As much as I'd like to have a more explicit way to specify build.compiler.emacs, the current way to do it has a huge advantage over what you propose:
I have a ~/.antrc consisting of ANT_OPTS='-Dbuild.compiler=jikes -Dbuild.compiler.emacs=yes' and this will make all <javac>s use jikes and set the emacs option. If we switched to the nested elements, I had to change every <javac> task to include my favorite settings (which might be different from what others want). What we need is more general concept for the user to specify global behavior, CSS like style sheets - ~/.ant.xml containing <taskconfig> elements, something like that - let's add "finding a real good solution for this problem" to the list for Ant 2.0. Stefan
