1 files changed, 100 insertions, 0 deletions
diff --git a/src/bootstrap/bin/main.rs b/src/bootstrap/bin/main.rs
new file mode 100644
index 000000000..9b4861ccd
--- /dev/null
+++ b/src/bootstrap/bin/main.rs
@@ -0,0 +1,100 @@
+//! rustbuild, the Rust build system
+//!
+//! This is the entry point for the build system used to compile the `rustc`
+//! compiler. Lots of documentation can be found in the `README.md` file in the
+//! parent directory, and otherwise documentation can be found throughout the `build`
+//! directory in each respective module.
+
+use std::env;
+
+use bootstrap::{t, Build, Config, Subcommand, VERSION};
+
+fn main() {
+    let args = env::args().skip(1).collect::<Vec<_>>();
+    let config = Config::parse(&args);
+
+    let mut build_lock;
+    let _build_lock_guard;
+    if cfg!(any(unix, windows)) {
+        build_lock = fd_lock::RwLock::new(t!(std::fs::File::create(config.out.join("lock"))));
+        _build_lock_guard = match build_lock.try_write() {
+            Ok(lock) => lock,
+            err => {
+                println!("warning: build directory locked, waiting for lock");
+                drop(err);
+                t!(build_lock.write())
+            }
+        };
+    } else {
+        println!("warning: file locking not supported for target, not locking build directory");
+    }
+
+    // check_version warnings are not printed during setup
+    let changelog_suggestion =
+        if matches!(config.cmd, Subcommand::Setup { .. }) { None } else { check_version(&config) };
+
+    // NOTE: Since `./configure` generates a `config.toml`, distro maintainers will see the
+    // changelog warning, not the `x.py setup` message.
+    let suggest_setup = !config.config.exists() && !matches!(config.cmd, Subcommand::Setup { .. });
+    if suggest_setup {
+        println!("warning: you have not made a `config.toml`");
+        println!(
+            "help: consider running `./x.py setup` or copying `config.toml.example` by running \
+            `cp config.toml.example config.toml`"
+        );
+    } else if let Some(suggestion) = &changelog_suggestion {
+        println!("{}", suggestion);
+    }
+
+    let pre_commit = config.src.join(".git").join("hooks").join("pre-commit");
+    Build::new(config).build();
+
+    if suggest_setup {
+        println!("warning: you have not made a `config.toml`");
+        println!(
+            "help: consider running `./x.py setup` or copying `config.toml.example` by running \
+            `cp config.toml.example config.toml`"
+        );
+    } else if let Some(suggestion) = &changelog_suggestion {
+        println!("{}", suggestion);
+    }
+
+    // Give a warning if the pre-commit script is in pre-commit and not pre-push.
+    // HACK: Since the commit script uses hard links, we can't actually tell if it was installed by x.py setup or not.
+    // We could see if it's identical to src/etc/pre-push.sh, but pre-push may have been modified in the meantime.
+    // Instead, look for this comment, which is almost certainly not in any custom hook.
+    if std::fs::read_to_string(pre_commit).map_or(false, |contents| {
+        contents.contains("https://github.com/rust-lang/rust/issues/77620#issuecomment-705144570")
+    }) {
+        println!(
+            "warning: You have the pre-push script installed to .git/hooks/pre-commit. \
+                  Consider moving it to .git/hooks/pre-push instead, which runs less often."
+        );
+    }
+
+    if suggest_setup || changelog_suggestion.is_some() {
+        println!("note: this message was printed twice to make it more likely to be seen");
+    }
+}
+
+fn check_version(config: &Config) -> Option<String> {
+    let mut msg = String::new();
+
+    let suggestion = if let Some(seen) = config.changelog_seen {
+        if seen != VERSION {
+            msg.push_str("warning: there have been changes to x.py since you last updated.\n");
+            format!("update `config.toml` to use `changelog-seen = {}` instead", VERSION)
+        } else {
+            return None;
+        }
+    } else {
+        msg.push_str("warning: x.py has made several changes recently you may want to look at\n");
+        format!("add `changelog-seen = {}` at the top of `config.toml`", VERSION)
+    };
+
+    msg.push_str("help: consider looking at the changes in `src/bootstrap/CHANGELOG.md`\n");
+    msg.push_str("note: to silence this warning, ");
+    msg.push_str(&suggestion);
+
+    Some(msg)
+}