fix(init): correct behavior of PATH argument

Fixes ocaml#9209

Signed-off-by: Shon Feder <shon.feder@gmail.com>

bin/init.ml

@@ -218,8 +218,12 @@ let project =
        let name = Dune_lang.Atom.to_string common.name in
        let root =
          match path with
+         (* If a path is given, we use that for the root during project
+            initialization, creating the path to it if needed. *)
+         | Some path -> path
+         (* Otherwise we will use the project's given name, and create a
+            directory accordingly. *)
          | None -> name
-         | Some path -> Filename.concat path name
        in
        let builder = Builder.set_root common_builder root in
        let (_ : Fpath.mkdir_p_result) = Fpath.mkdir_p root in
@@ -252,8 +256,10 @@ let group =
     ; `P
         {|Run a subcommand with $(b, --help) for for details on it's supported arguments|}
     ; `P
-        {|If the optional $(b,PATH) is provided, the component will be created
-        there. Otherwise, it is created in the current working directory.|}
+        {|If the optional $(b,PATH) is provided, it must be a path to a directory, and
+        the component will be created there. Otherwise, it is created in a child of the
+        current working directory, called $(b, NAME). To initialize a component in the
+        current working directory, use `.` as the $(b,PATH).|}
     ; `P
         {|Any prefix of a $(b,COMMAND)'s name can be supplied in place of
         full name (as illustrated in the synopsis).|}

doc/changes/9447_fix_dune_init_proj_with_path.md

@@ -0,0 +1,4 @@
+- Fix handling of the `PATH` argument to `dune init proj NAME PATH`. An
+  intermediate directory called `NAME` is no longer created if `PATH` is
+  supplied, so `dune init proj my_project .` will now initialize a project in
+  the current working directory. (#9447, fixes #9209, @shonfeder)

doc/usage.rst

@@ -9,9 +9,6 @@ This section describes using ``dune`` from the shell.
 Initializing Components
 =======================
 
-NOTE: The ``dune init`` command is still under development and subject to
-change.
-
 Dune's ``init`` subcommand provides limited support for generating Dune file
 stanzas and folder structures to define components. The ``dune init`` command can be used to
 quickly add new projects, libraries, tests, and executables without having to
@@ -77,7 +74,31 @@ the file and directory, if necessary):
      (preprocess
       (pps ppx_inline_tests)))
 
-Consult the manual page using the ``dune init --help`` command for more details.
+Initializing components in a specified directory
+------------------------------------------------
+
+All ``init`` subcommands take an optional ``PATH`` argument, which should be a
+path to a directory. When supplied, the component will be created in the
+specified directory. E.g., to initialize a project in the current working
+directory, run
+
+.. code:: console
+
+    $ dune init proj my_proj .
+
+To initialize a project in a directory in some nested path, run
+
+.. code:: console
+
+    $ dune init proj my_proj path/to/my/project
+
+If the specified directory does not already exist, it will be created.
+
+Learning more about the ``init`` commands
+-----------------------------------------
+
+Consult the manual page using the ```dune init --help`` command for more
+details.
 
 .. _finding-root:
 

test/blackbox-tests/test-cases/dune-init.t/run.t

@@ -144,6 +144,16 @@ Clean up from the dune file created at an absolute path
 
   $ rm -rf $PWD/_test_dir
 
+Add a library in the current working directory
+
+  $ dune init lib test_cwd_lib .
+  Success: initialized library component named test_cwd_lib
+  $ test -f dune
+
+Clean up from the dune file created in the current workding dir
+
+  $ rm dune
+
 Adding a library and an executable dependent on that library
 ------------------------------------------------------------
 
@@ -508,6 +518,27 @@ And we we can run the tests:
   test_new_lib_proj alias test/runtest
   Leaving directory 'new_lib_proj'
 
+
+Initializing projects using the PATH argument
+=============================================
+
+We can init a project in a specified directory:
+
+  $ dune init proj proj_at_path path/to/project
+  Entering directory 'path/to/project'
+  Success: initialized project component named proj_at_path
+  Leaving directory 'path/to/project'
+  $ test -f path/to/project/dune-project
+
+A project can be initialized in the current directory (addressing
+https://github.com/ocaml/dune/issues/9209):
+
+  $ mkdir a-new-dir
+  $ cd a-new-dir
+  $ dune init proj project_in_cwd .
+  Success: initialized project component named project_in_cwd
+  $ test -f dune-project
+
 Initializing projects using Esy
 ===============================
 

test/blackbox-tests/test-cases/github7806.t

@@ -1,5 +1,4 @@
   $ dune init project name $PWD 2>&1 | head -n 8
-  Entering directory 'name'
   Internal error, please report upstream including the contents of _build/log.
   Description:
     ("[as_in_source_tree_exn] called on something not in source tree",