Allow juxtaposition of macro and array literal. fixes #23519 (#23547)

Author: cdsousa

NEWS.md

@@ -16,6 +16,9 @@ New language features
    For example, `+̂ₐ″` is parsed as an infix operator with the same
    precedence as `+` ([#22089]).
 
+ * The macro call syntax `@macroname[args]` is now available and is parsed
+   as `@macroname([args])` ([#23519]).
+
 Language changes
 ----------------
 

doc/src/manual/metaprogramming.md

@@ -583,6 +583,13 @@ above; it passes the tuple `(expr1, expr2, ...)` as one argument to the macro:
 @name (expr1, expr2, ...)
 ```
 
+An alternative way to invoke a macro over an array literal (or comprehension) is to juxtapose both without using parentheses. In this case, the array will be the only expression fed to the macro. The following syntax is equivalent (and different from `@name [a b] * v`):
+
+```julia
+@name[a b] * v
+@name([a b]) * v
+```
+
 It is important to emphasize that macros receive their arguments as expressions, literals, or
 symbols. One way to explore macro arguments is to call the [`show`](@ref) function within the
 macro body:

src/julia-parser.scm

@@ -1189,16 +1189,18 @@
              ;; ref(a,i) = x
              (let* ((es end-symbol)
                     (al (with-end-symbol (parse-cat s #\] es))))
-               (if (null? al)
-                   (loop (list 'ref ex))
-                   (case (car al)
-                     ((vect)  (loop (list* 'ref ex (cdr al))))
-                     ((hcat)  (loop (list* 'typed_hcat ex (cdr al))))
-                     ((vcat)
-                      (loop (list* 'typed_vcat ex (cdr al))))
-                     ((comprehension)
-                      (loop (list* 'typed_comprehension ex (cdr al))))
-                     (else (error "unknown parse-cat result (internal error)"))))))
+               (if macrocall?
+                   (list 'call ex al)
+                   (if (null? al)
+                       (loop (list 'ref ex))
+                       (case (car al)
+                         ((vect)  (loop (list* 'ref ex (cdr al))))
+                         ((hcat)  (loop (list* 'typed_hcat ex (cdr al))))
+                         ((vcat)
+                          (loop (list* 'typed_vcat ex (cdr al))))
+                         ((comprehension)
+                          (loop (list* 'typed_comprehension ex (cdr al))))
+                         (else (error "unknown parse-cat result (internal error)")))))))
             ((|.|)
              (if (ts:space? s) (disallowed-space ex t))
              (take-token s)

test/parse.jl

@@ -1366,3 +1366,11 @@ let xs = [:(1+2), :(3+4), :(5+6)]
     ex2 = eval(ex)
     @test ex2.args[2:end] == [3,7,11]
 end
+
+# issue #23519
+@test parse("@foo[1]") == parse("@foo([1])")
+@test parse("@foo[1 2; 3 4]") == parse("@foo([1 2; 3 4])")
+@test parse("@foo[1] + [2]") == parse("@foo([1]) + [2]")
+@test parse("@foo [1] + [2]") == parse("@foo([1] + [2])")
+@test parse("@Mdl.foo[1] + [2]") == parse("@Mdl.foo([1]) + [2]")
+@test parse("@Mdl.foo [1] + [2]") == parse("@Mdl.foo([1] + [2])")