Display stdout and stderr if a command failed to run

build_system/src/build.rs

@@ -189,9 +189,16 @@ fn build_sysroot_inner(
 
     // Copy the source files to the sysroot (Rust for Linux needs this).
     let sysroot_src_path = "sysroot/lib/rustlib/src/rust";
-    fs::create_dir_all(&sysroot_src_path)
-        .map_err(|error| format!("Failed to create directory `{}`: {:?}", sysroot_src_path, error))?;
-    run_command(&[&"cp", &"-r", &"sysroot_src/library/", &sysroot_src_path], None)?;
+    fs::create_dir_all(&sysroot_src_path).map_err(|error| {
+        format!(
+            "Failed to create directory `{}`: {:?}",
+            sysroot_src_path, error
+        )
+    })?;
+    run_command(
+        &[&"cp", &"-r", &"sysroot_src/library/", &sysroot_src_path],
+        None,
+    )?;
 
     Ok(())
 }

build_system/src/main.rs

@@ -61,7 +61,7 @@ fn main() {
         Command::Build => build::run(),
         Command::Test => test::run(),
     } {
-        eprintln!("Command failed to run: {e:?}");
+        eprintln!("Command failed to run: {e}");
         process::exit(1);
     }
 }

build_system/src/utils.rs

@@ -29,11 +29,12 @@ fn check_exit_status(
     input: &[&dyn AsRef<OsStr>],
     cwd: Option<&Path>,
     exit_status: ExitStatus,
+    output: Option<&Output>,
 ) -> Result<(), String> {
     if exit_status.success() {
-        Ok(())
-    } else {
-        Err(format!(
+        return Ok(());
+    }
+    let mut error = format!(
         "Command `{}`{} exited with status {:?}",
         input
             .iter()
@@ -42,9 +43,23 @@ fn check_exit_status(
             .join(" "),
         cwd.map(|cwd| format!(" (running in folder `{}`)", cwd.display()))
             .unwrap_or_default(),
-            exit_status.code(),
-        ))
+        exit_status.code()
+    );
+    if let Some(output) = output {
+        unsafe {
+            let stdout = std::str::from_utf8_unchecked(&output.stdout);
+            if !stdout.is_empty() {
+                error.push_str("\n==== STDOUT ====\n");
+                error.push_str(stdout);
             }
+            let stderr = std::str::from_utf8_unchecked(&output.stderr);
+            if !stderr.is_empty() {
+                error.push_str("\n==== STDERR ====\n");
+                error.push_str(stderr);
+            }
+        }
+    }
+    Err(error)
 }
 
 fn command_error<D: Debug>(input: &[&dyn AsRef<OsStr>], cwd: &Option<&Path>, error: D) -> String {
@@ -73,7 +88,7 @@ pub fn run_command_with_env(
     let output = get_command_inner(input, cwd, env)
         .output()
         .map_err(|e| command_error(input, &cwd, e))?;
-    check_exit_status(input, cwd, output.status)?;
+    check_exit_status(input, cwd, output.status, Some(&output))?;
     Ok(output)
 }
 
@@ -86,7 +101,7 @@ pub fn run_command_with_output(
         .map_err(|e| command_error(input, &cwd, e))?
         .wait()
         .map_err(|e| command_error(input, &cwd, e))?;
-    check_exit_status(input, cwd, exit_status)?;
+    check_exit_status(input, cwd, exit_status, None)?;
     Ok(())
 }
 
@@ -100,7 +115,7 @@ pub fn run_command_with_output_and_env(
         .map_err(|e| command_error(input, &cwd, e))?
         .wait()
         .map_err(|e| command_error(input, &cwd, e))?;
-    check_exit_status(input, cwd, exit_status)?;
+    check_exit_status(input, cwd, exit_status, None)?;
     Ok(())
 }