How to fix warning: the following paths have collided (e.g. case-sensitive rename on case-insensitive filesystem) in Git

# List all files tracked by Git (case-sensitive listing)
git ls-tree -r HEAD --name-only | sort > /tmp/git-files.txt

# Find potential case collisions
git ls-tree -r HEAD --name-only | tr '[:upper:]' '[:lower:]' | sort | uniq -d

# For a more detailed view, compare lowercase versions
git ls-tree -r HEAD --name-only | while read f; do
  echo "$(echo "$f" | tr '[:upper:]' '[:lower:]') -> $f"
done | sort | uniq -D -f1

git ls-tree -r HEAD --name-only | awk '{
  lower = tolower($0)
  if (seen[lower]) {
    print "COLLISION: " seen[lower] " vs " $0
  }
  seen[lower] = $0
}'

# Git's mv command can handle case renames on case-insensitive systems
# This two-step process ensures Git tracks the rename properly

# Example: rename Utils.js to utils.js
git mv Utils.js utils-temp.js
git mv utils-temp.js utils.js
git commit -m "fix: rename Utils.js to utils.js for case-insensitive filesystems"

# Remove the file from Git's index (not from disk)
git rm --cached Utils.js

# Add the correctly-cased version
git add utils.js

git commit -m "fix: standardize file casing for cross-platform compatibility"

# If you have access to Linux or a case-sensitive disk image
mv Utils.js utils.js
git add -A
git commit -m "fix: rename Utils.js to utils.js"

# Create a 50GB case-sensitive APFS volume
# Replace "disk1" with your actual disk identifier (use 'diskutil list' to find it)
sudo diskutil apfs addVolume disk1 "Case-sensitive APFS" Development

# Or create a fixed-size volume
sudo diskutil apfs addVolume disk1 "Case-sensitive APFS" Development -quota 50g

# The new volume mounts at /Volumes/Development
cd /Volumes/Development
git clone https://github.com/user/repo.git

# Or move your existing project
mv ~/Projects/problematic-repo /Volumes/Development/

# Create a 10GB sparse case-sensitive disk image
hdiutil create -size 10g -type SPARSE -fs "Case-sensitive APFS" -volname CaseSensitive ~/CaseSensitive.sparseimage

# Mount the disk image
hdiutil attach ~/CaseSensitive.sparseimage

# Now /Volumes/CaseSensitive is case-sensitive
cd /Volumes/CaseSensitive
git clone https://github.com/user/repo.git

# When done, unmount
hdiutil detach /Volumes/CaseSensitive

# Add to your shell profile (~/.zshrc or ~/.bash_profile)
hdiutil attach ~/CaseSensitive.sparseimage -quiet 2>/dev/null || true

# Enable case-sensitive checking (warns when adding files that differ only in case)
git config --global core.ignorecase false

# Note: This doesn't make your filesystem case-sensitive, but Git will:
# - Track files with their original case
# - Warn about potential issues
# - Be more strict about path matching

git config --get core.ignorecase
# Returns "true" by default on macOS, "false" on Linux

cd /path/to/repo
git config core.ignorecase false

# If you're in the middle of a merge
# First, see what's happening
git status

# List the colliding files from the merge
git diff --name-only --diff-filter=U

# Option 1: Keep the version from your branch
git checkout --ours path/to/File.js
git add path/to/File.js

# Option 2: Keep the version from the other branch
git checkout --theirs path/to/file.js
git add path/to/file.js

# Option 3: Keep only one, delete the other from Git
git rm --cached path/to/Utils.js  # Remove the unwanted casing
git add path/to/utils.js          # Keep this version

# See which file actually exists on disk
ls -la path/to/

# Reset the problematic file to the correct version
git checkout HEAD -- path/to/utils.js

# Or from a specific commit
git checkout <commit-hash> -- path/to/utils.js

# Create or edit .git/hooks/pre-commit
cat << 'EOF' > .git/hooks/pre-commit
#!/bin/bash

# Check for case-insensitive filename collisions
collisions=$(git diff --cached --name-only --diff-filter=ACR | \
  tr '[:upper:]' '[:lower:]' | \
  sort | \
  uniq -d)

if [ -n "$collisions" ]; then
  echo "ERROR: Case-insensitive filename collision detected!"
  echo "The following filenames differ only in case:"
  echo "$collisions"
  echo ""
  echo "This will cause issues on case-insensitive filesystems (macOS, Windows)."
  echo "Please rename files to avoid collisions."
  exit 1
fi
EOF

chmod +x .git/hooks/pre-commit

npm install husky --save-dev
npx husky install
npx husky add .husky/pre-commit "scripts/check-case-collisions.sh"