change `log-error', etc., to support format mode

One subexpression => string literal. Multiple subexpressions
=> arguments to `format'.

collects/racket/private/more-scheme.rkt

@@ -345,7 +345,9 @@
        #'(define-syntax (id stx)
            (syntax-case stx ()
              [(_ str-expr)
-              #'(log-it id mode str-expr)]))]))
+              #'(log-it id mode str-expr)]
+             [(_ str-expr arg (... ...))
+              #'(log-it id mode (format str-expr arg (... ...)))]))]))
   (define-log log-fatal fatal)
   (define-log log-error error)
   (define-log log-warning warning)

collects/scribblings/reference/logging.scrbl

@@ -130,18 +130,23 @@ currently returns @racket[#f] for all levels.}
 
 
 @deftogether[(
-@defform[(log-fatal string-expr)]
-@defform[(log-error string-expr)]
-@defform[(log-warning string-expr)]
-@defform[(log-info string-expr)]
-@defform[(log-debug string-expr)]
+@defform*[[(log-fatal string-expr)
+           (log-fatal format-string-expr v ...)]]
+@defform*[[(log-error string-expr)
+           (log-error format-string-expr v ...)]]
+@defform*[[(log-warning string-expr)
+           (log-warning format-string-expr v ...)]]
+@defform*[[(log-info string-expr)
+           (log-info format-string-expr v ...)]]
+@defform*[[(log-debug string-expr)
+           (log-debug format-string-expr v ...)]]
 )]{
 
 Log an event with the @tech{current logger}, evaluating
-@racket[string-expr] only if the logger has receivers that are
-interested in the event. In addition, the current continuation's
-@tech{continuation marks} are sent to the logger with the message
-string.
+@racket[string-expr] or @racket[(format format-string-expr v ...)]
+only if the logger has receivers that are interested in the event. In
+addition, the current continuation's @tech{continuation marks} are
+sent to the logger with the message string.
 
 For each @racketkeywordfont{log-}@racket[_level],
 

doc/release-notes/racket/HISTORY.txt

@@ -1,6 +1,7 @@
 Version 5.3.0.22
 Changed a thread's initial prompt to use the default handler
  (instead of accepting and ignoring abort arguments)
+Changed log-error, etc., to support format mode
 Added racket/format, which is re-exported by racket
 ffi/unsafe: added cpointer-gcable?
 racket/class: added dynamic-get-field and dynamic-set-field!