Reimplement format-hook using a rust binary

.cargo/config

@@ -1,10 +1,10 @@
 [alias]
 # Automatically generates the ast and syntax kinds files
-gen-syntax =   "run --package tools -- gen-syntax"
-gen-tests =    "run --package tools -- gen-tests"
-install-code = "run --package tools -- install-code"
-format =       "run --package tools -- format"
-format-hook =  "run --package tools -- format-hook"
+gen-syntax =   "run --package tools --bin tools -- gen-syntax"
+gen-tests =    "run --package tools --bin tools -- gen-tests"
+install-code = "run --package tools --bin tools -- install-code"
+format =       "run --package tools --bin tools -- format"
+format-hook =  "run --package tools --bin tools -- format-hook"
 
 render-test =  "run --package ra_cli -- render-test"
 parse =        "run --package ra_cli -- parse"

crates/tools/src/bin/pre-commit.rs

@@ -0,0 +1,37 @@
+use std::{
+    process::{Command},
+};
+
+use tools::{Result, run_rustfmt, run, project_root};
+use failure::bail;
+
+fn main() -> tools::Result<()> {
+    run_rustfmt(tools::Overwrite)?;
+    update_staged()
+}
+
+fn update_staged() -> Result<()> {
+    let root = project_root();
+    let output = Command::new("git")
+        .arg("diff")
+        .arg("--name-only")
+        .arg("--cached")
+        .current_dir(&root)
+        .output()?;
+    if !output.status.success() {
+        bail!(
+            "`git diff --name-only --cached` exited with {}",
+            output.status
+        );
+    }
+    for line in String::from_utf8(output.stdout)?.lines() {
+        run(
+            &format!(
+                "git update-index --add {}",
+                root.join(line).to_string_lossy()
+            ),
+            ".",
+        )?;
+    }
+    Ok(())
+}

crates/tools/src/lib.rs

@@ -1,11 +1,9 @@
 use std::{
     path::{Path, PathBuf},
     process::{Command, Stdio},
-    fs::OpenOptions,
-    io::{Write, Error, ErrorKind}
+    fs::copy,
+    io::{Error, ErrorKind}
 };
-#[cfg(unix)]
-use std::os::unix::fs::OpenOptionsExt;
 
 use failure::bail;
 use itertools::Itertools;
@@ -69,7 +67,7 @@ pub fn generate(mode: Mode) -> Result<()> {
 }
 
 pub fn project_root() -> PathBuf {
-    Path::new(&std::env::var("CARGO_MANIFEST_DIR").unwrap())
+    Path::new(&env!("CARGO_MANIFEST_DIR"))
         .ancestors()
         .nth(2)
         .unwrap()
@@ -122,24 +120,14 @@ fn install_rustfmt() -> Result<()> {
 }
 
 pub fn install_format_hook() -> Result<()> {
-    let path = Path::new("./.git/hooks/pre-commit");
-    if !path.exists() {
-        let mut open_options = OpenOptions::new();
-        #[cfg(unix)]
-        {
-            // Set as executable
-            open_options.mode(0o770);
+    let result_path = Path::new("./.git/hooks/pre-commit");
+    if !result_path.exists() {
+        run("cargo build --package tools --bin pre-commit", ".")?;
+        if cfg!(windows) {
+            copy("./target/debug/pre-commit.exe", result_path)?;
+        } else {
+            copy("./target/debug/pre-commit", result_path)?;
         }
-        let mut file = open_options.write(true).create(true).open(path)?;
-        write!(
-            file,
-            r#"#!/bin/sh
-
-cargo format
-for path in $( git diff --name-only --cached ); do
-    git update-index --add $path
-done"#
-        )?;
     } else {
         return Err(Error::new(ErrorKind::AlreadyExists, "Git hook already created").into());
     }