF
AC_LANG_POP([C++])
=====================================
m4/Makefile.am
=====================================
@@ -14,7 +14,7 @@ EXTRA_DIST = \
nls.m4 \
po.m4 \
progtest.m4 \
- stdcxx_14.m4 \
+ ax_cxx_compile_stdcxx.m4 \
+ ax_cxx_compile_stdcxx_17.m4 \
vlc.m4 \
$(NULL)
-
=====================================
m4/ax_cxx_compile_stdcxx.m4
=====================================
@@ -0,0 +1,1018 @@
+# ===========================================================================
+# https://www.gnu.org/software/autoconf-archive/ax_cxx_compile_stdcxx.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+# AX_CXX_COMPILE_STDCXX(VERSION, [ext|noext], [mandatory|optional])
+#
+# DESCRIPTION
+#
+# Check for baseline language coverage in the compiler for the specified
+# version of the C++ standard. If necessary, add switches to CXX and
+# CXXCPP to enable support. VERSION may be '11', '14', '17', or '20' for
+# the respective C++ standard version.
+#
+# The second argument, if specified, indicates whether you insist on an
+# extended mode (e.g. -std=gnu++11) or a strict conformance mode (e.g.
+# -std=c++11). If neither is specified, you get whatever works, with
+# preference for no added switch, and then for an extended mode.
+#
+# The third argument, if specified 'mandatory' or if left unspecified,
+# indicates that baseline support for the specified C++ standard is
+# required and that the macro should error out if no mode with that
+# support is found. If specified 'optional', then configuration proceeds
+# regardless, after defining HAVE_CXX${VERSION} if and only if a
+# supporting mode is found.
+#
+# LICENSE
+#
+# Copyright (c) 2008 Benjamin Kosnik <bkoz at redhat.com>
+# Copyright (c) 2012 Zack Weinberg <zackw at panix.com>
+# Copyright (c) 2013 Roy Stogner <roystgnr at ices.utexas.edu>
+# Copyright (c) 2014, 2015 Google Inc.; contributed by Alexey Sokolov <sokolov at google.com>
+# Copyright (c) 2015 Paul Norman <penorman at mac.com>
+# Copyright (c) 2015 Moritz Klammler <moritz at klammler.eu>
+# Copyright (c) 2016, 2018 Krzesimir Nowak <qdlacz at gmail.com>
+# Copyright (c) 2019 Enji Cooper <yaneurabeya at gmail.com>
+# Copyright (c) 2020 Jason Merrill <jason at redhat.com>
+# Copyright (c) 2021 Jörn Heusipp <osmanx at problemloesungsmaschine.de>
+#
+# 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 18
+
+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"],
+ [$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
+
+ 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 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"
+ dnl MSVC needs -std:c++NN for C++17 and later (default is C++14)
+ for alternative in ${ax_cxx_compile_alternatives}; do
+ for switch in -std=c++${alternative} +std=c++${alternative} "-h std=c++${alternative}" MSVC; do
+ if test x"$switch" = xMSVC; then
+ dnl AS_TR_SH maps both `:` and `=` to `_` so -std:c++17 would collide
+ dnl with -std=c++17. We suffix the cache variable name with _MSVC to
+ dnl avoid this.
+ switch=-std:c++${alternative}
+ cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx$1_${switch}_MSVC])
+ else
+ cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx$1_$switch])
+ fi
+ 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"
+
+// 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 <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++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 && !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_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 && !defined _MSC_VER
+
+#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 && !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 <version>
+
+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
+
+]])
=====================================
m4/ax_cxx_compile_stdcxx_17.m4
=====================================
@@ -0,0 +1,35 @@
+# =============================================================================
+# https://www.gnu.org/software/autoconf-archive/ax_cxx_compile_stdcxx_17.html
+# =============================================================================
+#
+# SYNOPSIS
+#
+# AX_CXX_COMPILE_STDCXX_17([ext|noext], [mandatory|optional])
+#
+# DESCRIPTION
+#
+# Check for baseline language coverage in the compiler for the C++17
+# standard; if necessary, add switches to CXX and CXXCPP to enable
+# support.
+#
+# This macro is a convenience alias for calling the AX_CXX_COMPILE_STDCXX
+# macro with the version set to C++17. The two optional arguments are
+# forwarded literally as the second and third argument respectively.
+# Please see the documentation for the AX_CXX_COMPILE_STDCXX macro for
+# more information. If you want to use this macro, you also need to
+# download the ax_cxx_compile_stdcxx.m4 file.
+#
+# LICENSE
+#
+# Copyright (c) 2015 Moritz Klammler <moritz at klammler.eu>
+# Copyright (c) 2016 Krzesimir Nowak <qdlacz at 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 2
+
+AX_REQUIRE_DEFINED([AX_CXX_COMPILE_STDCXX])
+AC_DEFUN([AX_CXX_COMPILE_STDCXX_17], [AX_CXX_COMPILE_STDCXX([17], [$1], [$2])])
=====================================
m4/stdcxx_14.m4 deleted
=====================================
@@ -1,191 +0,0 @@
-# ============================================================================
-# Based on http://www.gnu.org/software/autoconf-archive/ax_cxx_compile_stdcxx_11.html
-# ============================================================================
-#
-# SYNOPSIS
-#
-# AX_CXX_COMPILE_STDCXX_14([ext|noext],[mandatory|optional])
-#
-# DESCRIPTION
-#
-# Check for baseline language coverage in the compiler for the C++14
-# standard; if necessary, add switches to CXXFLAGS to enable support.
-#
-# The first argument, if specified, indicates whether you insist on an
-# extended mode (e.g. -std=gnu++14) or a strict conformance mode (e.g.
-# -std=c++14). If neither is specified, you get whatever works, with
-# preference for an extended mode.
-#
-# The second argument, if specified 'mandatory' or if left unspecified,
-# indicates that baseline C++14 support 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_CXX14 if and only if a supporting mode is found.
-#
-# LICENSE
-#
-# Copyright (c) 2008 Benjamin Kosnik <bkoz at redhat.com>
-# Copyright (c) 2012 Zack Weinberg <zackw at panix.com>
-# Copyright (c) 2013 Roy Stogner <roystgnr at ices.utexas.edu>
-# Copyright (c) 2014 Alexey Sokolov <sokolov at google.com>
-# Copyright (c) 2014, 2015 Google Inc.
-# Copyright (c) 2015, 2019 VLC authors and VideoLAN
-#
-# 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 7
-
-m4_define([_AX_CXX_COMPILE_STDCXX_14_testbody], [[
- template <typename T>
- struct check
- {
- static_assert(sizeof(int) <= sizeof(T), "not big enough");
- };
-
- struct Base {
- virtual void f() {}
- };
- struct Child : public Base {
- virtual void f() override {}
- };
-
- typedef check<check<bool>> right_angle_brackets;
-
- int a;
- decltype(a) b;
-
- typedef check<int> check_type;
- check_type c;
- check_type&& cr = static_cast<check_type&&>(c);
-
- auto d = a;
- auto l = [](){};
-
- // 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() {
- func<foo>(0);
- }
- }
-
- #include <cinttypes>
- #include <climits>
- #include <cstddef>
-
- constexpr uint64_t constant_u64 = UINT64_C(0x100000000);
- constexpr unsigned constant_lim = UINT_MAX;
- const char *constant_fmt = "%" PRIu64, *constant_scn = "%" SCNu64;
- constexpr size_t constant_align = alignof (std::max_align_t);
-
- #include <memory>
-
- namespace lambda_init_capture
- {
- void foo()
- {
- std::unique_ptr<int> ptr(new int);
- auto lambda = [p = std::move(ptr)](){};
- lambda();
- }
- }
-
- #include <type_traits>
-
- namespace traits_helper_types
- {
- static_assert( std::is_same<char, std::remove_pointer_t<char*>>::value, "plonk" );
- }
-]])
-
-AC_DEFUN([AX_CXX_COMPILE_STDCXX_14], [dnl
- m4_if([$1], [], [],
- [$1], [ext], [],
- [$1], [noext], [],
- [m4_fatal([invalid argument `$1' to AX_CXX_COMPILE_STDCXX_14])])dnl
- m4_if([$2], [], [ax_cxx_compile_cxx14_required=true],
- [$2], [mandatory], [ax_cxx_compile_cxx14_required=true],
- [$2], [optional], [ax_cxx_compile_cxx14_required=false],
- [m4_fatal([invalid second argument `$2' to AX_CXX_COMPILE_STDCXX_14])])
- AC_LANG_PUSH([C++])dnl
- ac_success=no
- AC_CACHE_CHECK(whether $CXX supports C++14 features by default,
- ax_cv_cxx_compile_cxx14,
- [AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_14_testbody])],
- [ax_cv_cxx_compile_cxx14=yes],
- [ax_cv_cxx_compile_cxx14=no])])
- if test x$ax_cv_cxx_compile_cxx14 = xyes; then
- ac_success=yes
- fi
-
- m4_if([$1], [noext], [], [dnl
- if test x$ac_success = xno; then
- for switch in -std=gnu++14 -std=gnu++1y; do
- cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx14_$switch])
- AC_CACHE_CHECK(whether $CXX supports C++14 features with $switch,
- $cachevar,
- [ac_save_CXXFLAGS="$CXXFLAGS"
- CXXFLAGS="$CXXFLAGS $switch"
- AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_14_testbody])],
- [eval $cachevar=yes],
- [eval $cachevar=no])
- CXXFLAGS="$ac_save_CXXFLAGS"])
- if eval test x\$$cachevar = xyes; then
- CXXFLAGS="$CXXFLAGS $switch"
- ac_success=yes
- break
- fi
- done
- fi])
-
- m4_if([$1], [ext], [], [dnl
- if test x$ac_success = xno; then
- for switch in -std=c++14 -std=c++1y; do
- cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx14_$switch])
- AC_CACHE_CHECK(whether $CXX supports C++14 features with $switch,
- $cachevar,
- [ac_save_CXXFLAGS="$CXXFLAGS"
- CXXFLAGS="$CXXFLAGS $switch"
- AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_14_testbody])],
- [eval $cachevar=yes],
- [eval $cachevar=no])
- CXXFLAGS="$ac_save_CXXFLAGS"])
- if eval test x\$$cachevar = xyes; then
- CXXFLAGS="$CXXFLAGS $switch"
- ac_success=yes
- break
- fi
- done
- fi])
- AC_LANG_POP([C++])
- if test x$ax_cxx_compile_cxx14_required = xtrue; then
- if test x$ac_success = xno; then
- AC_MSG_ERROR([*** A compiler with support for C++14 language features is required.])
- fi
- else
- if test x$ac_success = xno; then
- HAVE_CXX14=0
- AC_MSG_NOTICE([No compiler with C++14 support was found])
- else
- HAVE_CXX14=1
- AC_DEFINE(HAVE_CXX14,1,
- [define if the compiler supports basic C++14 syntax])
- fi
-
- AC_SUBST(HAVE_CXX14)
- fi
-])
=====================================
meson.build
=====================================
@@ -1,6 +1,6 @@
project('VLC', ['c', 'cpp'],
version: '4.0.0-dev',
- default_options: ['c_std=gnu11', 'cpp_std=c++14'],
+ default_options: ['c_std=gnu11', 'cpp_std=c++17'],
meson_version: '>=0.60.0')
vlc_copyright_years = '1996-2018'
View it on GitLab: https://code.videolan.org/videolan/vlc/-/commit/5dcc5ff839b2b115aed35e9ead1f65d902ba820c
--
View it on GitLab: https://code.videolan.org/videolan/vlc/-/commit/5dcc5ff839b2b115aed35e9ead1f65d902ba820c
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