Can't you resolve this by doing a bit of extra work in scopes that have e.g. 'x' in source but not in the corresponding AST? I wasn't sure if generated ASTs wer

Can't you resolve this by doing a bit of extra work in scopes that have e.g. 'x' in source but not in the corresponding AST? I wasn't sure if generated ASTs were 1-1 matched with source top-level scopes, but apparently they are: http://icps.u-strasbg.fr/~pop/images/front-end.png http://icps.u-strasbg.fr/~pop/images/front-end.png It's a bit more work than cases where AST matches source level expectations, but can't you just walk that sub-tree and figure out that '0' was 'x - x'? http://icps.u-strasbg.fr/~pop/images/plus-expr.png http://icps.u-strasbg.fr/~pop/images/plus-expr.png