[new release] dune (1.9.0)

CHANGES:

- Warn when generated `.merlin` does not reflect the preprocessing
  specification. This occurs when multiple stanzas in the same directory use
  different preprocessing specifications. This warning can now be disabled with
  `allow_approx_merlin` (ocaml/dune#1947, fix ocaml/dune#1946, @rgrinberg)

- Watch mode: display "Success" in green and "Had errors" in red (ocaml/dune#1956,
  @emillon)

- Fix glob dependencies on installed directories (ocaml/dune#1965, @rgrinberg)

- Add support for library variants and default implementations. (ocaml/dune#1900,
  @TheLortex)

- Add experimental `$ dune init` command. This command is used to create or
  update project boilerplate. (ocaml/dune#1448, fixes ocaml/dune#159, @shonfeder)

- Experimental Coq support (fix ocaml/dune#1466, @ejgallego)

- Install .cmi files of private modules in a `.private` directory (ocaml/dune#1983, fix
  ocaml/dune#1973 @rgrinberg)

- Fix `dune subst` attempting to substitute on directories. (ocaml/dune#2000, fix ocaml/dune#1997,
  @rgrinberg)

- Do not list private modules in the generated index. (ocaml/dune#2009, fix ocaml/dune#2008,
  @rgrinberg)

- Warn instead of failing if an opam file fails to parse. This opam file can
  still be used to define scope. (ocaml/dune#2023, @rgrinberg)

- Do not crash if unable to read a directory when traversing to find root
  (ocaml/dune#2024, @rgrinberg)

- Do not exit dune if some source directories are unreadable. Instead, warn the
  user that such directories need to be ignored (ocaml/dune#2004, fix ocaml/dune#310, @rgrinberg)

- Fix nested `(binaries ..)` fields in the `env` stanza. Previously, parent
  `binaries` fields would be ignored, but instead they should be combined.
  (ocaml/dune#2029, @rgrinberg)

- Allow "." in `c_names` and `cxx_names` (ocaml/dune#2036, fix ocaml/dune#2033, @rgrinberg)

- Format rules: if a dune file uses OCaml syntax, do not format it.
  (ocaml/dune#2014, fix ocaml/dune#2012, @emillon)

packages/dune/dune.1.9.0/opam

@@ -0,0 +1,47 @@
+opam-version: "2.0"
+maintainer: "opensource@janestreet.com"
+authors: ["Jane Street Group, LLC <opensource@janestreet.com>"]
+homepage: "https://github.com/ocaml/dune"
+bug-reports: "https://github.com/ocaml/dune/issues"
+dev-repo: "git+https://github.com/ocaml/dune.git"
+license: "MIT"
+depends: [
+  "ocaml" {>= "4.02"}
+  "base-unix"
+  "base-threads"
+]
+build: [
+  # opam 2 sets OPAM_SWITCH_PREFIX, so we don't need a hardcoded path
+  ["ocaml" "configure.ml" "--libdir" lib] {opam-version < "2"}
+  ["ocaml" "bootstrap.ml"]
+  ["./boot.exe" "--release" "--subst"] {pinned}
+  ["./boot.exe" "--release" "-j" jobs]
+]
+conflicts: [
+  "jbuilder" {!= "transition"}
+  "odoc" {< "1.3.0"}
+]
+
+synopsis: "Fast, portable and opinionated build system"
+description: """
+dune is a build system that was designed to simplify the release of
+Jane Street packages. It reads metadata from "dune" files following a
+very simple s-expression syntax.
+
+dune is fast, it has very low-overhead and support parallel builds on
+all platforms. It has no system dependencies, all you need to build
+dune and packages using dune is OCaml. You don't need or make or bash
+as long as the packages themselves don't use bash explicitly.
+
+dune supports multi-package development by simply dropping multiple
+repositories into the same directory.
+
+It also supports multi-context builds, such as building against
+several opam roots/switches simultaneously. This helps maintaining
+packages across several versions of OCaml and gives cross-compilation
+for free.
+"""
+url {
+  src: "https://github.com/ocaml/dune/releases/download/1.9.0/dune-1.9.0.tbz"
+  checksum: "md5=732b2d9d273b3e3d8472a8094ec2e1ad"
+}