Added format-unique-id to unstable/syntax.

collects/unstable/scribblings/syntax.scrbl

@@ -238,6 +238,17 @@ in the argument list are automatically converted to symbols.
 the second error but not of the first.)
 }
 
+@margin-note{This binding was added by Vincent St-Amour.}
+@defproc[(format-unique-id [lctx (or/c syntax? #f)]
+                    	   [#:source src (or/c syntax? #f) #f]
+                    	   [#:props props (or/c syntax? #f) #f]
+                    	   [#:cert cert (or/c syntax? #f) #f]
+                    	   [fmt string?]
+                    	   [v (or/c string? symbol? identifier? keyword? char? number?)] ...)
+         identifier?]{
+Like @racket[format-id], but returned identifiers are guaranteed to be unique.
+}
+
 @defproc[(internal-definition-context-apply [intdef-ctx internal-definition-context?]
                                             [stx syntax?])
          syntax?]{

collects/unstable/syntax.rkt

@@ -1,5 +1,5 @@
 #lang racket/base
-;; owner: ryanc (and cce, where noted)
+;; owner: ryanc (and cce and stamourv, where noted)
 (require syntax/kerncase
          syntax/stx
          unstable/struct
@@ -49,6 +49,10 @@
 
          syntax-list
 
+         ;; by stamourv:
+         
+         format-unique-id
+
          )
 
 ;; Unwrapping syntax
@@ -383,3 +387,12 @@
 
   (call-with-composable-continuation body trampoline-prompt-tag)
   (void))
+
+(define (format-unique-id lctx
+                          #:source [src #f]
+                          #:props [props #f]
+                          #:cert [cert #f]
+                          fmt . args)
+  ((make-syntax-introducer) (apply format-id
+                                   lctx #:source src #:props props #:cert cert
+                                   fmt args)))