feat(cli): Interpret some subcommands as manifest-commands

src/bin/cargo/cli.rs

@@ -399,7 +399,11 @@ fn execute_subcommand(config: &mut Config, cmd: &str, subcommand_args: &ArgMatch
             .unwrap_or_default()
             .map(OsString::as_os_str),
     );
-    super::execute_external_subcommand(config, cmd, &ext_args)
+    if commands::run::is_manifest_command(cmd) {
+        commands::run::exec_manifest_command(config, cmd, &ext_args)
+    } else {
+        super::execute_external_subcommand(config, cmd, &ext_args)
+    }
 }
 
 #[derive(Default)]

src/bin/cargo/commands/run.rs

@@ -1,3 +1,7 @@
+use std::ffi::OsStr;
+use std::ffi::OsString;
+use std::path::Path;
+
 use crate::command_prelude::*;
 use crate::util::restricted_names::is_glob_pattern;
 use cargo::core::Verbosity;
@@ -13,7 +17,7 @@ pub fn cli() -> Command {
         .arg(
             Arg::new("args")
                 .help("Arguments for the binary or example to run")
-                .value_parser(value_parser!(std::ffi::OsString))
+                .value_parser(value_parser!(OsString))
                 .num_args(0..)
                 .trailing_var_arg(true),
         )
@@ -101,3 +105,16 @@ pub fn exec(config: &mut Config, args: &ArgMatches) -> CliResult {
         }
     })
 }
+
+pub fn is_manifest_command(arg: &str) -> bool {
+    let path = Path::new(arg);
+    1 < path.components().count() || path.extension() == Some(OsStr::new("rs"))
+}
+
+pub fn exec_manifest_command(config: &Config, cmd: &str, _args: &[&OsStr]) -> CliResult {
+    if !config.cli_unstable().script {
+        return Err(anyhow::anyhow!("running `{cmd}` requires `-Zscript`").into());
+    }
+
+    todo!("support for running manifest-commands is not yet implemented")
+}

tests/testsuite/main.rs

@@ -123,6 +123,7 @@ mod rustdoc_extern_html;
 mod rustdocflags;
 mod rustflags;
 mod rustup;
+mod script;
 mod search;
 mod shell_quoting;
 mod source_replacement;

tests/testsuite/script.rs

@@ -0,0 +1,106 @@
+const ECHO_SCRIPT: &str = r#"#!/usr/bin/env cargo
+
+fn main() {
+    let mut args = std::env::args_os();
+    let bin = args.next().unwrap().to_str().unwrap().to_owned();
+    let args = args.collect::<Vec<_>>();
+    println!("bin: {bin}");
+    println!("args: {args:?}");
+}
+"#;
+
+#[cargo_test]
+fn basic_rs() {
+    let p = cargo_test_support::project()
+        .file("echo.rs", ECHO_SCRIPT)
+        .build();
+
+    p.cargo("-Zscript echo.rs")
+        .arg("--help") // An arg that, if processed by cargo, will cause problems
+        .masquerade_as_nightly_cargo(&["script"])
+        .with_status(101)
+        .with_stdout("")
+        .with_stderr("\
+thread 'main' panicked at 'not yet implemented: support for running manifest-commands is not yet implemented', [..]
+note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
+")
+        .run();
+}
+
+#[cargo_test]
+fn basic_path() {
+    let p = cargo_test_support::project()
+        .file("echo", ECHO_SCRIPT)
+        .build();
+
+    p.cargo("-Zscript ./echo")
+        .arg("--help") // An arg that, if processed by cargo, will cause problems
+        .masquerade_as_nightly_cargo(&["script"])
+        .with_status(101)
+        .with_stdout("")
+        .with_stderr("\
+thread 'main' panicked at 'not yet implemented: support for running manifest-commands is not yet implemented', [..]
+note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
+")
+        .run();
+}
+
+#[cargo_test]
+fn path_required() {
+    let p = cargo_test_support::project()
+        .file("echo", ECHO_SCRIPT)
+        .build();
+
+    p.cargo("-Zscript echo")
+        .arg("--help") // An arg that, if processed by cargo, will cause problems
+        .masquerade_as_nightly_cargo(&["script"])
+        .with_status(101)
+        .with_stdout("")
+        .with_stderr(
+            "\
+error: no such command: `echo`
+
+<tab>Did you mean `bench`?
+
+<tab>View all installed commands with `cargo --list`
+",
+        )
+        .run();
+}
+
+#[cargo_test]
+fn requires_nightly() {
+    let p = cargo_test_support::project()
+        .file("echo.rs", ECHO_SCRIPT)
+        .build();
+
+    p.cargo("echo.rs")
+        .arg("--help") // An arg that, if processed by cargo, will cause problems
+        .with_status(101)
+        .with_stdout("")
+        .with_stderr(
+            "\
+error: running `echo.rs` requires `-Zscript`
+",
+        )
+        .run();
+}
+
+#[cargo_test]
+fn requires_z_flag() {
+    let p = cargo_test_support::project()
+        .file("echo.rs", ECHO_SCRIPT)
+        .build();
+
+    p.cargo("echo.rs")
+        .arg("--help") // An arg that, if processed by cargo, will cause problems
+        .masquerade_as_nightly_cargo(&["script"])
+        .with_status(101)
+        .with_stdout("")
+        .with_stderr(
+            "\
+error: running `echo.rs` requires `-Zscript`
+",
+        )
+        .run();
+}