strange include/trace behavior

[Alexandre Duret-Lutz]

I find the following output confusing

% cat configure.ac
AC_INIT(a,b)
include(x1.m4)
sinclude(x2.m4)
m4_include(x3.m4)
m4_sinclude(x4.m4)
AC_OUTPUT
% touch x{1..4}.m4
% autoconf --trace=m4_sinclude
configure.ac:3:sinclude:x2.m4
configure.ac:5:m4_sinclude:x4.m4
% autoconf --trace=m4_include
configure.ac:4:m4_include:x3.m4
% autoconf --trace=sinclude
configure.ac:3:sinclude:x2.m4
configure.ac:5:m4_sinclude:x4.m4
% autoconf --trace=include
configure.ac:4:m4_include:x3.m4
% fgrep 'include(' configure
include(x.m4)


Why do tracing for m4_sinclude or sinclude always returns _both_
variants?

Why is sinclude() expanded and include() not? 

Why does tracing for include returns m4_include?


Automake needs to trace for these.  Currently it only traces
m4_include and m4_sinclude and abort when Autoconf returns an
unrequested trace (such as sinclude).  Obviously I need to
adjust that code in some way, but given the above output I'm not
sure what I'm expected to do.  Should I trace for two, three, or
four macros?
-- 
Alexandre Duret-Lutz