import m4_ax_compile_check_sizeof.m4 from autoconf archive

diff --git a/build/autoconf/m4_ax_compile_check_sizeof.m4 b/build/autoconf/m4_ax_compile_check_sizeof.m4
new file mode 100644 (file)
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+++ b/build/autoconf/m4_ax_compile_check_sizeof.m4
@@ -0,0 +1,115 @@
+# ============================================================================
+#  https://www.gnu.org/software/autoconf-archive/ax_compile_check_sizeof.html
+# ============================================================================
+#
+# SYNOPSIS
+#
+#   AX_COMPILE_CHECK_SIZEOF(TYPE [, HEADERS [, EXTRA_SIZES...]])
+#
+# DESCRIPTION
+#
+#   This macro checks for the size of TYPE using compile checks, not run
+#   checks. You can supply extra HEADERS to look into. the check will cycle
+#   through 1 2 4 8 16 and any EXTRA_SIZES the user supplies. If a match is
+#   found, it will #define SIZEOF_`TYPE' to that value. Otherwise it will
+#   emit a configure time error indicating the size of the type could not be
+#   determined.
+#
+#   The trick is that C will not allow duplicate case labels. While this is
+#   valid C code:
+#
+#     switch (0) case 0: case 1:;
+#
+#   The following is not:
+#
+#     switch (0) case 0: case 0:;
+#
+#   Thus, the AC_COMPILE_IFELSE will fail if the currently tried size does
+#   not match.
+#
+#   Here is an example skeleton configure.in script, demonstrating the
+#   macro's usage:
+#
+#     AC_PROG_CC
+#     AC_CHECK_HEADERS(stddef.h unistd.h)
+#     AC_TYPE_SIZE_T
+#     AC_CHECK_TYPE(ssize_t, int)
+#
+#     headers='#ifdef HAVE_STDDEF_H
+#     #include <stddef.h>
+#     #endif
+#     #ifdef HAVE_UNISTD_H
+#     #include <unistd.h>
+#     #endif
+#     '
+#
+#     AX_COMPILE_CHECK_SIZEOF(char)
+#     AX_COMPILE_CHECK_SIZEOF(short)
+#     AX_COMPILE_CHECK_SIZEOF(int)
+#     AX_COMPILE_CHECK_SIZEOF(long)
+#     AX_COMPILE_CHECK_SIZEOF(unsigned char *)
+#     AX_COMPILE_CHECK_SIZEOF(void *)
+#     AX_COMPILE_CHECK_SIZEOF(size_t, $headers)
+#     AX_COMPILE_CHECK_SIZEOF(ssize_t, $headers)
+#     AX_COMPILE_CHECK_SIZEOF(ptrdiff_t, $headers)
+#     AX_COMPILE_CHECK_SIZEOF(off_t, $headers)
+#
+# LICENSE
+#
+#   Copyright (c) 2008 Kaveh Ghazi <ghazi@caip.rutgers.edu>
+#   Copyright (c) 2017 Reini Urban <rurban@cpan.org>
+#
+#   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 <https://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 8
+
+AU_ALIAS([AC_COMPILE_CHECK_SIZEOF], [AX_COMPILE_CHECK_SIZEOF])
+AC_DEFUN([AX_COMPILE_CHECK_SIZEOF],
+[changequote(<<, >>)dnl
+dnl The name to #define.
+define(<<AC_TYPE_NAME>>, translit(sizeof_$1, [a-z *], [A-Z_P]))dnl
+dnl The cache variable name.
+define(<<AC_CV_NAME>>, translit(ac_cv_sizeof_$1, [ *], [_p]))dnl
+changequote([, ])dnl
+AC_MSG_CHECKING(size of $1)
+AC_CACHE_VAL(AC_CV_NAME,
+[for ac_size in 4 8 1 2 16 $3 ; do # List sizes in rough order of prevalence.
+  AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
+#include <sys/types.h>
+$2
+]], [[switch (0) case 0: case (sizeof ($1) == $ac_size):;]])], [AC_CV_NAME=$ac_size])
+  if test x$AC_CV_NAME != x ; then break; fi
+done
+])
+if test x$AC_CV_NAME = x ; then
+  AC_MSG_ERROR([cannot determine a size for $1])
+fi
+AC_MSG_RESULT($AC_CV_NAME)
+AC_DEFINE_UNQUOTED(AC_TYPE_NAME, $AC_CV_NAME, [The number of bytes in type $1])
+undefine([AC_TYPE_NAME])dnl
+undefine([AC_CV_NAME])dnl
+])