[3.15] Backport #10327

CHANGES.md

@@ -1,3 +1,9 @@
+3.15.0~alpha2 (unreleased)
+--------------------------
+
+- Backport #10327: fix a regression in `dune install` not performing artifact
+  substitution.
+
 3.15.0~alpha1 (2024-03-26)
 --------------------------
 

bin/install_uninstall.ml

@@ -142,7 +142,6 @@ module Special_file = struct
 end
 
 type copy_kind =
-  | Plain (** Just copy the file. Can use fast paths through [Io.copy_file] *)
   | Substitute (** Use [Artifact_substitution.copy_file]. Will scan all bytes. *)
   | Special of Special_file.t (** Hooks to add version numbers, replace sections, etc *)
 
@@ -348,7 +347,6 @@ module File_ops_real (W : sig
       Fiber.return ()
     in
     match kind with
-    | Plain -> plain_copy ()
     | Substitute -> Artifact_substitution.copy_file ~conf ~src ~dst ~chmod ()
     | Special sf ->
       let open Fiber.O in
@@ -515,7 +513,12 @@ let install_entry
       let kind =
         match special_file with
         | Some special -> Special special
-        | None -> if executable then Substitute else Plain
+        | None ->
+          (* CR-emillon: for most cases we could use a fast copy here, but some
+             kinds of files do need artifact substitution(at least
+             executable files and artifacts built from generated sites
+             modules), but it's too late to know without reading the file. *)
+          Substitute
       in
       Ops.copy_file ~src:entry.src ~dst ~executable ~kind ~package ~conf
     in

otherlibs/dune-site/test/install-subst.t

@@ -0,0 +1,40 @@
+This checks that generated sites files correctly substituted with `dune install`.
+
+See #10317.
+
+  $ cat > dune-project << EOF
+  > (lang dune 3.0)
+  > (using dune_site 0.1)
+  > (package
+  >  (name a)
+  >  (sites (share data)))
+  > EOF
+
+  $ cat > dune << EOF
+  > (library
+  >  (public_name a)
+  >  (libraries dune-site))
+  > (generate_sites_module
+  >  (module s)
+  >  (sites a))
+  > EOF
+
+  $ dune build
+
+  $ check_placeholder() {
+  >   name=$1;
+  >   if grep -q DUNE_PLACEHOLDER "$name"; then
+  >     echo placeholder found in $name
+  >   fi
+  > }
+
+The generated module has placeholders.
+
+  $ check_placeholder _build/default/S.ml
+  placeholder found in _build/default/S.ml
+
+  $ dune install a --prefix out/ --datadir /nonexistent/data
+
+We expect no placeholders to be present after installation.
+
+  $ find out -type f | sort | while read f ; do check_placeholder $f ; done