Fix #9350 (cargo build -Z help is missing options)

src/bin/cargo/cli.rs

@@ -1,4 +1,4 @@
-use cargo::core::features;
+use cargo::core::{features, CliUnstable};
 use cargo::{self, drop_print, drop_println, CliResult, Config};
 use clap::{AppSettings, Arg, ArgMatches};
 
@@ -30,25 +30,32 @@ pub fn main(config: &mut Config) -> CliResult {
     };
 
     if args.value_of("unstable-features") == Some("help") {
+        let options = CliUnstable::help();
+        let longest_option = options
+            .iter()
+            .map(|(option_name, _)| option_name.len())
+            .max()
+            .unwrap_or(0);
+        let help_lines: Vec<String> = options
+            .iter()
+            .map(|(option_name, option_help_message)| {
+                let padding = " ".repeat(longest_option - option_name.len()); // safe to substract
+                format!(
+                    "    -Z {}{} -- {}",
+                    option_name, padding, option_help_message
+                )
+            })
+            .collect();
+        let joined = help_lines.join("\n");
         drop_println!(
             config,
             "
 Available unstable (nightly-only) flags:
 
-    -Z allow-features      -- Allow *only* the listed unstable features
-    -Z avoid-dev-deps      -- Avoid installing dev-dependencies if possible
-    -Z extra-link-arg      -- Allow `cargo:rustc-link-arg` in build scripts
-    -Z minimal-versions    -- Install minimal dependency versions instead of maximum
-    -Z no-index-update     -- Do not update the registry, avoids a network request for benchmarking
-    -Z unstable-options    -- Allow the usage of unstable options
-    -Z timings             -- Display concurrency information
-    -Z doctest-xcompile    -- Compile and run doctests for non-host target using runner config
-    -Z terminal-width      -- Provide a terminal width to rustc for error truncation
-    -Z namespaced-features -- Allow features with `dep:` prefix
-    -Z weak-dep-features   -- Allow `dep_name?/feature` feature syntax
-    -Z patch-in-config     -- Allow `[patch]` sections in .cargo/config.toml files
+{}
 
-Run with 'cargo -Z [FLAG] [SUBCOMMAND]'"
+Run with 'cargo -Z [FLAG] [SUBCOMMAND]'",
+            joined
         );
         if !config.nightly_features_allowed {
             drop_println!(

src/cargo/core/features.rs

@@ -538,51 +538,73 @@ impl Features {
     }
 }
 
-/// A parsed representation of all unstable flags that Cargo accepts.
-///
-/// Cargo, like `rustc`, accepts a suite of `-Z` flags which are intended for
-/// gating unstable functionality to Cargo. These flags are only available on
-/// the nightly channel of Cargo.
-#[derive(Default, Debug, Deserialize)]
-#[serde(default, rename_all = "kebab-case")]
-pub struct CliUnstable {
+macro_rules! cli_options {
+    (
+        $(#[$struct_meta:meta])*
+        $name: ident,
+        $($visibility: vis $element: ident: $ty: ty = ($help: literal $(, #[$meta:meta])?)),*
+    ) => {
+        $(#[$struct_meta])*
+        pub struct $name {
+            $(
+                $(#[$meta])?
+                $visibility $element: $ty
+            ),*
+        }
+        impl $name {
+            pub fn help() -> Vec<(&'static str, &'static str)> {
+                let fields = vec![$((stringify!($element), $help)),*];
+                fields
+            }
+        }
+    }
+}
+
+cli_options!(
+    /// A parsed representation of all unstable flags that Cargo accepts.
+    ///
+    /// Cargo, like `rustc`, accepts a suite of `-Z` flags which are intended for
+    /// gating unstable functionality to Cargo. These flags are only available on
+    /// the nightly channel of Cargo.
+    #[derive(Default, Debug, Deserialize)]
+    #[serde(default, rename_all = "kebab-case")]
+    CliUnstable,
     // Permanently unstable features:
-    pub allow_features: Option<BTreeSet<String>>,
-    pub print_im_a_teapot: bool,
+    pub allow_features: Option<BTreeSet<String>> = ("Allow *only* the listed unstable features"),
+    pub print_im_a_teapot: bool= (""),
 
     // All other unstable features.
     // Please keep this list lexiographically ordered.
-    pub advanced_env: bool,
-    pub avoid_dev_deps: bool,
-    pub binary_dep_depinfo: bool,
-    #[serde(deserialize_with = "deserialize_build_std")]
-    pub build_std: Option<Vec<String>>,
-    pub build_std_features: Option<Vec<String>>,
-    pub config_include: bool,
-    pub configurable_env: bool,
-    pub credential_process: bool,
-    pub doctest_in_workspace: bool,
-    pub doctest_xcompile: bool,
-    pub dual_proc_macros: bool,
-    pub enable_future_incompat_feature: bool,
-    pub extra_link_arg: bool,
-    pub features: Option<Vec<String>>,
-    pub jobserver_per_rustc: bool,
-    pub minimal_versions: bool,
-    pub mtime_on_use: bool,
-    pub multitarget: bool,
-    pub named_profiles: bool,
-    pub namespaced_features: bool,
-    pub no_index_update: bool,
-    pub panic_abort_tests: bool,
-    pub patch_in_config: bool,
-    pub rustdoc_map: bool,
-    pub separate_nightlies: bool,
-    pub terminal_width: Option<Option<usize>>,
-    pub timings: Option<Vec<String>>,
-    pub unstable_options: bool,
-    pub weak_dep_features: bool,
-}
+    pub advanced_env: bool = (""),
+    pub avoid_dev_deps: bool = ("Avoid installing dev-dependencies if possible"),
+    pub binary_dep_depinfo: bool = (""),
+    pub build_std: Option<Vec<String>>  = ("", #[serde(deserialize_with = "deserialize_build_std")]),
+    pub build_std_features: Option<Vec<String>>  = (""),
+    pub config_include: bool = (""),
+    pub configurable_env: bool = (""),
+    pub credential_process: bool = (""),
+    pub doctest_in_workspace: bool = (""),
+    pub doctest_xcompile: bool = ("Compile and run doctests for non-host target using runner config"),
+    pub dual_proc_macros: bool = (""),
+    pub enable_future_incompat_feature: bool = (""),
+    pub extra_link_arg: bool = ("Allow `cargo:rustc-link-arg` in build scripts"),
+    pub features: Option<Vec<String>>  = (""),
+    pub jobserver_per_rustc: bool = (""),
+    pub minimal_versions: bool = ("Install minimal dependency versions instead of maximum"),
+    pub mtime_on_use: bool = (""),
+    pub multitarget: bool = (""),
+    pub named_profiles: bool = (""),
+    pub namespaced_features: bool = ("Allow features with `dep:` prefix"),
+    pub no_index_update: bool = ("Do not update the registry, avoids a network request for benchmarking"),
+    pub panic_abort_tests: bool = (""),
+    pub patch_in_config: bool = ("Allow `[patch]` sections in .cargo/config.toml files"),
+    pub rustdoc_map: bool = (""),
+    pub separate_nightlies: bool = (""),
+    pub terminal_width: Option<Option<usize>>  = ("Provide a terminal width to rustc for error truncation"),
+    pub timings: Option<Vec<String>>  = ("Display concurrency information"),
+    pub unstable_options: bool = ("Allow the usage of unstable options"),
+    pub weak_dep_features: bool = ("Allow `dep_name?/feature` feature syntax")
+);
 
 const STABILIZED_COMPILE_PROGRESS: &str = "The progress bar is now always \
     enabled when used on an interactive console.\n\

tests/testsuite/help.rs

@@ -48,7 +48,9 @@ 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 unstable-options    -- Allow the usage of unstable options")
+        .with_stdout_contains(
+            "    -Z allow_features                 -- Allow *only* the listed unstable features",
+        )
         .run();
 }