detect outdated xargo version

src/bin/cargo-miri.rs

@@ -3,7 +3,7 @@
 extern crate cargo_metadata;
 
 use std::path::{PathBuf, Path};
-use std::io::{self, Write};
+use std::io::{self, Write, BufRead};
 use std::process::Command;
 use std::fs::{self, File};
 
@@ -114,6 +114,36 @@ fn list_targets() -> impl Iterator<Item=cargo_metadata::Target> {
     package.targets.into_iter()
 }
 
+fn xargo_version() -> Option<(u32, u32, u32)> {
+    let out = Command::new("xargo").arg("--version").output().ok()?;
+    if !out.status.success() {
+        return None;
+    }
+    // Parse output. The first line looks like "xargo 0.3.12 (b004f1c 2018-12-13)".
+    let line = out.stderr.lines().nth(0)
+        .expect("malformed `xargo --version` output: not at least one line")
+        .expect("malformed `xargo --version` output: error reading first line");
+    let version = line.split(' ').nth(1)
+        .expect("malformed `xargo --version` output: not at least two words");
+    let mut version_pieces = version.split('.');
+    let major = version_pieces.next()
+        .expect("malformed `xargo --version` output: not a major version piece")
+        .parse()
+        .expect("malformed `xargo --version` output: major version is not an integer");
+    let minor = version_pieces.next()
+        .expect("malformed `xargo --version` output: not a minor version piece")
+        .parse()
+        .expect("malformed `xargo --version` output: minor version is not an integer");
+    let patch = version_pieces.next()
+        .expect("malformed `xargo --version` output: not a patch version piece")
+        .parse()
+        .expect("malformed `xargo --version` output: patch version is not an integer");
+    if !version_pieces.next().is_none() {
+        panic!("malformed `xargo --version` output: more than three pieces in version");
+    }
+    Some((major, minor, patch))
+}
+
 fn ask(question: &str) {
     let mut buf = String::new();
     print!("{} [Y/n] ", question);
@@ -134,14 +164,14 @@ fn setup(ask_user: bool) {
     }
 
     // First, we need xargo
-    if Command::new("xargo").arg("--version").output().is_err()
-    {
+    let xargo = xargo_version();
+    if xargo.map_or(true, |v| v < (0, 3, 13)) {
         if ask_user {
-            ask("It seems you do not have xargo installed. I will run `cargo install xargo`. Proceed?");
+            ask("It seems you do not have a recent enough xargo installed. I will run `cargo install xargo -f`. Proceed?");
         } else {
-            println!("Installing xargo: `cargo install xargo`");
+            println!("Installing xargo: `cargo install xargo -f`");
         }
-        if !Command::new("cargo").args(&["install", "xargo"]).status().unwrap().success() {
+        if !Command::new("cargo").args(&["install", "xargo", "-f"]).status().unwrap().success() {
             show_error(format!("Failed to install xargo"));
         }
     }