From 6df275df3b8694daf16302b407520e3b1dee6724 Mon Sep 17 00:00:00 2001
From: Philip Hayes <philiphayes9@gmail.com>
Date: Thu, 12 Sep 2024 13:23:00 -0700
Subject: [PATCH] fix: cleanup xcode_backend.sh to fix iOS build w/
 `NixOS/nixpkgs` flutter

This patch cleans up `xcode_backend.sh`. It now effectively just runs
`exec $FLUTTER_ROOT/bin/dart ./xcode_backend.dart`.

The previous `xcode_backend.sh` tries to discover `$FLUTTER_ROOT` from
argv[0], even though its presence is already guaranteed (the wrapped
`xcode_backend.dart` also relies on this env).

When using nixpkgs flutter, the flutter SDK directory is composed of several
layers, joined together using symlinks (called a `symlinkJoin`). Without this
patch, the auto-discover traverses the symlinks into the wrong layer, and so it
uses an "unwrapped" `dart` command instead of a "wrapped" dart that sets some
important envs/flags (like `$FLUTTER_ROOT`).

Using the "unwrapped" dart then manifests in this error when compiling, since
it doesn't see the ios build-support artifacts:

```
$ flutter run -d iphone
Running Xcode build...
Xcode build done.                                            6.4s
Failed to build iOS app
Error (Xcode): Target debug_unpack_ios failed: Error: Flutter failed to create a directory at "/<nix-store>/XXXX-flutter-3.24.1-unwrapped/bin/cache/artifacts".
```
---
 packages/flutter_tools/bin/xcode_backend.sh | 25 ++++-----------------
 1 file changed, 4 insertions(+), 21 deletions(-)

diff --git a/packages/flutter_tools/bin/xcode_backend.sh b/packages/flutter_tools/bin/xcode_backend.sh
index 2889d7c8e4..48b9d06c6e 100755
--- a/packages/flutter_tools/bin/xcode_backend.sh
+++ b/packages/flutter_tools/bin/xcode_backend.sh
@@ -6,24 +6,7 @@
 # exit on error, or usage of unset var
 set -euo pipefail
 
-# Needed because if it is set, cd may print the path it changed to.
-unset CDPATH
-
-function follow_links() (
-  cd -P "$(dirname -- "$1")"
-  file="$PWD/$(basename -- "$1")"
-  while [[ -h "$file" ]]; do
-    cd -P "$(dirname -- "$file")"
-    file="$(readlink -- "$file")"
-    cd -P "$(dirname -- "$file")"
-    file="$PWD/$(basename -- "$file")"
-  done
-  echo "$file"
-)
-
-PROG_NAME="$(follow_links "${BASH_SOURCE[0]}")"
-BIN_DIR="$(cd "${PROG_NAME%/*}" ; pwd -P)"
-FLUTTER_ROOT="$BIN_DIR/../../.."
-DART="$FLUTTER_ROOT/bin/dart"
-
-"$DART" "$BIN_DIR/xcode_backend.dart" "$@"
+# Run `dart ./xcode_backend.dart` with the dart from $FLUTTER_ROOT.
+dart="${FLUTTER_ROOT}/bin/dart"
+xcode_backend_dart="${BASH_SOURCE[0]%.sh}.dart"
+exec "${dart}" "${xcode_backend_dart}" "$@"
-- 
2.46.0