Stream output of certain commands to the terminal

src/sync.rs

@@ -1,8 +1,8 @@
 use crate::SyncContext;
 use crate::josh::JoshProxy;
-use crate::utils::run_command;
 use crate::utils::run_command_at;
 use crate::utils::{ensure_clean_git_state, prompt};
+use crate::utils::{run_command, stream_command};
 use anyhow::{Context, Error};
 use std::path::{Path, PathBuf};
 
@@ -158,7 +158,8 @@ This merge was created using https://github.com/rust-lang/josh-sync.
         );
 
         // Merge the fetched commit.
-        run_command(&[
+        // It is useful to print stdout/stderr here, because it shows the git diff summary
+        stream_command(&[
             "git",
             "merge",
             "FETCH_HEAD",
@@ -301,7 +302,8 @@ fn prepare_rustc_checkout() -> anyhow::Result<PathBuf> {
             println!(
                 "Cloning rustc into `{path}`. Use RUSTC_GIT environment variable to override the location of the checkout"
             );
-            run_command(&[
+            // Stream stdout/stderr to the terminal, so that the user sees clone progress
+            stream_command(&[
                 "git",
                 "clone",
                 "--filter=blob:none",

src/utils.rs

@@ -6,9 +6,23 @@ pub fn run_command<'a, Args: AsRef<[&'a str]>>(args: Args) -> anyhow::Result<Str
     run_command_at(args, &std::env::current_dir()?)
 }
 
+/// Run command while streaming stdout and stderr to the terminal.
+pub fn stream_command<'a, Args: AsRef<[&'a str]>>(args: Args) -> anyhow::Result<()> {
+    run_command_inner(args, &std::env::current_dir()?, false)?;
+    Ok(())
+}
+
 pub fn run_command_at<'a, Args: AsRef<[&'a str]>>(
     args: Args,
     workdir: &Path,
+) -> anyhow::Result<String> {
+    run_command_inner(args, workdir, true)
+}
+
+fn run_command_inner<'a, Args: AsRef<[&'a str]>>(
+    args: Args,
+    workdir: &Path,
+    capture: bool,
 ) -> anyhow::Result<String> {
     let args = args.as_ref();
 
@@ -17,16 +31,32 @@ pub fn run_command_at<'a, Args: AsRef<[&'a str]>>(
     cmd.args(&args[1..]);
 
     eprintln!("+ {cmd:?}");
-    let out = cmd.output().expect("command failed");
-    let stdout = String::from_utf8_lossy(out.stdout.trim_ascii()).to_string();
-    let stderr = String::from_utf8_lossy(out.stderr.trim_ascii()).to_string();
-    if !out.status.success() {
-        Err(anyhow::anyhow!(
-            "Command `{cmd:?}` failed with exit code {:?}. STDOUT:\n{stdout}\nSTDERR:\n{stderr}",
-            out.status.code()
-        ))
+    if capture {
+        let out = cmd.output().expect("command failed");
+        let stdout = String::from_utf8_lossy(out.stdout.trim_ascii()).to_string();
+        let stderr = String::from_utf8_lossy(out.stderr.trim_ascii()).to_string();
+        if !out.status.success() {
+            Err(anyhow::anyhow!(
+                "Command `{cmd:?}` failed with exit code {:?}. STDOUT:\n{stdout}\nSTDERR:\n{stderr}",
+                out.status.code()
+            ))
+        } else {
+            Ok(stdout)
+        }
     } else {
-        Ok(stdout)
+        let status = cmd
+            .spawn()
+            .expect("cannot spawn command")
+            .wait()
+            .expect("command failed");
+        if !status.success() {
+            Err(anyhow::anyhow!(
+                "Command `{cmd:?}` failed with exit code {:?}",
+                status.code()
+            ))
+        } else {
+            Ok(String::new())
+        }
     }
 }