Fix #2061 and allow to promote a subset of the targets

CHANGES.md

@@ -11,6 +11,20 @@ unreleased
 - [coq] Add `coq.pp` stanza to help with pre-processing of grammar
   files (#2054, @ejgallego, review by @rgrinberg)
 
+- Add a new more generic form for the *promote* mode: `(promote
+  (until-clean) (into <dir>))` (#2068, @diml)
+
+- Allow to promote only a subset of the targets via `(promote (only
+  <pred>))`. For instance: `(promote (only *.mli))` (#2068, @diml)
+
+- Improve the behavior when a strict subset of the targets of a rule
+  is already in the source tree for projects using the dune language < 1.10
+  (#2068, fixes #2061, @diml)
+
+- With lang dune >= 1.10, rules in standard mode are no longer allowed
+  to produce targets that are present in the source tree. This has
+  been a warning for long enough (#2068, @diml)
+
 1.9.1 (11/04/2019)
 ------------------
 

bin/common.ml

@@ -194,11 +194,11 @@ let term =
              ~doc:"Instead of terminating build after completion, wait continuously
               for file changes.")
   and+ root,
-      only_packages,
-      ignore_promoted_rules,
-      config_file,
-      profile,
-      default_target =
+     only_packages,
+     ignore_promoted_rules,
+     config_file,
+     profile,
+     default_target =
     let default_target_default =
       match Wp.t with
       | Dune     -> "@@default"
@@ -230,7 +230,8 @@ let term =
       Arg.(value
            & flag
            & info ["ignore-promoted-rules"] ~docs
-               ~doc:"Ignore rules with (mode promote)")
+               ~doc:"Ignore rules with (mode promote),
+                     except ones with (only ...)")
     and+ (config_file_opt, config_file) =
       Term.ret @@
       let+ config_file =

doc/dune-files.rst

@@ -450,27 +450,40 @@ field. The following modes are available:
   of fallback rules is to generate default configuration files that
   may be generated by a configure script.
 
-- ``promote``, in this mode, the files in the source tree will be
-  ignored. Once the rule has been executed, the targets will be copied
-  back to the source tree
-
-- ``promote-until-clean`` is the same as ``promote`` except than
-  ``dune clean`` will remove the promoted files from the source
-  tree
-
-- ``(promote-into <dir>)`` (resp. ``(promote-until-clean-into
-  <dir>)``) is the same as ``promote`` (resp. ``promote-until-clean``)
-  except that the files are promoted in ``<dir>`` instead of the
-  current directory. This feature is available since Dune 1.8.
+- ``promote`` or ``(promote <options>)``, in this mode, the files
+  in the source tree will be ignored. Once the rule has been executed,
+  the targets will be copied back to the source tree
+
+     The following options are available:
+     - ``(until-clean)`` means that ``dune clean`` will remove the
+     promoted files from the source tree
+     - ``(into <dir>)`` means that the files are promoted in ``<dir>``
+     instead of the current directory. This feature is available since
+     Dune 1.8
+     - ``(only <predicate>)`` means that only a subset of the targets
+     should be promoted. The argument is a predicate in a syntax
+     similar to the argument of :ref:`(dirs ...) <dune-subdirs>`. This
+     feature is available since dune 1.10
+
+- ``promote-until-clean`` is the same as ``(promote (until-clean))``
+- ``(promote-into <dir>)`` is the same as ``(promote (into <dir>))``
+- ``(promote-until-clean-into <dir>)`` is the same as ``(promote
+  (until-clean) (into <dir>))``
+
+The ``(promote <options>)`` form is only available since Dune
+1.10. Before Dune 1.10, you need to use one of the ``promote-...``
+forms. The ``promote-...`` forms should disappear in Dune 2.0, so
+using the more generic ``(promote <options>)`` form should be prefered
+in new projects.
 
 There are two use cases for promote rules. The first one is when the
 generated code is easier to review than the generator, so it's easier
 to commit the generated code and review it. The second is to cut down
 dependencies during releases: by passing ``--ignore-promoted-rules``
-to dune, rules will ``(mode promote)`` will be ignored and the
-source files will be used instead. The
-``-p/--for-release-of-packages`` flag implies
-``--ignore-promote-rules``.
+to dune, rules will ``(mode promote)`` will be ignored and the source
+files will be used instead. The ``-p/--for-release-of-packages`` flag
+implies ``--ignore-promote-rules``. However, rules that promotes only
+a subset of their targets via ``(only ...)`` are never ignored.
 
 inferred rules
 ~~~~~~~~~~~~~~