fix(compiler): Prevent impossible string error from pattern matching (#2218)

Author: spotandjake

compiler/src/typed/parmatch.re

@@ -1939,7 +1939,8 @@ let untype_constant =
     )
   | Const_bytes(b) =>
     Parsetree.PConstBytes(Location.mknoloc(Bytes.to_string(b)))
-  | Const_string(s) => Parsetree.PConstString(Location.mknoloc(s))
+  | Const_string(s) =>
+    Parsetree.PConstString(Location.mknoloc(Printf.sprintf("\"%s\"", s)))
   | Const_char(c) => Parsetree.PConstChar(Location.mknoloc(c))
   | Const_bool(b) => Parsetree.PConstBool(b)
   | Const_void => Parsetree.PConstVoid;

compiler/test/suites/pattern_matching.re

@@ -479,4 +479,23 @@ describe("pattern matching", ({test, testSkip}) => {
     |},
     "Rec is a record constructor but a tuple constructor pattern was given.",
   );
+  //
+  assertWarning(
+    "regression_2261_str_nested_list",
+    {|
+      match ([]) {
+        ["str"] => void,
+      }
+    |},
+    Warnings.PartialMatch({|(["str", _, _]|["", _]|[])|}),
+  );
+  assertWarning(
+    "regression_2261_str_nested_arr",
+    {|
+      match ([> ]) {
+        [> "str"] => void,
+      }
+    |},
+    Warnings.PartialMatch({|([> ""]|[> ])|}),
+  );
 });