Having autoconf script check for libexecinfo when looking for backtrace

[brad0]

Currently the autoconf script checks for the execinfo.h header and backtrace function in libc (.e.g. glibc). But FreeBSD / NetBSD / OpenBSD and DragonFlyBSD as well as musl-based Linux OS's use libexecinfo for the backtrace functionality. Please have the script also check for libexecinfo if the function does not exist in libc.

[ljluestc]

To check for the presence of libexecinfo on BSD-based systems and musl-based Linux OS's in addition to the execinfo.h header and the backtrace function from libc, you can modify your autoconf script as follows:

AC_CHECK_HEADERS([execinfo.h])
AC_CHECK_FUNCS([backtrace])

# Check for libexecinfo
AC_ARG_WITH([libexecinfo],
    AS_HELP_STRING([--with-libexecinfo], [Use libexecinfo for backtrace]),
    [use_libexecinfo="$withval"],
    [use_libexecinfo="no"])

if test "x$use_libexecinfo" = "xyes"; then
    AC_CHECK_LIB([execinfo], [backtrace], [LIBEXECINFO_LIBS="-lexecinfo"])
fi

# Check if backtrace is found
if test -z "$LIBEXECINFO_LIBS"; then
    AC_MSG_ERROR([Cannot find backtrace function or libexecinfo])
fi

AC_SUBST([LIBEXECINFO_LIBS])

In this updated script:

1. We use AC_ARG_WITH to introduce an optional --with-libexecinfo flag, which allows the user to explicitly specify whether to use libexecinfo or not.

2. If the user specifies --with-libexecinfo=yes, we check for the presence of libexecinfo using AC_CHECK_LIB.

3. We then ensure that either the backtrace function from libc or libexecinfo is found. If neither is found, we display an error message.