[12.x] Fix integer range patterns at int32 boundaries

CHANGELOG.md

@@ -15,6 +15,8 @@
 #### :bug: Bug fix
 
 - Fix integer range patterns, including nested record and exception patterns, incorrectly matching values below the range. https://github.com/rescript-lang/rescript/pull/8714
+- Fix integer range patterns at int32 boundaries and wrapped nondecimal patterns matching incorrect values. https://github.com/rescript-lang/rescript/pull/8717 https://github.com/rescript-lang/rescript/pull/8858
+- Integer patterns that alias the same int32 value (e.g. `0xFFFF_FFFF` and `-1`) may now produce unused-case warnings. https://github.com/rescript-lang/rescript/pull/8717 https://github.com/rescript-lang/rescript/pull/8858
 
 #### :nail_care: Polish
 

compiler/ml/matching.ml

@@ -25,6 +25,9 @@ open Printf
 
 let dbg = false
 
+let int32_low = Int32.to_int Int32.min_int
+let int32_high = Int32.to_int Int32.max_int
+
 (* See Peyton-Jones, ``The Implementation of functional programming
    languages'', chapter 5. *)
 (*
@@ -2032,7 +2035,10 @@ let combine_constant names loc arg cst partial ctx def
             | _ -> assert false)
           const_lambda_list
       in
-      call_switcher loc fail arg min_int max_int int_lambda_list names
+      (* Match intervals must use ReScript's int32 bounds, not the host's.
+         Otherwise the upper fail interval starts at 2147483648, which wraps
+         when converted to a Lambda integer constant. *)
+      call_switcher loc fail arg int32_low int32_high int_lambda_list names
     | Const_char _ ->
       let int_lambda_list =
         List.map
@@ -2212,13 +2218,13 @@ let combine_constructor sw_names loc arg ex_pat cstr partial ctx def
 
 let make_test_sequence_variant_constant fail arg int_lambda_list =
   let _, (cases, actions) =
-    as_interval fail min_int max_int
+    as_interval fail int32_low int32_high
       (List.map (fun (a, (_, c)) -> (a, c)) int_lambda_list)
   in
   Switcher.test_sequence arg cases actions
 
 let call_switcher_variant_constant loc fail arg int_lambda_list names =
-  call_switcher loc fail arg min_int max_int
+  call_switcher loc fail arg int32_low int32_high
     (List.map (fun (a, (_, c)) -> (a, c)) int_lambda_list)
     names
 
@@ -2229,7 +2235,7 @@ let call_switcher_variant_constr loc fail arg int_lambda_list names =
       Pgenval,
       v,
       Lprim (Pfield (0, Fld_poly_var_tag), [arg], loc),
-      call_switcher loc fail (Lvar v) min_int max_int
+      call_switcher loc fail (Lvar v) int32_low int32_high
         (List.map (fun (a, (_, c)) -> (a, c)) int_lambda_list)
         names )
 

compiler/ml/typecore.ml

@@ -252,7 +252,12 @@ let type_constant = function
 let constant : Parsetree.constant -> (Asttypes.constant, error) result =
   function
   | Pconst_integer (i, None) -> (
-    try Ok (Const_int (Misc.Int_literal_converter.int i))
+    try
+      (* After the existing host-dependent literal parsing, pattern grouping
+         and intervals must see Lambda's int32 value, so -0xFFFF_FFFF and 1
+         are the same key. This does not change overflow diagnostics. *)
+      let value = Misc.Int_literal_converter.int i in
+      Ok (Const_int (Int32.to_int (Int32.of_int value)))
     with Failure _ -> Error (Literal_overflow "int"))
   | Pconst_integer (i, Some 'n') ->
     let sign, i = Bigint_utils.parse_bigint i in

tests/build_tests/super_errors/expected/intoverflow.res.expected

@@ -53,5 +53,42 @@
   11 │ let v9: int = 0x1_0000_0000 // overflow
   12 │ let v10: int = -0x1_0000_0000 // underflow
   13 │ 
+  14 │ // Wrapped aliases are redundant after int32 normalization.
 
-  Integer literal exceeds the range of representable integers of type int
+  Integer literal exceeds the range of representable integers of type int
+
+
+  Warning number 107
+  /.../fixtures/intoverflow.res:17:5-14
+
+  15 │ let wrappedAlias = value =>
+  16 │   switch value {
+  17 │   | 4294967295 => 1
+  18 │   | -1 => 2
+  19 │   | _ => 0
+
+  Integer literal exceeds the range of representable integers of type int
+
+
+  Warning number 11
+  /.../fixtures/intoverflow.res:18:5-6
+
+  16 ┆ switch value {
+  17 ┆ | 4294967295 => 1
+  18 ┆ | -1 => 2
+  19 ┆ | _ => 0
+  20 ┆ }
+
+  this match case is unused.
+
+
+  Warning number 11
+  /.../fixtures/intoverflow.res:25:5
+
+  23 ┆ switch value {
+  24 ┆ | -0xFFFF_FFFF => 1
+  25 ┆ | 1 => 2
+  26 ┆ | _ => 0
+  27 ┆ }
+
+  this match case is unused.

tests/build_tests/super_errors/fixtures/intoverflow.res

@@ -10,3 +10,18 @@ let v7: int = 0xFFFF_FFFF // -1
 let v8: int = -0xFFFF_FFFF // 1
 let v9: int = 0x1_0000_0000 // overflow
 let v10: int = -0x1_0000_0000 // underflow
+
+// Wrapped aliases are redundant after int32 normalization.
+let wrappedAlias = value =>
+  switch value {
+  | 4294967295 => 1
+  | -1 => 2
+  | _ => 0
+  }
+
+let nondecimalAlias = value =>
+  switch value {
+  | -0xFFFF_FFFF => 1
+  | 1 => 2
+  | _ => 0
+  }

tests/ounit_tests/ounit_integer_constant_tests.ml

@@ -0,0 +1,35 @@
+open OUnit
+
+let suites =
+  __FILE__
+  >::: [
+         ( "integer pattern constants agree with Lambda" >:: fun _ ->
+           List.iter
+             (fun (literal, expected) ->
+               match Typecore.constant (Pconst_integer (literal, None)) with
+               | Ok (Asttypes.Const_int value as typed) ->
+                 assert_equal expected value;
+                 assert_equal
+                   (Lam_constant.Const_int
+                      {i = Int32.of_int expected; comment = None})
+                   (Lam_constant_convert.convert_constant
+                      (Lambda.Const_base typed))
+               | _ -> assert_failure ("integer literal was rejected: " ^ literal))
+             [
+               ("-0xFFFF_FFFF", 1);
+               ("0xFFFF_FFFF", -1);
+               ("2147483647", 2147483647);
+               ("-2147483648", -2147483648);
+             ] );
+         ( "overflow parsing keeps its existing host limits" >:: fun _ ->
+           let result =
+             Typecore.constant (Pconst_integer ("2147483649", None))
+           in
+           assert_equal
+             (if Sys.int_size > 32 then Ok (Asttypes.Const_int (-2147483647))
+              else Error (Typecore.Literal_overflow "int"))
+             result;
+           assert_equal (Error (Typecore.Literal_overflow "int"))
+             (Typecore.constant
+                (Pconst_integer ("999999999999999999999999999", None))) );
+       ]

tests/ounit_tests/ounit_tests_main.ml

@@ -21,6 +21,7 @@ let suites =
       Ounit_bsb_regex_tests.suites;
       Ounit_bsb_pkg_tests.suites;
       Ounit_util_tests.suites;
+      Ounit_integer_constant_tests.suites;
       Ounit_jsx_loc_tests.suites;
       Ounit_analysis_references_tests.suites;
     ]