Multirust-compatible racer wrapper

README.md

This wrapper automatically sets the RUST_SRC_DIRECTORY environment variable for whatever rust compiler is currently active, automatically creating a new checkout whenever necessary. This should be compatible with all of the multirust-alike tools, but it has only been tested with rustup.rs

Installation

Simply place this somewhere on your path before the main racer binary and set the execute bit.

Uninstallation

See rm(1).

Bugs

If you keep up to date with nightly, this will likely result in your disk slowly filling with copies of the rust source tree. While there are far worse uses for the disk space, you also likely have better. You may simply delete all directories beginning with rust- in $RUST_SOURCE_ROOT (${RUSTUP_HOME}/src or ${HOME}/.multirust/src, whichever is defined) to reclaim the disk space. (Strictly speaking, you can also remove the git directory, but it will automatically be redownloaded the next time the wrapper is run so this usually doens't make sense.)

racer

#!/bin/bash

# Set a default for RUSTUP_HOME
: ${RUSTUP_HOME:=${HOME}/.multirust}
: ${RUST_SOURCE_ROOT:=${RUSTUP_HOME}/src}

[[ -d ${RUST_SOURCE_ROOT} ]] || mkdir -p "${RUST_SOURCE_ROOT}"

SELF_FOUND=0
# TODO: This doesn't deal well with path entries that contain spaces
for cmd in $(which -a "$(basename "$0")"); do
    if (( $SELF_FOUND == 1 )); then
	NEXT_RACER="${cmd}"
    elif [[ "${cmd}" -ef "$0" ]]; then
	SELF_FOUND=1
    fi
done
if ! (( $SELF_FOUND )); then
   : ${NEXT_RACER:=racer}
fi

function vivify() {
    HASH=$1
    
    export GIT_DIR="$RUSTUP_HOME/src/git"
    if ! [[ -d "${GIT_DIR}" ]]; then
	git clone --bare --quiet https://github.com/rust-lang/rust "${GIT_DIR}"
    fi
    
    if (( $(date +%s) - 3600*12 > $(stat -c %Y "${GIT_DIR}") )); then
	git fetch --all
    fi
    
    TREE="$(git rev-parse --verify --quiet "${HASH}^{tree}")"
    if [[ $? -ne 0 ]]; then
	echo "Inable to resolve ${HASH}" >/dev/stderr
	exit 1
    fi
    
    if ! [[ -d "${RUST_SOURCE_ROOT}/rust-${TREE}" ]]; then
	git archive --prefix=rust-"${TREE}/" ${HASH} | tar xC "${RUST_SOURCE_ROOT}"
    fi
    readlink -f "${RUST_SOURCE_ROOT}/rust-${TREE}"
}

function rust_version() {
    # Get the current rust compiler version
    local RUST_COMMIT="$(rustc -vV 2>/dev/null |awk '($1 == "commit-hash:") { print $2 }')"
    if (( $? )); then
	echo "Rust isn't installed!" >/dev/stderr
	exit 2
    fi
    echo $RUST_COMMIT
}

exec env RUST_SRC_PATH="$(vivify "$(rust_version)")/src" "${NEXT_RACER}" "$@"