deprecate &x in ccall. fixes #6080

NEWS.md

@@ -88,6 +88,9 @@ Language changes
   * Variable bindings local to `while` loop bodies are now freshly allocated on each loop iteration,
     matching the behavior of `for` loops.
 
+  * Prefix `&` for by-reference arguments to `ccall` has been deprecated in favor of
+    `Ref` argument types ([#6080]).
+
 Breaking changes
 ----------------
 

src/julia-syntax.scm

@@ -3511,6 +3511,13 @@ f(x) = yt(x)
             ((call new foreigncall)
              (let* ((args
                      (cond ((eq? (car e) 'foreigncall)
+                            (for-each (lambda (a)
+                                        (if (and (length= a 2) (eq? (car a) '&))
+                                            (deprecation-message
+                                             (string "Syntax \"&argument\"" (linenode-string current-loc)
+                                                     " is deprecated. Remove the \"&\" and use a \"Ref\" argument "
+                                                     "type instead."))))
+                                      (list-tail e 6))
                             ;; NOTE: 2nd to 5th arguments of ccall must be left in place
                             ;;       the 1st should be compiled if an atom.
                             (append (if (atom? (cadr e))

test/ccall.jl

@@ -122,7 +122,6 @@ let a
     a = 2.84 + 5.2im
 
     @test_throws MethodError ccall((:cptest, libccalltest), Ptr{Complex{Int}}, (Ptr{Complex{Int}},), a)
-    @test_throws MethodError ccall((:cptest, libccalltest), Ptr{Complex{Int}}, (Complex{Int},), &a)
 end