The attached program prints out

    let x = """;;

when compiled with ocamlc and camlp4 version 3.12.0.  As you can see,
the string literal lacks an escape character.  I haven't tried version
3.12.1, but I didn't find anything about it in the release notes.  (To
reproduce:

    ocamlc.opt -c -I +camlp4 -pp camlp4orf -o quotation_bug.cmo quotation_bug.ml
    ocamlc.opt dynlink.cma -I +camlp4 camlp4lib.cma quotation_bug.cmo
-o quotation_bug.byte
    ./quotation_bug.byte
)

Petter