Change the default of --promote from check to copy

As said in the PR. I forgot to push the commit.

bin/main.ml

@@ -291,10 +291,11 @@ let common =
     Arg.(value
          & opt (some mode) None
          & info ["promote"] ~docs
-             ~doc:"How to interpret promote actions. $(b,check), the default, means to
-                   only check that promoted files are equal to the source files.
-                   $(b,ignore) means to ignore promote action altogether and $(b,copy)
-                   means to copy generated files to the source tree.")
+             ~doc:"How to interpret promote actions. $(b,copy) means to print
+                   a diff and copy the generated files to the source tree when
+                   they differ. $(b,copy) is the default. $(b,check) means to
+                   only print a diff without copying files. $(b,ignore) means
+                   to ignore promote action altogether.")
   in
   let for_release = "for-release-of-packages" in
   let frop =
@@ -327,7 +328,7 @@ let common =
       | None, _, _, _ ->
         `Ok (root,
              only_packages,
-             Option.value promote ~default:Clflags.Promote_mode.Check,
+             Option.value promote ~default:Clflags.Promote_mode.Copy,
              List.concat
                [ dump_opt "--root" root
                ; dump_opt "--only-packages" only_packages

doc/jbuild.rst

@@ -563,7 +563,7 @@ With this jbuild file, running jbuilder as follow will replace the
 
 .. code:: shell
 
-    $ jbuilder build @jbuild --promote copy
+    $ jbuilder build @jbuild
 
 Common items
 ============
@@ -1158,12 +1158,13 @@ How jbuilder interprets promotions can be controlled using the
 ``--promote`` command line argument. The following behaviors are
 available:
 
-- ``--promote check``: this is the default. Jbuilder just checks that
-  the two files given in each ``(<a> as <b>)`` form are equal. If not,
-  it prints a diff
+- ``--promote copy``: when the two files given in a ``(<a> as <b>)``
+  form are different, jbuilder prints a diff and copies ``<a>`` to
+  ``<b>`` directly in the source
+   tree. This is the default
+- ``--promote check``: Jbuilder just checks that the two files are
+  equal and print a diff when there are not
 - ``--promote ignore``: ``promote`` actions are simply ignored
-- ``--promote copy``: when the two files are different, jbuilder
-  prints a diff and copies ``<a>`` to ``<b>`` directly in the source tree
 
 Note that ``-p/--for-release-of-packages`` implies ``--promote
 ignore``.

src/clflags.ml

@@ -28,4 +28,4 @@ module Promote_mode = struct
     | "copy" -> Some Copy
     | _ -> None
 end
-let promote_mode = ref Promote_mode.Check
+let promote_mode = ref Promote_mode.Copy

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

@@ -1,6 +1,6 @@
   $ echo titi > x
 
-  $ $JBUILDER build --root . -j1 --diff-command false @blah
+  $ $JBUILDER build --root . -j1 --diff-command false @blah --promote check
             sh (internal) (exit 1)
   /usr/bin/sh -c 'false '\''x'\'' '\''_build/default/x.gen'\'''
   [1]
@@ -11,11 +11,11 @@
   $ cat x
   titi
 
-  $ $JBUILDER build --root . -j1 --diff-command false @blah --promote copy
+  $ $JBUILDER build --root . -j1 --diff-command false @blah
             sh (internal) (exit 1)
   /usr/bin/sh -c 'false '\''x'\'' '\''_build/default/x.gen'\'''
   Promoting _build/default/x.gen to x.
   [1]
   $ cat x
   toto
-  $ $JBUILDER build --root . -j1 --diff-command false @blah --promote copy
+  $ $JBUILDER build --root . -j1 --diff-command false @blah