Add and use Mill wrapper script (backport #4119) (#4125)

* Add and use Mill wrapper script (#4119)

This saves developers from having to install a dependency. It also
allows us to drop an old Github Actions dependency that hasn't been
updated in 2 years. This is the standard practice for projects using
Mill on Github.

(cherry picked from commit 0f2efb5)

# Conflicts:
#	.github/workflows/test.yml
#	CONTRIBUTING.md
#	benchmark/src/main/scala/chisel3/benchmark/Benchmark.scala

* Resolve backport conflicts

---------

Co-authored-by: Jack Koenig <koenig@sifive.com>

.github/workflows/test.yml

@@ -99,10 +99,6 @@ jobs:
           distribution: 'adopt'
           java-version: '21'
           cache: 'sbt'
-      - name: Install Mill
-        uses: jodersky/setup-mill@v0.3.0
-        with:
-          mill-version: 0.11.5
       # Mill needs firtool to compile with bindings, cannot use firtool-resolver at runtime
       - name: Pick CIRCT version
         id: circt-version
@@ -120,7 +116,7 @@ jobs:
       - name: Compile Mill
         run: |
           export CIRCT_INSTALL_PATH="$(pwd)/circt"
-          mill __.compile
+          ./mill __.compile
 
   doc:
     name: Formatting

.mill-version

@@ -0,0 +1 @@
+0.11.7

mill

@@ -0,0 +1,241 @@
+#!/usr/bin/env sh
+
+# This is a wrapper script, that automatically download mill from GitHub release pages
+# You can give the required mill version with --mill-version parameter
+# If no version is given, it falls back to the value of DEFAULT_MILL_VERSION
+#
+# Project page: https://github.com/lefou/millw
+# Script Version: 0.4.11
+#
+# If you want to improve this script, please also contribute your changes back!
+#
+# Licensed under the Apache License, Version 2.0
+
+set -e
+
+if [ -z "${DEFAULT_MILL_VERSION}" ] ; then
+  DEFAULT_MILL_VERSION="0.11.4"
+fi
+
+
+if [ -z "${GITHUB_RELEASE_CDN}" ] ; then
+  GITHUB_RELEASE_CDN=""
+fi
+
+
+MILL_REPO_URL="https://github.com/com-lihaoyi/mill"
+
+if [ -z "${CURL_CMD}" ] ; then
+  CURL_CMD=curl
+fi
+
+# Explicit commandline argument takes precedence over all other methods
+if [ "$1" = "--mill-version" ] ; then
+  shift
+  if [ "x$1" != "x" ] ; then
+    MILL_VERSION="$1"
+    shift
+  else
+    echo "You specified --mill-version without a version." 1>&2
+    echo "Please provide a version that matches one provided on" 1>&2
+    echo "${MILL_REPO_URL}/releases" 1>&2
+    false
+  fi
+fi
+
+# Please note, that if a MILL_VERSION is already set in the environment,
+# We reuse it's value and skip searching for a value.
+
+# If not already set, read .mill-version file
+if [ -z "${MILL_VERSION}" ] ; then
+  if [ -f ".mill-version" ] ; then
+    MILL_VERSION="$(head -n 1 .mill-version 2> /dev/null)"
+  elif [ -f ".config/mill-version" ] ; then
+    MILL_VERSION="$(head -n 1 .config/mill-version 2> /dev/null)"
+  fi
+fi
+
+MILL_USER_CACHE_DIR="${XDG_CACHE_HOME:-${HOME}/.cache}/mill"
+
+if [ -z "${MILL_DOWNLOAD_PATH}" ] ; then
+  MILL_DOWNLOAD_PATH="${MILL_USER_CACHE_DIR}/download"
+fi
+
+# If not already set, try to fetch newest from Github
+if [ -z "${MILL_VERSION}" ] ; then
+  # TODO: try to load latest version from release page
+  echo "No mill version specified." 1>&2
+  echo "You should provide a version via '.mill-version' file or --mill-version option." 1>&2
+
+  mkdir -p "${MILL_DOWNLOAD_PATH}"
+  LANG=C touch -d '1 hour ago' "${MILL_DOWNLOAD_PATH}/.expire_latest" 2>/dev/null || (
+    # we might be on OSX or BSD which don't have -d option for touch
+    # but probably a -A [-][[hh]mm]SS
+    touch "${MILL_DOWNLOAD_PATH}/.expire_latest"; touch -A -010000 "${MILL_DOWNLOAD_PATH}/.expire_latest"
+  ) || (
+    # in case we still failed, we retry the first touch command with the intention
+    # to show the (previously suppressed) error message
+    LANG=C touch -d '1 hour ago' "${MILL_DOWNLOAD_PATH}/.expire_latest"
+  )
+
+  # POSIX shell variant of bash's -nt operator, see https://unix.stackexchange.com/a/449744/6993
+  # if [ "${MILL_DOWNLOAD_PATH}/.latest" -nt "${MILL_DOWNLOAD_PATH}/.expire_latest" ] ; then
+  if [ -n "$(find -L "${MILL_DOWNLOAD_PATH}/.latest" -prune -newer "${MILL_DOWNLOAD_PATH}/.expire_latest")" ]; then
+    # we know a current latest version
+    MILL_VERSION=$(head -n 1 "${MILL_DOWNLOAD_PATH}"/.latest 2> /dev/null)
+  fi
+
+  if [ -z "${MILL_VERSION}" ] ; then
+    # we don't know a current latest version
+    echo "Retrieving latest mill version ..." 1>&2
+    LANG=C ${CURL_CMD} -s -i -f -I ${MILL_REPO_URL}/releases/latest 2> /dev/null  | grep --ignore-case Location: | sed s'/^.*tag\///' | tr -d '\r\n' > "${MILL_DOWNLOAD_PATH}/.latest"
+    MILL_VERSION=$(head -n 1 "${MILL_DOWNLOAD_PATH}"/.latest 2> /dev/null)
+  fi
+
+  if [ -z "${MILL_VERSION}" ] ; then
+    # Last resort
+    MILL_VERSION="${DEFAULT_MILL_VERSION}"
+    echo "Falling back to hardcoded mill version ${MILL_VERSION}" 1>&2
+  else
+    echo "Using mill version ${MILL_VERSION}" 1>&2
+  fi
+fi
+
+MILL="${MILL_DOWNLOAD_PATH}/${MILL_VERSION}"
+
+try_to_use_system_mill() {
+  if [ "$(uname)" != "Linux" ]; then
+    return 0
+  fi
+
+  MILL_IN_PATH="$(command -v mill || true)"
+
+  if [ -z "${MILL_IN_PATH}" ]; then
+    return 0
+  fi
+
+  SYSTEM_MILL_FIRST_TWO_BYTES=$(head --bytes=2 "${MILL_IN_PATH}")
+  if [ "${SYSTEM_MILL_FIRST_TWO_BYTES}" = "#!" ]; then
+	  # MILL_IN_PATH is (very likely) a shell script and not the mill
+	  # executable, ignore it.
+	  return 0
+  fi
+
+  SYSTEM_MILL_PATH=$(readlink -e "${MILL_IN_PATH}")
+  SYSTEM_MILL_SIZE=$(stat --format=%s "${SYSTEM_MILL_PATH}")
+  SYSTEM_MILL_MTIME=$(stat --format=%y "${SYSTEM_MILL_PATH}")
+
+  if [ ! -d "${MILL_USER_CACHE_DIR}" ]; then
+    mkdir -p "${MILL_USER_CACHE_DIR}"
+  fi
+
+  SYSTEM_MILL_INFO_FILE="${MILL_USER_CACHE_DIR}/system-mill-info"
+  if [ -f "${SYSTEM_MILL_INFO_FILE}" ]; then
+    parseSystemMillInfo() {
+        LINE_NUMBER="${1}"
+        # Select the line number of the SYSTEM_MILL_INFO_FILE, cut the
+        # variable definition in that line in two halves and return
+        # the value, and finally remove the quotes.
+        sed -n "${LINE_NUMBER}p" "${SYSTEM_MILL_INFO_FILE}" |\
+            cut -d= -f2 |\
+            sed 's/"\(.*\)"/\1/'
+    }
+
+    CACHED_SYSTEM_MILL_PATH=$(parseSystemMillInfo 1)
+    CACHED_SYSTEM_MILL_VERSION=$(parseSystemMillInfo 2)
+    CACHED_SYSTEM_MILL_SIZE=$(parseSystemMillInfo 3)
+    CACHED_SYSTEM_MILL_MTIME=$(parseSystemMillInfo 4)
+
+    if [ "${SYSTEM_MILL_PATH}" = "${CACHED_SYSTEM_MILL_PATH}" ] \
+           && [ "${SYSTEM_MILL_SIZE}" = "${CACHED_SYSTEM_MILL_SIZE}" ] \
+           && [ "${SYSTEM_MILL_MTIME}" = "${CACHED_SYSTEM_MILL_MTIME}" ]; then
+      if [ "${CACHED_SYSTEM_MILL_VERSION}" = "${MILL_VERSION}" ]; then
+          MILL="${SYSTEM_MILL_PATH}"
+          return 0
+      else
+          return 0
+      fi
+    fi
+  fi
+
+  SYSTEM_MILL_VERSION=$(${SYSTEM_MILL_PATH} --version | head -n1 | sed -n 's/^Mill.*version \(.*\)/\1/p')
+
+  cat <<EOF > "${SYSTEM_MILL_INFO_FILE}"
+CACHED_SYSTEM_MILL_PATH="${SYSTEM_MILL_PATH}"
+CACHED_SYSTEM_MILL_VERSION="${SYSTEM_MILL_VERSION}"
+CACHED_SYSTEM_MILL_SIZE="${SYSTEM_MILL_SIZE}"
+CACHED_SYSTEM_MILL_MTIME="${SYSTEM_MILL_MTIME}"
+EOF
+
+  if [ "${SYSTEM_MILL_VERSION}" = "${MILL_VERSION}" ]; then
+    MILL="${SYSTEM_MILL_PATH}"
+  fi
+}
+try_to_use_system_mill
+
+# If not already downloaded, download it
+if [ ! -s "${MILL}" ] ; then
+
+  # support old non-XDG download dir
+  MILL_OLD_DOWNLOAD_PATH="${HOME}/.mill/download"
+  OLD_MILL="${MILL_OLD_DOWNLOAD_PATH}/${MILL_VERSION}"
+  if [ -x "${OLD_MILL}" ] ; then
+    MILL="${OLD_MILL}"
+  else
+    case $MILL_VERSION in
+      0.0.* | 0.1.* | 0.2.* | 0.3.* | 0.4.* )
+        DOWNLOAD_SUFFIX=""
+        DOWNLOAD_FROM_MAVEN=0
+        ;;
+      0.5.* | 0.6.* | 0.7.* | 0.8.* | 0.9.* | 0.10.* | 0.11.0-M* )
+        DOWNLOAD_SUFFIX="-assembly"
+        DOWNLOAD_FROM_MAVEN=0
+        ;;
+      *)
+        DOWNLOAD_SUFFIX="-assembly"
+        DOWNLOAD_FROM_MAVEN=1
+        ;;
+    esac
+
+    DOWNLOAD_FILE=$(mktemp mill.XXXXXX)
+
+    if [ "$DOWNLOAD_FROM_MAVEN" = "1" ] ; then
+      DOWNLOAD_URL="https://repo1.maven.org/maven2/com/lihaoyi/mill-dist/${MILL_VERSION}/mill-dist-${MILL_VERSION}.jar"
+    else
+      MILL_VERSION_TAG=$(echo "$MILL_VERSION" | sed -E 's/([^-]+)(-M[0-9]+)?(-.*)?/\1\2/')
+      DOWNLOAD_URL="${GITHUB_RELEASE_CDN}${MILL_REPO_URL}/releases/download/${MILL_VERSION_TAG}/${MILL_VERSION}${DOWNLOAD_SUFFIX}"
+      unset MILL_VERSION_TAG
+    fi
+
+    # TODO: handle command not found
+    echo "Downloading mill ${MILL_VERSION} from ${DOWNLOAD_URL} ..." 1>&2
+    ${CURL_CMD} -f -L -o "${DOWNLOAD_FILE}" "${DOWNLOAD_URL}"
+    chmod +x "${DOWNLOAD_FILE}"
+    mkdir -p "${MILL_DOWNLOAD_PATH}"
+    mv "${DOWNLOAD_FILE}" "${MILL}"
+
+    unset DOWNLOAD_FILE
+    unset DOWNLOAD_SUFFIX
+  fi
+fi
+
+if [ -z "$MILL_MAIN_CLI" ] ; then
+  MILL_MAIN_CLI="${0}"
+fi
+
+MILL_FIRST_ARG=""
+if [ "$1" = "--bsp" ] || [ "$1" = "-i" ] || [ "$1" = "--interactive" ] || [ "$1" = "--no-server" ] || [ "$1" = "--repl" ] || [ "$1" = "--help" ] ; then
+  # Need to preserve the first position of those listed options
+  MILL_FIRST_ARG=$1
+  shift
+fi
+
+unset MILL_DOWNLOAD_PATH
+unset MILL_OLD_DOWNLOAD_PATH
+unset OLD_MILL
+unset MILL_VERSION
+unset MILL_REPO_URL
+
+# We don't quote MILL_FIRST_ARG on purpose, so we can expand the empty value without quotes
+# shellcheck disable=SC2086
+exec "${MILL}" $MILL_FIRST_ARG -D "mill.main.cli=${MILL_MAIN_CLI}" "$@"