Hi Scott, I didn't realize that you had deleted the old post, so I responded to it after all. I'm happy to update that reply in this thread.
I think that you're seeing a bug in the current expander's marshaling of information for a compiled module. In your original program, the problem affects the "metadata.rkt" module that supplies `racquel-namespace`. As you note, the bug was introduced in recent versions. Specifically, it was introduced in v6.3 with the set-of-scopes expander. Happily, a re-implementation of the expander doesn't have the bug, but the re-implementation isn't quite ready to replace the current expander. I'll fix the bug as soon as I can. Meanwhile, if you'd like a workaround for your original program: The conflicting "lifted.0" is created in "metadata.rkt" by the contract system's expansion of `~a`. You can work around the problem by changing (~a col-fld) to (format "~a" col-fld) In your smaller version below, something similar should happen with `query-rows`. Even though the function is never called, the `query-rows` call syntactically triggers a contract expansion that introduces "lifted.0". More generally, the workaround is to use `define-namespace-anchor` in a module that does not call any functions with a contract via `racket/contract` (which is, of course, something you generally should not have to know or worry about). Matthew At Sat, 1 Oct 2016 21:01:05 -0700 (PDT), "'brown131' via Racket Users" wrote: > I am getting strange error in my Racquel package unit tests. I'm not sure > what > Racket release it started appearing in, but certainly 6.6 or 6.5. A couple of > days ago, I posted the all of code that was causing the error, but there was > too much going on for anyone to make sense of it (including me) and so I > deleted the post. Now I've spent a few hours and reduced the bug to the > minimum code required to reproduce it. > > The error I'm seeing in my tests is: > > define-values: assignment disallowed > cannot re-define a constant > constant: lifted.0 > > This error is rather obtuse and I have no I idea what it trying to > communicate > given that the code in question has no constant named "lifted". I can only > assume that it is some internal error related to syntax lifting. > > Below are the two modules needed to reproduce the error. What makes this > error > particularly strange is that the error occurs until the foobar function in > bug2.rkt is commented out. This function is not even called anywhere! > > Interestingly it must call query-rows. If foobar calls anything else, the bug > goes away. This may mean that there is an error somewhere in the db package. > > When the foobar function is commented out, everything works fine. In this > example, for the sake of brevity, it will give an error that error-me% is > undefined. I could have defined it and the other classes, and it would have > ran with no errors. > > The problem is that in the real version of the code, the foobar function is > used and necessary. I can't just comment it out. Until I know what's going on > here, I can't even devise a workaround. > > bug.rkt: > #lang racket > > (require "bug2.rkt" (for-syntax racket/syntax syntax/parse "bug2.rkt")) > > (define-syntax (data-class stx) > (syntax-parse stx > [(_ base-cls:id (i-face:id ...) elem:data-class-element ...) > (with-syntax ([m-data (generate-temporary)]) > #'(let* ([m-data (new error-me%)]) > (class* base-cls (bar% i-face ...) > elem.cls-expr ... > (inspect #f))))])) > > (define (gen-data-class) > (let* ([cls-nm 'cls-nm] > [stx #`(data-class object% (foo%) (super-new))]) > (eval-syntax stx bug-namespace))) > > (define fred% (gen-data-class)) > > bug2.rkt: > #lang racket > > (require syntax/parse db (for-syntax racket/syntax syntax/parse)) > > (provide (all-defined-out)) > > ;;; Until this is commented-out the error persists. > (define (foobar con) (query-rows con "")) > > (define-namespace-anchor bug-namespace-anchor) > (define bug-namespace (namespace-anchor->namespace bug-namespace-anchor)) > > (define-syntax-class data-class-element > #:attributes (cls-expr) > (pattern (x:expr ...) > #:attr cls-expr #'(x ...))) -- You received this message because you are subscribed to the Google Groups "Racket Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to racket-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
