add fixture tests for error/warning messages

Author: tsnobip

compiler/ml/typecore.ml

@@ -1608,15 +1608,6 @@ and type_pat_aux ~constrs ~labels ~no_existentials ~mode ~explode ~env sp
               (fun (l : Types.label_declaration) -> Ident.name l.ld_id)
               rest_labels
           in
-          (* Warn if all rest fields are already explicit — the rest record will be empty *)
-          if
-            rest_field_names <> []
-            && List.for_all
-                 (fun f -> List.mem f explicit_fields)
-                 rest_field_names
-          then
-            Location.prerr_warning rest_pat.ppat_loc
-              Warnings.Bs_record_rest_empty;
           (* Validate: fields in both explicit and rest must be optional in the explicit pattern *)
           let not_optional =
             List.filter
@@ -1674,6 +1665,15 @@ and type_pat_aux ~constrs ~labels ~no_existentials ~mode ~explode ~env sp
                            (Ident.name rest_label.ld_id, rest_type_lid.txt) )))
               rest_labels
           | [] -> ());
+          (* Warn if all rest fields are already explicit — the rest record will be empty *)
+          if
+            rest_field_names <> []
+            && List.for_all
+                 (fun f -> List.mem f explicit_fields)
+                 rest_field_names
+          then
+            Location.prerr_warning rest_pat.ppat_loc
+              Warnings.Bs_record_rest_empty;
           let rest_type_args =
             match rest_type_args_syntax with
             | [] -> List.map (fun _ -> newvar ()) rest_decl.type_params

tests/build_tests/super_errors/expected/record_rest_empty_warning.res.expected

@@ -0,0 +1,10 @@
+
+  Warning number 111
+  /.../fixtures/record_rest_empty_warning.res:3:16-26
+
+  1 │ type source = {a: int, b?: string}
+  2 │ type sub = {b?: string}
+  3 │ let {a, ?b, ...sub as rest} = ({a: 1}: source)
+  4 │ 
+
+  All fields of the rest type are already present in the explicit pattern. The rest record will always be empty.

tests/build_tests/super_errors/expected/record_rest_extra_field.res.expected

@@ -0,0 +1,10 @@
+
+  We've found a bug for you!
+  /.../fixtures/record_rest_extra_field.res:3:12-14
+
+  1 │ type source = {a: int, x: int}
+  2 │ type sub = {a: int, b: string}
+  3 │ let {x, ...sub as rest} = ({a: 1, x: 2}: source)
+  4 │ 
+
+  Field `b` in the rest type `sub` does not exist in the source record type.

tests/build_tests/super_errors/expected/record_rest_field_missing.res.expected

@@ -0,0 +1,14 @@
+
+  We've found a bug for you!
+  /.../fixtures/record_rest_field_missing.res:3:12-22
+
+  1 │ type source = {a: int, b: string, c: bool, d: float}
+  2 │ type sub = {b: string}
+  3 │ let {a, ...sub as rest} = ({a: 1, b: "x", c: true, d: 1.0}: source)
+  4 │ 
+
+  The following fields are not part of the rest type `sub`:
+- c
+- d
+
+List these fields in the record pattern before the spread so they're not present in the rest record.

tests/build_tests/super_errors/expected/record_rest_field_not_optional.res.expected

@@ -0,0 +1,13 @@
+
+  We've found a bug for you!
+  /.../fixtures/record_rest_field_not_optional.res:3:12-22
+
+  1 │ type source = {a?: int, b?: string, c: bool}
+  2 │ type sub = {a?: int, b?: string}
+  3 │ let {a, ...sub as rest}: source = {c: true}
+  4 │ 
+
+  The following field appears in both the explicit pattern and the rest type `sub`:
+- a
+
+Mark it as optional (`?a`) in the explicit pattern.

tests/build_tests/super_errors/expected/record_rest_invalid_type.res.expected

@@ -0,0 +1,9 @@
+
+  We've found a bug for you!
+  /.../fixtures/record_rest_invalid_type.res:2:12-21
+
+  1 │ type source = {a: int, b: string}
+  2 │ let {a, ...'a as rest} = ({a: 1, b: "x"}: source)
+  3 │ 
+
+  Record rest pattern must have the form: ...Type.t as name

tests/build_tests/super_errors/expected/record_rest_not_record.res.expected

@@ -0,0 +1,10 @@
+
+  We've found a bug for you!
+  /.../fixtures/record_rest_not_record.res:3:12-20
+
+  1 │ type source = {a: int, b: string}
+  2 │ type notRecord = One | Two
+  3 │ let {a, ...notRecord as rest} = ({a: 1, b: "x"}: source)
+  4 │ 
+
+  Type notRecord is not a record type and cannot be used as a record rest pattern.

tests/build_tests/super_errors/expected/record_rest_requires_type_annotation.res.expected

@@ -0,0 +1,9 @@
+
+  We've found a bug for you!
+  /.../fixtures/record_rest_requires_type_annotation.res:2:12-18
+
+  1 │ type source = {a: int, b: string}
+  2 │ let {a, ...theRest} = ({a: 1, b: "x"}: source)
+  3 │ 
+
+  Record rest pattern `...theRest` requires a type annotation. Use `...Type.t as theRest`.

tests/build_tests/super_errors/fixtures/record_rest_empty_warning.res

@@ -0,0 +1,3 @@
+type source = {a: int, b?: string}
+type sub = {b?: string}
+let {a, ?b, ...sub as rest} = ({a: 1}: source)

tests/build_tests/super_errors/fixtures/record_rest_extra_field.res

@@ -0,0 +1,3 @@
+type source = {a: int, x: int}
+type sub = {a: int, b: string}
+let {x, ...sub as rest} = ({a: 1, x: 2}: source)