#!/usr/bin/env bash
set -euo pipefail
unset MAKEFLAGS MFLAGS GNUMAKEFLAGS
make_bin=$(command -v gmake || command -v make)
m() { "$make_bin" --no-print-directory -rR "$@"; }
work_dir=$(mktemp -d)
if [ "${KEEP_WORK:-0}" = 1 ]; then
  trap 'printf "Artifacts: %s\n" "$work_dir"' EXIT
else
  trap 'rm -rf -- "$work_dir"' EXIT
fi
cd "$work_dir"
export TMPDIR="$work_dir"
cat > input.txt <<'INPUT_17_1'
7
INPUT_17_1
cat > Makefile <<'MAKEFILE'
build/report.txt: input.txt | build
	@cp input.txt $@
	@printf "report created\n"
build:
	@mkdir -p $@
MAKEFILE
m -s build/report.txt
printf "unrelated\n" > build/other.txt
printf "again\n"
m -s build/report.txt