fix: support relative forward-slash paths on Windows

src/benchmark/executor.rs

@@ -16,6 +16,35 @@ use super::timing_result::TimingResult;
 use anyhow::{bail, Context, Result};
 use statistical::mean;
 
+#[cfg(windows)]
+fn normalize_relative_command_path_for_cmd(command_line: &str) -> String {
+    let executable_end = command_line
+        .find(char::is_whitespace)
+        .unwrap_or(command_line.len());
+    format!(
+        "{}{}",
+        command_line[..executable_end].replace('/', "\\"),
+        &command_line[executable_end..]
+    )
+}
+
+#[cfg(all(test, windows))]
+mod tests {
+    use super::normalize_relative_command_path_for_cmd;
+
+    #[test]
+    fn normalizes_only_the_relative_executable_path() {
+        assert_eq!(
+            normalize_relative_command_path_for_cmd("../target/debug/tool.exe --output value/a"),
+            "..\\target\\debug\\tool.exe --output value/a"
+        );
+        assert_eq!(
+            normalize_relative_command_path_for_cmd("./tool.exe \"input file.txt\""),
+            ".\\tool.exe \"input file.txt\""
+        );
+    }
+}
+
 pub enum BenchmarkIteration {
     NonBenchmarkRun,
     Warmup(u64),
@@ -193,13 +222,21 @@ impl Executor for ShellExecutor<'_> {
         let on_windows_cmd = cfg!(windows) && *self.shell == Shell::Default("cmd.exe");
         let mut command_builder = self.shell.command();
         command_builder.arg(if on_windows_cmd { "/C" } else { "-c" });
+        let command_line = command.get_command_line();
 
         // Windows needs special treatment for its behavior on parsing cmd arguments
         if on_windows_cmd {
             #[cfg(windows)]
-            command_builder.raw_arg(command.get_command_line());
+            if command_line.starts_with("./") || command_line.starts_with("../") {
+                // `cmd.exe /C` treats the leading `.` as a command when passed
+                // verbatim. Normalize only the executable path while retaining
+                // cmd.exe's existing raw quoting semantics for the full command.
+                command_builder.raw_arg(normalize_relative_command_path_for_cmd(&command_line));
+            } else {
+                command_builder.raw_arg(&command_line);
+            }
         } else {
-            command_builder.arg(command.get_command_line());
+            command_builder.arg(&command_line);
         }
 
         let mut result = run_command_and_measure_common(

tests/integration_tests.rs

@@ -705,6 +705,21 @@ fn speed_comparison_sort_order() {
         ));
 }
 
+#[cfg(windows)]
+#[test]
+fn windows_runs_executable_paths_with_forward_slashes() {
+    let hyperfine_exe = assert_cmd::cargo::cargo_bin!("hyperfine");
+    let working_directory = std::env::current_dir().unwrap();
+    let relative_path = hyperfine_exe.strip_prefix(working_directory).unwrap();
+    let command_path = std::path::Path::new("..").join(relative_path);
+    let command = format!(
+        "{} --version",
+        command_path.to_string_lossy().replace('\\', "/")
+    );
+
+    hyperfine().arg("--runs=1").arg(command).assert().success();
+}
+
 #[cfg(windows)]
 #[test]
 fn windows_quote_args() {