wcgit utils for pushing a one-patch-is-one-change local repository to a one-branch-per-change remote (see https://wchargin.github.io/posts/managing-dependent-pull-requests for explanation)

discussion.url

https://wchargin.github.io/posts/managing-dependent-pull-requests

git-push-to-target.sh

#!/bin/bash
#
# git-push-to-target: Push this commit to a branch specified in its
# commit description.
#
# Copyright (c) 2018 William Chargin. Released under the MIT license.

set -eu

usage() {
    printf 'usage: git push-to-target [[REF...] | --since REVISION]\n'
    printf '                          [(--remote|-r) REMOTE]\n'
    printf '                          [--dry-run|-n] [--help|-h]\n'
    printf '\n'
    printf 'Push commits to remote branches specified in their messages.\n'
    printf '\n'
    printf '%s\n' '[REF...]'
    printf '  If explicit revisions are specified, push those commits.\n'
    printf '  If no revisions are specified, act as if HEAD was given.\n'
    printf '\n'
    printf '%s\n' '--since REVISION'
    printf '  Push those commits reachable from HEAD but not reachable\n'
    printf '  from REVISION. Incompatible with explicit revisions.\n'
    printf '\n'
    printf '%s\n' '(--remote|-r) REMOTE'
    printf '  Push to REMOTE. Defaults to "origin".\n'
    printf '\n'
    printf '%s\n' '(--dry-run|-n), or environment variable DRY_RUN nonempty'
    printf '  Invoke git-push with --dry-run.\n'
    printf '\n'
    printf '%s\n' '--help'
    printf '  Show this message.\n'
    printf '\n'
    printf 'See: git-target-branch(1).\n'
}

# Read refs from stdin and push them. Stdin must be nonempty.
process_refs() {
    remote="$1"
    refspecs=( )
    while read -r ref; do
        sha="$(git rev-parse --short --verify "${ref}")"
        target="$(git target-branch "${sha}")"
        refspec="${sha}:refs/heads/${target}"
        refspecs+=( "${refspec}" )
        message="$(git show --no-patch --format=%s "${sha}")"
        printf ' * %s:%s (%s)\n' "${sha}" "${target}" "${message}"
    done
    dry_run=
    if [ -n "${DRY_RUN:-}" ]; then
        dry_run="--dry-run"
    fi
    (set -x; git push $dry_run --force-with-lease "${remote}" "${refspecs[@]}")
}

main() {
    since=
    remote=origin
    refs=( )
    while [ $# -gt 0 ]; do
        case "$1" in
            --help|-h)
                usage
                exit 0
                ;;
            --remote|-r)
                shift
                remote="$1"
                ;;
            --dry-run|-n)
                DRY_RUN=1
                ;;
            --since)
                shift
                since="$1"
                ;;
            *)
                refs+=( "$1" )
                ;;
        esac
        shift
    done
    if [ -n "${since}" ]; then
        if [ "${#refs[@]}" -ne 0 ]; then
            printf >&2 'fatal: --since used with explicit revisions\n'
            return 1
        fi
        ref_list="$(git rev-list --reverse HEAD "^${since}")"
        printf '%s\n' "${ref_list}" | process_refs "${remote}"
    elif [ "${#refs[@]}" -gt 0 ]; then
        printf '%s\n' "${refs[@]}" | process_refs "${remote}"
    else
        printf 'HEAD\n' | process_refs "${remote}"
    fi
}

main "$@"

git-target-branch.sh

#!/bin/sh
#
# git-target-branch: Identify the remote tracking branch specified in a
# commit message.
#
# Copyright (c) 2018 William Chargin. Released under the MIT license.

set -eu

DIRECTIVE='wchargin-branch'
BRANCH_PREFIX='wchargin-'

target_branch() {
    # shellcheck disable=SC1004
    awk -v FS=": " -v directive="${DIRECTIVE}" -v prefix="${BRANCH_PREFIX}" '
    NR == 1 { summary = $0 }
    $1 == directive {
        if (NF == 2 && $2 !~ /[^A-Za-z0-9_.-]/) {
            found[count++] = $2;
        } else {
            printf("bad \"%s\" directive (%s): %s\n", directive, $0, summary) \
                >"/dev/stderr";
            aborted = 1;
            exit 1;
        }
    }
    END {
        if (aborted) exit;
        if (count == 0) {
            printf("missing \"%s\" directive: %s\n", directive, summary) \
                >"/dev/stderr";
            exit 1;
        } else if (count > 1) {
            printf("multiple \"%s\" directives: %s\n", directive, summary) \
                >"/dev/stderr";
            exit 1;
        } else {
            printf("%s%s\n", prefix, found[0]);
        }
    }
    '
}

main() {
    # TODO: --help
    src="${1:-HEAD}"
    if [ "${src}" = '-' ]; then
        target_branch
    else
        git show --no-patch --format=%B "${src}" | target_branch
    fi
}

main "$@"