Add a line continuation digraph \#

src/julia-parser.scm

@@ -522,6 +522,21 @@
 
 (define (scolno port) (string " near column " (input-port-column port)))
 
+(define (line-continuation port s)
+  (if (eqv? (skip-to-eol port) #\newline)
+      (read-char port)) ;; Consume newline
+  (if (eof-object? (peek-char port))
+      (error "incomplete: expression ends in line continuation"))
+  (let ((tok (next-token port s)))
+    (aset! s 2 #t)
+    tok))
+
+(define (line-continuation-comment port s)
+  (read-char port) ;; Consume #
+  (if (eqv? (peek-char port) #\= )
+      (error "Cannot start block comment after \\#"))
+  (line-continuation port s))
+
 (define (next-token port s)
   (aset! s 2 (eq? (skip-ws port whitespace-newline) #t))
   (let ((c (peek-char port)))
@@ -535,6 +550,12 @@
 
           ((eqv? c #\#)                   (skip-comment port) (next-token port s))
 
+          ((eqv? c #\\)
+            (let ((c (read-char port)))
+              (if (eqv? (peek-char port) #\#)
+                  (line-continuation-comment port s)
+                  (read-operator port c))))
+
           ;; . is difficult to handle; it could start a number or operator
           ((and (eqv? c #\.)
                 (let ((c (read-char port))

test/syntax.jl

@@ -2221,3 +2221,9 @@ end
 h35201(x; k=1) = (x, k)
 f35201(c) = h35201((;c...), k=true)
 @test f35201(Dict(:a=>1,:b=>3)) === ((a=1,b=3), true)
+
+# Line contination: issues #18612 and #27533
+@test Meta.parse("[1 \\#\n 2]") == Expr(:hcat, 1, 2)
+@test Meta.parse("@f \\#\n a") == Expr(:macrocall, Symbol("@f"), LineNumberNode(1, :none), :a)
+@test Meta.isexpr(Meta.parse("@f \\#"), :incomplete)
+@test_throws ParseError("Cannot start block comment after \\#") Meta.parse("x \\#=")