#! /bin/sh
# See the discussion at https://stackoverflow.com/q/67724347/7976758

if [ -z "$1" ]; then
    echo "Usage $0 from_commit [to_commit]"
    exit 1
fi

from_commit="$1"
to_commit="${2:-HEAD}"

# In the superproject
git --no-pager diff --name-only "$from_commit" "$to_commit"

git submodule foreach "
    # In submodule \"\$name\"
    prev_commit=\`(git -C \"\$toplevel\" ls-tree "$from_commit" \"\$sm_path\" | awk '{print \$3}')\`
    curr_commit=\`(git -C \"\$toplevel\" ls-tree "$to_commit" \"\$sm_path\" | awk '{print \$3}')\`
    git --no-pager diff --name-only \$prev_commit \$curr_commit
"