[flow][match] Error on as patterns directly on binding patterns

Summary:
Error on `as` patterns directly on binding patterns.

Changelog: [internal]

Reviewed By: SamChou19815

Differential Revision: D67502324

fbshipit-source-id: 82cb5634c4ac3bbf88cc8020dfe013982cc19458

src/typing/debug_js.ml

@@ -1913,6 +1913,7 @@ let dump_error_message =
     | EMatchDuplicateObjectProperty { loc; name } ->
       spf "EMatchDuplicateObjectProperty (%s) (%s)" (string_of_aloc loc) name
     | EMatchBindingInOrPattern { loc } -> spf "EMatchBindingInOrPattern (%s)" (string_of_aloc loc)
+    | EMatchInvalidAsPattern { loc } -> spf "EMatchInvalidAsPattern (%s)" (string_of_aloc loc)
     | EDevOnlyRefinedLocInfo { refined_loc; refining_locs = _ } ->
       spf "EDevOnlyRefinedLocInfo {refined_loc=%s}" (string_of_aloc refined_loc)
     | EDevOnlyInvalidatedRefinementInfo { read_loc; invalidation_info = _ } ->

src/typing/errors/error_message.ml

@@ -630,6 +630,7 @@ and 'loc t' =
       name: string;
     }
   | EMatchBindingInOrPattern of { loc: 'loc }
+  | EMatchInvalidAsPattern of { loc: 'loc }
   (* Dev only *)
   | EDevOnlyRefinedLocInfo of {
       refined_loc: 'loc;
@@ -1440,6 +1441,7 @@ let rec map_loc_of_error_message (f : 'a -> 'b) : 'a t' -> 'b t' =
   | EMatchDuplicateObjectProperty { loc; name } ->
     EMatchDuplicateObjectProperty { loc = f loc; name }
   | EMatchBindingInOrPattern { loc } -> EMatchBindingInOrPattern { loc = f loc }
+  | EMatchInvalidAsPattern { loc } -> EMatchInvalidAsPattern { loc = f loc }
   | EDevOnlyInvalidatedRefinementInfo { read_loc; invalidation_info } ->
     EDevOnlyInvalidatedRefinementInfo
       {
@@ -1743,7 +1745,8 @@ let util_use_op_of_msg nope util = function
   | EMatchInvalidUnaryZero _
   | EMatchInvalidUnaryPlusBigInt _
   | EMatchDuplicateObjectProperty _
-  | EMatchBindingInOrPattern _ ->
+  | EMatchBindingInOrPattern _
+  | EMatchInvalidAsPattern _ ->
     nope
 
 (* Not all messages (i.e. those whose locations are based on use_ops) have locations that can be
@@ -1951,6 +1954,7 @@ let loc_of_msg : 'loc t' -> 'loc option = function
   | EMatchInvalidUnaryPlusBigInt { loc } -> Some loc
   | EMatchDuplicateObjectProperty { loc; _ } -> Some loc
   | EMatchBindingInOrPattern { loc } -> Some loc
+  | EMatchInvalidAsPattern { loc } -> Some loc
   | EDevOnlyRefinedLocInfo { refined_loc; refining_locs = _ } -> Some refined_loc
   | EDevOnlyInvalidatedRefinementInfo { read_loc; invalidation_info = _ } -> Some read_loc
   | EUnableToSpread _
@@ -2907,6 +2911,7 @@ let friendly_message_of_msg = function
   | EMatchDuplicateObjectProperty { loc = _; name } ->
     Normal (MessageMatchDuplicateObjectProperty { name })
   | EMatchBindingInOrPattern { loc = _ } -> Normal MessageMatchBindingInOrPattern
+  | EMatchInvalidAsPattern { loc = _ } -> Normal MessageMatchInvalidAsPattern
 
 let defered_in_speculation = function
   | EUntypedTypeImport _
@@ -3250,3 +3255,4 @@ let error_code_of_message err : error_code option =
   | EMatchInvalidUnaryPlusBigInt _ -> Some MatchInvalidPattern
   | EMatchDuplicateObjectProperty _ -> Some MatchInvalidPattern
   | EMatchBindingInOrPattern _ -> Some MatchInvalidPattern
+  | EMatchInvalidAsPattern _ -> Some MatchInvalidPattern

src/typing/errors/flow_intermediate_error.ml

@@ -4010,6 +4010,8 @@ let to_printable_error :
       [text "Duplicate property "; code name; text " in object pattern."]
     | MessageMatchBindingInOrPattern ->
       [text "New bindings in 'or' patterns are not yet supported."]
+    | MessageMatchInvalidAsPattern ->
+      [text "Invalid "; code "as"; text " pattern. Direct use on a binding pattern is not allowed."]
   in
   let rec convert_error_message { kind; loc; error_code; root; message; misplaced_source_file = _ }
       =

src/typing/errors/flow_intermediate_error_types.ml

@@ -904,6 +904,7 @@ type 'loc message =
   | MessageMatchInvalidUnaryPlusBigInt
   | MessageMatchDuplicateObjectProperty of { name: string }
   | MessageMatchBindingInOrPattern
+  | MessageMatchInvalidAsPattern
 
 type 'loc intermediate_error = {
   kind: Flow_errors_utils.error_kind;

src/typing/match_pattern.ml

@@ -165,6 +165,9 @@ let rec pattern_ cx ~on_identifier ~on_expression ~on_binding ~in_or_pattern acc
       in
       OrPattern { OrPattern.patterns; comments }
     | AsPattern { AsPattern.pattern = p; target; comments } ->
+      (match p with
+      | (_, BindingPattern _) -> Flow_js.add_output cx (Error_message.EMatchInvalidAsPattern { loc })
+      | _ -> ());
       let p = pattern_ cx ~on_identifier ~on_expression ~on_binding ~in_or_pattern acc p in
       let target =
         match target with

tests/match/match.exp

@@ -652,6 +652,22 @@ New bindings in 'or' patterns are not yet supported. [match-invalid-pattern]
                           ^
 
 
+Error ------------------------------------------------------------------------------------------ pattern-errors.js:109:5
+
+Invalid `as` pattern. Direct use on a binding pattern is not allowed. [match-invalid-pattern]
+
+   109|     const a as b: 0, // ERROR
+            ^^^^^^^^^^^^
+
+
+Error ------------------------------------------------------------------------------------------ pattern-errors.js:110:5
+
+Invalid `as` pattern. Direct use on a binding pattern is not allowed. [match-invalid-pattern]
+
+   110|     const a as const b: 0, // ERROR
+            ^^^^^^^^^^^^^^^^^^
+
+
 Error -------------------------------------------------------------------------------------------------- patterns.js:9:3
 
 Cannot cast `out` to empty because number [1] is incompatible with empty [2]. [incompatible-cast]
@@ -777,4 +793,4 @@ References:
 
 
 
-Found 62 errors
+Found 64 errors

tests/match/pattern-errors.js

@@ -100,3 +100,13 @@
     _ | {...const a}: 0, // ERROR
   };
 }
+
+// As pattern on binding pattern
+{
+  declare const x: [boolean];
+
+  const e1 = match (x) {
+    const a as b: 0, // ERROR
+    const a as const b: 0, // ERROR
+  }
+}