Merge branch 'main' into test-ocaml-5.1.1

src/dune_rules/pkg_rules.ml

@@ -1757,9 +1757,27 @@ let build_rule context_name ~source_deps (pkg : Pkg.t) =
         in
         copy_action
         @ List.map pkg.info.extra_sources ~f:(fun (local, _) ->
+          (* If the package has extra sources, they will be
+             initially stored in the extra_sources directory for that
+             package. Prior to building, the contents of
+             extra_sources must be copied into the package's source
+             directory. *)
           let src = Paths.extra_source pkg.paths local in
           let dst = Path.Build.append_local pkg.write_paths.source_dir local in
-          Action.copy src dst |> Action.Full.make |> Action_builder.With_targets.return)
+          Action.progn
+            [ (* If the package has no source directory (some
+                 low-level packages are exclusively made up of extra
+                 sources), the source directory is first created. *)
+              Action.mkdir pkg.write_paths.source_dir
+            ; (* It's possible for some extra sources to already be at
+                 the destination. If these files are write-protected
+                 then the copy action will fail if we don't first remove
+                 them. *)
+              Action.remove_tree dst
+            ; Action.copy src dst
+            ]
+          |> Action.Full.make
+          |> Action_builder.With_targets.return)
       and+ build_action =
         match Action_expander.build_command context_name pkg with
         | None -> Memo.return []

test/blackbox-tests/test-cases/pkg/exclusively-extra-sources.t

@@ -0,0 +1,24 @@
+Test for packages with no source field but with extra_sources.
+
+  $ . ./helpers.sh
+  $ make_lockdir
+
+  $ cat > dune.lock/foo.pkg <<EOF
+  > (version 1)
+  > (extra_sources
+  >  (foo.txt
+  >   (fetch
+  >    (url file://$PWD/foo.txt))))
+  > EOF
+
+  $ touch foo.txt
+
+  $ cat > dune-project <<EOF
+  > (lang dune 3.16)
+  > (package
+  >  (allow_empty)
+  >  (name a)
+  >  (depends foo))
+  > EOF
+
+  $ dune build

test/blackbox-tests/test-cases/pkg/extra-source-overlap-with-source.t

@@ -0,0 +1,35 @@
+Test for packages with an extra-source file with the same name as a
+file in the package's source.
+
+  $ . ./helpers.sh
+  $ make_lockdir
+
+  $ cat > dune.lock/foo.pkg <<EOF
+  > (version 1)
+  > (source
+  >  (copy $PWD/foo-source))
+  > (extra_sources
+  >  (foo.txt
+  >   (fetch
+  >    (url file://$PWD/foo.txt))))
+  > EOF
+
+  $ mkdir -p foo-source
+  $ echo "from source" > foo-source/foo.txt
+
+  $ echo "from extra source" > foo.txt
+
+  $ cat > dune-project <<EOF
+  > (lang dune 3.16)
+  > (package
+  >  (allow_empty)
+  >  (name a)
+  >  (depends foo))
+  > EOF
+
+  $ dune build
+
+Make sure that the package's source directory ends up with the version
+of foo.txt from extra_sources:
+  $ cat _build/_private/default/.pkg/foo/source/foo.txt
+  from extra source