check if the dune constraint matches the dune-project file

dune_constraints.ml

@@ -0,0 +1,81 @@
+(* This source code is comming from https://github.com/ocurrent/opam-repo-ci/blob/master/lib/lint.ml
+ * with a slight modification *)
+
+type error =
+  | DuneConstraintMissing
+  | DuneIsBuild
+  | BadDuneConstraint of string * string
+
+let is_dune name =
+    OpamPackage.Name.equal name (OpamPackage.Name.of_string "dune")
+
+let get_dune_constraint opam =
+  let get_max = function
+    | None, None -> None
+    | Some x, None -> Some x
+    | None, Some x -> Some x
+    | Some x, Some y when OpamVersionCompare.compare x y >= 0 -> Some x
+    | Some _, Some y -> Some y
+  in
+  let get_min = function
+    | None, None | Some _, None | None, Some _ -> None
+    | Some x, Some y when OpamVersionCompare.compare x y >= 0 -> Some y
+    | Some x, Some _ -> Some x
+  in
+  let is_build = ref false in
+  let rec get_lower_bound = function
+    | OpamFormula.Atom (OpamTypes.Constraint ((`Gt | `Geq), OpamTypes.FString version)) -> Some version
+    | Atom (Filter (FIdent (_, var, _))) when String.equal (OpamVariable.to_string var) "build" -> is_build := true; None (* TODO: remove this hack *)
+    | Empty | Atom (Filter _) | Atom (Constraint _) -> None
+    | Block x -> get_lower_bound x
+    | And (x, y) -> get_max (get_lower_bound x, get_lower_bound y)
+    | Or (x, y) -> get_min (get_lower_bound x, get_lower_bound y)
+  in
+  let rec aux = function
+    | OpamFormula.Atom (pkg, constr) ->
+      if is_dune pkg then
+        let v = get_lower_bound constr in
+        Some (Option.value ~default:"1.0" v)
+      else
+        None
+    | Empty -> None
+    | Block x -> aux x
+    | And (x, y) -> get_max (aux x, aux y)
+    | Or (x, y) -> get_min (aux x, aux y)
+  in
+  (!is_build, aux opam.OpamFile.OPAM.depends)
+
+let check_dune_constraints ~errors ~dune_version pkg_name opam =
+  let is_build, dune_constraint = get_dune_constraint opam in
+  let errors =
+    match dune_constraint with
+    | None ->
+      if is_dune pkg_name then
+        errors
+      else
+        (pkg_name, DuneConstraintMissing) :: errors
+    | Some dep ->
+      if OpamVersionCompare.compare dep dune_version >= 0 then
+        errors
+      else
+        (pkg_name, BadDuneConstraint (dep, dune_version)) :: errors
+  in
+  if is_build then (pkg_name, DuneIsBuild) :: errors else errors
+
+let msg_of_errors =
+    List.iter (fun (package, err) ->
+      let pkg = OpamPackage.Name.to_string package in
+      match err with
+      | DuneConstraintMissing ->
+          Fmt.epr "Warning in %s: The package has a dune-project file but no explicit dependency on dune was found." pkg
+      | DuneIsBuild ->
+          Fmt.epr "Warning in %s: The package tagged dune as a build dependency. \
+                   Due to a bug in dune (https://github.com/ocaml/dune/issues/2147) this should never be the case. \
+                   Please remove the {build} tag from its filter."
+            pkg
+      | BadDuneConstraint (dep, ver) ->
+          Fmt.failwith
+            "Error in %s: Your dune-project file indicates that this package requires at least dune %s \
+                   but your opam file only requires dune >= %s. Please check which requirement is the right one, and fix the other."
+            pkg ver dep
+    )

dune_project.ml

@@ -112,6 +112,14 @@ let packages t =
   |> List.to_seq
   |> Libraries.of_seq
 
+let version t =
+  List.find_map (function
+      | Sexp.List [Atom "lang"; Atom "dune"; Atom version] -> Some version
+      | _ -> None) t
+  |> function
+     | None -> Fmt.failwith "dune-project file without `(lang dune _)` stanza"
+     | Some version -> version
+
 let dune_format dune =
   Bos.OS.Cmd.(in_string dune |>  run_io Bos.Cmd.(v "dune" % "format-dune-file") |> out_string)
   |> Bos.OS.Cmd.success

dune_project.mli

@@ -14,6 +14,8 @@ val write_project_file : t -> unit
 
 val packages : t -> string Paths.t
 
+val version : t -> string
+
 module Deps : sig
   type t = Dir_set.t Libraries.t
   (** The set of OCamlfind libraries needed, each with the directories needing it. *)

main.ml

@@ -31,11 +31,7 @@ let () =
       )
   | x -> Fmt.epr "WARNING: bad sexp from opam config env: %a@." Sexplib.Sexp.pp_hum x
 
-let get_libraries ~pkg ~target =
-  Dune_project.Deps.get_external_lib_deps ~pkg ~target
-  |> fun libs ->
-      if String.equal pkg "dune" then libs
-      else Libraries.add "dune" Dir_set.empty libs          (* We always need dune *)
+let get_libraries ~pkg ~target = Dune_project.Deps.get_external_lib_deps ~pkg ~target
 
 let to_opam ~index lib =
   match Astring.String.take ~sat:((<>) '.') lib with
@@ -210,6 +206,15 @@ let main force dir =
       exit 1
     )
   );
+  let dune_version = Dune_project.version project in
+  get_opam_files ()
+  |> Paths.to_seq
+  |> List.of_seq
+  |> List.map (fun (path, opam) ->
+      let pkg_name = (OpamPackage.Name.of_string (Filename.chop_suffix path ".opam")) in
+      Dune_constraints.check_dune_constraints ~errors:[] ~dune_version pkg_name opam)
+  |> List.flatten
+  |> Dune_constraints.msg_of_errors;
   if not (Paths.is_empty stale_files) then exit 1
 
 open Cmdliner