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-rw-r--r--config/override.m4104
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diff --git a/config/override.m4 b/config/override.m4
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+++ b/config/override.m4
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+dnl Fix Autoconf bugs by overriding broken internal Autoconf
+dnl macros with backports of fixes from newer releases.
+dnl
+dnl The override bits of this file should be a no-op for the newest
+dnl Autoconf version, which means they can be removed once the complete
+dnl tree has moved to a new enough Autoconf version.
+dnl
+dnl The _GCC_AUTOCONF_VERSION_TEST ensures that exactly the desired
+dnl Autoconf version is used. It should be kept for consistency.
+
+dnl Use ifdef/ifelse over m4_ifdef/m4_ifelse to be clean for 2.13.
+ifdef([m4_PACKAGE_VERSION], [
+
+dnl Provide m4_copy_force and m4_rename_force for old Autoconf versions.
+
+m4_ifndef([m4_copy_force],
+[m4_define([m4_copy_force],
+[m4_ifdef([$2], [m4_undefine([$2])])m4_copy($@)])])
+
+m4_ifndef([m4_rename_force],
+[m4_define([m4_rename_force],
+[m4_ifdef([$2], [m4_undefine([$2])])m4_rename($@)])])
+
+dnl AC_DEFUN a commonly used macro so this file is picked up.
+m4_copy([AC_PREREQ], [_AC_PREREQ])
+AC_DEFUN([AC_PREREQ], [frob])
+m4_copy_force([_AC_PREREQ], [AC_PREREQ])
+
+
+dnl Ensure exactly this Autoconf version is used
+m4_ifndef([_GCC_AUTOCONF_VERSION],
+ [m4_define([_GCC_AUTOCONF_VERSION], [2.64])])
+
+dnl Test for the exact version when AC_INIT is expanded.
+dnl This allows to update the tree in steps (for testing)
+dnl by putting
+dnl m4_define([_GCC_AUTOCONF_VERSION], [X.Y])
+dnl in configure.ac before AC_INIT,
+dnl without rewriting this file.
+dnl Or for updating the whole tree at once with the definition above.
+AC_DEFUN([_GCC_AUTOCONF_VERSION_CHECK],
+[m4_if(m4_defn([_GCC_AUTOCONF_VERSION]),
+ m4_defn([m4_PACKAGE_VERSION]), [],
+ [m4_fatal([Please use exactly Autoconf ]_GCC_AUTOCONF_VERSION[ instead of ]m4_defn([m4_PACKAGE_VERSION])[.])])
+])
+m4_define([AC_INIT], m4_defn([AC_INIT])[
+_GCC_AUTOCONF_VERSION_CHECK
+])
+
+
+dnl Ensure we do not use a buggy M4.
+m4_if(m4_index([..wi.d.], [.d.]), [-1],
+ [m4_fatal(m4_do([m4 with buggy strstr detected. Please install
+GNU M4 1.4.16 or newer and set the M4 environment variable]))])
+
+
+dnl Fix 2.64 cross compile detection for AVR and RTEMS
+dnl by not trying to compile fopen.
+m4_if(m4_defn([m4_PACKAGE_VERSION]), [2.64],
+ [m4_foreach([_GCC_LANG], [C, C++, Fortran, Fortran 77],
+ [m4_define([_AC_LANG_IO_PROGRAM(]_GCC_LANG[)], m4_defn([AC_LANG_PROGRAM(]_GCC_LANG[)]))])])
+
+m4_version_prereq([2.66],, [
+dnl We need AC_CHECK_DECL which works for overloaded C++ functions.
+
+# _AC_CHECK_DECL_BODY
+# -------------------
+# Shell function body for AC_CHECK_DECL.
+m4_define([_AC_CHECK_DECL_BODY],
+[ AS_LINENO_PUSH([$[]1])
+ [as_decl_name=`echo $][2|sed 's/ *(.*//'`]
+ [as_decl_use=`echo $][2|sed -e 's/(/((/' -e 's/)/) 0&/' -e 's/,/) 0& (/g'`]
+ AC_CACHE_CHECK([whether $as_decl_name is declared], [$[]3],
+ [AC_COMPILE_IFELSE([AC_LANG_PROGRAM([$[]4],
+[@%:@ifndef $[]as_decl_name
+@%:@ifdef __cplusplus
+ (void) $[]as_decl_use;
+@%:@else
+ (void) $[]as_decl_name;
+@%:@endif
+@%:@endif
+])],
+ [AS_VAR_SET([$[]3], [yes])],
+ [AS_VAR_SET([$[]3], [no])])])
+ AS_LINENO_POP
+])# _AC_CHECK_DECL_BODY
+
+# _AC_CHECK_DECLS(SYMBOL, ACTION-IF_FOUND, ACTION-IF-NOT-FOUND,
+# INCLUDES)
+# -------------------------------------------------------------
+# Helper to AC_CHECK_DECLS, which generates the check for a single
+# SYMBOL with INCLUDES, performs the AC_DEFINE, then expands
+# ACTION-IF-FOUND or ACTION-IF-NOT-FOUND.
+m4_define([_AC_CHECK_DECLS],
+[AC_CHECK_DECL([$1], [ac_have_decl=1], [ac_have_decl=0], [$4])]dnl
+[AC_DEFINE_UNQUOTED(AS_TR_CPP(m4_bpatsubst(HAVE_DECL_[$1],[ *(.*])),
+ [$ac_have_decl],
+ [Define to 1 if you have the declaration of `$1',
+ and to 0 if you don't.])]dnl
+[m4_ifvaln([$2$3], [AS_IF([test $ac_have_decl = 1], [$2], [$3])])])
+
+])
+
+])