From 6992133ad5a14dafc3f4464fb5a2616b3d1731ad Mon Sep 17 00:00:00 2001
From: Cristiano Calcagno <ccrisccris@gmail.com>
Date: Wed, 28 Apr 2021 15:40:05 +0200
Subject: [PATCH 01/10] Towards better treatment of modules and module types.

Fixes https://github.com/rescript-lang/rescript-vscode/issues/178
---
 analysis/src/Commands.ml                  | 3 +++
 analysis/src/Hover.ml                     | 4 +++-
 analysis/src/ProcessCmt.ml                | 8 ++++++--
 analysis/src/References.ml                | 3 ++-
 analysis/src/SharedTypes.ml               | 5 ++++-
 analysis/tests/src/Hover.res              | 9 +++++++++
 analysis/tests/src/expected/A.res.txt     | 3 +++
 analysis/tests/src/expected/Hover.res.txt | 3 +++
 8 files changed, 33 insertions(+), 5 deletions(-)
 create mode 100644 analysis/tests/src/expected/A.res.txt

diff --git a/analysis/src/Commands.ml b/analysis/src/Commands.ml
index 40dbac7d3..d77188a62 100644
--- a/analysis/src/Commands.ml
+++ b/analysis/src/Commands.ml
@@ -170,6 +170,9 @@ let documentSymbol ~path =
           | MValue v -> (v |> SharedTypes.variableKind, [])
           | MType (t, _) -> (t.decl |> SharedTypes.declarationKind, [])
           | Module (Structure contents) -> (Module, getItems contents)
+          | Module (Constraint (_, Structure contents)) ->
+            (Module, getItems contents)
+          | Module (Constraint _) -> (Module, [])
           | Module (Ident _) -> (Module, [])
         in
         if extentLoc.loc_ghost then siblings
diff --git a/analysis/src/Hover.ml b/analysis/src/Hover.ml
index 4903fe115..0ef1f4e43 100644
--- a/analysis/src/Hover.ml
+++ b/analysis/src/Hover.ml
@@ -45,7 +45,9 @@ let showModule ~docstring ~(file : SharedTypes.file) ~name
   | None -> showModuleTopLevel ~docstring ~name file.contents.topLevel
   | Some {item = Structure {topLevel}} ->
     showModuleTopLevel ~docstring ~name topLevel
-  | Some {item = Ident _} -> Some "Unable to resolve module reference"
+  | Some {item = Constraint(Structure {topLevel}, _)} ->
+    showModuleTopLevel ~docstring ~name topLevel
+  | Some _ -> Some "Unable to resolve module reference"
 
 let newHover ~(file : SharedTypes.file) ~package locItem =
   match locItem.SharedTypes.locType with
diff --git a/analysis/src/ProcessCmt.ml b/analysis/src/ProcessCmt.ml
index d840632a5..76d9a1849 100644
--- a/analysis/src/ProcessCmt.ml
+++ b/analysis/src/ProcessCmt.ml
@@ -375,6 +375,7 @@ let rec forItem ~env ~(exported : exported) item =
              | _ -> Types.Trec_next
            in
            decl |> forTypeDeclaration ~env ~exported ~recStatus)
+  | Tstr_modtype _ -> []
   | _ -> []
 
 and forModule env mod_desc moduleName =
@@ -422,12 +423,14 @@ and forModule env mod_desc moduleName =
     (* e.g. when the same id is defined twice (e.g. make with @react.component) *)
     (* skip the constraint and use the original module definition *)
     forModule env expr.mod_desc moduleName
-  | Tmod_constraint (_expr, typ, _constraint, _coercion) ->
+  | Tmod_constraint (expr, typ, _constraint, _coercion) ->
     (* TODO do this better I think *)
+    let forMod = forModule env expr.mod_desc moduleName in
     let env =
       {env with modulePath = ExportedModule (moduleName, env.modulePath)}
     in
-    forModuleType env typ
+    let forModTyp = forModuleType env typ in
+    Constraint (forMod, forModTyp)
 
 and forStructure ~env items =
   let exported = initExported () in
@@ -636,6 +639,7 @@ and findInModule ~env kind path =
   match kind with
   | Structure {exported} ->
     resolvePathInner ~env:{env with qExported = exported} ~path
+  | Constraint (_, k) -> findInModule ~env k path
   | Ident modulePath -> (
     let stamp, moduleName, fullPath = joinPaths modulePath path in
     if stamp = 0 then Some (`Global (moduleName, fullPath))
diff --git a/analysis/src/References.ml b/analysis/src/References.ml
index a92bdd6ac..f23628208 100644
--- a/analysis/src/References.ml
+++ b/analysis/src/References.ml
@@ -197,7 +197,8 @@ let alternateDeclared ~file ~package declared tip =
 let resolveModuleReference ~file ~package (declared : moduleKind declared) =
   match declared.item with
   | Structure _ -> Some (file, Some declared)
-  | Ident path -> (
+  | Constraint ((Structure _ | Constraint _), _) -> Some (file, Some declared)
+  | Ident path | Constraint (Ident path, _) -> (
     let env = ProcessCmt.fileEnv file in
     match ProcessCmt.fromCompilerPath ~env path with
     | `Not_found -> None
diff --git a/analysis/src/SharedTypes.ml b/analysis/src/SharedTypes.ml
index 05ccd4eaa..48e011075 100644
--- a/analysis/src/SharedTypes.ml
+++ b/analysis/src/SharedTypes.ml
@@ -117,7 +117,10 @@ and moduleContents = {
   topLevel : moduleItem declared list;
 }
 
-and moduleKind = Ident of Path.t | Structure of moduleContents
+and moduleKind =
+  | Ident of Path.t
+  | Structure of moduleContents
+  | Constraint of moduleKind * moduleKind
 
 type 't stampMap = (int, 't) Hashtbl.t
 
diff --git a/analysis/tests/src/Hover.res b/analysis/tests/src/Hover.res
index 5a6501f36..b5659ff4a 100644
--- a/analysis/tests/src/Hover.res
+++ b/analysis/tests/src/Hover.res
@@ -44,3 +44,12 @@ let make2 = (~name:string) => React.string(name)
 
 let num = 34
 //        ^hov
+
+module type Logger = {
+  let log: string => unit
+}
+
+module JsLogger: Logger = {
+//     ^hov
+  let log = (msg: string) => Js.log(msg)
+}
\ No newline at end of file
diff --git a/analysis/tests/src/expected/A.res.txt b/analysis/tests/src/expected/A.res.txt
new file mode 100644
index 000000000..75bf4748b
--- /dev/null
+++ b/analysis/tests/src/expected/A.res.txt
@@ -0,0 +1,3 @@
+Hover tests/src/A.res 4:7
+{"contents": "```rescript\nmodule JsLogger = {\n  let log: string => unit\n}\n```"}
+
diff --git a/analysis/tests/src/expected/Hover.res.txt b/analysis/tests/src/expected/Hover.res.txt
index 7a0e4f5fe..25da21654 100644
--- a/analysis/tests/src/expected/Hover.res.txt
+++ b/analysis/tests/src/expected/Hover.res.txt
@@ -28,3 +28,6 @@ Hover tests/src/Hover.res 41:13
 Hover tests/src/Hover.res 44:10
 {"contents": "```rescript\nint\n```"}
 
+Hover tests/src/Hover.res 51:7
+{"contents": "```rescript\nmodule JsLogger = {\n  let log: string => unit\n}\n```"}
+

From d2aef8941a54732a4a5937b3ab429b458c96a6d0 Mon Sep 17 00:00:00 2001
From: Cristiano Calcagno <ccrisccris@gmail.com>
Date: Wed, 28 Apr 2021 16:57:59 +0200
Subject: [PATCH 02/10] Add jump to definition test.

---
 analysis/tests/src/Hover.res              | 5 ++++-
 analysis/tests/src/expected/Hover.res.txt | 3 +++
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/analysis/tests/src/Hover.res b/analysis/tests/src/Hover.res
index b5659ff4a..8a0c83d34 100644
--- a/analysis/tests/src/Hover.res
+++ b/analysis/tests/src/Hover.res
@@ -52,4 +52,7 @@ module type Logger = {
 module JsLogger: Logger = {
 //     ^hov
   let log = (msg: string) => Js.log(msg)
-}
\ No newline at end of file
+}
+
+module JJ = JsLogger
+//            ^def
diff --git a/analysis/tests/src/expected/Hover.res.txt b/analysis/tests/src/expected/Hover.res.txt
index 25da21654..e6fdb5ad2 100644
--- a/analysis/tests/src/expected/Hover.res.txt
+++ b/analysis/tests/src/expected/Hover.res.txt
@@ -31,3 +31,6 @@ Hover tests/src/Hover.res 44:10
 Hover tests/src/Hover.res 51:7
 {"contents": "```rescript\nmodule JsLogger = {\n  let log: string => unit\n}\n```"}
 
+Definition tests/src/Hover.res 56:14
+{"uri": "Hover.res", "range": {"start": {"line": 51, "character": 7}, "end": {"line": 51, "character": 15}}}
+

From 0556a8f0e61950a6f653340010c77daefe11b5ea Mon Sep 17 00:00:00 2001
From: Cristiano Calcagno <ccrisccris@gmail.com>
Date: Thu, 29 Apr 2021 02:10:42 +0200
Subject: [PATCH 03/10] Teat modules more uniformly.

---
 analysis/src/Commands.ml                  | 18 ++++++++----------
 analysis/src/Hover.ml                     | 10 ++++++----
 analysis/src/ProcessCmt.ml                |  6 +++---
 analysis/tests/src/Hover.res              |  1 +
 analysis/tests/src/expected/Hover.res.txt |  4 ++--
 5 files changed, 20 insertions(+), 19 deletions(-)

diff --git a/analysis/src/Commands.ml b/analysis/src/Commands.ml
index d77188a62..4a5c7da88 100644
--- a/analysis/src/Commands.ml
+++ b/analysis/src/Commands.ml
@@ -164,17 +164,15 @@ let documentSymbol ~path =
   | Ok (file, _extra) ->
     let open SharedTypes in
     let rec getItems {topLevel} =
+      let rec getItem = function
+        | MValue v -> (v |> SharedTypes.variableKind, [])
+        | MType (t, _) -> (t.decl |> SharedTypes.declarationKind, [])
+        | Module (Structure contents) -> (Module, getItems contents)
+        | Module (Constraint (_, modTypeItem)) -> getItem (Module modTypeItem)
+        | Module (Ident _) -> (Module, [])
+      in
       let fn {name = {txt}; extentLoc; item} =
-        let item, siblings =
-          match item with
-          | MValue v -> (v |> SharedTypes.variableKind, [])
-          | MType (t, _) -> (t.decl |> SharedTypes.declarationKind, [])
-          | Module (Structure contents) -> (Module, getItems contents)
-          | Module (Constraint (_, Structure contents)) ->
-            (Module, getItems contents)
-          | Module (Constraint _) -> (Module, [])
-          | Module (Ident _) -> (Module, [])
-        in
+        let item, siblings = getItem item in
         if extentLoc.loc_ghost then siblings
         else (txt, extentLoc, item) :: siblings
       in
diff --git a/analysis/src/Hover.ml b/analysis/src/Hover.ml
index 0ef1f4e43..fba9c2c09 100644
--- a/analysis/src/Hover.ml
+++ b/analysis/src/Hover.ml
@@ -39,15 +39,17 @@ let showModuleTopLevel ~docstring ~name
   in
   Some (doc ^ full)
 
-let showModule ~docstring ~(file : SharedTypes.file) ~name
+let rec showModule ~docstring ~(file : SharedTypes.file) ~name
     (declared : SharedTypes.moduleKind SharedTypes.declared option) =
   match declared with
   | None -> showModuleTopLevel ~docstring ~name file.contents.topLevel
   | Some {item = Structure {topLevel}} ->
     showModuleTopLevel ~docstring ~name topLevel
-  | Some {item = Constraint(Structure {topLevel}, _)} ->
-    showModuleTopLevel ~docstring ~name topLevel
-  | Some _ -> Some "Unable to resolve module reference"
+  | Some ({item = Constraint (_, moduleType)} as declared) ->
+    (* show the interface *)
+    showModule ~docstring ~file ~name (Some {declared with item = moduleType})
+  | Some {item = Ident path} ->
+    Some ("Unable to resolve module reference " ^ Path.name path)
 
 let newHover ~(file : SharedTypes.file) ~package locItem =
   match locItem.SharedTypes.locType with
diff --git a/analysis/src/ProcessCmt.ml b/analysis/src/ProcessCmt.ml
index 76d9a1849..4d418869f 100644
--- a/analysis/src/ProcessCmt.ml
+++ b/analysis/src/ProcessCmt.ml
@@ -425,12 +425,12 @@ and forModule env mod_desc moduleName =
     forModule env expr.mod_desc moduleName
   | Tmod_constraint (expr, typ, _constraint, _coercion) ->
     (* TODO do this better I think *)
-    let forMod = forModule env expr.mod_desc moduleName in
+    let modKind = forModule env expr.mod_desc moduleName in
     let env =
       {env with modulePath = ExportedModule (moduleName, env.modulePath)}
     in
-    let forModTyp = forModuleType env typ in
-    Constraint (forMod, forModTyp)
+    let modTypeKind = forModuleType env typ in
+    Constraint (modKind, modTypeKind)
 
 and forStructure ~env items =
   let exported = initExported () in
diff --git a/analysis/tests/src/Hover.res b/analysis/tests/src/Hover.res
index 8a0c83d34..b86280aa5 100644
--- a/analysis/tests/src/Hover.res
+++ b/analysis/tests/src/Hover.res
@@ -52,6 +52,7 @@ module type Logger = {
 module JsLogger: Logger = {
 //     ^hov
   let log = (msg: string) => Js.log(msg)
+  let _oneMore = 3
 }
 
 module JJ = JsLogger
diff --git a/analysis/tests/src/expected/Hover.res.txt b/analysis/tests/src/expected/Hover.res.txt
index e6fdb5ad2..1bcc99002 100644
--- a/analysis/tests/src/expected/Hover.res.txt
+++ b/analysis/tests/src/expected/Hover.res.txt
@@ -29,8 +29,8 @@ Hover tests/src/Hover.res 44:10
 {"contents": "```rescript\nint\n```"}
 
 Hover tests/src/Hover.res 51:7
-{"contents": "```rescript\nmodule JsLogger = {\n  let log: string => unit\n}\n```"}
+{"contents": "Unable to resolve module reference Logger"}
 
-Definition tests/src/Hover.res 56:14
+Definition tests/src/Hover.res 57:14
 {"uri": "Hover.res", "range": {"start": {"line": 51, "character": 7}, "end": {"line": 51, "character": 15}}}
 

From a8c0de42bc6a02e9b57e941916f287ee4147aa06 Mon Sep 17 00:00:00 2001
From: Cristiano Calcagno <ccrisccris@gmail.com>
Date: Thu, 29 Apr 2021 02:11:14 +0200
Subject: [PATCH 04/10] Remove one constraint special case.

---
 analysis/src/ProcessCmt.ml | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/analysis/src/ProcessCmt.ml b/analysis/src/ProcessCmt.ml
index 4d418869f..6d3e08512 100644
--- a/analysis/src/ProcessCmt.ml
+++ b/analysis/src/ProcessCmt.ml
@@ -418,11 +418,6 @@ and forModule env mod_desc moduleName =
       {env with modulePath = ExportedModule (moduleName, env.modulePath)}
     in
     forModuleType env moduleType
-  | Tmod_constraint (expr, _typ, Tmodtype_implicit, Tcoerce_structure _) ->
-    (* implicit contraint synthesized during typechecking *)
-    (* e.g. when the same id is defined twice (e.g. make with @react.component) *)
-    (* skip the constraint and use the original module definition *)
-    forModule env expr.mod_desc moduleName
   | Tmod_constraint (expr, typ, _constraint, _coercion) ->
     (* TODO do this better I think *)
     let modKind = forModule env expr.mod_desc moduleName in

From 66a31b7f966943815aeb77fa834a2a8a0b38cf5e Mon Sep 17 00:00:00 2001
From: Cristiano Calcagno <ccrisccris@gmail.com>
Date: Thu, 29 Apr 2021 02:15:21 +0200
Subject: [PATCH 05/10] Add example of id redefined.

---
 analysis/tests/src/Hover.res              | 8 ++++++++
 analysis/tests/src/expected/Hover.res.txt | 3 +++
 2 files changed, 11 insertions(+)

diff --git a/analysis/tests/src/Hover.res b/analysis/tests/src/Hover.res
index b86280aa5..c1f79da33 100644
--- a/analysis/tests/src/Hover.res
+++ b/analysis/tests/src/Hover.res
@@ -57,3 +57,11 @@ module JsLogger: Logger = {
 
 module JJ = JsLogger
 //            ^def
+
+
+module IdDefinedTwice = {
+//       ^hov
+  let x = 10
+  let y = 20
+  let x = 10
+}
\ No newline at end of file
diff --git a/analysis/tests/src/expected/Hover.res.txt b/analysis/tests/src/expected/Hover.res.txt
index 1bcc99002..6dbf1e5f8 100644
--- a/analysis/tests/src/expected/Hover.res.txt
+++ b/analysis/tests/src/expected/Hover.res.txt
@@ -34,3 +34,6 @@ Hover tests/src/Hover.res 51:7
 Definition tests/src/Hover.res 57:14
 {"uri": "Hover.res", "range": {"start": {"line": 51, "character": 7}, "end": {"line": 51, "character": 15}}}
 
+Hover tests/src/Hover.res 61:9
+{"contents": "```rescript\nmodule IdDefindeTwice = {\n  let x: int\n  let y: int\n  let x: int\n}\n```"}
+

From 6e57d84132c6ac37a6328fdb74a0e9943f90aea3 Mon Sep 17 00:00:00 2001
From: Cristiano Calcagno <ccrisccris@gmail.com>
Date: Thu, 29 Apr 2021 02:23:30 +0200
Subject: [PATCH 06/10] Clean up module references.

---
 analysis/src/ProcessCmt.ml                | 2 +-
 analysis/src/References.ml                | 7 ++++---
 analysis/tests/src/expected/Hover.res.txt | 4 ++--
 3 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/analysis/src/ProcessCmt.ml b/analysis/src/ProcessCmt.ml
index 6d3e08512..867c66298 100644
--- a/analysis/src/ProcessCmt.ml
+++ b/analysis/src/ProcessCmt.ml
@@ -634,7 +634,7 @@ and findInModule ~env kind path =
   match kind with
   | Structure {exported} ->
     resolvePathInner ~env:{env with qExported = exported} ~path
-  | Constraint (_, k) -> findInModule ~env k path
+  | Constraint (_, moduleTypeKind) -> findInModule ~env moduleTypeKind path
   | Ident modulePath -> (
     let stamp, moduleName, fullPath = joinPaths modulePath path in
     if stamp = 0 then Some (`Global (moduleName, fullPath))
diff --git a/analysis/src/References.ml b/analysis/src/References.ml
index f23628208..8b8477101 100644
--- a/analysis/src/References.ml
+++ b/analysis/src/References.ml
@@ -194,11 +194,12 @@ let alternateDeclared ~file ~package declared tip =
           | Some declared -> Some (file, extra, declared)))
     | _ -> None)
 
-let resolveModuleReference ~file ~package (declared : moduleKind declared) =
+let rec resolveModuleReference ~file ~package (declared : moduleKind declared) =
   match declared.item with
   | Structure _ -> Some (file, Some declared)
-  | Constraint ((Structure _ | Constraint _), _) -> Some (file, Some declared)
-  | Ident path | Constraint (Ident path, _) -> (
+  | Constraint (moduleItem, _moduleTypeItem) ->
+    resolveModuleReference ~file ~package {declared with item = moduleItem}
+  | Ident path -> (
     let env = ProcessCmt.fileEnv file in
     match ProcessCmt.fromCompilerPath ~env path with
     | `Not_found -> None
diff --git a/analysis/tests/src/expected/Hover.res.txt b/analysis/tests/src/expected/Hover.res.txt
index 6dbf1e5f8..fd4a947b7 100644
--- a/analysis/tests/src/expected/Hover.res.txt
+++ b/analysis/tests/src/expected/Hover.res.txt
@@ -29,11 +29,11 @@ Hover tests/src/Hover.res 44:10
 {"contents": "```rescript\nint\n```"}
 
 Hover tests/src/Hover.res 51:7
-{"contents": "Unable to resolve module reference Logger"}
+{"contents": "```rescript\nmodule JsLogger = {\n  let log: string => unit\n  let _oneMore: int\n}\n```"}
 
 Definition tests/src/Hover.res 57:14
 {"uri": "Hover.res", "range": {"start": {"line": 51, "character": 7}, "end": {"line": 51, "character": 15}}}
 
 Hover tests/src/Hover.res 61:9
-{"contents": "```rescript\nmodule IdDefindeTwice = {\n  let x: int\n  let y: int\n  let x: int\n}\n```"}
+{"contents": "```rescript\nmodule IdDefinedTwice = {\n  let x: int\n  let y: int\n  let x: int\n}\n```"}
 

From 84def2fa852698de1faf0193683662e145f613bd Mon Sep 17 00:00:00 2001
From: Cristiano Calcagno <ccrisccris@gmail.com>
Date: Thu, 29 Apr 2021 02:31:04 +0200
Subject: [PATCH 07/10] Add example showing transitive module resolution is
 missing.

---
 analysis/tests/src/Hover.res              | 10 +++++++++-
 analysis/tests/src/expected/Hover.res.txt |  6 ++++++
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/analysis/tests/src/Hover.res b/analysis/tests/src/Hover.res
index c1f79da33..cbb1386c8 100644
--- a/analysis/tests/src/Hover.res
+++ b/analysis/tests/src/Hover.res
@@ -64,4 +64,12 @@ module IdDefinedTwice = {
   let x = 10
   let y = 20
   let x = 10
-}
\ No newline at end of file
+}
+
+module A = {let x=13}
+
+module B = A
+//     ^hov
+
+module C = B
+//     ^hov
diff --git a/analysis/tests/src/expected/Hover.res.txt b/analysis/tests/src/expected/Hover.res.txt
index fd4a947b7..d1adcca9d 100644
--- a/analysis/tests/src/expected/Hover.res.txt
+++ b/analysis/tests/src/expected/Hover.res.txt
@@ -37,3 +37,9 @@ Definition tests/src/Hover.res 57:14
 Hover tests/src/Hover.res 61:9
 {"contents": "```rescript\nmodule IdDefinedTwice = {\n  let x: int\n  let y: int\n  let x: int\n}\n```"}
 
+Hover tests/src/Hover.res 70:7
+{"contents": "```rescript\nmodule A = {\n  let x: int\n}\n```"}
+
+Hover tests/src/Hover.res 73:7
+{"contents": "Unable to resolve module reference A"}
+

From f97f62d6cd02d8166e4d826908485beb73114b0c Mon Sep 17 00:00:00 2001
From: Cristiano Calcagno <ccrisccris@gmail.com>
Date: Thu, 29 Apr 2021 02:37:01 +0200
Subject: [PATCH 08/10] Example: currently no hover on module type.

---
 analysis/tests/src/Hover.res              |  1 +
 analysis/tests/src/expected/Hover.res.txt | 15 +++++++++------
 2 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/analysis/tests/src/Hover.res b/analysis/tests/src/Hover.res
index cbb1386c8..500d51f82 100644
--- a/analysis/tests/src/Hover.res
+++ b/analysis/tests/src/Hover.res
@@ -46,6 +46,7 @@ let num = 34
 //        ^hov
 
 module type Logger = {
+//           ^hov
   let log: string => unit
 }
 
diff --git a/analysis/tests/src/expected/Hover.res.txt b/analysis/tests/src/expected/Hover.res.txt
index d1adcca9d..d3c74c631 100644
--- a/analysis/tests/src/expected/Hover.res.txt
+++ b/analysis/tests/src/expected/Hover.res.txt
@@ -28,18 +28,21 @@ Hover tests/src/Hover.res 41:13
 Hover tests/src/Hover.res 44:10
 {"contents": "```rescript\nint\n```"}
 
-Hover tests/src/Hover.res 51:7
+Hover tests/src/Hover.res 47:13
+null
+
+Hover tests/src/Hover.res 52:7
 {"contents": "```rescript\nmodule JsLogger = {\n  let log: string => unit\n  let _oneMore: int\n}\n```"}
 
-Definition tests/src/Hover.res 57:14
-{"uri": "Hover.res", "range": {"start": {"line": 51, "character": 7}, "end": {"line": 51, "character": 15}}}
+Definition tests/src/Hover.res 58:14
+{"uri": "Hover.res", "range": {"start": {"line": 52, "character": 7}, "end": {"line": 52, "character": 15}}}
 
-Hover tests/src/Hover.res 61:9
+Hover tests/src/Hover.res 62:9
 {"contents": "```rescript\nmodule IdDefinedTwice = {\n  let x: int\n  let y: int\n  let x: int\n}\n```"}
 
-Hover tests/src/Hover.res 70:7
+Hover tests/src/Hover.res 71:7
 {"contents": "```rescript\nmodule A = {\n  let x: int\n}\n```"}
 
-Hover tests/src/Hover.res 73:7
+Hover tests/src/Hover.res 74:7
 {"contents": "Unable to resolve module reference A"}
 

From b4032df8b3f453acce4441dcf8390bfda6953d3d Mon Sep 17 00:00:00 2001
From: Cristiano Calcagno <ccrisccris@gmail.com>
Date: Thu, 29 Apr 2021 02:52:07 +0200
Subject: [PATCH 09/10] Handle mod type declarations.

---
 analysis/src/ProcessCmt.ml                | 19 ++++++++++++++++++-
 analysis/tests/src/expected/Hover.res.txt |  2 +-
 2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/analysis/src/ProcessCmt.ml b/analysis/src/ProcessCmt.ml
index 867c66298..9c05b6e36 100644
--- a/analysis/src/ProcessCmt.ml
+++ b/analysis/src/ProcessCmt.ml
@@ -343,6 +343,24 @@ let rec forItem ~env ~(exported : exported) item =
         mb_attributes exported.modules env.stamps.modules
     in
     [{declared with item = Module declared.item}]
+  | Tstr_modtype
+      {
+        mtd_name = name;
+        mtd_id;
+        mtd_attributes;
+        mtd_type = Some {mty_type = modType};
+        mtd_loc;
+      } ->
+    let env =
+      {env with modulePath = ExportedModule (name.txt, env.modulePath)}
+    in
+    let modTypeItem = forModuleType env modType in
+    let declared =
+      addItem ~item:modTypeItem ~name ~extent:mtd_loc
+        ~stamp:(Ident.binding_time mtd_id)
+        ~env mtd_attributes exported.modules env.stamps.modules
+    in
+    [{declared with item = Module modTypeItem}]
   | Tstr_include {incl_mod; incl_type} ->
     let env =
       match getModulePath incl_mod.mod_desc with
@@ -375,7 +393,6 @@ let rec forItem ~env ~(exported : exported) item =
              | _ -> Types.Trec_next
            in
            decl |> forTypeDeclaration ~env ~exported ~recStatus)
-  | Tstr_modtype _ -> []
   | _ -> []
 
 and forModule env mod_desc moduleName =
diff --git a/analysis/tests/src/expected/Hover.res.txt b/analysis/tests/src/expected/Hover.res.txt
index d3c74c631..87f223e28 100644
--- a/analysis/tests/src/expected/Hover.res.txt
+++ b/analysis/tests/src/expected/Hover.res.txt
@@ -29,7 +29,7 @@ Hover tests/src/Hover.res 44:10
 {"contents": "```rescript\nint\n```"}
 
 Hover tests/src/Hover.res 47:13
-null
+{"contents": "```rescript\nmodule Logger = {\n  let log: string => unit\n}\n```"}
 
 Hover tests/src/Hover.res 52:7
 {"contents": "```rescript\nmodule JsLogger = {\n  let log: string => unit\n  let _oneMore: int\n}\n```"}

From 7706e64df69b091bfe76474d5a8aa5828465101b Mon Sep 17 00:00:00 2001
From: Cristiano Calcagno <ccrisccris@gmail.com>
Date: Thu, 29 Apr 2021 02:55:18 +0200
Subject: [PATCH 10/10] Use module type to resolve references.

---
 analysis/src/Hover.ml                     | 5 +++--
 analysis/src/References.ml                | 4 ++--
 analysis/tests/src/expected/Hover.res.txt | 6 +++---
 3 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/analysis/src/Hover.ml b/analysis/src/Hover.ml
index fba9c2c09..c08f4f11f 100644
--- a/analysis/src/Hover.ml
+++ b/analysis/src/Hover.ml
@@ -45,9 +45,10 @@ let rec showModule ~docstring ~(file : SharedTypes.file) ~name
   | None -> showModuleTopLevel ~docstring ~name file.contents.topLevel
   | Some {item = Structure {topLevel}} ->
     showModuleTopLevel ~docstring ~name topLevel
-  | Some ({item = Constraint (_, moduleType)} as declared) ->
+  | Some ({item = Constraint (_moduleItem, moduleTypeItem)} as declared) ->
     (* show the interface *)
-    showModule ~docstring ~file ~name (Some {declared with item = moduleType})
+    showModule ~docstring ~file ~name
+      (Some {declared with item = moduleTypeItem})
   | Some {item = Ident path} ->
     Some ("Unable to resolve module reference " ^ Path.name path)
 
diff --git a/analysis/src/References.ml b/analysis/src/References.ml
index 8b8477101..c64199797 100644
--- a/analysis/src/References.ml
+++ b/analysis/src/References.ml
@@ -197,8 +197,8 @@ let alternateDeclared ~file ~package declared tip =
 let rec resolveModuleReference ~file ~package (declared : moduleKind declared) =
   match declared.item with
   | Structure _ -> Some (file, Some declared)
-  | Constraint (moduleItem, _moduleTypeItem) ->
-    resolveModuleReference ~file ~package {declared with item = moduleItem}
+  | Constraint (_moduleItem, moduleTypeItem) ->
+    resolveModuleReference ~file ~package {declared with item = moduleTypeItem}
   | Ident path -> (
     let env = ProcessCmt.fileEnv file in
     match ProcessCmt.fromCompilerPath ~env path with
diff --git a/analysis/tests/src/expected/Hover.res.txt b/analysis/tests/src/expected/Hover.res.txt
index 87f223e28..4891f2bc0 100644
--- a/analysis/tests/src/expected/Hover.res.txt
+++ b/analysis/tests/src/expected/Hover.res.txt
@@ -32,13 +32,13 @@ Hover tests/src/Hover.res 47:13
 {"contents": "```rescript\nmodule Logger = {\n  let log: string => unit\n}\n```"}
 
 Hover tests/src/Hover.res 52:7
-{"contents": "```rescript\nmodule JsLogger = {\n  let log: string => unit\n  let _oneMore: int\n}\n```"}
+{"contents": "```rescript\nmodule Logger = {\n  let log: string => unit\n}\n```"}
 
 Definition tests/src/Hover.res 58:14
-{"uri": "Hover.res", "range": {"start": {"line": 52, "character": 7}, "end": {"line": 52, "character": 15}}}
+{"uri": "Hover.res", "range": {"start": {"line": 47, "character": 12}, "end": {"line": 47, "character": 18}}}
 
 Hover tests/src/Hover.res 62:9
-{"contents": "```rescript\nmodule IdDefinedTwice = {\n  let x: int\n  let y: int\n  let x: int\n}\n```"}
+{"contents": "```rescript\nmodule IdDefinedTwice = {\n  let y: int\n  let x: int\n}\n```"}
 
 Hover tests/src/Hover.res 71:7
 {"contents": "```rescript\nmodule A = {\n  let x: int\n}\n```"}