feather/contrib/depends/gen_id
2023-03-20 16:13:52 +01:00

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#!/usr/bin/env bash
# Usage: env [ CC=... ] [ C_STANDARD=...] [ CXX=... ] [CXX_STANDARD=...] \
# [ AR=... ] [ RANLIB=... ] [ STRIP=... ] [ DEBUG=... ] \
# [ LTO=... ] ./build-id [ID_SALT]...
#
# Prints to stdout a SHA256 hash representing the current toolset, used by
# depends/Makefile as a build id for caching purposes (detecting when the
# toolset has changed and the cache needs to be invalidated).
#
# If the DEBUG environment variable is non-empty and the system has `tee`
# available in its $PATH, the pre-image to the SHA256 hash will be printed to
# stderr. This is to help developers debug caching issues in depends.
# This script explicitly does not `set -e` because id determination is mostly
# opportunistic: it is fine that things fail, as long as they fail consistently.
# Command variables (CC/CXX/AR) which can be blank are invoked with `bash -c`,
# because the "command not found" error message printed by shells often include
# the line number, like so:
#
# ./depends/gen_id: line 43: --version: command not found
#
# By invoking with `bash -c`, we ensure that the line number is always 1
(
# Redirect stderr to stdout
exec 2>&1
echo "BEGIN ALL"
# Include any ID salts supplied via command line
echo "BEGIN ID SALT"
echo "$@"
echo "END ID SALT"
# GCC only prints COLLECT_LTO_WRAPPER when invoked with just "-v", but we want
# the information from "-v -E -" as well, so just include both.
echo "BEGIN CC"
bash -c "${CC} -v"
bash -c "${CC} -v -E -xc -o /dev/null - < /dev/null"
bash -c "${CC} -v -E -xobjective-c -o /dev/null - < /dev/null"
echo "C_STANDARD=${C_STANDARD}"
echo "END CC"
echo "BEGIN CXX"
bash -c "${CXX} -v"
bash -c "${CXX} -v -E -xc++ -o /dev/null - < /dev/null"
bash -c "${CXX} -v -E -xobjective-c++ -o /dev/null - < /dev/null"
echo "CXX_STANDARD=${CXX_STANDARD}"
echo "END CXX"
echo "BEGIN AR"
bash -c "${AR} --version"
env | grep '^AR_'
echo "ZERO_AR_DATE=${ZERO_AR_DATE}"
echo "END AR"
echo "BEGIN RANLIB"
bash -c "${RANLIB} --version"
env | grep '^RANLIB_'
echo "END RANLIB"
echo "BEGIN STRIP"
bash -c "${STRIP} --version"
env | grep '^STRIP_'
echo "END STRIP"
echo "END ALL"
) | if [ -n "$DEBUG_GENID" ] && command -v tee > /dev/null 2>&1; then
# When debugging and `tee` is available, output the preimage to stderr
# in addition to passing through stdin to stdout
tee >(cat 1>&2)
else
# Otherwise, passthrough stdin to stdout
cat
fi | ${SHA256SUM} - | cut -d' ' -f1