windows doesn't apply patch that works on other platforms

[minrk]

The patch in question removes a symlink, and was created with:

git rm cpp/test/vcpkg.json
git commit -m "..."
git format-patch HEAD^1

The patch:

From 0ad004448855d5968a7dfc7bc60890c2f803865b Mon Sep 17 00:00:00 2001
From: Min RK <benjaminrk@gmail.com>
Date: Sat, 21 Feb 2026 09:16:16 -0800
Subject: [PATCH] remove symlink

---
 cpp/test/vcpkg.json | 1 -
 1 file changed, 1 deletion(-)
 delete mode 120000 cpp/test/vcpkg.json

diff --git a/cpp/test/vcpkg.json b/cpp/test/vcpkg.json
deleted file mode 120000
index e24efb77fb..0000000000
--- a/cpp/test/vcpkg.json
+++ /dev/null
@@ -1 +0,0 @@
-../vcpkg.json
\ No newline at end of file
-- 
2.49.0

On mac and linux, the patch applies cleanly, but on Windows, it errors trying to remove the wrong file, removing test/vcpkg.json instead of cpp/test/vcpkg.json:

╭─ Running build for recipe: fenics-libdolfinx-0.10.0-py310hd68938e_3
 │
 │ ╭─ Fetching source code
 │ │ Fetching source from url: https://github.com/fenics/dolfinx/archive/refs/tags/v0.10.0.tar.gz
 │ │ Found filename from Content-Disposition: dolfinx-0.10.0.tar.gz
 │ │ Downloaded file from https://github.com/fenics/dolfinx/archive/refs/tags/v0.10.0.tar.gz
 │ │ Validated SHA256 values of the downloaded file!
 │ │ Extracting tar file to cache: D:\bld\src_cache\dolfinx-0_10_0_24cbad2f.tar.gz
 │ │ Copying source from url: D:\bld\src_cache\dolfinx-0_10_0_24cbad2f to D:\bld\bld\rattler-build_fenics-libdolfinx_1771696175\work
 │ │ Applying patch: D:\a\1\s\recipe\4004.patch
 │ │ Applying patch: D:\a\1\s\recipe\remove-symlink.patch
 │ │
 │ ╰─────────────────── (took 1 second)
 │
 ╰─────────────────── (took 1 second)
Error:   × IO Error: failed to remove file `D:\bld\bld\rattler-build_fenics-
  │ libdolfinx_1771696175\work\test\vcpkg.json`: The system cannot find the
  │ path specified. (os error 3)
  ╰─▶ failed to remove file `D:\bld\bld\rattler-build_fenics-
      libdolfinx_1771696175\work\test\vcpkg.json`: The system cannot find the
      path specified. (os error 3)

Possibly relevant, the symlink to be removed points one level up, to ../vcpkg.json.

The recipe containing the patch

[minrk]

a simpler hand-written patch also produces the same error:

--- cpp/test/vcpkg.json
+++ /dev/null

[minrk]

ah, but this simpler patch does work on Windows:

--- a/cpp/test/vcpkg.json
+++ /dev/null

I don't know why the same lines in the git format-patch output doesn't do the right thing. But in any case, all 3 patches correctly apply everywhere but Windows, but only the last one applies on Windows.

[wolfv]

@minrk thank you for digging into this. We'll take a look. Already improved patching in a few areas for the upcoming release!