Hello Guilers,
Hi Andy,

Here below a mini module [1], which raises an exception [2] using 2.1.3.104-8f2f8 (it
compiles fine using 2.0.12).  It looks a bit of a 'silly' module but the real one
here do need this combination, I just minimized it for tracking purposes...

For info, if I either comment the use of srfi-1, or merge-generics, _or_ the for-each
expression, it compiles fine. I also tried foo to just do a (filter-map string?
words) and no for-each, to circumvent the problem as far as I could, and it
compiles fie as well: it appears there is a side effect of the for-each version from
srfi-1 over the core version, when using goops and declaring #:duplicates
(merge-generics ...).

Cheers,
David

[1]

(define-module (foo)
  #:use-module (srfi srfi-1)
  #:use-module (oop goops)
  
  #:duplicates (merge-generics
		replace
		warn-override-core
		warn
		last)
 
  #:export (foo))

(define (foo words)
  (for-each (lambda (word)
	      (display (string-append word " ")))
      words)
  (newline))

[2]

guild --version
guild (GNU Guile) 2.1.3.104-8f2f8

guild compile foo.scm
Backtrace:
In system/base/compile.scm:
     43:4 19 (call-once _)
In ice-9/boot-9.scm:
    829:4 18 (with-throw-handler _ _ _)
In system/base/compile.scm:
    59:11 17 (_)
   155:11 16 (_ #<closed: file 2067e00>)
   235:18 15 (read-and-compile #<input: foo.scm 13> #:from _ #:to _ # …)
   183:32 14 (compile-fold (#<procedure compile-tree-il (x e opts)>) …)
In ice-9/boot-9.scm:
   2325:4 13 (save-module-excursion #<procedure 1e09ba0 at language/…>)
In language/scheme/compile-tree-il.scm:
    31:15 12 (_)
In ice-9/psyntax.scm:
  1208:22 11 (expand-top-sequence ((define (foo words) (# (…) #) #)) …)
In ice-9/boot-9.scm:
   224:17 10 (map1 (#<procedure 205db90 at ice-9/psyntax.scm:1125:3…>))
In ice-9/psyntax.scm:
  1383:12  9 (_)
  1763:11  8 (lp (#(syntax-object (for-each (lambda (#) #) #) # …) …) …)
  1586:33  7 (parse (((("placeholder" placeholder) (# . #) …) . #) …) …)
  1307:27  6 (syntax-type (for-each (lambda (word) (display #)) #) # …)
  1291:39  5 (syntax-type for-each (("placeholder" placeholder) # #) …)
   302:24  4 (resolve-identifier _ _ (("placeholder" placeholder) …) …)
In unknown file:
           3 (module-variable #<directory (foo) 20c4bd0> for-each)
In oop/goops.scm:
   1437:4  2 (cache-miss #<directory (foo) 20c4bd0> for-each #<inte…> …)
In unknown file:
           1 (scm-error goops-error #f "No applicable method for ~S…" …)
In ice-9/boot-9.scm:
   753:26  0 (dispatch-exception _ _ _)

ice-9/boot-9.scm:753:26: In procedure dispatch-exception:
ice-9/boot-9.scm:753:26: No applicable method for #<<generic> merge-generics (3)> in
call (merge-generics #<directory (foo) 20c4bd0> for-each #<interface (guile)
1e02ea0> #<procedure for-each (f l) | (f l1 l2) | (f l1 . rest)> #<interface (srfi
1e02ea0> srfi-1) 1e4ca20> #<procedure for-each (f l) | (f l1 l2) | (f l1 . rest)> #f
1e02ea0> #f)