The inline expansion of PRINC might contain escape characters that were improperly caught by c-inline itself

src/cmp/cmpffi.lsp

@@ -661,3 +661,14 @@
 		  (cmperr "C-INLINE: Variable code exceeds number of arguments")))))
 	(otherwise
 	 (write-char c *compiler-output1*))))))
+
+(defun c-inline-safe-string (constant-string)
+  ;; Produce a text representation of a string that can be used
+  ;; in a C-INLINE form, without triggering the @ or # escape
+  ;; characters
+  (c-filtered-string
+   (concatenate 'string
+		(loop for c across constant-string
+		   when (member c '(#\# #\@))
+		   collect c
+		   collect c))))

src/cmp/cmpopt-printer.lsp

@@ -50,7 +50,7 @@
                   (ffi:c-inline ,(list stream) (:object) :void
                                 ,(concatenate 'string
                                               "ecl_princ_str("
-                                              (c-filtered-string value)
+                                              (c-inline-safe-string value)
                                               ",#0)")
                                 :one-liner t)
                   ,value))