autoconf: Fix C++17 detection not working on Ubuntu 16.04.
And probably many other distributions.
Until now, ./configure would fail silently printing a warning
./configure: line 4621: AX_CXX_COMPILE_STDCXX_17: command not found
and then continuing, later failing with a C++ #error saying that some C++11
feature isn't supported (it didn't even get to the C++17 features).
This is because older distributions don't come with the
`AX_CXX_COMPILE_STDCXX_17` m4 macro.
This commit vendors that macro accordingly.
Now ./configure complains correctly:
configure: error: *** A compiler with support for C++17 language features is required.
On Ubuntu 16.04, ./configure completes if a newer compiler is used, e.g. with
gcc-7 from https://launchpad.net/~ubuntu-toolchain-r/+archive/ubuntu/test
using:
./bootstrap.sh
./configure CXX=g++-7 --disable-doc-gen --with-boost=$(nix-build --no-link '<nixpkgs>' -A boost.dev)
This commit is contained in:
Niklas Hambüchen
parent
1f97b16b1d
commit
57daa860e8
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@ -1,4 +1,5 @@
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AC_INIT(nix, m4_esyscmd([bash -c "echo -n $(cat ./.version)$VERSION_SUFFIX"]))
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AC_CONFIG_MACRO_DIRS([m4])
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AC_CONFIG_SRCDIR(README.md)
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AC_CONFIG_AUX_DIR(config)
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@ -62,7 +63,7 @@ CXXFLAGS=
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AC_PROG_CC
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AC_PROG_CXX
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AC_PROG_CPP
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AX_CXX_COMPILE_STDCXX_17
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AX_CXX_COMPILE_STDCXX_17([noext], [mandatory])
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AC_CHECK_TOOL([AR], [ar])
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@ -13,7 +13,7 @@
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<listitem><para>Bash Shell. The <literal>./configure</literal> script
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relies on bashisms, so Bash is required.</para></listitem>
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<listitem><para>A version of GCC or Clang that supports C++14.</para></listitem>
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<listitem><para>A version of GCC or Clang that supports C++17.</para></listitem>
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<listitem><para><command>pkg-config</command> to locate
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dependencies. If your distribution does not provide it, you can get
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951
m4/ax_cxx_compile_stdcxx.m4
Normal file
951
m4/ax_cxx_compile_stdcxx.m4
Normal file
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@ -0,0 +1,951 @@
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# ===========================================================================
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# https://www.gnu.org/software/autoconf-archive/ax_cxx_compile_stdcxx.html
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# ===========================================================================
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#
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# SYNOPSIS
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#
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# AX_CXX_COMPILE_STDCXX(VERSION, [ext|noext], [mandatory|optional])
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#
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# DESCRIPTION
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#
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# Check for baseline language coverage in the compiler for the specified
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# version of the C++ standard. If necessary, add switches to CXX and
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# CXXCPP to enable support. VERSION may be '11' (for the C++11 standard)
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# or '14' (for the C++14 standard).
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#
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# The second argument, if specified, indicates whether you insist on an
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# extended mode (e.g. -std=gnu++11) or a strict conformance mode (e.g.
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# -std=c++11). If neither is specified, you get whatever works, with
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# preference for an extended mode.
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#
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# The third argument, if specified 'mandatory' or if left unspecified,
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# indicates that baseline support for the specified C++ standard is
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# required and that the macro should error out if no mode with that
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# support is found. If specified 'optional', then configuration proceeds
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# regardless, after defining HAVE_CXX${VERSION} if and only if a
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# supporting mode is found.
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#
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# LICENSE
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#
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# Copyright (c) 2008 Benjamin Kosnik <bkoz@redhat.com>
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# Copyright (c) 2012 Zack Weinberg <zackw@panix.com>
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# Copyright (c) 2013 Roy Stogner <roystgnr@ices.utexas.edu>
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# Copyright (c) 2014, 2015 Google Inc.; contributed by Alexey Sokolov <sokolov@google.com>
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# Copyright (c) 2015 Paul Norman <penorman@mac.com>
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# Copyright (c) 2015 Moritz Klammler <moritz@klammler.eu>
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# Copyright (c) 2016, 2018 Krzesimir Nowak <qdlacz@gmail.com>
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# Copyright (c) 2019 Enji Cooper <yaneurabeya@gmail.com>
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#
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# Copying and distribution of this file, with or without modification, are
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# permitted in any medium without royalty provided the copyright notice
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# and this notice are preserved. This file is offered as-is, without any
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# warranty.
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#serial 11
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dnl This macro is based on the code from the AX_CXX_COMPILE_STDCXX_11 macro
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dnl (serial version number 13).
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AC_DEFUN([AX_CXX_COMPILE_STDCXX], [dnl
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m4_if([$1], [11], [ax_cxx_compile_alternatives="11 0x"],
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[$1], [14], [ax_cxx_compile_alternatives="14 1y"],
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[$1], [17], [ax_cxx_compile_alternatives="17 1z"],
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[m4_fatal([invalid first argument `$1' to AX_CXX_COMPILE_STDCXX])])dnl
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m4_if([$2], [], [],
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[$2], [ext], [],
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[$2], [noext], [],
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[m4_fatal([invalid second argument `$2' to AX_CXX_COMPILE_STDCXX])])dnl
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m4_if([$3], [], [ax_cxx_compile_cxx$1_required=true],
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[$3], [mandatory], [ax_cxx_compile_cxx$1_required=true],
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[$3], [optional], [ax_cxx_compile_cxx$1_required=false],
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[m4_fatal([invalid third argument `$3' to AX_CXX_COMPILE_STDCXX])])
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AC_LANG_PUSH([C++])dnl
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ac_success=no
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m4_if([$2], [noext], [], [dnl
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if test x$ac_success = xno; then
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for alternative in ${ax_cxx_compile_alternatives}; do
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switch="-std=gnu++${alternative}"
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cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx$1_$switch])
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AC_CACHE_CHECK(whether $CXX supports C++$1 features with $switch,
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$cachevar,
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[ac_save_CXX="$CXX"
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CXX="$CXX $switch"
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AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_testbody_$1])],
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[eval $cachevar=yes],
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[eval $cachevar=no])
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CXX="$ac_save_CXX"])
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if eval test x\$$cachevar = xyes; then
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CXX="$CXX $switch"
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if test -n "$CXXCPP" ; then
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CXXCPP="$CXXCPP $switch"
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fi
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ac_success=yes
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break
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fi
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done
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fi])
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m4_if([$2], [ext], [], [dnl
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if test x$ac_success = xno; then
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dnl HP's aCC needs +std=c++11 according to:
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dnl http://h21007.www2.hp.com/portal/download/files/unprot/aCxx/PDF_Release_Notes/769149-001.pdf
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dnl Cray's crayCC needs "-h std=c++11"
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for alternative in ${ax_cxx_compile_alternatives}; do
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for switch in -std=c++${alternative} +std=c++${alternative} "-h std=c++${alternative}"; do
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cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx$1_$switch])
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AC_CACHE_CHECK(whether $CXX supports C++$1 features with $switch,
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$cachevar,
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[ac_save_CXX="$CXX"
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CXX="$CXX $switch"
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AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_testbody_$1])],
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[eval $cachevar=yes],
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[eval $cachevar=no])
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CXX="$ac_save_CXX"])
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if eval test x\$$cachevar = xyes; then
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CXX="$CXX $switch"
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if test -n "$CXXCPP" ; then
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CXXCPP="$CXXCPP $switch"
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fi
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ac_success=yes
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break
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fi
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done
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if test x$ac_success = xyes; then
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break
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fi
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done
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fi])
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AC_LANG_POP([C++])
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if test x$ax_cxx_compile_cxx$1_required = xtrue; then
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if test x$ac_success = xno; then
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AC_MSG_ERROR([*** A compiler with support for C++$1 language features is required.])
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fi
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fi
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if test x$ac_success = xno; then
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HAVE_CXX$1=0
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AC_MSG_NOTICE([No compiler with C++$1 support was found])
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else
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HAVE_CXX$1=1
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AC_DEFINE(HAVE_CXX$1,1,
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[define if the compiler supports basic C++$1 syntax])
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fi
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AC_SUBST(HAVE_CXX$1)
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])
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dnl Test body for checking C++11 support
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m4_define([_AX_CXX_COMPILE_STDCXX_testbody_11],
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_AX_CXX_COMPILE_STDCXX_testbody_new_in_11
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)
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dnl Test body for checking C++14 support
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m4_define([_AX_CXX_COMPILE_STDCXX_testbody_14],
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_AX_CXX_COMPILE_STDCXX_testbody_new_in_11
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_AX_CXX_COMPILE_STDCXX_testbody_new_in_14
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)
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m4_define([_AX_CXX_COMPILE_STDCXX_testbody_17],
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_AX_CXX_COMPILE_STDCXX_testbody_new_in_11
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_AX_CXX_COMPILE_STDCXX_testbody_new_in_14
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_AX_CXX_COMPILE_STDCXX_testbody_new_in_17
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)
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dnl Tests for new features in C++11
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m4_define([_AX_CXX_COMPILE_STDCXX_testbody_new_in_11], [[
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// If the compiler admits that it is not ready for C++11, why torture it?
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// Hopefully, this will speed up the test.
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#ifndef __cplusplus
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#error "This is not a C++ compiler"
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#elif __cplusplus < 201103L
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#error "This is not a C++11 compiler"
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#else
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namespace cxx11
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{
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namespace test_static_assert
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{
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template <typename T>
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struct check
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{
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static_assert(sizeof(int) <= sizeof(T), "not big enough");
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};
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}
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namespace test_final_override
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{
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struct Base
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{
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virtual ~Base() {}
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virtual void f() {}
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};
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struct Derived : public Base
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{
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virtual ~Derived() override {}
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virtual void f() override {}
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};
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}
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namespace test_double_right_angle_brackets
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{
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template < typename T >
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struct check {};
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typedef check<void> single_type;
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typedef check<check<void>> double_type;
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typedef check<check<check<void>>> triple_type;
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typedef check<check<check<check<void>>>> quadruple_type;
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}
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namespace test_decltype
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{
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int
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f()
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{
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int a = 1;
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decltype(a) b = 2;
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return a + b;
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}
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}
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namespace test_type_deduction
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{
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template < typename T1, typename T2 >
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struct is_same
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{
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static const bool value = false;
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};
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template < typename T >
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struct is_same<T, T>
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{
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static const bool value = true;
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};
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template < typename T1, typename T2 >
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auto
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add(T1 a1, T2 a2) -> decltype(a1 + a2)
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{
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return a1 + a2;
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}
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int
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test(const int c, volatile int v)
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{
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static_assert(is_same<int, decltype(0)>::value == true, "");
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static_assert(is_same<int, decltype(c)>::value == false, "");
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static_assert(is_same<int, decltype(v)>::value == false, "");
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auto ac = c;
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auto av = v;
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auto sumi = ac + av + 'x';
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auto sumf = ac + av + 1.0;
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static_assert(is_same<int, decltype(ac)>::value == true, "");
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static_assert(is_same<int, decltype(av)>::value == true, "");
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static_assert(is_same<int, decltype(sumi)>::value == true, "");
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static_assert(is_same<int, decltype(sumf)>::value == false, "");
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static_assert(is_same<int, decltype(add(c, v))>::value == true, "");
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return (sumf > 0.0) ? sumi : add(c, v);
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}
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}
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namespace test_noexcept
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{
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int f() { return 0; }
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int g() noexcept { return 0; }
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|
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static_assert(noexcept(f()) == false, "");
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static_assert(noexcept(g()) == true, "");
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}
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namespace test_constexpr
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{
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template < typename CharT >
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unsigned long constexpr
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strlen_c_r(const CharT *const s, const unsigned long acc) noexcept
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{
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return *s ? strlen_c_r(s + 1, acc + 1) : acc;
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}
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template < typename CharT >
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unsigned long constexpr
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strlen_c(const CharT *const s) noexcept
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{
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return strlen_c_r(s, 0UL);
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}
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static_assert(strlen_c("") == 0UL, "");
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static_assert(strlen_c("1") == 1UL, "");
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static_assert(strlen_c("example") == 7UL, "");
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static_assert(strlen_c("another\0example") == 7UL, "");
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}
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namespace test_rvalue_references
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{
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template < int N >
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struct answer
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{
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static constexpr int value = N;
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};
|
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answer<1> f(int&) { return answer<1>(); }
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answer<2> f(const int&) { return answer<2>(); }
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answer<3> f(int&&) { return answer<3>(); }
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void
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test()
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{
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int i = 0;
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const int c = 0;
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static_assert(decltype(f(i))::value == 1, "");
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static_assert(decltype(f(c))::value == 2, "");
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static_assert(decltype(f(0))::value == 3, "");
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}
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|
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}
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|
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namespace test_uniform_initialization
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{
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|
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struct test
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{
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static const int zero {};
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static const int one {1};
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};
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|
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static_assert(test::zero == 0, "");
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static_assert(test::one == 1, "");
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|
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}
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namespace test_lambdas
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{
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|
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void
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test1()
|
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{
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auto lambda1 = [](){};
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auto lambda2 = lambda1;
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lambda1();
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lambda2();
|
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}
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int
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test2()
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{
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auto a = [](int i, int j){ return i + j; }(1, 2);
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auto b = []() -> int { return '0'; }();
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auto c = [=](){ return a + b; }();
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auto d = [&](){ return c; }();
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auto e = [a, &b](int x) mutable {
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const auto identity = [](int y){ return y; };
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for (auto i = 0; i < a; ++i)
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a += b--;
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return x + identity(a + b);
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}(0);
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return a + b + c + d + e;
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}
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|
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int
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test3()
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{
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const auto nullary = [](){ return 0; };
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const auto unary = [](int x){ return x; };
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using nullary_t = decltype(nullary);
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using unary_t = decltype(unary);
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const auto higher1st = [](nullary_t f){ return f(); };
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const auto higher2nd = [unary](nullary_t f1){
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return [unary, f1](unary_t f2){ return f2(unary(f1())); };
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};
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return higher1st(nullary) + higher2nd(nullary)(unary);
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}
|
||||
|
||||
}
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|
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namespace test_variadic_templates
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{
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template <int...>
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struct sum;
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|
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template <int N0, int... N1toN>
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struct sum<N0, N1toN...>
|
||||
{
|
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static constexpr auto value = N0 + sum<N1toN...>::value;
|
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};
|
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|
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template <>
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struct sum<>
|
||||
{
|
||||
static constexpr auto value = 0;
|
||||
};
|
||||
|
||||
static_assert(sum<>::value == 0, "");
|
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static_assert(sum<1>::value == 1, "");
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static_assert(sum<23>::value == 23, "");
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static_assert(sum<1, 2>::value == 3, "");
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static_assert(sum<5, 5, 11>::value == 21, "");
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static_assert(sum<2, 3, 5, 7, 11, 13>::value == 41, "");
|
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|
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}
|
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|
||||
// http://stackoverflow.com/questions/13728184/template-aliases-and-sfinae
|
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// Clang 3.1 fails with headers of libstd++ 4.8.3 when using std::function
|
||||
// because of this.
|
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namespace test_template_alias_sfinae
|
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{
|
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|
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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
|
||||
|
||||
]])
|
||||
35
m4/ax_cxx_compile_stdcxx_17.m4
Normal file
35
m4/ax_cxx_compile_stdcxx_17.m4
Normal file
|
|
@ -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@klammler.eu>
|
||||
# Copyright (c) 2016 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 2
|
||||
|
||||
AX_REQUIRE_DEFINED([AX_CXX_COMPILE_STDCXX])
|
||||
AC_DEFUN([AX_CXX_COMPILE_STDCXX_17], [AX_CXX_COMPILE_STDCXX([17], [$1], [$2])])
|
||||
Loading…
Reference in a new issue