Fix module printing (#6963)

* Handle parens when mod type is a module signature

* Refactor

* Update CHANGELOG

* Add tests

* Handle more edge cases

* Add more test cases from jscomp/test/coercion_module_alias_test.res

Author: shulhi

CHANGELOG.md

@@ -26,6 +26,7 @@
 #### :bug: Bug Fix
 - Fix issue where long layout break added a trailing comma in partial application `...`. https://github.com/rescript-lang/rescript-compiler/pull/6949
 - Fix incorrect format of function under unary operator. https://github.com/rescript-lang/rescript-compiler/pull/6953
+- Fix incorrect incorrect printing of module binding with signature. https://github.com/rescript-lang/rescript-compiler/pull/6963
 
 # 12.0.0-alpha.1
 

jscomp/syntax/src/res_parens.ml

@@ -452,6 +452,23 @@ let include_mod_expr mod_expr =
   | Parsetree.Pmod_constraint _ -> true
   | _ -> false
 
+let mod_expr_parens mod_expr =
+  match mod_expr with
+  | {
+   Parsetree.pmod_desc =
+     Pmod_constraint
+       ( {Parsetree.pmod_desc = Pmod_structure _},
+         {Parsetree.pmty_desc = Pmty_signature [{psig_desc = Psig_module _}]} );
+  } ->
+    false
+  | {
+   Parsetree.pmod_desc =
+     Pmod_constraint
+       (_, {Parsetree.pmty_desc = Pmty_signature [{psig_desc = Psig_module _}]});
+  } ->
+    true
+  | _ -> false
+
 let arrow_return_typ_expr typ_expr =
   match typ_expr.Parsetree.ptyp_desc with
   | Parsetree.Ptyp_arrow _ -> true

jscomp/syntax/src/res_parens.mli

@@ -33,6 +33,8 @@ val call_expr : Parsetree.expression -> kind
 
 val include_mod_expr : Parsetree.module_expr -> bool
 
+val mod_expr_parens : Parsetree.module_expr -> bool
+
 val arrow_return_typ_expr : Parsetree.core_type -> bool
 
 val pattern_record_row_rhs : Parsetree.pattern -> bool

jscomp/syntax/src/res_printer.ml

@@ -685,6 +685,11 @@ and print_module_binding ~state ~is_rec module_binding cmt_tbl i =
         Doc.concat [Doc.text ": "; print_mod_type ~state mod_type cmt_tbl] )
     | mod_expr -> (print_mod_expr ~state mod_expr cmt_tbl, Doc.nil)
   in
+  let mod_expr_doc_parens =
+    if Parens.mod_expr_parens module_binding.pmb_expr then
+      Doc.concat [Doc.lparen; mod_expr_doc; Doc.rparen]
+    else mod_expr_doc
+  in
   let mod_name =
     let doc = Doc.text module_binding.pmb_name.Location.txt in
     print_comments doc cmt_tbl module_binding.pmb_name.loc
@@ -698,7 +703,7 @@ and print_module_binding ~state ~is_rec module_binding cmt_tbl i =
         mod_name;
         mod_constraint_doc;
         Doc.text " = ";
-        mod_expr_doc;
+        mod_expr_doc_parens;
       ]
   in
   print_comments doc cmt_tbl module_binding.pmb_loc

jscomp/syntax/tests/printer/modExpr/expected/structure.res.txt

@@ -22,3 +22,49 @@ let g = {
   module M: T = {}
   0
 }
+
+module M7: {
+  module N': {
+    let x: int
+  }
+} = (M6: {
+  module N: {
+    let x: int
+  }
+  module N' = N
+})
+
+module M8 = M7
+
+module M5 = G0()
+
+module M7: {
+  let x: int
+} = {
+  let x = 8
+}
+
+module M3: {
+  module N': {
+    let x: int
+  }
+} = {
+  include M'
+}
+
+module G0: (X: {}) =>
+{
+  module N': {
+    let x: int
+  }
+} = F0
+
+module M6 = {
+  module D = {
+    let y = 3
+  }
+  module N = {
+    let x = 1
+  }
+  module N' = N
+}

jscomp/syntax/tests/printer/modExpr/structure.res

@@ -21,4 +21,51 @@ module type T = {}
 let g = {
   module M: T = {}
   0
-}
+}
+
+module M7: {
+  module N': {
+    let x: int
+  }
+} = (M6: {
+  module N: {
+    let x: int
+  }
+  module N' = N
+})
+
+
+module M8 = M7
+
+module M5 = G0()
+
+module M7: {
+  let x: int
+} = {
+  let x = 8
+}
+
+module M3: {
+  module N': {
+    let x: int
+  }
+} = {
+  include M'
+}
+
+module G0: (X: {}) =>
+{
+  module N': {
+    let x: int
+  }
+} = F0
+
+module M6 = {
+  module D = {
+    let y = 3
+  }
+  module N = {
+    let x = 1
+  }
+  module N' = N
+}