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Updated stdcxx.m4 script to the latest version.
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The Autoconf macros in the m4 script now also support C++20. However,
the DCMTK Autoconf build system currently only makes use of the C++11
standard. This might change in the future.
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@jriesmeier
jriesmeier committed Mar 11, 2024
1 parent 4726d34 commit 94f771d
Showing 1 changed file with 84 additions and 46 deletions.
130 changes: 84 additions & 46 deletions config/stdcxx.m4
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Original file line number Diff line number Diff line change
Expand Up @@ -10,13 +10,13 @@
#
# 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
Expand All @@ -33,14 +33,17 @@
# Copyright (c) 2014, 2015 Google Inc.; contributed by Alexey Sokolov <[email protected]>
# Copyright (c) 2015 Paul Norman <[email protected]>
# Copyright (c) 2015 Moritz Klammler <[email protected]>
# Copyright (c) 2016 Krzesimir Nowak <[email protected]>
# Copyright (c) 2016, 2018 Krzesimir Nowak <[email protected]>
# Copyright (c) 2019 Enji Cooper <[email protected]>
# Copyright (c) 2020 Jason Merrill <[email protected]>
# Copyright (c) 2021 Joern Heusipp <[email protected]>
#
# 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
#serial 18

dnl This macro is based on the code from the AX_CXX_COMPILE_STDCXX_11 macro
dnl (serial version number 13).
Expand All @@ -49,6 +52,7 @@ 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], [],
Expand All @@ -60,14 +64,16 @@ AC_DEFUN([AX_CXX_COMPILE_STDCXX], [dnl
[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
Expand Down Expand Up @@ -98,9 +104,18 @@ AC_DEFUN([AX_CXX_COMPILE_STDCXX], [dnl
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}"; do
cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx$1_$switch])
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"
Expand Down Expand Up @@ -134,8 +149,8 @@ AC_DEFUN([AX_CXX_COMPILE_STDCXX], [dnl
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.])
AC_DEFINE(HAVE_CXX$1,1,
[define if the compiler supports basic C++$1 syntax])
fi
AC_SUBST(HAVE_CXX$1)
])
Expand All @@ -147,20 +162,31 @@ 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], [[
Expand All @@ -172,7 +198,11 @@ m4_define([_AX_CXX_COMPILE_STDCXX_testbody_new_in_11], [[
#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"
Expand All @@ -197,11 +227,13 @@ namespace cxx11
struct Base
{
virtual ~Base() {}
virtual void f() {}
};
struct Derived : public Base
{
virtual ~Derived() override {}
virtual void f() override {}
};
Expand Down Expand Up @@ -461,7 +493,7 @@ m4_define([_AX_CXX_COMPILE_STDCXX_testbody_new_in_14], [[
#error "This is not a C++ compiler"
#elif __cplusplus < 201402L
#elif __cplusplus < 201402L && !defined _MSC_VER
#error "This is not a C++14 compiler"
Expand Down Expand Up @@ -585,37 +617,25 @@ m4_define([_AX_CXX_COMPILE_STDCXX_testbody_new_in_17], [[
#error "This is not a C++ compiler"
#elif __cplusplus <= 201402L
#elif __cplusplus < 201703L && !defined _MSC_VER
#error "This is not a C++17 compiler"
#else
#if defined(__clang__)
#define REALLY_CLANG
#else
#if defined(__GNUC__)
#define REALLY_GCC
#endif
#endif
#include <initializer_list>
#include <utility>
#include <type_traits>
namespace cxx17
{
#if !defined(REALLY_CLANG)
namespace test_constexpr_lambdas
{
// TODO: test it with clang++ from git
constexpr int foo = [](){return 42;}();
}
#endif // !defined(REALLY_CLANG)
namespace test::nested_namespace::definitions
{
Expand Down Expand Up @@ -850,12 +870,9 @@ namespace cxx17
}
#if !defined(REALLY_CLANG)
namespace test_template_argument_deduction_for_class_templates
{
// TODO: test it with clang++ from git
template <typename T1, typename T2>
struct pair
{
Expand All @@ -874,7 +891,6 @@ namespace cxx17
}
}
#endif // !defined(REALLY_CLANG)
namespace test_non_type_auto_template_parameters
{
Expand All @@ -888,12 +904,9 @@ namespace cxx17
}
#if !defined(REALLY_CLANG)
namespace test_structured_bindings
{
// TODO: test it with clang++ from git
int arr[2] = { 1, 2 };
std::pair<int, int> pr = { 1, 2 };
Expand Down Expand Up @@ -925,14 +938,10 @@ namespace cxx17
const auto [ x3, y3 ] = f3();
}
#endif // !defined(REALLY_CLANG)
#if !defined(REALLY_CLANG)
namespace test_exception_spec_type_system
{
// TODO: test it with clang++ from git
struct Good {};
struct Bad {};
Expand All @@ -950,7 +959,6 @@ namespace cxx17
static_assert (std::is_same_v<Good, decltype(f(g1, g2))>);
}
#endif // !defined(REALLY_CLANG)
namespace test_inline_variables
{
Expand All @@ -975,6 +983,36 @@ namespace cxx17
} // namespace cxx17
#endif // __cplusplus <= 201402L
#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
]])

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