feat(cli): add colors to -Zhelp console output

src/bin/cargo/cli.rs

@@ -55,38 +55,34 @@ pub fn main(config: &mut LazyConfig) -> CliResult {
         .map(String::as_str)
         == Some("help")
     {
+        let header = style::HEADER.render();
+        let literal = style::LITERAL.render();
+        let placeholder = style::PLACEHOLDER.render();
+        let reset = anstyle::Reset.render();
+
         let options = CliUnstable::help();
-        let non_hidden_options: Vec<(String, String)> = options
-            .iter()
-            .filter(|(_, help_message)| *help_message != HIDDEN)
-            .map(|(name, help)| (name.to_string(), help.to_string()))
-            .collect();
-        let longest_option = non_hidden_options
+        let max_length = options
             .iter()
+            .filter(|(_, help)| *help != HIDDEN)
             .map(|(option_name, _)| option_name.len())
             .max()
             .unwrap_or(0);
-        let help_lines: Vec<String> = non_hidden_options
+        let z_flags = options
             .iter()
-            .map(|(option_name, option_help_message)| {
-                let option_name_kebab_case = option_name.replace("_", "-");
-                let padding = " ".repeat(longest_option - option_name.len()); // safe to subtract
-                format!(
-                    "    -Z {}{} -- {}",
-                    option_name_kebab_case, padding, option_help_message
-                )
+            .filter(|(_, help)| *help != HIDDEN)
+            .map(|(opt, help)| {
+                let opt = opt.replace("_", "-");
+                format!("    {literal}-Z {opt:<max_length$}{reset}  {help}")
             })
-            .collect();
-        let joined = help_lines.join("\n");
+            .join("\n");
         drop_println!(
             config,
-            "
-Available unstable (nightly-only) flags:
+            "\
+{header}Available unstable (nightly-only) flags:{reset}
 
-{}
+{z_flags}
 
-Run with 'cargo -Z [FLAG] [COMMAND]'",
-            joined
+Run with `{literal}cargo -Z{reset} {placeholder}[FLAG] [COMMAND]{reset}`",
         );
         if !config.nightly_features_allowed {
             drop_println!(

tests/testsuite/cargo/mod.rs

@@ -1 +1,2 @@
 mod help;
+mod z_help;

tests/testsuite/cargo/z_help/mod.rs

@@ -0,0 +1,13 @@
+use cargo_test_support::curr_dir;
+use cargo_test_support::prelude::*;
+
+#[cargo_test]
+fn case() {
+    snapbox::cmd::Command::cargo_ui()
+        .masquerade_as_nightly_cargo(&["-Z help"])
+        .args(["-Z", "help"])
+        .assert()
+        .success()
+        .stdout_matches_path(curr_dir!().join("stdout.log"))
+        .stderr_matches_path(curr_dir!().join("stderr.log"));
+}

tests/testsuite/cargo/z_help/stdout.log

@@ -0,0 +1,36 @@
+Available unstable (nightly-only) flags:
+
+    -Z allow-features           Allow *only* the listed unstable features
+    -Z asymmetric-token         Allows authenticating with asymmetric tokens
+    -Z avoid-dev-deps           Avoid installing dev-dependencies if possible
+    -Z binary-dep-depinfo       Track changes to dependency artifacts
+    -Z bindeps                  Allow Cargo packages to depend on bin, cdylib, and staticlib crates, and use the artifacts built by those crates
+    -Z build-std                Enable Cargo to compile the standard library itself as part of a crate graph compilation
+    -Z build-std-features       Configure features enabled for the standard library itself when building the standard library
+    -Z check-cfg                Enable compile-time checking of `cfg` names/values/features
+    -Z codegen-backend          Enable the `codegen-backend` option in profiles in .cargo/config.toml file
+    -Z config-include           Enable the `include` key in config files
+    -Z direct-minimal-versions  Resolve minimal dependency versions instead of maximum (direct dependencies only)
+    -Z doctest-xcompile         Compile and run doctests for non-host target using runner config
+    -Z dual-proc-macros         Build proc-macros for both the host and the target
+    -Z gc                       Track cache usage and "garbage collect" unused files
+    -Z gitoxide                 Use gitoxide for the given git interactions, or all of them if no argument is given
+    -Z host-config              Enable the [host] section in the .cargo/config.toml file
+    -Z lints                    Pass `[lints]` to the linting tools
+    -Z minimal-versions         Resolve minimal dependency versions instead of maximum
+    -Z msrv-policy              Enable rust-version aware policy within cargo
+    -Z mtime-on-use             Configure Cargo to update the mtime of used files
+    -Z no-index-update          Do not update the registry index even if the cache is outdated
+    -Z panic-abort-tests        Enable support to run tests with -Cpanic=abort
+    -Z profile-rustflags        Enable the `rustflags` option in profiles in .cargo/config.toml file
+    -Z publish-timeout          Enable the `publish.timeout` key in .cargo/config.toml file
+    -Z rustdoc-map              Allow passing external documentation mappings to rustdoc
+    -Z rustdoc-scrape-examples  Allows Rustdoc to scrape code examples from reverse-dependencies
+    -Z script                   Enable support for single-file, `.rs` packages
+    -Z target-applies-to-host   Enable the `target-applies-to-host` key in the .cargo/config.toml file
+    -Z trim-paths               Enable the `trim-paths` option in profiles
+    -Z unstable-options         Allow the usage of unstable options
+
+Run with `cargo -Z [FLAG] [COMMAND]`
+
+See https://doc.rust-lang.org/nightly/cargo/reference/unstable.html for more information about these flags.

tests/testsuite/help.rs

@@ -43,17 +43,6 @@ fn help_external_subcommand() {
         .run();
 }
 
-#[cargo_test]
-fn z_flags_help() {
-    // Test that the output of `cargo -Z help` shows a different help screen with
-    // all the `-Z` flags.
-    cargo_process("-Z help")
-        .with_stdout_contains(
-            "    -Z allow-features[..]-- Allow *only* the listed unstable features",
-        )
-        .run();
-}
-
 fn help_with_man(display_command: &str) {
     // Build a "man" process that just echoes the contents.
     let p = project()
@@ -169,51 +158,11 @@ fn help_alias() {
 
 #[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();
+    for cmd in ["build", "run", "check", "test", "b", "r", "c", "t"] {
+        cargo_process(&format!("{cmd} -Z help"))
+            .with_stdout_contains(
+                "    -Z allow-features[..]  Allow *only* the listed unstable features",
+            )
+            .run();
+    }
 }