+# Find a C++11 compiler with GNU extensions (-std=gnu++11)
+AX_CXX_COMPILE_STDCXX([11], [ext], [mandatory])
+
+# Detect warning flags specific to the C++ compiler and append them to
+# WARN_CXXFLAGS.
+m4_define([WARN_FLAGS_CXX_LIST], [ dnl
+ dnl GCC enables this with -Wall in C++, and that generates a
+ dnl lot of warnings that have on average a low value to fix.
+ -Wno-sign-compare dnl
+])
+
+# Pass -Werror as an extra flag during the test: this is needed to make the
+# -Wunknown-warning-option diagnostic fatal with clang.
+AC_LANG_PUSH([C++])
+AX_APPEND_COMPILE_FLAGS([WARN_FLAGS_COMMON_LIST WARN_FLAGS_CXX_LIST], [WARN_CXXFLAGS], [-Werror])
+AC_LANG_POP([C++])
+
+# Disable 'strict aliasing' if the C++ compiler supports it.
+AC_LANG_PUSH([C++])
+AX_APPEND_COMPILE_FLAGS([-fno-strict-aliasing], [OPT_CXXFLAGS], [-Werror])
+AC_LANG_POP([C++])
+
+
+# When given, add -Werror to WARN_CFLAGS and WARN_CXXFLAGS.
+AC_ARG_ENABLE([Werror],[
+ AS_HELP_STRING([--enable-Werror], [Treat compiler warnings as errors.])
+])
+
+AS_IF([test "x$enable_Werror" = "xyes"], [
+ WARN_CFLAGS="${WARN_CFLAGS} -Werror"
+ WARN_CXXFLAGS="${WARN_CXXFLAGS} -Werror"
+])
+
+# Checks for programs.
+AC_PROG_GREP
+AC_PROG_MAKE_SET
+AC_PROG_SED
+AC_PATH_PROG([report_fold], [fold])
+LT_INIT
+
+# Check for objcopy, required by the base address statedump and dynamic linker tests
+AC_CHECK_TOOL([OBJCOPY], [objcopy])
+AS_IF([test "x$OBJCOPY" = "x"],
+ [AC_MSG_WARN([Cannot find objcopy. The base address statedump and dynamic linker tests will be disabled. Install the binutils package to remediate this.])]
+)
+AM_CONDITIONAL([HAVE_OBJCOPY], [test "x$OBJCOPY" != "x"])
+
+# check for pgrep
+AC_PATH_PROG([PGREP], [pgrep])
+AM_CONDITIONAL([HAVE_PGREP], [test "x$PGREP" != "x"])
+
+AC_PATH_PROG([SHELLCHECK], [shellcheck])
+AM_CONDITIONAL([HAVE_SHELLCHECK], [test "x$SHELLCHECK" != "x"])
+
+# set $IN_GIT_REPO if we're in the Git repository; the `bootstrap` file
+# is not distributed in tarballs
+AS_IF([test -f "$srcdir/bootstrap"], [in_git_repo=yes], [in_git_repo=no])
+AM_CONDITIONAL([IN_GIT_REPO], [test "x$in_git_repo" = "xyes"])
+
+# check for bison
+AC_PROG_YACC
+BISON=$YACC
+AX_PROG_BISON_VERSION([2.4], [have_bison=yes])
+
+AS_IF([test "x$have_bison" != "xyes"], [
+ AS_IF([test "x$in_git_repo" = "xyes"], [
+ AC_MSG_FAILURE([
+Bison >= 2.4 is required when building from the Git repository. You can
+set the YACC variable to override automatic detection.
+ ])
+ ], [
+ AC_MSG_WARN([
+Missing Bison >= 2.4. Note that the parser files are already built in
+this distribution tarball, so Bison is only needed if you intend to
+modify their sources. You can set the YACC variable to override automatic
+detection.
+ ])
+ ])
+])
+AM_CONDITIONAL([HAVE_BISON], [test "x$have_bison" = "xyes"])
+
+# check for flex
+# Prior to autoconf 2.70, AC_PROG_FLEX did not take an argument. This is not a
+# problem since the argument is silently ignored by older versions.
+AC_PROG_LEX([noyywrap])
+FLEX=$LEX
+AX_PROG_FLEX_VERSION([2.5.35], [have_flex=yes])
+
+AS_IF([test "x$have_flex" != "xyes"], [
+ AS_IF([test "x$in_git_repo" = "xyes"], [
+ AC_MSG_FAILURE([
+Flex >= 2.5.35 is required when building from the Git repository. You can
+set the LEX variable to override automatic detection.
+ ])
+ ], [
+ AC_MSG_WARN([
+Missing Flex >= 2.5.35. Note that the lexer files are already built in
+this distribution tarball, so Flex is only needed if you intend to
+modify their sources. You can set the LEX variable to override automatic
+detection.
+ ])
+ ])
+])
+AM_CONDITIONAL([HAVE_FLEX], [test "x$have_flex" = "xyes"])
+
+
+
+# Check if linker has the -no-pie option.
+AX_CHECK_LINK_FLAG([-no-pie], [linker_have_no_pie_option=yes])
+AM_CONDITIONAL([LINKER_HAVE_NO_PIE_OPTION], [test "x$linker_have_no_pie_option" = "xyes"])