Store bootstrap command-line into metrics

src/bootstrap/src/utils/metrics.rs

@@ -200,6 +200,14 @@ pub(crate) fn persist(&self, build: &Build) {
             }
         };
         invocations.push(JsonInvocation {
+            // The command-line invocation with which bootstrap was invoked.
+            // Skip the first argument, as it is a potentially long absolute
+            // path that is not interesting.
+            cmdline: std::env::args_os()
+                .skip(1)
+                .map(|arg| arg.to_string_lossy().to_string())
+                .collect::<Vec<_>>()
+                .join(" "),
             start_time: state
                 .invocation_start
                 .duration_since(SystemTime::UNIX_EPOCH)

src/build_helper/src/metrics.rs

@@ -12,6 +12,8 @@ pub struct JsonRoot {
 #[derive(Serialize, Deserialize)]
 #[serde(rename_all = "snake_case")]
 pub struct JsonInvocation {
+    // Remembers the command-line invocation with which bootstrap was invoked.
+    pub cmdline: String,
     // Unix timestamp in seconds
     //
     // This is necessary to easily correlate this invocation with logs or other data.