Remove warning about empty packages pre 3.0

CHANGES.md

@@ -19,9 +19,9 @@ Unreleased
 - Fix jsoo builds when dynamically linked foreign archives are disabled
   (@hhugo, #5049)
 
-- Warn on empty packages for projects < 3.0 and disallow them starting from 3.0
-  Empty packages may be re-enabled by adding the `(allow_empty)` to the package
-  stanza in the dune-project file. (#4867, fix #2882, @kit-ty-kate, @rgrinberg)
+- Disallow empty packages starting from 3.0.  Empty packages may be
+  re-enabled by adding the `(allow_empty)` to the package stanza in
+  the dune-project file. (#4867, fix #2882, @kit-ty-kate, @rgrinberg)
 
 - Add `link_flags` field to the `executable` field of `inline_tests` (#5088,
   fix #1530, @jvillard)

otherlibs/build-info/test/run.t

@@ -6,9 +6,9 @@ Test embedding of build information
   $ for i in a b c d; do
   >   mkdir -p $i
   >   cat >$i/dune-project <<EOF
-  > (lang dune 3.0)
+  > (lang dune 2.0)
   > (name $i)
-  > (package (name $i) (allow_empty))
+  > (package (name $i))
   > EOF
   >   (cd $i;
   >    git init -q;
@@ -52,15 +52,7 @@ Test embedding of build information
   > EOF
 
   $ dune build
-  Error: Package c is missing the following package dependencies
-  - a
-  - b
-  -> required by _build/default/c/c.install
-  -> required by alias c/all
-  -> required by alias default
-  [1]
   $ dune install --prefix _install 2> /dev/null
-  [1]
 
 Inside _build, we have no version information:
 
@@ -79,15 +71,16 @@ Inside _build, we have no version information:
 Once installed, we have the version information:
 
   $ _install/bin/c | sed 's/build-info: .*/build-info: XXX/'
-  _install/bin/c: No such file or directory
+  1.0+c
+  lib a: 1.0+a
+  lib b: 1.0+b
+  lib dune-build-info: XXX
 
   $ grep version _install/lib/a/dune-package
-  grep: _install/lib/a/dune-package: No such file or directory
-  [2]
+  (version 1.0+a)
 
   $ grep version _install/lib/a/META
-  grep: _install/lib/a/META: No such file or directory
-  [2]
+  version = "1.0+a"
 
 Check what the generated build info module looks like:
 
@@ -156,14 +149,9 @@ Version is picked from dune-project if available
 
   $ echo '(version project-version)' >> c/dune-project
   $ dune build
-  Error: Package c is missing the following package dependencies
-  - a
-  - b
-  -> required by _build/default/c/c.install
-  -> required by alias c/all
-  -> required by alias default
-  [1]
   $ dune install --prefix _install 2> /dev/null
-  [1]
   $ _install/bin/c | sed 's/build-info: .*/build-info: XXX/'
-  _install/bin/c: No such file or directory
+  project-version
+  lib a: 1.0+a
+  lib b: 1.0+b
+  lib dune-build-info: XXX

otherlibs/site/test/bug_4219.t

@@ -2,11 +2,10 @@ Test when sites name which are ocaml keyword
 ---------------------------------
 
   $ cat >dune-project <<EOF
-  > (lang dune 3.0)
+  > (lang dune 2.9)
   > (using dune_site 0.1)
   > (package
   >  (name my-package)
-  >  (allow_empty)
   >  (sites (lib include)))
   > EOF
 

otherlibs/site/test/run.t

@@ -6,23 +6,23 @@ Test embedding of sites locations information
   $ for i in a b d; do
   > mkdir -p $i
   > cat >$i/dune-project <<EOF
-  > (lang dune 3.0)
+  > (lang dune 2.9)
   > (generate_opam_files true)
   > (using dune_site 0.1)
   > (name $i)
   > (version 0.$i)
-  > (package (name $i) (sites (share data)) (allow_empty))
+  > (package (name $i) (sites (share data)))
   > EOF
   > done
 
   $ for i in c; do
   >   mkdir -p $i
   >   cat >$i/dune-project <<EOF
-  > (lang dune 3.0)
+  > (lang dune 2.9)
   > (generate_opam_files true)
   > (using dune_site 0.1)
   > (name $i)
-  > (package (name $i) (allow_empty) (sites (share data) (lib plugins)))
+  > (package (name $i) (sites (share data) (lib plugins)))
   > EOF
   > done
 
@@ -139,7 +139,7 @@ Test with an opam like installation
   opam-version: "2.0"
   version: "0.a"
   depends: [
-    "dune" {>= "3.0"}
+    "dune" {>= "2.9"}
     "odoc" {with-doc}
   ]
   build: [
@@ -178,54 +178,63 @@ Build everything
 ----------------
 
   $ dune build
-  Error: Package b is missing the following package dependencies
-  - c
-  -> required by _build/default/b/b.install
-  -> required by alias b/all
-  -> required by alias default
-  Error: Package c is missing the following package dependencies
-  - a
-  -> required by _build/default/c/c.install
-  -> required by alias c/all
-  -> required by alias default
-  [1]
 
 Test with a normal installation
 --------------------------------
 
   $ dune install --prefix _install 2> /dev/null
-  [1]
 
 Once installed, we have the sites information:
 
   $ OCAMLPATH=_install/lib:$OCAMLPATH _install/bin/c
-  _install/bin/c: No such file or directory
-  [127]
+  run a
+  a: $TESTCASE_ROOT/_install/share/a/data
+  run c: a linked registered:.
+  no sourceroot
+  c: $TESTCASE_ROOT/_install/share/c/data
+  b is available: true
+  run b
+  b: $TESTCASE_ROOT/_install/share/b/data
+  info.txt is found: true
+  run c: registered:b.
 
 Test with a relocatable installation
 --------------------------------
 
   $ dune install --prefix _install_relocatable --relocatable 2> /dev/null
-  [1]
 
 Once installed, we have the sites information:
 
   $ _install_relocatable/bin/c
-  _install_relocatable/bin/c: No such file or directory
-  [127]
+  run a
+  a: $TESTCASE_ROOT/_install_relocatable/share/a/data
+  run c: a linked registered:.
+  no sourceroot
+  c: $TESTCASE_ROOT/_install_relocatable/share/c/data
+  b is available: true
+  run b
+  b: $TESTCASE_ROOT/_install_relocatable/share/b/data
+  info.txt is found: true
+  run c: registered:b.
 
 Test after moving a relocatable installation
 --------------------------------
 
   $ mv _install_relocatable  _install_relocatable2
-  mv: cannot stat '_install_relocatable': No such file or directory
-  [1]
 
 Once installed, we have the sites information:
 
   $ _install_relocatable2/bin/c
-  _install_relocatable2/bin/c: No such file or directory
-  [127]
+  run a
+  a: $TESTCASE_ROOT/_install_relocatable2/share/a/data
+  run c: a linked registered:.
+  no sourceroot
+  c: $TESTCASE_ROOT/_install_relocatable2/share/c/data
+  b is available: true
+  run b
+  b: $TESTCASE_ROOT/_install_relocatable2/share/b/data
+  info.txt is found: true
+  run c: registered:b.
 
 Test substitution when promoting
 --------------------------------
@@ -247,11 +256,6 @@ development because b is not promoted
 Test within dune rules
 --------------------------------
   $ dune build c/out.log
-  Error: Package c is missing the following package dependencies
-  - a
-  -> required by alias c/.c-files
-  -> required by _build/default/c/out.log
-  [1]
 
   $ cat _build/default/c/out.log
   run a
@@ -319,49 +323,66 @@ Test compiling an external plugin
 
   $ OCAMLPATH=$(pwd)/_install/lib:$OCAMLPATH dune build --root=e
   Entering directory 'e'
-  File "dune", line 5, characters 47-58:
-  5 | (plugin (name c-plugins-e) (libraries e) (site (c plugins)))
-                                                     ^^^^^^^^^^^
-  Error: The package c is not found
-  [1]
 
   $ OCAMLPATH=$(pwd)/_install/lib:$OCAMLPATH PATH=$(pwd)/_install/bin:$PATH dune exec  --root=e -- c
   Entering directory 'e'
-  File "dune", line 5, characters 47-58:
-  5 | (plugin (name c-plugins-e) (libraries e) (site (c plugins)))
-                                                     ^^^^^^^^^^^
-  Error: The package c is not found
-  [1]
+  run a
+  a: $TESTCASE_ROOT/_install/share/a/data
+  run c: a linked registered:.
+  no sourceroot
+  c: $TESTCASE_ROOT/_install/share/c/data
+  b is available: true
+  run b
+  b: $TESTCASE_ROOT/_install/share/b/data
+  info.txt is found: true
+  run e
+  e: $TESTCASE_ROOT/e/_build/install/default/share/e/data
+  info.txt is found: true
+  run c: registered:e,b.
 
   $ OCAMLPATH=$(pwd)/_install/lib:$OCAMLPATH dune install --root=e --prefix $(pwd)/_install 2> /dev/null
-  [1]
 
   $ OCAMLPATH=_install/lib:$OCAMLPATH _install/bin/c
-  _install/bin/c: No such file or directory
-  [127]
+  run a
+  a: $TESTCASE_ROOT/_install/share/a/data
+  run c: a linked registered:.
+  no sourceroot
+  c: $TESTCASE_ROOT/_install/share/c/data
+  b is available: true
+  run b
+  b: $TESTCASE_ROOT/_install/share/b/data
+  info.txt is found: true
+  run e
+  e: $TESTCASE_ROOT/_install/share/e/data
+  info.txt is found: true
+  run c: registered:e,b.
 
   $ OCAMLPATH=_install/lib:$OCAMLPATH dune build @runtest
-  Error: Package b is missing the following package dependencies
-  - c
-  -> required by alias b/.b-files
-  -> required by alias e/runtest in e/dune:7
-  Error: Package c is missing the following package dependencies
-  - a
-  -> required by alias c/.c-files
-  -> required by alias e/runtest in e/dune:7
-  [1]
+  run a
+  a: $TESTCASE_ROOT/_build/install/default/share/a/data
+  run c: a linked registered:.
+  sourceroot is "$TESTCASE_ROOT"
+  c: $TESTCASE_ROOT/_build/install/default/share/c/data
+  b is available: true
+  run b
+  b: $TESTCASE_ROOT/_build/install/default/share/b/data
+  info.txt is found: true
+  run e
+  e: $TESTCASE_ROOT/_build/install/default/share/e/data
+  info.txt is found: true
+  run c: registered:e,b.
 
 Test %{version:installed-pkg}
 -----------------------------
 
   $ for i in f; do
   >   mkdir -p $i
   >   cat >$i/dune-project <<EOF
-  > (lang dune 3.0)
+  > (lang dune 2.9)
   > (using dune_site 0.1)
   > (name $i)
   > (version 0.$i)
-  > (package (name $i) (allow_empty) (sites (share data) (lib plugins)))
+  > (package (name $i) (sites (share data) (lib plugins)))
   > EOF
   > done
 
@@ -377,20 +398,9 @@ Test %{version:installed-pkg}
 
   $ OCAMLPATH=_install/lib:$OCAMLPATH dune build --root=f
   Entering directory 'f'
-  File "dune", line 6, characters 15-27:
-  6 |     (echo "a = %{version:a}\n")
-                     ^^^^^^^^^^^^
-  Error: Package "a" doesn't exist in the current project and isn't installed
-  either.
-  File "dune", line 7, characters 15-27:
-  7 |     (echo "e = %{version:e}\n")))))
-                     ^^^^^^^^^^^^
-  Error: Package "e" doesn't exist in the current project and isn't installed
-  either.
-  [1]
   $ cat $(pwd)/f/_build/default/test.target
-  cat: $TESTCASE_ROOT/f/_build/default/test.target: No such file or directory
-  [1]
+  a = 0.a
+  e = 
 
   $ cat f/dune | sed 's/version:a/version:a.test/' > f/dune.tmp && mv f/dune.tmp f/dune
   $ OCAMLPATH=_install/lib:$OCAMLPATH dune build --root=f
@@ -400,11 +410,6 @@ Test %{version:installed-pkg}
                      ^^^^^^^^^^^^^^^^^
   Error: Library names are not allowed in this position. Only package names are
   allowed
-  File "dune", line 7, characters 15-27:
-  7 |     (echo "e = %{version:e}\n")))))
-                     ^^^^^^^^^^^^
-  Error: Package "e" doesn't exist in the current project and isn't installed
-  either.
   [1]
 
   $ rm f/dune
@@ -433,12 +438,7 @@ Test error location
   > (generate_sites_module (module sites) (sites non-existent))
   > EOF
 
-  $ dune build -j1
-  Error: Package b is missing the following package dependencies
-  - c
-  -> required by _build/default/b/b.install
-  -> required by alias b/all
-  -> required by alias default
+  $ dune build
   File "a/dune", line 4, characters 45-57:
   4 | (generate_sites_module (module sites) (sites non-existent))
                                                    ^^^^^^^^^^^^

src/dune_engine/package.ml

@@ -644,6 +644,12 @@ let decode ~dir =
      and+ allow_empty =
        field_b "allow_empty"
          ~check:(Dune_lang.Syntax.since Stanza.syntax (3, 0))
+     and+ lang_version = Dune_lang.Syntax.get_exn Stanza.syntax in
+     let allow_empty =
+       if lang_version < (3, 0) then
+         true
+       else
+         allow_empty
      in
      let id = { Id.name; dir } in
      { id
@@ -790,7 +796,7 @@ let load_opam_file file name =
   ; tags = Option.value (get_many "tags") ~default:[]
   ; deprecated_package_names = Name.Map.empty
   ; sites = Section.Site.Map.empty
-  ; allow_empty = false
+  ; allow_empty = true
   }
 
 let equal = Poly.equal