Support --toolchain in front of rustup which

src/cli/rustup_mode.rs

@@ -32,6 +32,7 @@ pub fn main() -> Result<()> {
     let matches = cli().get_matches();
     let verbose = matches.is_present("verbose");
     let quiet = matches.is_present("quiet");
+    let toolchain = matches.value_of("toolchain");
     let cfg = &common::set_globals(verbose, quiet)?;
 
     if maybe_upgrade_data(cfg, &matches)? {
@@ -79,7 +80,7 @@ pub fn main() -> Result<()> {
             (_, _) => unreachable!(),
         },
         ("run", Some(m)) => run(cfg, m)?,
-        ("which", Some(m)) => which(cfg, m)?,
+        ("which", Some(m)) => which(cfg, m, toolchain)?,
         ("doc", Some(m)) => doc(cfg, m)?,
         ("man", Some(m)) => man(cfg, m)?,
         ("self", Some(c)) => match c.subcommand() {
@@ -817,16 +818,20 @@ fn run(cfg: &Cfg, m: &ArgMatches<'_>) -> Result<()> {
     process::exit(c)
 }
 
-fn which(cfg: &Cfg, m: &ArgMatches<'_>) -> Result<()> {
+fn which(cfg: &Cfg, m: &ArgMatches<'_>, toolchain_by_root_cmd: Option<&str>) -> Result<()> {
     let binary = m.value_of("command").expect("");
-    let toolchain_provided = m.is_present("toolchain");
-    let binary_path = if toolchain_provided {
-        let toolchain = m.value_of("toolchain").expect("");
-        cfg.which_binary_by_toolchain(toolchain, binary)?
+    let binary_path = if let Some(toolchain_by_root_cmd) = toolchain_by_root_cmd {
+        cfg.which_binary_by_toolchain(toolchain_by_root_cmd, binary)?
             .expect("binary not found")
     } else {
-        cfg.which_binary(&utils::current_dir()?, binary)?
-            .expect("binary not found")
+        if m.is_present("toolchain") {
+            let toolchain = m.value_of("toolchain").expect("");
+            cfg.which_binary_by_toolchain(toolchain, binary)?
+                .expect("binary not found")
+        } else {
+            cfg.which_binary(&utils::current_dir()?, binary)?
+                .expect("binary not found")
+        }
     };
 
     utils::assert_is_file(&binary_path)?;

tests/cli-misc.rs

@@ -903,5 +903,17 @@ fn which() {
             &["rustup", "which", "--toolchain=custom-2", "rustc"],
             "/toolchains/custom-2/bin/rustc",
         );
+        #[cfg(windows)]
+        expect_stdout_ok(
+            config,
+            &["rustup", "--toolchain=custom-2", "which", "rustc"],
+            "\\toolchains\\custom-2\\bin\\rustc",
+        );
+        #[cfg(not(windows))]
+        expect_stdout_ok(
+            config,
+            &["rustup", "--toolchain=custom-2", "which", "rustc"],
+            "/toolchains/custom-2/bin/rustc",
+        );
     });
 }