[flow][match] Error on invalid unary pattern on 0

Summary:
Error on invalid unary pattern on `0`.

The spec suggests using `Object.is` equality for this instead of `===`, which distinguishes `+0` and `-0`. Flow doesn't model this. Let's just avoid it for now.

Changelog: [internal]

Reviewed By: SamChou19815

Differential Revision: D67502321

fbshipit-source-id: ce6bf7936edc4d5d9cd95d6177690f075c0dbdf6

src/typing/debug_js.ml

@@ -1907,6 +1907,7 @@ let dump_error_message =
         (Flow_ast_utils.string_of_variable_kind kind)
     | EMatchInvalidObjectPropertyLiteral { loc } ->
       spf "EMatchInvalidObjectPropertyLiteral (%s)" (string_of_aloc loc)
+    | EMatchInvalidUnaryZero { loc } -> spf "EMatchInvalidUnaryZero (%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

@@ -623,6 +623,7 @@ and 'loc t' =
       kind: Flow_ast.Variable.kind;
     }
   | EMatchInvalidObjectPropertyLiteral of { loc: 'loc }
+  | EMatchInvalidUnaryZero of { loc: 'loc }
   (* Dev only *)
   | EDevOnlyRefinedLocInfo of {
       refined_loc: 'loc;
@@ -1428,6 +1429,7 @@ let rec map_loc_of_error_message (f : 'a -> 'b) : 'a t' -> 'b t' =
     EMatchNotExhaustive { loc = f loc; reason = map_reason reason }
   | EMatchInvalidBindingKind { loc; kind } -> EMatchInvalidBindingKind { loc = f loc; kind }
   | EMatchInvalidObjectPropertyLiteral { loc } -> EMatchInvalidObjectPropertyLiteral { loc = f loc }
+  | EMatchInvalidUnaryZero { loc } -> EMatchInvalidUnaryZero { loc = f loc }
   | EDevOnlyInvalidatedRefinementInfo { read_loc; invalidation_info } ->
     EDevOnlyInvalidatedRefinementInfo
       {
@@ -1727,7 +1729,8 @@ let util_use_op_of_msg nope util = function
   | ECannotCallReactComponent _
   | EMatchNotExhaustive _
   | EMatchInvalidBindingKind _
-  | EMatchInvalidObjectPropertyLiteral _ ->
+  | EMatchInvalidObjectPropertyLiteral _
+  | EMatchInvalidUnaryZero _ ->
     nope
 
 (* Not all messages (i.e. those whose locations are based on use_ops) have locations that can be
@@ -1931,6 +1934,7 @@ let loc_of_msg : 'loc t' -> 'loc option = function
   | EMatchNotExhaustive { loc; _ } -> Some loc
   | EMatchInvalidBindingKind { loc; _ } -> Some loc
   | EMatchInvalidObjectPropertyLiteral { loc } -> Some loc
+  | EMatchInvalidUnaryZero { loc } -> Some loc
   | EDevOnlyRefinedLocInfo { refined_loc; refining_locs = _ } -> Some refined_loc
   | EDevOnlyInvalidatedRefinementInfo { read_loc; invalidation_info = _ } -> Some read_loc
   | EUnableToSpread _
@@ -2882,6 +2886,7 @@ let friendly_message_of_msg = function
   | EMatchInvalidBindingKind { loc = _; kind } -> Normal (MessageMatchInvalidBindingKind { kind })
   | EMatchInvalidObjectPropertyLiteral { loc = _ } ->
     Normal MessageMatchInvalidObjectPropertyLiteral
+  | EMatchInvalidUnaryZero { loc = _ } -> Normal MessageMatchInvalidUnaryZero
 
 let defered_in_speculation = function
   | EUntypedTypeImport _
@@ -3221,3 +3226,4 @@ let error_code_of_message err : error_code option =
   | EMatchNotExhaustive _ -> Some MatchNotExhaustive
   | EMatchInvalidBindingKind _ -> Some MatchInvalidPattern
   | EMatchInvalidObjectPropertyLiteral _ -> Some MatchInvalidPattern
+  | EMatchInvalidUnaryZero _ -> Some MatchInvalidPattern

src/typing/errors/flow_intermediate_error.ml

@@ -4002,6 +4002,8 @@ let to_printable_error :
         text "Unsupported object property literal in match pattern. ";
         text "String literals and int-like number literals are supported.";
       ]
+    | MessageMatchInvalidUnaryZero ->
+      [text "Unary pattern on "; code "0"; text " is not supported."]
   in
   let rec convert_error_message { kind; loc; error_code; root; message; misplaced_source_file = _ }
       =

src/typing/errors/flow_intermediate_error_types.ml

@@ -900,6 +900,7 @@ type 'loc message =
   | MessageMatchNotExhaustive of 'loc virtual_reason
   | MessageMatchInvalidBindingKind of { kind: Flow_ast.Variable.kind }
   | MessageMatchInvalidObjectPropertyLiteral
+  | MessageMatchInvalidUnaryZero
 
 type 'loc intermediate_error = {
   kind: Flow_errors_utils.error_kind;

src/typing/match_pattern.ml

@@ -139,7 +139,13 @@ let rec pattern cx ~on_identifier ~on_expression ~on_binding acc (loc, p) :
     | StringPattern x -> StringPattern x
     | BooleanPattern x -> BooleanPattern x
     | NullPattern x -> NullPattern x
-    | UnaryPattern x -> UnaryPattern x
+    | UnaryPattern x ->
+      let { UnaryPattern.argument; _ } = x in
+      (match argument with
+      | (_, UnaryPattern.NumberLiteral { Ast.NumberLiteral.value = 0.0; _ }) ->
+        Flow_js.add_output cx (Error_message.EMatchInvalidUnaryZero { loc })
+      | _ -> ());
+      UnaryPattern x
     | MemberPattern mem ->
       let (_, mem) = member cx ~on_identifier ~on_expression mem in
       MemberPattern mem

tests/match/match.exp

@@ -477,6 +477,31 @@ Cannot use `var` for match pattern binding. Only `const` is allowed. [match-inva
             ^^^^^
 
 
+Error ------------------------------------------------------------------------------------------- pattern-errors.js:25:6
+
+Unsupported object property literal in match pattern. String literals and int-like number literals are supported.
+[match-invalid-pattern]
+
+   25|     {1.1: _}: 0, // ERROR
+            ^^^
+
+
+Error ------------------------------------------------------------------------------------------- pattern-errors.js:35:5
+
+Unary pattern on `0` is not supported. [match-invalid-pattern]
+
+   35|     -0: true, // ERROR
+           ^^
+
+
+Error ------------------------------------------------------------------------------------------- pattern-errors.js:36:5
+
+Unary pattern on `0` is not supported. [match-invalid-pattern]
+
+   36|     +0: true, // ERROR
+           ^^
+
+
 Error -------------------------------------------------------------------------------------------------- patterns.js:9:3
 
 Cannot cast `out` to empty because number [1] is incompatible with empty [2]. [incompatible-cast]
@@ -602,4 +627,4 @@ References:
 
 
 
-Found 44 errors
+Found 47 errors

tests/match/pattern-errors.js

@@ -16,3 +16,24 @@
      var a: 0, // ERROR
   };
 }
+
+// Invalid numeric property
+{
+  declare const x: {1: true};
+
+  const e1 = match (x) {
+    {1.1: _}: 0, // ERROR
+    _: 0,
+  };
+}
+
+// Unary pattern on `0` banned
+{
+  declare const x: 0;
+
+  const e1 = match (x) {
+    -0: true, // ERROR
+    +0: true, // ERROR
+    0: true, // OK
+  };
+}