+;;;; miscellaneous support utilities
+
+;;; Signalling an error when trying to print an error condition is
+;;; generally a PITA, so whatever the failure encountered when
+;;; wondering about FILE-POSITION within a condition printer, 'tis
+;;; better silently to give up than to try to complain.
+(defun file-position-or-nil-for-error (stream &optional (pos nil posp))
+ ;; Arguably FILE-POSITION shouldn't be signalling errors at all; but
+ ;; "NIL if this cannot be determined" in the ANSI spec doesn't seem
+ ;; absolutely unambiguously to prohibit errors when, e.g., STREAM
+ ;; has been closed so that FILE-POSITION is a nonsense question. So
+ ;; my (WHN) impression is that the conservative approach is to
+ ;; IGNORE-ERRORS. (I encountered this failure from within a homebrew
+ ;; defsystemish operation where the ERROR-STREAM had been CL:CLOSEd,
+ ;; I think by nonlocally exiting through a WITH-OPEN-FILE, by the
+ ;; time an error was reported.)
+ (if posp
+ (ignore-errors (file-position stream pos))
+ (ignore-errors (file-position stream))))
+\f