This is mostly a stub, it will require some improvements, no doubts about it.
It’s based on work I did on vcsn. commit c193a4c3291e95fd92d0274ef9e263772ffed2ae Author: Akim Demaille <[email protected]> Date: Sun Sep 16 18:20:56 2018 +0200 build: strengthen the C++ standard flag test On the CI, we have this spurious failure with clang 3.9 with -std=c++17: In file included from list.y:23: In file included from /usr/include/c++/4.8/iostream:39: In file included from /usr/include/c++/4.8/ostream:38: In file included from /usr/include/c++/4.8/ios:42: In file included from /usr/include/c++/4.8/bits/ios_base.h:41: In file included from /usr/include/c++/4.8/bits/locale_classes.h:40: In file included from /usr/include/c++/4.8/string:52: In file included from /usr/include/c++/4.8/bits/basic_string.h:2815: In file included from /usr/include/c++/4.8/ext/string_conversions.h:43: /usr/include/c++/4.8/cstdio:120:11: error: no member named 'gets' in the global namespace using ::gets; ~~^ This shows that our test, based on gl_WARN_ADD, is a joke. We have to really check for at least a bit of C++. * m4/ax_check_compile_flag.m4, m4/bison-cxx-std.m4: New. * configure.ac: Use them to make sure the compiler actually works. diff --git a/configure.ac b/configure.ac index f8faa2b7..a1c52b6d 100644 --- a/configure.ac +++ b/configure.ac @@ -21,7 +21,8 @@ # better to avoid a typo in the 'configure --help' entry for the YACC # environment variable. AC_PREREQ([2.68]) -m4_pattern_forbid([^gl_[A-Z]]) +m4_pattern_forbid([^_?(gl_[A-Z]|BISON_)]) +m4_pattern_allow([^BISON_USE_NLS$]) AC_INIT([GNU Bison], m4_esyscmd([build-aux/git-version-gen .tarball-version]), @@ -52,18 +53,6 @@ AC_CONFIG_HEADERS([lib/config.h:lib/config.in.h]) # Checks for the compiler. AC_PROG_CC_STDC AC_PROG_CXX -AC_LANG_PUSH([C++]) -gl_WARN_ADD([-fno-exceptions], [NO_EXCEPTIONS_CXXFLAGS]) -gl_WARN_ADD([-std=c++98], [CXX98_CXXFLAGS]) -gl_WARN_ADD([-std=c++03], [CXX03_CXXFLAGS]) -gl_WARN_ADD([-std=c++11], [CXX11_CXXFLAGS]) -gl_WARN_ADD([-std=c++14], [CXX14_CXXFLAGS]) -gl_WARN_ADD([-std=c++17], [CXX17_CXXFLAGS]) -gl_WARN_ADD([-std=c++2a], [CXX2A_CXXFLAGS]) -AC_SUBST([STDCXX_FLAGS], -["$CXX98_CXXFLAGS $CXX03_CXXFLAGS $CXX11_CXXFLAGS $CXX14_CXXFLAGS $CXX17_CXXFLAGS $CXX2A_CXXFLAGS "]) -AM_CONDITIONAL([ENABLE_CXX11], [test x"$CXX11_CXXFLAGS" != x]) -AC_LANG_POP([C++]) # Gnulib (early checks). gl_EARLY @@ -82,6 +71,19 @@ AC_CACHE_CHECK([whether pragma GCC diagnostic push works], [lv_cv_gcc_pragma_push_works=no]) CFLAGS=$save_CFLAGS]) +AC_LANG_PUSH([C++]) +gl_WARN_ADD([-fno-exceptions], [NO_EXCEPTIONS_CXXFLAGS]) +gl_WARN_ADD([-std=c++98], [CXX98_CXXFLAGS]) +gl_WARN_ADD([-std=c++03], [CXX03_CXXFLAGS]) +BISON_CXX_COMPILE_STDCXX_11 +BISON_CXX_COMPILE_STDCXX_14 +BISON_CXX_COMPILE_STDCXX_17 +gl_WARN_ADD([-std=c++2a], [CXX2A_CXXFLAGS]) +AC_SUBST([STDCXX_FLAGS], +["$CXX98_CXXFLAGS $CXX03_CXXFLAGS $CXX11_CXXFLAGS $CXX14_CXXFLAGS $CXX17_CXXFLAGS $CXX2A_CXXFLAGS "]) +AM_CONDITIONAL([ENABLE_CXX11], [test x"$CXX11_CXXFLAGS" != x]) +AC_LANG_POP([C++]) + AC_ARG_ENABLE([gcc-warnings], [ --enable-gcc-warnings turn on lots of GCC warnings (not recommended). Also, issue synclines from the examples/ to diff --git a/m4/ax_check_compile_flag.m4 b/m4/ax_check_compile_flag.m4 new file mode 100644 index 00000000..71d4f365 --- /dev/null +++ b/m4/ax_check_compile_flag.m4 @@ -0,0 +1,70 @@ +# =========================================================================== +# http://www.gnu.org/software/autoconf-archive/ax_check_compile_flag.html +# =========================================================================== +# +# SYNOPSIS +# +# AX_CHECK_COMPILE_FLAG(FLAG, [ACTION-SUCCESS], [ACTION-FAILURE], [EXTRA-FLAGS]) +# +# DESCRIPTION +# +# Check whether the given FLAG works with the current language's compiler +# or gives an error. (Warnings, however, are ignored) +# +# ACTION-SUCCESS/ACTION-FAILURE are shell commands to execute on +# success/failure. +# +# If EXTRA-FLAGS is defined, it is added to the current language's default +# flags (e.g. CFLAGS) when the check is done. The check is thus made with +# the flags: "CFLAGS EXTRA-FLAGS FLAG". This can for example be used to +# force the compiler to issue an error when a bad flag is given. +# +# NOTE: Implementation based on AX_CFLAGS_GCC_OPTION. Please keep this +# macro in sync with AX_CHECK_{PREPROC,LINK}_FLAG. +# +# LICENSE +# +# Copyright (c) 2008 Guido U. Draheim <[email protected]> +# Copyright (c) 2011 Maarten Bosmans <[email protected]> +# +# This program is free software: you can redistribute it and/or modify it +# under the terms of the GNU General Public License as published by the +# Free Software Foundation, either version 3 of the License, or (at your +# option) any later version. +# +# This program is distributed in the hope that it will be useful, but +# WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General +# Public License for more details. +# +# You should have received a copy of the GNU General Public License along +# with this program. If not, see <http://www.gnu.org/licenses/>. +# +# As a special exception, the respective Autoconf Macro's copyright owner +# gives unlimited permission to copy, distribute and modify the configure +# scripts that are the output of Autoconf when processing the Macro. You +# need not follow the terms of the GNU General Public License when using +# or distributing such scripts, even though portions of the text of the +# Macro appear in them. The GNU General Public License (GPL) does govern +# all other use of the material that constitutes the Autoconf Macro. +# +# This special exception to the GPL applies to versions of the Autoconf +# Macro released by the Autoconf Archive. When you make and distribute a +# modified version of the Autoconf Macro, you may extend this special +# exception to the GPL to apply to your modified version as well. + +#serial 2 + +AC_DEFUN([AX_CHECK_COMPILE_FLAG], +[AC_PREREQ(2.59)dnl for _AC_LANG_PREFIX +AS_VAR_PUSHDEF([CACHEVAR],[ax_cv_check_[]_AC_LANG_ABBREV[]flags_$4_$1])dnl +AC_CACHE_CHECK([whether _AC_LANG compiler accepts $1], CACHEVAR, [ + ax_check_save_flags=$[]_AC_LANG_PREFIX[]FLAGS + _AC_LANG_PREFIX[]FLAGS="$[]_AC_LANG_PREFIX[]FLAGS $4 $1" + AC_COMPILE_IFELSE([m4_default([$5], [AC_LANG_PROGRAM()])], + [AS_VAR_SET(CACHEVAR,[yes])], + [AS_VAR_SET(CACHEVAR,[no])]) + _AC_LANG_PREFIX[]FLAGS=$ax_check_save_flags]) +AS_IF([test x"AS_VAR_GET(CACHEVAR)" = xyes], [$2], [$3]) +AS_VAR_POPDEF([CACHEVAR])dnl +])dnl AX_CHECK_COMPILE_FLAGS diff --git a/m4/bison-cxx-std.m4 b/m4/bison-cxx-std.m4 new file mode 100644 index 00000000..f41216d4 --- /dev/null +++ b/m4/bison-cxx-std.m4 @@ -0,0 +1,148 @@ +# bison-cxx-std.m4 serial 1 + +# Copyright (C) 2018 Free Software Foundation, # Inc. + +# This file is free software; the Free Software Foundation +# gives unlimited permission to copy and/or distribute it, +# with or without modifications, as long as this notice is preserved. + +m4_define([_BISON_CXX_COMPILE_STDCXX_11_snippet], +[#include <algorithm> +#include <memory> +#include <set> +#include <sstream> +#include <string> +#include <vector> + + // C++11 + template <typename T> + struct check + { + static_assert(sizeof(int) <= sizeof(T), "not big enough"); + }; + + using right_angle_brackets = check<check<bool>>; + + auto f = std::make_shared<std::string>("shared_ptr"); + + int a; + decltype(a) b; + + typedef check<int> check_type; + check_type c; + check_type&& cr = static_cast<check_type&&>(c); + + auto d = a; + + // Some versions of libstdc++ do not support std::set::emplace. + void foo() + { + std::set<int> is; + is.emplace(42); + } + + // Clang++ 3.5, for a while, was unable to process properly + // the for-loop because its variable, r, is a typedef... + // It failed as follows: + // + // error: unexpected ':' in nested name specifier; did you mean '::'? + // for (auto r: std::set<int>{1, 2}) + // ^ + // :: + using r = std::set<int>; + void bar() + { + for (int r: std::set<int>{1, 2}) + continue; + } +]) + +m4_define([_BISON_CXX_COMPILE_STDCXX_14_snippet], +[ // C++14 + void mismatch() + { + using ints = std::vector<int>; + auto v1 = ints{1, 2, 3}; + auto v2 = ints{1, 2}; + std::mismatch(std::begin(v1), std::end(v1), + std::begin(v2), std::end(v2)); + } +]) + +m4_define([_BISON_CXX_COMPILE_STDCXX_17_snippet], +[ // C++17 + namespace ns1::ns2::ns3 {} + +#include <optional> + auto opt_string = std::optional<std::string>{}; + auto out = std::ostringstream{}; +]) + + +m4_define([_BISON_CXX_COMPILE_STDCXX_11_testbody], +[AC_LANG_SOURCE([ +_BISON_CXX_COMPILE_STDCXX_11_snippet +])]) + +m4_define([_BISON_CXX_COMPILE_STDCXX_14_testbody], +[AC_LANG_SOURCE([ +_BISON_CXX_COMPILE_STDCXX_11_snippet +_BISON_CXX_COMPILE_STDCXX_14_snippet +])]) + +m4_define([_BISON_CXX_COMPILE_STDCXX_17_testbody], +[AC_LANG_SOURCE([ +_BISON_CXX_COMPILE_STDCXX_11_snippet +_BISON_CXX_COMPILE_STDCXX_14_snippet +_BISON_CXX_COMPILE_STDCXX_17_snippet +])]) + + + +AC_DEFUN([BISON_CXX_COMPILE_STDCXX_11], +[AC_REQUIRE([AC_PROG_CXX]) +AC_LANG_PUSH([C++]) +for f in '-std=c++11' '-std=c++11 -stdlib=libc++' +do + AX_CHECK_COMPILE_FLAG([$f], [CXXFLAGS="$CXXFLAGS $f" stdpass=true], [], [], + [_BISON_CXX_COMPILE_STDCXX_11_testbody]) + if "${stdpass-false}"; then + CXX11_CXXFLAGS=$f + break + fi +done +AC_LANG_POP([C++]) +]) + + +AC_DEFUN([BISON_CXX_COMPILE_STDCXX_14], +[AC_REQUIRE([AC_PROG_CXX]) +AC_LANG_PUSH([C++]) +for f in '-std=c++14' '-std=c++14 -stdlib=libc++' +do + AX_CHECK_COMPILE_FLAG([$f], [CXXFLAGS="$CXXFLAGS $f" stdpass=true], [], [], + [_BISON_CXX_COMPILE_STDCXX_14_testbody]) + if "${stdpass-false}"; then + CXX14_CXXFLAGS=$f + break + fi +done +AC_LANG_POP([C++]) +]) + + +AC_DEFUN([BISON_CXX_COMPILE_STDCXX_17], +[AC_REQUIRE([AC_PROG_CXX]) +AC_LANG_PUSH([C++]) +for f in '-std=c++17' '-std=c++17 -stdlib=libc++' \ + '-std=c++1z' '-std=c++1z -stdlib=libc++' +do + AX_CHECK_COMPILE_FLAG([$f], [CXXFLAGS="$CXXFLAGS $f" stdpass=true], [], [], + [_BISON_CXX_COMPILE_STDCXX_17_testbody]) + if "${stdpass-false}"; then + CXX17_CXXFLAGS=$f + break + fi +done +AC_LANG_POP([C++]) +])
