Merge pull request JuliaLang#17224 from ihnorton/fix17219

Fix JuliaLang#17219: conditionally lower ccall first arg

src/julia-syntax.scm

@@ -3018,8 +3018,12 @@ f(x) = yt(x)
  ((call new)
  (let* ((ccall? (and (eq? (car e) 'call) (equal? (cadr e) '(core ccall))))
  (args (if ccall?
- ;; NOTE: first 3 arguments of ccall must be left in place
- (append (list-head (cdr e) 4)
+ ;; NOTE: 2nd and 3rd arguments of ccall must be left in place
+ ;; the 1st should be compiled if an atom.
+ (append (list (cadr e))
+ (cond (atom? (caddr e) (compile-args (list (caddr e)) break-labels))
+ (else (caddr e)))
+ (list-head (cdddr e) 2)
  (compile-args (list-tail e 5) break-labels))
  (compile-args (cdr e) break-labels)))
  (callex (cons (car e) args)))

test/ccall.jl

@@ -575,6 +575,13 @@ foo13031(x,y,z) = z
 foo13031p = cfunction(foo13031, Cint, (Ref{Tuple{}},Ref{Tuple{}},Cint))
 ccall(foo13031p, Cint, (Ref{Tuple{}},Ref{Tuple{}},Cint), (), (), 8)
 
+# issue 17219
+function ccall_reassigned_ptr(ptr::Ptr{Void})
+ ptr = Libdl.dlsym(Libdl.dlopen(libccalltest), "test_echo_p")
+ ccall(ptr, Any, (Any,), "foo")
+end
+@test ccall_reassigned_ptr(C_NULL) == "foo"
+
 # @threadcall functionality
 threadcall_test_func(x) =
  @threadcall((:testUcharX, libccalltest), Int32, (UInt8,), x % UInt8)