adjust double splicing behavior of rename-transformer-parameter

pkgs/racket-test-core/tests/racket/stxparam.rktl

@@ -139,6 +139,7 @@
        #`#,(syntax-local-value #'t)]))
   (define-syntax one 1)
   (define-syntax two 2)
+  (define-syntax three 3)
   (define-rename-transformer-parameter num
     (make-rename-transformer #'one))
   (test #t = (slv num) 1)
@@ -146,7 +147,11 @@
     (test #t = (slv num) 2))
   (splicing-syntax-parameterize ([num (make-rename-transformer #'two)])
     (define too (slv num)))
-  (test #t = too 2))
+  (test #t = too 2)
+  (splicing-syntax-parameterize ([num (make-rename-transformer #'two)])
+    (splicing-syntax-parameterize ([num (make-rename-transformer #'three)])
+      (define trois (slv num))))
+  (test #t = trois 3))
 
 ;; ----------------------------------------
 

racket/collects/racket/private/stxparamkey.rkt

@@ -51,6 +51,22 @@
                    rt)])
       sp))
 
+  (define (syntax-parameter-local-value-pre id)
+    (define-values (rt* rt-target) (syntax-local-value/immediate id (λ () #f)))
+    (cond
+      [(not rt-target)
+       rt*]
+      [(syntax-parameter? rt*)
+       rt-target]
+      [(parameter-binding? rt*)
+       rt*]
+      [else
+       (syntax-parameter-local-value-pre rt-target)]))
+
+  (define (syntax-parameter-local-value-for-parameter target)
+    (or (syntax-parameter-local-value-pre (syntax-local-get-shadower target #t))
+        (syntax-parameter-local-value-pre target)))
+
   (define (target-value target)
     (syntax-local-value (syntax-local-get-shadower target #t)
                         (lambda ()
@@ -72,7 +88,7 @@
       v)))
 
   (define (syntax-parameter-target-parameter target)
-    (let ([v (target-value target)])
+    (let ([v (syntax-parameter-local-value-for-parameter target)])
       (parameter-binding-param v)))
 
   (define (convert-renamer must-be-renamer?-stx v)

racket/collects/racket/splicing.rkt

@@ -350,10 +350,7 @@
       'transparent)]))
 
 (define-for-syntax (parameter-of id)
-  (let* ([rt (syntax-local-value id)]
-         [sp (if (set!-transformer? rt)
-                 (set!-transformer-procedure rt)
-                 rt)])
+  (let ([sp (syntax-parameter-local-value id)])
     (syntax-parameter-target-parameter
      (syntax-parameter-target sp))))