Improve myers and merge3 vendoring

NOTICE.md

@@ -81,10 +81,10 @@ Myers is vendored from by Thomas Gazagnaire (released under `ISC`)
 [ocaml-merge3](https://tangled.org/gazagnaire.org/ocaml-merge3). Only the pure
 diff computation is vendored; the parts unused by this project are not included.
 The exact provenance and list of changes are documented at the top of
-`src/myers/merge3.ml` and in `src/myers/vendor.json`.
+`src/merge3/merge3.ml` and in `src/merge3/vendor.json`.
 
 A copy of the license file for ocaml-merge3 is located under
-`third-party-license/gazagnaire/ocaml-merge3/LICENSE`.
+`third-party-license/gazagnaire/ocaml-merge3/LICENSE.md`.
 
 ## Windtrap (unified-diff renderer)
 

src/merge3/COPYING.HEADER

@@ -0,0 +1,3 @@
+crs-merge3 - Myers shortest-edit-script computation
+SPDX-FileCopyrightText: 2026 Mathieu Barbin <mathieu.barbin@gmail.com>
+SPDX-License-Identifier: ISC

src/merge3/dune

@@ -0,0 +1,9 @@
+(library
+ (name crs_merge3)
+ (package crs-tests)
+ (flags :standard -w +a-4-40-41-42-44-45-48-66 -warn-error +a)
+ (instrumentation
+  (backend bisect_ppx))
+ (lint
+  (pps ppx_js_style -allow-let-operators -check-doc-comments))
+ (preprocess no_preprocessing))

src/myers/merge3.ml → src/merge3/merge3.ml

@@ -1,11 +1,22 @@
-(**************************************************************************)
-(*  crs-myers - Myers diff computation and unified-diff printing          *)
-(*  Copyright (C) 2026 Mathieu Barbin <mathieu.barbin@gmail.com>          *)
-(*  SPDX-License-Identifier: ISC                                          *)
-(**************************************************************************)
-
-(* Copyright (c) 2024-2026 Thomas Gazagnaire <thomas@gazagnaire.org>      *)
-(* SPDX-License-Identifier: ISC                                           *)
+(****************************************************************************)
+(*  crs-merge3 - Myers shortest-edit-script computation                     *)
+(*  SPDX-FileCopyrightText: 2026 Mathieu Barbin <mathieu.barbin@gmail.com>  *)
+(*  SPDX-License-Identifier: ISC                                            *)
+(****************************************************************************)
+
+(* Copyright (c) 2024-2026 Thomas Gazagnaire <thomas@gazagnaire.org>
+
+   Permission to use, copy, modify, and distribute this software for any
+   purpose with or without fee is hereby granted, provided that the above
+   copyright notice and this permission notice appear in all copies.
+
+   THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+   WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+   MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+   ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+   WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+   ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+   OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. *)
 
 (* Notice: This file was vendored from gazagnaire/ocaml-merge3 (the [Merge3]
    module, [lib/merge3.ml]) as documented in [vendor.json] and the project's

src/merge3/merge3.mli

@@ -0,0 +1,55 @@
+(*_***************************************************************************)
+(*_  crs-merge3 - Myers shortest-edit-script computation                     *)
+(*_  SPDX-FileCopyrightText: 2026 Mathieu Barbin <mathieu.barbin@gmail.com>  *)
+(*_  SPDX-License-Identifier: ISC                                            *)
+(*_***************************************************************************)
+
+(*_ Copyright (c) 2024-2026 Thomas Gazagnaire <thomas@gazagnaire.org>
+
+  Permission to use, copy, modify, and distribute this software for any
+  purpose with or without fee is hereby granted, provided that the above
+  copyright notice and this permission notice appear in all copies.
+
+  THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. *)
+
+(*_ Notice: This file was vendored from gazagnaire/ocaml-merge3 (the [Merge3]
+  module, [lib/merge3.mli]) as documented in [vendor.json] and the project's
+  root [NOTICE.md].
+
+  List of changes:
+
+  - Applied local project ocamlformat (janestreet profile).
+  - Removed the parts unused by this project.
+
+  - Replace use of globally-visible [Stdlib.Exit] exception by a custom one.
+    An [eq] that itself raised [Exit] would be silently swallowed and yield
+    a wrong diff. *)
+
+(** Myers' O(ND) shortest-edit-script, vendored from gazagnaire/ocaml-merge3.
+
+    Only the pure diff computation is vendored; see [merge3.ml] and the root
+    [NOTICE.md] for the list of (non-algorithmic) parts removed. *)
+
+(** An edit operation in the shortest edit script. *)
+type 'a edit =
+  | Keep of 'a (** Line present in both sequences. *)
+  | Delete of 'a (** Line present in old, absent in new. *)
+  | Insert of 'a (** Line absent in old, present in new. *)
+
+(** [diff ~eq a b] computes the shortest edit script from [a] to [b] using
+    Myers' O(ND) algorithm. [eq] is the equality predicate.
+
+    The result is a list of edits that transforms [a] into [b]:
+    - [Keep x]: line [x] is present in both
+    - [Delete x]: line [x] from [a] is removed
+    - [Insert x]: line [x] from [b] is added
+
+    Time: O(ND) where N = |a| + |b| and D = edit distance. Space: O(D²) for the
+    trace. *)
+val diff : eq:('a -> 'a -> bool) -> 'a array -> 'a array -> 'a edit list

src/merge3/vendor.json

@@ -0,0 +1,13 @@
+{
+    "note": "This directory vendors the Myers shortest-edit-script computation from gazagnaire/ocaml-merge3. See the in-file Notice block for the list of changes.",
+    "sources": [
+        {
+            "file": "merge3.ml",
+            "description": "Myers shortest-edit-script computation",
+            "url": "https://tangled.sh/@gazagnaire.org/monopampam",
+            "gitRev": "f09e84825149d6b76365bd7af347577182fe9c79",
+            "path": "ocaml-merge3/lib/merge3.ml",
+            "license": "ISC"
+        }
+    ]
+}

src/myers/COPYING.HEADER

@@ -1,3 +1,3 @@
 crs-myers - Myers diff computation and unified-diff printing
-Copyright (C) 2026 Mathieu Barbin <mathieu.barbin@gmail.com>
+SPDX-FileCopyrightText: 2026 Mathieu Barbin <mathieu.barbin@gmail.com>
 SPDX-License-Identifier: ISC

src/myers/dune

@@ -1,8 +1,15 @@
 (library
  (name crs_myers)
  (package crs-tests)
- (private_modules merge3)
- (flags :standard -w +a-4-40-41-42-44-45-48-66 -warn-error +a)
+ (libraries crs_merge3)
+ (flags
+  :standard
+  -w
+  +a-4-40-41-42-44-45-48-66
+  -warn-error
+  +a
+  -open
+  Crs_merge3)
  (instrumentation
   (backend bisect_ppx))
  (lint

src/myers/myers.ml

@@ -1,11 +1,22 @@
-(**************************************************************************)
-(*  crs-myers - Myers diff computation and unified-diff printing          *)
-(*  Copyright (C) 2026 Mathieu Barbin <mathieu.barbin@gmail.com>          *)
-(*  SPDX-License-Identifier: ISC                                          *)
-(**************************************************************************)
+(****************************************************************************)
+(*  crs-myers - Myers diff computation and unified-diff printing            *)
+(*  SPDX-FileCopyrightText: 2026 Mathieu Barbin <mathieu.barbin@gmail.com>  *)
+(*  SPDX-License-Identifier: ISC                                            *)
+(****************************************************************************)
 
-(* Copyright (c) 2026 Invariant Systems. All rights reserved.             *)
-(* SPDX-License-Identifier: ISC                                           *)
+(* Copyright (c) 2026 Invariant Systems. All rights reserved.
+
+   Permission to use, copy, modify, and/or distribute this software for any
+   purpose with or without fee is hereby granted, provided that the above
+   copyright notice and this permission notice appear in all copies.
+
+   THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+   WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+   MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+   ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+   WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+   ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+   OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. *)
 
 (* Notice: The unified-diff renderer and the [Equal] / [Line] / [compute] API
    shape in this file were vendored from windtrap (the [Myers] module,

src/myers/myers.mli

@@ -1,11 +1,42 @@
-(*_*************************************************************************)
-(*_  crs-myers - Myers diff computation and unified-diff printing          *)
-(*_  Copyright (C) 2026 Mathieu Barbin <mathieu.barbin@gmail.com>          *)
-(*_  SPDX-License-Identifier: ISC                                          *)
-(*_*************************************************************************)
-
-(*_ Copyright (c) 2026 Invariant Systems. All rights reserved.             *)
-(*_ SPDX-License-Identifier: ISC                                           *)
+(*_***************************************************************************)
+(*_  crs-myers - Myers diff computation and unified-diff printing            *)
+(*_  SPDX-FileCopyrightText: 2026 Mathieu Barbin <mathieu.barbin@gmail.com>  *)
+(*_  SPDX-License-Identifier: ISC                                            *)
+(*_***************************************************************************)
+
+(*_ Copyright (c) 2026 Invariant Systems. All rights reserved.
+
+  Permission to use, copy, modify, and/or distribute this software for any
+  purpose with or without fee is hereby granted, provided that the above
+  copyright notice and this permission notice appear in all copies.
+
+  THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. *)
+
+(*_ Notice: The unified-diff renderer and the [Equal] / [Line] / [compute] API
+  shape in this file were vendored from windtrap (the [Myers] module,
+  [lib/myers/myers.mli]) as documented in [vendor.json] and the project's root
+  [NOTICE.md]. Only the shortest-edit-script computation was replaced (it now
+  lives in [merge3.mli], vendored from gazagnaire/ocaml-merge3); the rendering
+  logic — [type hunk], [lines_of_string], [hunks_of_lines], [diff],
+  [print_diff] — derives from windtrap.
+
+  List of changes relative to windtrap:
+
+  - Applied local project ocamlformat (janestreet profile).
+  - [compute] delegates to the vendored {!Merge3.diff}.
+  - Hunk lines use the [Line] variant instead of windtrap's [(char * string)]
+    encoding ([type hunk.lines : string Line.t list]).
+  - [lines_of_string] returns a [string list] and the intermediate [Array]
+    representation in [hunks_of_lines] was removed.
+  - Diff rendering tweaks: line prefixes are ["-|"] / ["+|"] / ["  "], and the
+    [--- / +++] header is emitted only when a label is explicitly provided
+    (windtrap always emitted it with the defaults "expected" / "actual"). *)
 
 (** Unified-diff renderer built on a vendored Myers shortest-edit-script.
 

src/myers/vendor.json

@@ -1,14 +1,6 @@
 {
-    "note": "This directory vendors code from two upstreams. The Myers shortest-edit-script computation is in [merge3.ml] (from gazagnaire/ocaml-merge3). The unified-diff renderer and the Equal/Line/compute API shape are in [myers.ml] (from windtrap). See the in-file Notice blocks and the root [NOTICE.md] for the list of changes.",
+    "note": "This directory vendors the unified-diff renderer and the Equal/Line/compute API shape from windtrap. The Myers shortest-edit-script computation it calls into lives in ../merge3, vendored separately from gazagnaire/ocaml-merge3. See the in-file Notice block for the list of changes.",
     "sources": [
-        {
-            "file": "merge3.ml",
-            "description": "Myers shortest-edit-script computation",
-            "url": "https://tangled.sh/@gazagnaire.org/monopampam",
-            "gitRev": "f09e84825149d6b76365bd7af347577182fe9c79",
-            "path": "ocaml-merge3/lib/merge3.ml",
-            "license": "ISC"
-        },
         {
             "file": "myers.ml",
             "description": "Unified-diff renderer and Equal/Line/compute API shape",