[cargo-miri] support nextest

Add the ability to run the `list` and `run` nextest commands, which
enable per-test isolation.

Author: sunshowers

cargo-miri/bin.rs

@@ -27,6 +27,7 @@ Usage:
 Subcommands:
     run, r                   Run binaries
     test, t                  Run tests
+    nextest                  Run tests with nextest (requires cargo-nextest installed)
     setup                    Only perform automatic setup, but without asking questions (for getting a proper libstd)
 
 The cargo options are exactly the same as for `cargo run` and `cargo test`, respectively.
@@ -40,8 +41,8 @@ Examples:
 enum MiriCommand {
     /// Our own special 'setup' command.
     Setup,
-    /// A command to be forwarded to cargo.
-    Forward(String),
+    /// A command (+ possible initial arguments) to be forwarded to cargo.
+    Forward(Vec<String>),
 }
 
 /// The information to run a crate with the given environment.
@@ -586,11 +587,19 @@ fn phase_cargo_miri(mut args: env::Args) {
     };
     let subcommand = match &*subcommand {
         "setup" => MiriCommand::Setup,
-        "test" | "t" | "run" | "r" => MiriCommand::Forward(subcommand),
+        "test" | "t" | "run" | "r" => MiriCommand::Forward(vec![subcommand]),
+        "nextest" => {
+            // nextest requires a subcommand (e.g. nextest run) to be specified before --target, so
+            // grab the next argument.
+            let Some(subcommand2) = args.next() else {
+                show_error(format!("`cargo miri {subcommand}` must have a subcommand as its next command"));
+            };
+            MiriCommand::Forward(vec![subcommand, subcommand2])
+        }
         // Invalid command.
         _ =>
             show_error(format!(
-                "`cargo miri` supports the following subcommands: `run`, `test`, and `setup`."
+                "`cargo miri` supports the following subcommands: `run`, `test`, `nextest`, and `setup`."
             )),
     };
     let verbose = num_arg_flag("-v");
@@ -610,7 +619,7 @@ fn phase_cargo_miri(mut args: env::Args) {
         MiriCommand::Setup => return, // `cargo miri setup` stops here.
     };
     let mut cmd = cargo();
-    cmd.arg(cargo_cmd);
+    cmd.args(cargo_cmd);
 
     // Make sure we know the build target, and cargo does, too.
     // This is needed to make the `CARGO_TARGET_*_RUNNER` env var do something,