Fix #11045 (#11801)

* test: reproduce #11045

Signed-off-by: Benjamin Jorge <benjamin.jorge@cea.fr>

* fix: dune subst should not fail when adding the version field in opam files

Signed-off-by: Benjamin Jorge <benjamin.jorge@cea.fr>

* feature: dune subst use version from dune-project when there is no vcs

Signed-off-by: Benjamin Jorge <benjamin.jorge@cea.fr>

---------

Signed-off-by: Benjamin Jorge <benjamin.jorge@cea.fr>

Author: rgrinberg

bin/subst.ml

@@ -141,8 +141,7 @@ let subst_file path ~map opam_package_files =
         try
           subst_string ("version: \"%%" ^ "VERSION_NUM" ^ "%%\"") ~map (Path.source path)
         with
-        | User_error.E e ->
-          raise (User_error.E { e with loc = Some (Loc.in_file (Path.source path)) }))
+        | User_error.E _ -> None)
       else None
     in
     let path = Path.source path in
@@ -264,6 +263,11 @@ end
 
 let make_watermark_map ~commit ~version ~dune_project ~info =
   let dune_project = Dune_project.project dune_project in
+  let version =
+    match version with
+    | Some _ -> version
+    | None -> Option.map ~f:Package_version.to_string (Dune_project.version dune_project)
+  in
   let version_num =
     let open Option.O in
     let+ version = version in

doc/changes/11801.md

@@ -0,0 +1,5 @@
+- fix: `$ dune subst` should not fail when adding the version field in opam
+  files (#11801, fixes #11045, @btjorge)
+
+- feature: `$ dune subst` use version from `dune-project` when no version control repository
+  has been detected

src/source/dune_project.ml

@@ -49,6 +49,7 @@ let equal : t -> t -> bool = phys_equal
 let hash = Poly.hash
 let packages t = t.packages
 let name t = t.name
+let version t = t.version
 let root t = t.root
 let stanza_parser t = Dune_lang.Decoder.set key t t.stanza_parser
 let file t = t.project_file

src/source/dune_project.mli

@@ -8,6 +8,7 @@ type t
 val to_dyn : t -> Dyn.t
 val packages : t -> Package.t Package.Name.Map.t
 val name : t -> Dune_project_name.t
+val version : t -> Package_version.t option
 val root : t -> Path.Source.t
 val stanza_parser : t -> Dune_lang.Stanza.t list Dune_lang.Decoder.t
 val generate_opam_files : t -> bool

test/blackbox-tests/test-cases/subst/dont-fail-on-opam-files.t

@@ -0,0 +1,62 @@
+dune subst should not fail when adding the version field in opam files
+
+  $ cat > dune-project << EOF
+  > (lang dune 3.19)
+  > (name test)
+  > (version 0.1)
+  > (generate_opam_files)
+  > (package (name test) (allow_empty))
+  > EOF
+
+  $ dune build
+
+  $ cat test.opam
+  # This file is generated by dune, edit dune-project instead
+  opam-version: "2.0"
+  version: "0.1"
+  depends: [
+    "dune" {>= "3.19"}
+    "odoc" {with-doc}
+  ]
+  build: [
+    ["dune" "subst"] {dev}
+    [
+      "dune"
+      "build"
+      "-p"
+      name
+      "-j"
+      jobs
+      "@install"
+      "@runtest" {with-test}
+      "@doc" {with-doc}
+    ]
+  ]
+  x-maintenance-intent: ["(latest)"]
+
+  $ dune subst
+
+  $ cat test.opam
+  version: "0.1"
+  # This file is generated by dune, edit dune-project instead
+  opam-version: "2.0"
+  version: "0.1"
+  depends: [
+    "dune" {>= "3.19"}
+    "odoc" {with-doc}
+  ]
+  build: [
+    ["dune" "subst"] {dev}
+    [
+      "dune"
+      "build"
+      "-p"
+      name
+      "-j"
+      jobs
+      "@install"
+      "@runtest" {with-test}
+      "@doc" {with-doc}
+    ]
+  ]
+  x-maintenance-intent: ["(latest)"]

test/blackbox-tests/test-cases/subst/without-repo.t

@@ -11,3 +11,19 @@ Demonstrate $ dune subst without a git repository
 
   $ cat README.md
   test
+
+dune subst should take the project version from the dune-project file when
+there is no vcs
+
+  $ cat > dune-project << EOF
+  > (lang dune 3.19)
+  > (name test)
+  > (version 0.1)
+  > EOF
+
+  $ echo "%%VERSION%%" > README.md
+
+  $ dune subst
+
+  $ cat README.md
+  0.1