'[]' can now be used for iterators (#18814)

compiler/semexprs.nim

@@ -1596,7 +1596,7 @@ proc semArrayAccess(c: PContext, n: PNode, flags: TExprFlags): PNode =
   result = semSubscript(c, n, flags)
   if result == nil:
     # overloaded [] operator:
-    result = semExpr(c, buildOverloadedSubscripts(n, getIdent(c.cache, "[]")))
+    result = semExpr(c, buildOverloadedSubscripts(n, getIdent(c.cache, "[]")), flags)
 
 proc propertyWriteAccess(c: PContext, n, nOrig, a: PNode): PNode =
   var id = considerQuotedIdent(c, a[1], a)

tests/iter/tarrayiter.nim

@@ -0,0 +1,14 @@
+block:
+  iterator `[]`(a: int, r: int): int = 
+    for q in 0 .. r:
+      yield a
+    
+  for val in 10[2]: discard
+  
+  type Custom = distinct string
+
+  iterator `[]`(a: Custom, r: int): char = 
+    for q in 0 .. r:
+      yield a.string[q]
+      
+  for val in Custom("test")[2]: discard