Format switch case blocks without redundant braces

CHANGELOG.md

@@ -26,6 +26,7 @@
 
 #### :nail_care: Polish
 
+- Omit redundant braces around multi-statement switch case bodies when formatting. https://github.com/rescript-lang/rescript/pull/8677
 - Avoid running `rescript-schema-ppx` and `sury-ppx` on source files without an `@schema` annotation. https://github.com/rescript-lang/rescript/pull/8662
 
 #### :house: Internal

compiler/syntax/Formatter.md

@@ -16,7 +16,6 @@ that all source line breaks must be retained.
 
 When changing the formatter:
 
-- test both narrow and wide print widths;
 - cover comments and the parentheses needed to preserve parsing;
 - run `make test-syntax` and `make test-syntax-roundtrip`;
 - inspect snapshot changes for unrelated reformatting;

compiler/syntax/src/res_printer.ml

@@ -5272,18 +5272,15 @@ and print_cases ~state (cases : Parsetree.case list) cmt_tbl =
        ])
 
 and print_case ~state (case : Parsetree.case) cmt_tbl =
+  let is_block_rhs = Parsetree_viewer.is_block_expr case.pc_rhs in
   let rhs =
-    match case.pc_rhs.pexp_desc with
-    | Pexp_let _ | Pexp_letmodule _ | Pexp_letexception _ | Pexp_open _
-    | Pexp_sequence _ ->
-      print_expression_block ~state
-        ~braces:(Parsetree_viewer.is_braced_expr case.pc_rhs)
-        case.pc_rhs cmt_tbl
-    | _ -> (
+    if is_block_rhs then
+      print_expression_block ~state ~braces:false case.pc_rhs cmt_tbl
+    else
       let doc = print_expression_with_comments ~state case.pc_rhs cmt_tbl in
       match Parens.expr case.pc_rhs with
       | Parenthesized -> add_parens doc
-      | _ -> doc)
+      | _ -> doc
   in
 
   let guard =
@@ -5299,12 +5296,14 @@ and print_case ~state (case : Parsetree.case) cmt_tbl =
            ])
   in
   let should_inline_rhs =
-    match case.pc_rhs.pexp_desc with
-    | Pexp_construct ({txt = Longident.Lident ("()" | "true" | "false")}, _)
-    | Pexp_constant _ | Pexp_ident _ ->
-      true
-    | _ when Parsetree_viewer.is_huggable_rhs case.pc_rhs -> true
-    | _ -> false
+    if is_block_rhs then false
+    else
+      match case.pc_rhs.pexp_desc with
+      | Pexp_construct ({txt = Longident.Lident ("()" | "true" | "false")}, _)
+      | Pexp_constant _ | Pexp_ident _ ->
+        true
+      | _ when Parsetree_viewer.is_huggable_rhs case.pc_rhs -> true
+      | _ -> false
   in
   let should_indent_pattern =
     match case.pc_lhs.ppat_desc with

packages/@rescript/runtime/Primitive_exceptions.res

@@ -86,14 +86,12 @@ let idMap = Dict.empty()
 
 let create = (str: string): string => {
   switch idMap->Dict.dangerouslyGetNonOption(str) {
-  | Some(v) => {
-      let id = v + 1
-      idMap->Dict.set(str, id)
-      str ++ ("/" ++ (Obj.magic((id: int)): string))
-    }
-  | None => {
-      idMap->Dict.set(str, 1)
-      str
-    }
+  | Some(v) =>
+    let id = v + 1
+    idMap->Dict.set(str, id)
+    str ++ ("/" ++ (Obj.magic((id: int)): string))
+  | None =>
+    idMap->Dict.set(str, 1)
+    str
   }
 }