Forbid parentheses

Author: Keno

src/julia-parser.scm

@@ -1329,7 +1329,8 @@
 
 (define (valid-func-sig? paren sig)
   (and (pair? sig)
-       (or (memq (car sig) '(macrocall call tuple))
+       (or (memq (car sig) '(call tuple))
+           (and (not paren) (eq? (car sig) 'macrocall))
            (and paren (eq? (car sig) 'block))
            (and paren (eq? (car sig) '...))
            (and (eq? (car sig) '|::|)

test/syntax.jl

@@ -3932,3 +3932,6 @@ end
 @test callme(2.0) === 2
 @test callme(3, 3) === 3
 @test callme(4, 4, 4) === 4.0
+
+# Ambiguous 1-arg anymous vs macrosig
+@test_parseerror "function (@foo(a)) end"