change setup subcommand to take a single path only

Author: bentongxyz

src/bootstrap/builder.rs

@@ -824,7 +824,7 @@ impl<'a> Builder<'a> {
             Subcommand::Install { ref paths } => (Kind::Install, &paths[..]),
             Subcommand::Run { ref paths } => (Kind::Run, &paths[..]),
             Subcommand::Format { .. } => (Kind::Format, &[][..]),
-            Subcommand::Setup { ref paths } => (Kind::Setup, &paths[..]),
+            Subcommand::Setup { ref path } => (Kind::Setup, if let Some(p) = path { std::slice::from_ref(p) } else { &[] }),
             Subcommand::Clean { .. } => {
                 panic!()
             }

src/bootstrap/flags.rs

@@ -141,7 +141,7 @@ pub enum Subcommand {
         paths: Vec<PathBuf>,
     },
     Setup {
-        paths: Vec<PathBuf>,
+        path: Option<PathBuf>,
     },
 }
 
@@ -543,7 +543,7 @@ Arguments:
             Kind::Bench | Kind::Clean | Kind::Dist | Kind::Install => {}
         };
         // Get any optional paths which occur after the subcommand
-        let paths = matches.free[1..].iter().map(|p| p.into()).collect::<Vec<PathBuf>>();
+        let mut paths = matches.free[1..].iter().map(|p| p.into()).collect::<Vec<PathBuf>>();
 
         let verbose = matches.opt_present("verbose");