Give a better error message when the CI download fails

Author: Teapot4195

src/bootstrap/src/core/download.rs

@@ -6,6 +6,7 @@ use std::{
     path::{Path, PathBuf},
     process::{Command, Stdio},
     sync::OnceLock,
+    time::SystemTime,
 };
 
 use build_helper::ci::CiEnv;
@@ -250,19 +251,74 @@ impl Config {
                             "(New-Object System.Net.WebClient).DownloadFile('{}', '{}')",
                             url, tempfile.to_str().expect("invalid UTF-8 not supported with powershell downloads"),
                         ),
-                    ])).is_err() {
+                    ])).is_ok() {
                         return;
                     }
                     eprintln!("\nspurious failure, trying again");
                 }
             }
             if !help_on_error.is_empty() {
                 eprintln!("{help_on_error}");
+                if Self::check_outdated() {
+                    eprintln!("NOTE: you seem to have an outdated version of rust source");
+                }
             }
             crate::exit!(1);
         }
     }
 
+    fn check_outdated() -> bool {
+        let user: String = Command::new("git")
+            .arg("config")
+            .arg("user.name")
+            .output()
+            .expect("Failed to get git user.name")
+            .stdout
+            .into_iter()
+            .map(|c| c as char)
+            .collect();
+        let log: String = Command::new("git")
+            .arg("log")
+            .arg("--pretty=short")
+            .arg("origin/master..HEAD")
+            .output()
+            .expect("Failed to get git log")
+            .stdout
+            .into_iter()
+            .map(|c| c as char)
+            .collect();
+        for s in log.split("\n") {
+            if s.contains("Author:") {
+                if !s.contains(&format!("Author: {}", user.replace("\n", ""))) {
+                    return true;
+                }
+            }
+        }
+        let last_commit: String = Command::new("git")
+            .arg("show")
+            .arg("-s")
+            .arg("--date=short")
+            .arg("--format=%ct")
+            .arg("origin/master")
+            .output()
+            .expect("Failed to get git log")
+            .stdout
+            .into_iter()
+            .map(|c| c as char)
+            .collect();
+        match SystemTime::now().duration_since(SystemTime::UNIX_EPOCH) {
+            Ok(n) => {
+                let replaced = last_commit.replace("\n", "");
+                if n.as_secs() - replaced.parse::<u64>().unwrap() >= 10 * 24 * 60 * 60 {
+                    // HEAD is more than 10 days out of date
+                    return true;
+                }
+            }
+            Err(_) => panic!("SystemTime before UNIX EPOCH!"),
+        }
+        return false;
+    }
+
     fn unpack(&self, tarball: &Path, dst: &Path, pattern: &str) {
         eprintln!("extracting {} to {}", tarball.display(), dst.display());
         if !dst.exists() {