Emit progress state escape codes

src/cargo/util/progress.rs

@@ -31,6 +31,8 @@ struct State<'cfg> {
     throttle: Throttle,
     last_line: Option<String>,
     fixed_width: Option<usize>,
+    #[cfg(windows)] // Windows is the only currently supported platform
+    last_pbar: u8,
 }
 
 struct Format {
@@ -39,6 +41,26 @@ struct Format {
     max_print: usize,
 }
 
+/// Which escape code to use for progress reporting.
+///
+/// There is more codes, but we only use these two.
+#[cfg(windows)] // Windows is the only currently supported platform
+enum ProgressCode {
+    None,
+    Normal(u8),
+}
+
+#[cfg(windows)] // Windows is the only currently supported platform
+impl std::fmt::Display for ProgressCode {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let (state, progress) = match self {
+            Self::None => (0, 0),
+            Self::Normal(v) => (1, *v),
+        };
+        write!(f, "\x1b]9;4;{state};{progress}\x1b\\")
+    }
+}
+
 impl<'cfg> Progress<'cfg> {
     pub fn with_style(name: &str, style: ProgressStyle, cfg: &'cfg Config) -> Progress<'cfg> {
         // report no progress when -q (for quiet) or TERM=dumb are set
@@ -81,6 +103,8 @@ impl<'cfg> Progress<'cfg> {
                 throttle: Throttle::new(),
                 last_line: None,
                 fixed_width: progress_config.width,
+                #[cfg(windows)] // Windows is the only currently supported platform
+                last_pbar: u8::MAX,
             }),
         }
     }
@@ -183,6 +207,8 @@ impl Throttle {
 impl<'cfg> State<'cfg> {
     fn tick(&mut self, cur: usize, max: usize, msg: &str) -> CargoResult<()> {
         if self.done {
+            #[cfg(windows)] // Windows is the only currently supported platform
+            write!(self.config.shell().err(), "{}", ProgressCode::None)?;
             return Ok(());
         }
 
@@ -194,6 +220,14 @@ impl<'cfg> State<'cfg> {
         // return back to the beginning of the line for the next print.
         self.try_update_max_width();
         if let Some(pbar) = self.format.progress(cur, max) {
+            #[cfg(windows)] // Windows is the only currently supported platform
+            {
+                let prog = ((cur as f32) / (max as f32) * 100.0) as u8;
+                if self.last_pbar != prog {
+                    write!(self.config.shell().err(), "{}", ProgressCode::Normal(prog))?;
+                    self.last_pbar = prog;
+                }
+            }
             self.print(&pbar, msg)?;
         }
         Ok(())
@@ -232,6 +266,11 @@ impl<'cfg> State<'cfg> {
         if self.last_line.is_some() && !self.config.shell().is_cleared() {
             self.config.shell().err_erase_line();
             self.last_line = None;
+            #[cfg(windows)] // Windows is the only currently supported platform
+            {
+                let _ = write!(self.config.shell().err(), "{}", ProgressCode::None);
+                self.last_pbar = u8::MAX;
+            }
         }
     }