Fix printing of local module with type.

CHANGELOG.md

@@ -20,6 +20,7 @@
 
 - Remove unnecessary require and import statements when using dynamic imports. https://github.com/rescript-lang/rescript-compiler/pull/6232
 - Fix option unboxing logic in the presence of untagged variants. https://github.com/rescript-lang/rescript-compiler/pull/6233
+- Fix printing of local module with type. https://github.com/rescript-lang/rescript-compiler/issues/6212
 
 #### :nail_care: Polish
 

jscomp/syntax/src/res_printer.ml

@@ -4965,6 +4965,15 @@ and printExpressionBlock ~state ~braces expr cmtTbl =
         let doc = Doc.text modName.txt in
         printComments doc cmtTbl modName.loc
       in
+      let name, modExpr =
+        match modExpr.pmod_desc with
+        | Pmod_constraint (modExpr, modType) ->
+          let name =
+            Doc.concat [name; Doc.text ": "; printModType ~state modType cmtTbl]
+          in
+          (name, modExpr)
+        | _ -> (name, modExpr)
+      in
       let letModuleDoc =
         Doc.concat
           [

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

@@ -15,3 +15,10 @@ module Empty = {/* test */}
 module EmptyModule = {
   /* TODO: management on vacation */
 }
+
+module type T = {}
+
+let g = {
+  module M: T = {}
+  0
+}

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

@@ -15,3 +15,10 @@ module Empty = {/* test */}
 module EmptyModule = {
   /* TODO: management on vacation */
 }
+
+module type T = {}
+
+let g = {
+  module M: T = {}
+  0
+}