Fix syntax depth calculation

cover/strace.rkt

@@ -168,19 +168,21 @@ The module implements code coverage annotations as described in cover.rkt
 
 ;; Syntax -> Natural
 ;; Maxiumum depth of begin-for-syntaxes
-(define (get-syntax-depth expr)
+(define (get-syntax-depth expr [phase 0])
-  (kernel-syntax-case
+  (kernel-syntax-case/phase
-   (disarm expr) #f
+   (disarm expr) phase
    [(module _ _ mb)
     (get-syntax-depth #'mb)]
    [(module* _ _ mb)
     (get-syntax-depth #'mb)]
    [(begin-for-syntax b ...)
-    (add1 (apply max 1 (map get-syntax-depth (syntax->list #'(b ...)))))]
+    (add1 (apply max 1 (for/list ([b (in-list (syntax->list #'(b ...)))])
+                         (get-syntax-depth b (add1 phase)))))]
    [(define-syntaxes a ...)
     2]
    [(b ...)
-    (apply max 1 (map get-syntax-depth (syntax->list #'(b ...))))]
+    (apply max 1 (for/list ([b (in-list (syntax->list #'(b ...)))])
+                   (get-syntax-depth b phase)))]
    [_ 1]))
 
 ;; Natural PathString Symbol -> Syntax

cover/tests/bfs+define-syntax.rkt

@@ -0,0 +1,6 @@
+#lang racket/base
+
+(require (for-meta 1 racket/base)
+         (for-meta 2 racket/base))
+
+(begin-for-syntax (define-syntax x #f))

cover/tests/do-bfs+module.rkt

@@ -6,6 +6,7 @@
 (define-runtime-path-list others
   (list "bfs+module-nolex.rkt"
         "bfs+module.rkt"
+        "bfs+define-syntax.rkt"
         "lazy-require.rkt"))
 (test-case
  "begin-for-syntax with modules should be okay"