Makefile.am target name prefix *.o

[Vincent Blondel]

Hello,

Encounter a strange behaviour with autoconf.
I do not understand why all the compiled *.o files are prefixed with
target-xxx.o.

Below an example ... have no progname yet for my executable hence let's
call it main for now ...

bin_PROGRAMS = main
main_SOURCES =  obj1.cc obj2.cc

Executable is OK but have no clue why I have something like this at the end
? ...

src/main-obj1.o
src/main-obj2.o

Thanks for your help ...
-V