commit 5ce688f4193828197130b4c91c7c32b53b5b5568 Author: Zack Weinberg <zackw@cmu.edu> Date: Wed Mar 28 09:01:09 2012 -0700 Add fallback logic for static_assert in compilers that don't support it. --- configure.ac | 1 + m4/cxx_delete_method.m4 | 8 ++++-- m4/cxx_static_assert.m4 | 57 ++++++++++++++++++++++++++++++++++++++++++++++ m4/cxxflags_stdcxx_11.m4 | 4 --- 4 files changed, 63 insertions(+), 7 deletions(-) diff --git a/configure.ac b/configure.ac index 9002078..69f4150 100644 --- a/configure.ac +++ b/configure.ac @@ -68,6 +68,7 @@ AC_CHECK_HEADERS([execinfo.h],,, [AC_INCLUDES_DEFAULT()]) AX_CXXFLAGS_STDCXX_11([ext]) AX_CXX_DELETE_METHOD +AX_CXX_STATIC_ASSERT ### Output ### diff --git a/m4/cxx_delete_method.m4 b/m4/cxx_delete_method.m4 index 2f7decf..2d467e7 100644 --- a/m4/cxx_delete_method.m4 +++ b/m4/cxx_delete_method.m4 @@ -50,7 +50,8 @@ AC_DEFUN([AX_CXX_DELETE_METHOD], [dnl [ax_cv_cxx_delete_method_syntax=yes], [ax_cv_cxx_delete_method_syntax=no])]) # ... and this one should fail. - AC_CACHE_CHECK(whether $CXX enforces method deletion, + if test x$ax_cv_cxx_delete_method_syntax = xyes; then + AC_CACHE_CHECK(whether $CXX enforces method deletion, ax_cv_cxx_delete_method_enforced, [ AC_COMPILE_IFELSE([AC_LANG_SOURCE([[ struct foo { @@ -62,8 +63,9 @@ AC_DEFUN([AX_CXX_DELETE_METHOD], [dnl ]])], [ax_cv_cxx_delete_method_enforced=no], [ax_cv_cxx_delete_method_enforced=yes])]) - if test $ax_cv_cxx_delete_method_syntax = yes && - test $ax_cv_cxx_delete_method_enforced = yes + fi + if test x$ax_cv_cxx_delete_method_syntax = xyes && + test x$ax_cv_cxx_delete_method_enforced = xyes then AC_DEFINE([DELETE_METHOD], [= delete], [Define as `= delete' if your compiler supports C++11 method diff --git a/m4/cxx_static_assert.m4 b/m4/cxx_static_assert.m4 new file mode 100644 index 0000000..7bf69f8 --- /dev/null +++ b/m4/cxx_static_assert.m4 @@ -0,0 +1,57 @@ +# SYNOPSIS +# +# AX_CXX_STATIC_ASSERT +# +# DESCRIPTION +# +# Detect whether the C++ compiler, in its present operating mode, +# supports the C++11 'static_assert' construct. If it doesn't, +# define 'static_assert' as a preprocessor macro which provides +# more-or-less the same functionality. +# +# LICENSE +# +# Copyright (c) 2012 Zack Weinberg <zackw@panix.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 1 + +AC_DEFUN([AX_CXX_STATIC_ASSERT], [dnl + AC_LANG_ASSERT([C++])dnl + AC_CACHE_CHECK(whether $CXX accepts static_assert, ax_cv_cxx_static_assert, + [AC_COMPILE_IFELSE([AC_LANG_SOURCE([dnl + template <typename T> + struct check + { static_assert(sizeof(int) <= sizeof(T), "not big enough"); }; + check<int> ok;])], + [ax_cv_cxx_static_assert=yes], [ax_cv_cxx_static_assert=no])]) + if test x$ax_cv_cxx_static_assert = xyes; then + AC_CACHE_CHECK(whether $CXX enforces static_assert, ax_cv_cxx_static_assert_e, + [AC_COMPILE_IFELSE([AC_LANG_SOURCE([dnl + template <typename T> + struct check + { static_assert(sizeof(char[2]) <= sizeof(T), "not big enough"); }; + check<char> bad;])], + [ax_cv_cxx_static_assert_e=no], [ax_cv_cxx_static_assert_e=yes])]) + fi + if test x$ax_cv_cxx_static_assert = xyes && + test x$ax_cv_cxx_static_assert_e = xyes; then + AC_DEFINE(HAVE_STATIC_ASSERT, 1, + [Define to 1 if the C++ compiler supports static_assert.]) + fi + AH_VERBATIM([HAVE_STATIC_ASSERT_], +[#ifndef HAVE_STATIC_ASSERT +# define static_assert(expr, msg) typedef char static_assert_id[(expr)?1:-1] +# ifdef __COUNTER__ +# define static_assert_id static_assert_paste(static_assert_, __COUNTER__) +# else +# define static_assert_id static_assert_paste(static_assert_, __LINE__) +# endif +# define static_assert_paste(a,b) static_assert_paste_(a,b) +# define static_assert_paste_(a,b) a##b +#endif]) +]) diff --git a/m4/cxxflags_stdcxx_11.m4 b/m4/cxxflags_stdcxx_11.m4 index 383b708..7f06ed2 100644 --- a/m4/cxxflags_stdcxx_11.m4 +++ b/m4/cxxflags_stdcxx_11.m4 @@ -99,8 +99,4 @@ AC_DEFUN([AX_CXXFLAGS_STDCXX_11], [dnl fi done fi]) - - if test x$ac_success = xno; then - AC_MSG_WARN([*** Compiler support for C++11 language features not detected.]) - fi ])