From: Daniel Elstner Date: Mon, 24 Aug 2015 07:25:37 +0000 (+0200) Subject: Build: Add private copy of C++11 check macro X-Git-Tag: libsigrok-0.4.0~405 X-Git-Url: http://sigrok.org/gitweb/?p=libsigrok.git;a=commitdiff_plain;h=2d143826b0862a25a599825e50d78b58b53c67ac Build: Add private copy of C++11 check macro Place a copy of ax_cxx_compile_stdcxx_11.m4 from the Autoconf macro archive into our private m4/ directory. This is cleaner than trying to parse M4 file versions etc. Plus, the macro is now always available. --- diff --git a/configure.ac b/configure.ac index f7b2e489..7b3b24b1 100644 --- a/configure.ac +++ b/configure.ac @@ -252,9 +252,7 @@ AC_ARG_ENABLE([java], sr_cxx_missing= # Check if the C++ compiler supports the C++11 standard. -m4_ifdef([AX_CXX_COMPILE_STDCXX_11], - [AX_CXX_COMPILE_STDCXX_11(, [optional])], - [m4_warn([unsupported], [Missing macro AX_CXX_COMPILE_STDCXX_11: no C++11 check possible])]) +AX_CXX_COMPILE_STDCXX_11(, [optional]) AS_IF([test "x$HAVE_CXX11" != x1], [SR_APPEND([sr_cxx_missing], [', '], ['C++11'])]) diff --git a/m4/ax_cxx_compile_stdcxx_11.m4 b/m4/ax_cxx_compile_stdcxx_11.m4 new file mode 100644 index 00000000..163a4c64 --- /dev/null +++ b/m4/ax_cxx_compile_stdcxx_11.m4 @@ -0,0 +1,142 @@ +# ============================================================================ +# http://www.gnu.org/software/autoconf-archive/ax_cxx_compile_stdcxx_11.html +# ============================================================================ +# +# SYNOPSIS +# +# AX_CXX_COMPILE_STDCXX_11([ext|noext],[mandatory|optional]) +# +# DESCRIPTION +# +# Check for baseline language coverage in the compiler for the C++11 +# 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++11) or a strict conformance mode (e.g. +# -std=c++11). If neither is specified, you get whatever works, with +# preference for an extended mode. +# +# The second argument, if specified 'mandatory' or if left unspecified, +# indicates that baseline C++11 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_CXX11 if and only if a supporting mode is found. +# +# LICENSE +# +# Copyright (c) 2008 Benjamin Kosnik +# Copyright (c) 2012 Zack Weinberg +# Copyright (c) 2013 Roy Stogner +# Copyright (c) 2014 Alexey Sokolov +# +# 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 4 + +m4_define([_AX_CXX_COMPILE_STDCXX_11_testbody], [[ + template + 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> right_angle_brackets; + + int a; + decltype(a) b; + + typedef check check_type; + check_type c; + check_type&& cr = static_cast(c); + + auto d = a; + auto l = [](){}; +]]) + +AC_DEFUN([AX_CXX_COMPILE_STDCXX_11], [dnl + m4_if([$1], [], [], + [$1], [ext], [], + [$1], [noext], [], + [m4_fatal([invalid argument `$1' to AX_CXX_COMPILE_STDCXX_11])])dnl + m4_if([$2], [], [ax_cxx_compile_cxx11_required=true], + [$2], [mandatory], [ax_cxx_compile_cxx11_required=true], + [$2], [optional], [ax_cxx_compile_cxx11_required=false], + [m4_fatal([invalid second argument `$2' to AX_CXX_COMPILE_STDCXX_11])]) + AC_LANG_PUSH([C++])dnl + ac_success=no + AC_CACHE_CHECK(whether $CXX supports C++11 features by default, + ax_cv_cxx_compile_cxx11, + [AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_11_testbody])], + [ax_cv_cxx_compile_cxx11=yes], + [ax_cv_cxx_compile_cxx11=no])]) + if test x$ax_cv_cxx_compile_cxx11 = xyes; then + ac_success=yes + fi + + m4_if([$1], [noext], [], [dnl + if test x$ac_success = xno; then + for switch in -std=gnu++11 -std=gnu++0x; do + cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx11_$switch]) + AC_CACHE_CHECK(whether $CXX supports C++11 features with $switch, + $cachevar, + [ac_save_CXXFLAGS="$CXXFLAGS" + CXXFLAGS="$CXXFLAGS $switch" + AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_11_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++11 -std=c++0x; do + cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx11_$switch]) + AC_CACHE_CHECK(whether $CXX supports C++11 features with $switch, + $cachevar, + [ac_save_CXXFLAGS="$CXXFLAGS" + CXXFLAGS="$CXXFLAGS $switch" + AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_11_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_cxx11_required = xtrue; then + if test x$ac_success = xno; then + AC_MSG_ERROR([*** A compiler with support for C++11 language features is required.]) + fi + else + if test x$ac_success = xno; then + HAVE_CXX11=0 + AC_MSG_NOTICE([No compiler with C++11 support was found]) + else + HAVE_CXX11=1 + AC_DEFINE(HAVE_CXX11,1, + [define if the compiler supports basic C++11 syntax]) + fi + + AC_SUBST(HAVE_CXX11) + fi +])