Feature only available in Dune >= 3.13

Signed-off-by: Nicolás Ojeda Bär <[email protected]>

Author: nojb

src/dune_lang/ordered_set_lang.ml

@@ -288,13 +288,56 @@ module Unexpanded = struct
     }
   ;;
 
-  let field ?check name =
+  let is_expanded t =
+    let rec loop (t : ast) =
+      let open Ast in
+      match t with
+      | Standard -> true
+      | Include _ -> false
+      | Element s -> Option.is_some (String_with_vars.text_only s)
+      | Union l -> List.for_all l ~f:loop
+      | Diff (l, r) -> loop l && loop r
+    in
+    loop t.ast
+  ;;
+
+  let field_gen field ?check ?since_expanded is_expanded =
     let decode =
       match check with
       | None -> decode
       | Some x -> Decoder.( >>> ) x decode
     in
-    Decoder.field name decode ~default:standard
+    let x = field decode in
+    match since_expanded with
+    | None -> x
+    | Some since_expanded ->
+      let open Decoder in
+      let+ loc, x = located x
+      and+ ver = Syntax.get_exn Stanza.syntax in
+      if ver < since_expanded && not (is_expanded x)
+      then
+        Syntax.Error.since
+          loc
+          Stanza.syntax
+          since_expanded
+          ~what:"the ability to specify non-constant module lists";
+      x
+  ;;
+
+  let field ?check ?since_expanded name =
+    field_gen
+      (Decoder.field name ~default:standard ?on_dup:None)
+      ?check
+      ?since_expanded
+      is_expanded
+  ;;
+
+  let field_o ?check ?since_expanded name =
+    field_gen
+      (Decoder.field_o name ?on_dup:None)
+      ?check
+      ?since_expanded
+      (Option.forall ~f:is_expanded)
   ;;
 
   let has_special_forms t =

src/dune_lang/ordered_set_lang.mli

@@ -53,7 +53,19 @@ module Unexpanded : sig
   val standard : t
   val of_strings : pos:string * int * int * int -> string list -> t
   val include_single : context:Univ_map.t -> pos:string * int * int * int -> string -> t
-  val field : ?check:unit Decoder.t -> string -> t Decoder.fields_parser
+
+  val field
+    :  ?check:unit Decoder.t
+    -> ?since_expanded:Syntax.Version.t
+    -> string
+    -> t Decoder.fields_parser
+
+  val field_o
+    :  ?check:unit Decoder.t
+    -> ?since_expanded:Syntax.Version.t
+    -> string
+    -> t option Decoder.fields_parser
+
   val has_special_forms : t -> bool
   val has_standard : t -> bool
 

src/dune_rules/dune_file.ml

@@ -665,10 +665,10 @@ module Library = struct
          ()
        and+ sub_systems = Sub_system_info.record_parser
        and+ virtual_modules =
-         field_o
+         Ordered_set_lang.Unexpanded.field_o
+           ~check:(Dune_lang.Syntax.since Stanza.syntax (1, 7))
+           ~since_expanded:Stanza_common.Modules_settings.since_expanded
            "virtual_modules"
-           (Dune_lang.Syntax.since Stanza.syntax (1, 7)
-            >>> Ordered_set_lang.Unexpanded.decode)
        and+ implements =
          field_o
            "implements"
@@ -678,10 +678,10 @@ module Library = struct
            "default_implementation"
            (Dune_lang.Syntax.since Stanza.syntax (2, 6) >>> located Lib_name.decode)
        and+ private_modules =
-         field_o
+         Ordered_set_lang.Unexpanded.field_o
+           ~check:(Dune_lang.Syntax.since Stanza.syntax (1, 2))
+           ~since_expanded:Stanza_common.Modules_settings.since_expanded
            "private_modules"
-           (Dune_lang.Syntax.since Stanza.syntax (1, 2)
-            >>> Ordered_set_lang.Unexpanded.decode)
        and+ stdlib =
          field_o
            "stdlib"

src/dune_rules/stanza_common.ml

@@ -206,11 +206,13 @@ module Modules_settings = struct
     ; modules : Ordered_set_lang.Unexpanded.t
     }
 
+  let since_expanded = 3, 13
+
   let decode =
     let+ root_module = field_o "root_module" Module_name.decode_loc
     and+ modules_without_implementation =
-      Ordered_set_lang.Unexpanded.field "modules_without_implementation"
-    and+ modules = Ordered_set_lang.Unexpanded.field "modules" in
+      Ordered_set_lang.Unexpanded.field ~since_expanded "modules_without_implementation"
+    and+ modules = Ordered_set_lang.Unexpanded.field ~since_expanded "modules" in
     { root_module; modules; modules_without_implementation }
   ;;
 end

src/dune_rules/stanza_common.mli

@@ -26,5 +26,6 @@ module Modules_settings : sig
     ; modules : Ordered_set_lang.Unexpanded.t
     }
 
+  val since_expanded : Syntax.Version.t
   val decode : t Dune_lang.Decoder.fields_parser
 end

test/blackbox-tests/test-cases/modules-expansion.t

@@ -1,8 +1,7 @@
 Here we test the ability of (modules) to be contain dynamic forms such as
 `(:include)` and variables such as `"%{read-lines:}"`.
 
-Begin by setting up a project. Note that the feature is not currently versioned;
-this should be done before merging.
+Begin by setting up a project and check the versioning guards.
 
   $ cat >dune-project <<EOF
   > (lang dune 3.11)
@@ -34,7 +33,24 @@ file `gen/lst`:
   > (executable (name mod) (modules (:include gen/lst)))
   > EOF
 
-Let's check that it works:
+Let's check that it fails in the current version of Dune:
+
+  $ dune exec ./mod.exe
+  File "dune", line 1, characters 23-51:
+  1 | (executable (name mod) (modules (:include gen/lst)))
+                             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+  Error: the ability to specify non-constant module lists is only available
+  since version 3.13 of the dune language. Please update your dune-project file
+  to have (lang dune 3.13).
+  [1]
+
+Update the version...
+
+  $ cat >dune-project <<EOF
+  > (lang dune 3.13)
+  > EOF
+
+... and it works!
 
   $ dune exec ./mod.exe
   Hello, Mod!