Insert a constraint on the version of dune (#3434)

Even if the dependency is explicitly listed in the dune-project file

Fixes #3427

Signed-off-by: Jeremie Dimino <jeremie@dimino.org>

CHANGES.md

@@ -1,5 +1,9 @@
-Unreleased
-----------
+next
+----
+
+- Insert a constraint one the version of dune when the user explicitly
+  specify the dependency on dune in the `dune-project` file (#3434 ,
+  fixes #3427, @diml)
 
 - Generate correct META files for sub-libraries (of the form `lib.foo`) that
   contain .js runtime files. (#3445, @hhugo)

doc/dune-files.rst

@@ -12,7 +12,7 @@ like:
 
 .. code:: scheme
 
-          (lang dune 2.5)
+          (lang dune 2.6)
 
 Additionally, they can contains the following stanzas.
 
@@ -1748,7 +1748,7 @@ a typical ``dune-workspace`` file looks like:
 
 .. code:: scheme
 
-    (lang dune 2.5)
+    (lang dune 2.6)
     (context (opam (switch 4.02.3)))
     (context (opam (switch 4.03.0)))
     (context (opam (switch 4.04.0)))
@@ -1760,7 +1760,7 @@ containing exactly:
 
 .. code:: scheme
 
-    (lang dune 2.5)
+    (lang dune 2.6)
     (context default)
 
 This allows you to use an empty ``dune-workspace`` file to mark the root of your

doc/opam.rst

@@ -94,7 +94,7 @@ configuration will tell ``dune`` to generate two opam files: ``cohttp.opam`` and
 
 .. code:: scheme
 
-   (lang dune 2.5)
+   (lang dune 2.6)
    (name cohttp)
    ; version field is optional
    (version 1.0.0)

src/dune/opam_create.ml

@@ -81,27 +81,46 @@ let package_fields
   in
   List.concat fields
 
+let dune_name = Package.Name.of_string "dune"
+
+let insert_dune_dep depends dune_version =
+  let constraint_ : Package.Dependency.Constraint.t =
+    let dune_version = Dune_lang.Syntax.Version.to_string dune_version in
+    Uop (Gte, QVar dune_version)
+  in
+  let rec loop acc = function
+    | [] ->
+      let dune_dep =
+        { Package.Dependency.name = dune_name; constraint_ = Some constraint_ }
+      in
+      dune_dep :: List.rev acc
+    | (dep : Package.Dependency.t) :: rest ->
+      if Package.Name.equal dep.name dune_name then
+        let dep =
+          if dune_version < (2, 6) then
+            dep
+          else
+            { dep with
+              constraint_ =
+                Some
+                  ( match dep.constraint_ with
+                  | None -> constraint_
+                  | Some c -> And [ constraint_; c ] )
+            }
+        in
+        List.rev_append acc (dep :: rest)
+      else
+        loop (dep :: acc) rest
+  in
+  loop [] depends
+
 let opam_fields project (package : Package.t) =
   let dune_version = Dune_project.dune_version project in
-  let dune_name = Package.Name.of_string "dune" in
   let package =
     if dune_version < (1, 11) || Package.Name.equal package.name dune_name then
       package
     else
-      let dune_dep =
-        let dune_version = Dune_lang.Syntax.Version.to_string dune_version in
-        let constraint_ : Package.Dependency.Constraint.t =
-          Uop (Gte, QVar dune_version)
-        in
-        { Package.Dependency.name = dune_name; constraint_ = Some constraint_ }
-      in
-      let is_dune_depend (pkg : Package.Dependency.t) =
-        Package.Name.equal pkg.name dune_dep.name
-      in
-      if List.exists package.depends ~f:is_dune_depend then
-        package
-      else
-        { package with depends = dune_dep :: package.depends }
+      { package with depends = insert_dune_dep package.depends dune_version }
   in
   let package_fields = package_fields package ~project in
   let open Opam_file.Create in

src/dune/stanza.ml

@@ -6,7 +6,7 @@ module Parser = struct
   type nonrec t = string * t list Dune_lang.Decoder.t
 end
 
-let latest_version = (2, 5)
+let latest_version = (2, 6)
 
 let since v = (v, `Since v)
 

test/blackbox-tests/test-cases/dune-project-meta/run.t

@@ -346,3 +346,54 @@ Supported since 2.1:
   Entering directory 'binops'
   $ grep conf-libX11 binops/foo.opam
     "conf-libX11" {os != "win32"}
+
+Version constraint on dune deps
+-------------------------------
+
+  $ mkdir dune-dep
+  $ cd dune-dep
+
+Without the dune dependency declared in the dune-project file, we
+generate a dune dependency with a constraint:
+
+  $ cat > dune-project <<EOF
+  > (lang dune 2.1)
+  > (name foo)
+  > (generate_opam_files true)
+  > (package (name foo))
+  > EOF
+
+  $ dune build foo.opam
+  $ grep -A2 ^depends: foo.opam
+  depends: [
+    "dune" {>= "2.1"}
+  ]
+
+With the dune dependency declared in the dune-project file and version
+of the langauge < 2.6 we don't add the constraint:
+
+  $ cat > dune-project <<EOF
+  > (lang dune 2.5)
+  > (name foo)
+  > (generate_opam_files true)
+  > (package (name foo) (depends dune))
+  > EOF
+
+  $ dune build foo.opam
+  $ grep ^depends: foo.opam
+  depends: ["dune"]
+
+Same with version of the langauge >= 2.6, we now add the constraint:
+
+  $ cat > dune-project <<EOF
+  > (lang dune 2.6)
+  > (name foo)
+  > (generate_opam_files true)
+  > (package (name foo) (depends dune))
+  > EOF
+
+  $ dune build foo.opam
+  $ grep -A2 ^depends: foo.opam
+  depends: [
+    "dune" {>= "2.6"}
+  ]