4.04.0+trunk support

[avsm]

ppx_tools fails to compile with 4.04.0+trunk as of last night with this error:

ocamlc -bin-annot -annot -w +A-4-17-44-45 -I +compiler-libs -safe-string -c ast_mapper_class.ml
ocamlc -bin-annot -annot -a -o ppx_tools.cma ast_convenience.cmo ast_mapper_class.cmo
ocamlc -bin-annot -annot -w +A-4-17-44-45 -I +compiler-libs -safe-string -c genlifter.ml
ocamlc -bin-annot -annot -w +A-4-17-44-45 -I +compiler-libs -safe-string -o genlifter ocamlcommon.cma ppx_tools.cma genlifter.cmo
./genlifter -I +compiler-libs Parsetree.expression > ast_lifter.ml || rm -rf ast_lifter.ml
ocamlc -bin-annot -annot -w +A-4-17-44-45 -I +compiler-libs -safe-string -c ast_lifter.ml
ocamlc -bin-annot -annot -w +A-4-17-44-45 -I +compiler-libs -safe-string -c dumpast.ml
ocamlc -bin-annot -annot -w +A-4-17-44-45 -I +compiler-libs -safe-string -o dumpast ocamlcommon.cma ocamlbytecomp.cma ast_lifter.cmo dumpast.cmo
ocamlc -bin-annot -annot -w +A-4-17-44-45 -I +compiler-libs -safe-string -c ppx_metaquot.ml
ocamlc -bin-annot -annot -w +A-4-17-44-45 -I +compiler-libs -safe-string -o ppx_metaquot ocamlcommon.cma ppx_tools.cma ast_lifter.cmo ppx_metaquot.cmo
ocamlc -bin-annot -annot -w +A-4-17-44-45 -I +compiler-libs -safe-string -c rewriter.ml
File "rewriter.ml", line 95, characters 16-44:
Error: This expression has type string but an expression was expected of type
         'a Pparse.ast_kind

Would be useful to have support to unblock testing 4.04 features (e.g. cstruct depends on this)

[alainfrisch]

I've pushed a commit to the master branch to fix the issue. Is it enough to enable your testing workflow (through OPAM pinning I guess)?

[yami-no-ryuu]

Supposedly it builds on 4.04, is there any specific reason the branch is not created yet? Guess many would gladly test both new compiler and ppx_tools.