This make the last failure be the default installed nightly if any

Author: spastorino

Cargo.lock

@@ -19,7 +19,9 @@ flate2 = "1.0.1"
 git2 = "0.8"
 log = "0.4"
 pbr = "1.0.0"
+regex = "1.3.1"
 reqwest = "0.9"
+rustc_version = "0.2"
 structopt = "0.2.5"
 tar = "0.4"
 tee = "0.1"

Cargo.toml

@@ -18,7 +18,9 @@ extern crate log;
 extern crate pbr;
 #[cfg(test)]
 extern crate quickcheck;
+extern crate regex;
 extern crate reqwest;
+extern crate rustc_version;
 extern crate structopt;
 extern crate tar;
 extern crate tee;
@@ -35,13 +37,15 @@ use std::path::{Path, PathBuf};
 use std::process::{self, Command, Stdio};
 use std::str::FromStr;
 
-use chrono::{Date, Duration, Utc};
+use chrono::{Date, Duration, naive, Utc};
 use dialoguer::Select;
 use failure::Error;
 use flate2::read::GzDecoder;
 use pbr::{ProgressBar, Units};
+use regex::Regex;
 use reqwest::header::CONTENT_LENGTH;
 use reqwest::{Client, Response};
+use rustc_version::Channel;
 use structopt::StructOpt;
 use tar::Archive;
 use tee::TeeReader;
@@ -464,10 +468,47 @@ enum TestOutcome {
 }
 
 impl Toolchain {
+    /// This returns the date of the default toolchain, if it is a nightly toolchain.
+    /// Returns `None` if the installed toolchain is not a nightly toolchain.
+    fn default_nightly() -> Option<Date<Utc>> {
+        let version_meta = rustc_version::version_meta().unwrap();
+
+        if let Channel::Nightly = version_meta.channel {
+            if let Some(str_date) = version_meta.commit_date {
+                let regex = Regex::new(r"(?m)^(\d{4})-(\d{2})-(\d{2})$").unwrap();
+                if let Some(cap) = regex.captures(&str_date) {
+                    let year = cap.get(1)?.as_str().parse::<i32>().ok()?;
+                    let month = cap.get(2)?.as_str().parse::<u32>().ok()?;
+                    let day = cap.get(3)?.as_str().parse::<u32>().ok()?;
+
+                    return Some(Date::from_utc(
+                        naive::NaiveDate::from_ymd(year, month, day),
+                        Utc,
+                    ));
+                }
+            }
+        }
+
+        None
+    }
+
+    fn is_current_nightly(&self) -> bool {
+        if let ToolchainSpec::Nightly { date } = self.spec {
+            if let Some(default_date) = Self::default_nightly() {
+                return default_date == date;
+            }
+        }
+
+        false
+    }
+
     fn remove(&self, dl_params: &DownloadParams) -> Result<(), Error> {
-        eprintln!("uninstalling {}", self);
-        let dir = dl_params.install_dir.join(self.rustup_name());
-        fs::remove_dir_all(&dir)?;
+        if !self.is_current_nightly() {
+            eprintln!("uninstalling {}", self);
+            let dir = dl_params.install_dir.join(self.rustup_name());
+            fs::remove_dir_all(&dir)?;
+        }
+
         Ok(())
     }
 
@@ -551,6 +592,11 @@ impl Toolchain {
     }
 
     fn install(&self, client: &Client, dl_params: &DownloadParams) -> Result<(), InstallError> {
+        if self.is_current_nightly() {
+            // pre existing installation
+            return Ok(());
+        }
+
         debug!("installing {}", self);
         let tmpdir = TempDir::new_in(&dl_params.tmp_dir, &self.rustup_name())
             .map_err(InstallError::TempDir)?;
@@ -847,8 +893,18 @@ fn bisect_nightlies(cfg: &Config, client: &Client) -> Result<BisectionResult, Er
     let mut last_failure = if let Some(Bound::Date(date)) = cfg.args.end {
         date
     } else {
-        today
+        if let Some(date) = Toolchain::default_nightly() {
+            // start date must be prior to end date
+            if !has_start {
+                nightly_date = date;
+            }
+
+            date
+        } else {
+            today
+        }
     };
+
     while nightly_date > end_at {
         let mut t = Toolchain {
             spec: ToolchainSpec::Nightly { date: nightly_date },
@@ -857,7 +913,12 @@ fn bisect_nightlies(cfg: &Config, client: &Client) -> Result<BisectionResult, Er
         };
         t.std_targets.sort();
         t.std_targets.dedup();
-        eprintln!("checking {}", t);
+        if t.is_current_nightly() {
+            eprintln!("checking {} from the currently installed default nightly \
+                       toolchain as the last failure", t);
+        } else {
+            eprintln!("checking {}", t);
+        }
         match t.install(client, &dl_spec) {
             Ok(()) => {
                 let outcome = t.test(&cfg, &dl_spec);