Move the alias field of a rule to 2.0.0, fix the tests

Signed-off-by: Arseniy Alekseyev <aalekseyev@janestreet.com>

CHANGES.md

@@ -1,12 +1,9 @@
-2.1.0 (unreleased)
-----------------
+2.0.0 (unreleased)
+------------------
 
 - Introduce `alias` and `package` fields to the `rule` stanza. This is the
   preferred way of attaching rules to aliases. (#2744, @rgrinberg)
 
-2.0.0 (unreleased)
-------------------
-
 - Add field `(optional)` for executable stanzas (#2463, fixes #2433, @bobot)
 
 - Infer targets for rule stanzas expressed in long form (#2494, fixes #2469,

src/dune/dune_file.ml

@@ -1795,10 +1795,10 @@ module Rule = struct
     and+ enabled_if = enabled_if ~since:(Some (1, 4))
     and+ package =
       field_o "package"
-        (Dune_lang.Syntax.since Stanza.syntax (2, 1) >>> Pkg.decode)
+        (Dune_lang.Syntax.since Stanza.syntax (2, 0) >>> Pkg.decode)
     and+ alias =
       field_o "alias"
-        (Dune_lang.Syntax.since Stanza.syntax (2, 1) >>> Alias.Name.decode)
+        (Dune_lang.Syntax.since Stanza.syntax (2, 0) >>> Alias.Name.decode)
     in
     { targets; deps; action; mode; locks; loc; enabled_if; alias; package }
 

test/blackbox-tests/test-cases/github2681/run.t

@@ -2,7 +2,7 @@ A rule may have an alias field. This denotes that the action of the rule is a
 dependency of the alias.
   $ mkdir simple && cd simple
   $ cat > dune-project <<EOF
-  > (lang dune 2.1)
+  > (lang dune 2.0)
   > EOF
   $ cat > dune <<EOF
   > (rule
@@ -17,7 +17,7 @@ dependency of the alias.
 A rule may now have an empty set of targets if it has an alias field
   $ mkdir no-targets && cd no-targets
   $ cat > dune-project <<EOF
-  > (lang dune 2.1)
+  > (lang dune 2.0)
   > EOF
   $ cat > dune <<EOF
   > (rule