fix #20406, parse infix ~ as a normal operator

Author: JeffBezanson

NEWS.md

@@ -112,6 +112,9 @@ This section lists changes that do not have deprecation warnings.
   * In macro calls with parentheses, e.g. `@m(a=1)`, assignments are now parsed as
     `=` expressions, instead of as `kw` expressions. ([#7669])
 
+  * When used as an infix operator, `~` is now parsed as a call to an ordinary operator
+    with assignment precedence, instead of as a macro call. ([#20406])
+
   * (µ "micro" and ɛ "latin epsilon") are considered equivalent to
     the corresponding Greek characters in identifiers.  `\varepsilon`
     now tab-completes to U+03B5 (greek small letter epsilon) ([#19464]).

doc/src/devdocs/ast.md

@@ -422,7 +422,6 @@ call. Finally, chains of comparisons have their own special expression structure
 | `x"y"z`         | `(macrocall @x_str "y" "z")` |
 | `"x = $x"`      | `(string "x = " x)`          |
 | ``` `a b c` ``` | `(macrocall @cmd "a b c")`   |
-| `x ~ distr`     | `(macrocall @~ x distr)`     |
 
 Doc string syntax:
 

src/julia-parser.scm

@@ -754,9 +754,7 @@
                             (not (eqv? (peek-char (ts:port s)) #\ )))
                        (begin (ts:put-back! s t)
                               ex)
-                       (let ((args (parse-chain s down '~)))
-                         `(macrocall @~ ,ex ,@(butlast args)
-                                     ,(loop (last args) (peek-token s)))))
+                       (list 'call t ex (parse-assignment s down)))
                    (list t ex (parse-assignment s down)))))))
 
 (define (parse-eq s)