Add missing parentheses around constructor used as indexing op (#1740)

Author: gpetiot

CHANGES.md

@@ -12,6 +12,8 @@
 
   + Support sugared form of coercions in let bindings (#1739, @gpetiot)
 
+  + Add missing parentheses around constructor used as indexing op (#1740, @gpetiot)
+
 #### Changes
 
 #### New features

lib/Ast.ml

@@ -2286,6 +2286,10 @@ end = struct
       , {pexp_desc= Pexp_construct _ | Pexp_variant _; _} )
       when e == exp ->
         true
+    | ( Exp {pexp_desc= Pexp_apply (e0, ((_, e) :: _ as args)); _}
+      , {pexp_desc= Pexp_construct _; _} )
+      when e == exp && Option.is_some (Indexing_op.get_sugar e0 args) ->
+        true
     | ( Exp {pexp_desc= Pexp_apply (op1, [(_, e)]); _}
       , {pexp_desc= Pexp_apply (_, [(_, x); _]); _} )
       when e == exp && Exp.is_prefix op1 && Exp.exposed_left x ->

test/passing/tests/index_op.ml

@@ -172,3 +172,27 @@ let _ = Array.unsafe_get [||] (-8)
 let _ = Bigarray.Genarray.get x [||] (-8)
 
 let _ = Bigarray.Genarray.unsafe_get x [||] (-8)
+
+let _ = [%p (Some).(tickers)]
+
+let _ = [%p (Explicit).(0 / 2)]
+
+let _ = [%p Some.(tickers)]
+
+let _ = [%p Explicit.(0 / 2)]
+
+let _ = (Some).(tickers)
+
+let _ = (Explicit).(0 / 2)
+
+let _ = Some.(tickers)
+
+let _ = Explicit.(0 / 2)
+
+let _ = f (Some).(tickers)
+
+let _ = f (Explicit).(0 / 2)
+
+let _ = f Some.(tickers)
+
+let _ = f Explicit.(0 / 2)