Fix the problem that help cannot be displayed properly

src/bin/cargo/cli.rs

@@ -43,7 +43,12 @@ pub fn main(config: &mut Config) -> CliResult {
         }
     };
 
-    if args.value_of("unstable-features") == Some("help") {
+    // Global args need to be extracted before expanding aliases because the
+    // clap code for extracting a subcommand discards global options
+    // (appearing before the subcommand).
+    let (expanded_args, global_args) = expand_aliases(config, args, vec![])?;
+
+    if expanded_args.value_of("unstable-features") == Some("help") {
         let options = CliUnstable::help();
         let non_hidden_options: Vec<(String, String)> = options
             .iter()
@@ -95,20 +100,20 @@ Run with 'cargo -Z [FLAG] [SUBCOMMAND]'",
         return Ok(());
     }
 
-    let is_verbose = args.occurrences_of("verbose") > 0;
-    if args.is_present("version") {
+    let is_verbose = expanded_args.occurrences_of("verbose") > 0;
+    if expanded_args.is_present("version") {
         let version = get_version_string(is_verbose);
         drop_print!(config, "{}", version);
         return Ok(());
     }
 
-    if let Some(code) = args.value_of("explain") {
+    if let Some(code) = expanded_args.value_of("explain") {
         let mut procss = config.load_global_rustc(None)?.process();
         procss.arg("--explain").arg(code).exec()?;
         return Ok(());
     }
 
-    if args.is_present("list") {
+    if expanded_args.is_present("list") {
         drop_println!(config, "Installed Commands:");
         for (name, command) in list_commands(config) {
             let known_external_desc = KNOWN_EXTERNAL_COMMAND_DESCRIPTIONS.get(name.as_str());
@@ -140,10 +145,6 @@ Run with 'cargo -Z [FLAG] [SUBCOMMAND]'",
         return Ok(());
     }
 
-    // Global args need to be extracted before expanding aliases because the
-    // clap code for extracting a subcommand discards global options
-    // (appearing before the subcommand).
-    let (expanded_args, global_args) = expand_aliases(config, args, vec![])?;
     let (cmd, subcommand_args) = match expanded_args.subcommand() {
         (cmd, Some(args)) => (cmd, args),
         _ => {

tests/testsuite/help.rs

@@ -138,3 +138,54 @@ fn help_alias() {
     .unwrap();
     help_with_man_and_path("", "my-alias", "build", Path::new(""));
 }
+
+#[cargo_test]
+fn alias_z_flag_help() {
+    cargo_process("build -Z help")
+        .with_stdout_contains(
+            "    -Z allow-features[..]-- Allow *only* the listed unstable features",
+        )
+        .run();
+
+    cargo_process("run -Z help")
+        .with_stdout_contains(
+            "    -Z allow-features[..]-- Allow *only* the listed unstable features",
+        )
+        .run();
+
+    cargo_process("check -Z help")
+        .with_stdout_contains(
+            "    -Z allow-features[..]-- Allow *only* the listed unstable features",
+        )
+        .run();
+
+    cargo_process("test -Z help")
+        .with_stdout_contains(
+            "    -Z allow-features[..]-- Allow *only* the listed unstable features",
+        )
+        .run();
+
+    cargo_process("b -Z help")
+        .with_stdout_contains(
+            "    -Z allow-features[..]-- Allow *only* the listed unstable features",
+        )
+        .run();
+
+    cargo_process("r -Z help")
+        .with_stdout_contains(
+            "    -Z allow-features[..]-- Allow *only* the listed unstable features",
+        )
+        .run();
+
+    cargo_process("c -Z help")
+        .with_stdout_contains(
+            "    -Z allow-features[..]-- Allow *only* the listed unstable features",
+        )
+        .run();
+
+    cargo_process("t -Z help")
+        .with_stdout_contains(
+            "    -Z allow-features[..]-- Allow *only* the listed unstable features",
+        )
+        .run();
+}