Even more cleanup

src/bin/cargo-miri.rs

@@ -533,10 +533,6 @@ fn in_cargo_miri() {
         let args_vec: Vec<String> = args.collect();
         cmd.env("MIRI_MAGIC_ARGS", serde_json::to_string(&args_vec).expect("failed to serialize args"));
 
-        // Add `--` (to end the `cargo` flags), and then the user flags. We add markers around the
-        // user flags to be able to identify them later.  "cargo rustc" adds more stuff after this,
-        // so we have to mark both the beginning and the end.
-        //cmd.arg("--").arg("cargo-miri-marker-begin").args(args).arg("cargo-miri-marker-end");
         let path = std::env::current_exe().expect("current executable path invalid");
         cmd.env("RUSTC_WRAPPER", path);
         if verbose {
@@ -574,11 +570,12 @@ fn inside_cargo_rustc() {
         args
     };
 
-    // See if we can find the `cargo-miri` markers. Those only get added to the binary we want to
-    // run. They also serve to mark the user-defined arguments, which we have to move all the way
-    // to the end (they get added somewhere in the middle).
     let needs_miri =
         if is_target_crate(in_build_script) {
+            // This is the 'target crate '- the binary or test crate that
+            // we want to interpret under Miri. We deserialize the user-provided arguments
+            // from the special environment variable "MIRI_MAGIC_ARGS", and feed them
+            // to the 'miri' binary.
             let magic = std::env::var("MIRI_MAGIC_ARGS").expect("missing MIRI_MAGIC_ARGS");
             let mut user_args: Vec<String> = serde_json::from_str(&magic).expect("failed to deserialize args");
             args.append(&mut user_args);