feat(cargo-codspeed): show warning when min time is 0

Author: not-matthias

crates/cargo-codspeed/src/run.rs

@@ -202,6 +202,15 @@ fn aggregate_raw_walltime_data(workspace_root: &Path) -> Result<()> {
         return Ok(());
     }
 
+    for bench in &walltime_benchmarks {
+        if bench.is_invalid() {
+            eprintln!(
+                "Warning: Benchmark {} was possibly optimized away",
+                bench.name()
+            );
+        }
+    }
+
     let results_folder = std::env::var("CODSPEED_PROFILE_FOLDER")
         .map(PathBuf::from)
         .unwrap_or_else(|_| workspace_root.join("target/codspeed/profiles"))

crates/cargo-codspeed/src/walltime_results.rs

@@ -41,6 +41,16 @@ pub struct WalltimeBenchmark {
     stats: BenchmarkStats,
 }
 
+impl WalltimeBenchmark {
+    pub(crate) fn is_invalid(&self) -> bool {
+        self.stats.min_ns < f64::EPSILON
+    }
+
+    pub(crate) fn name(&self) -> &str {
+        &self.metadata.name
+    }
+}
+
 impl From<RawWallTimeData> for WalltimeBenchmark {
     fn from(value: RawWallTimeData) -> Self {
         let times_ns: Vec<f64> = value.times_ns.iter().map(|&t| t as f64).collect();