feat: list availables for rustc,rustdoc,run,pkgid

Author: weihanglo

src/bin/cargo/commands/pkgid.rs

@@ -1,6 +1,7 @@
 use crate::command_prelude::*;
 
 use cargo::ops;
+use cargo::util::print_available_packages;
 
 pub fn cli() -> App {
     subcommand("pkgid")
@@ -14,7 +15,12 @@ pub fn cli() -> App {
 
 pub fn exec(config: &mut Config, args: &ArgMatches<'_>) -> CliResult {
     let ws = args.workspace(config)?;
-    let spec = args.value_of("spec").or_else(|| args.value_of("package"));
+    if !args.is_present("spec") && args.is_present_with_zero_values("package") {
+        print_available_packages(&ws)?
+    }
+    let spec = args.value_of("spec").or_else(|| {
+        args.value_of("package")
+    });
     let spec = ops::pkgid(&ws, spec)?;
     cargo::drop_println!(config, "{}", spec);
     Ok(())

src/cargo/util/command_prelude.rs

@@ -56,7 +56,7 @@ pub trait AppExt: Sized {
     }
 
     fn arg_package(self, package: &'static str) -> Self {
-        self._arg(opt("package", package).short("p").value_name("SPEC"))
+        self._arg(optinal_opt("package", package).short("p").value_name("SPEC"))
     }
 
     fn arg_jobs(self) -> Self {
@@ -220,6 +220,10 @@ pub fn opt(name: &'static str, help: &'static str) -> Arg<'static, 'static> {
     Arg::with_name(name).long(name).help(help)
 }
 
+pub fn optinal_opt(name: &'static str, help: &'static str) -> Arg<'static, 'static> {
+    opt(name, help).min_values(0)
+}
+
 pub fn optional_multi_opt(
     name: &'static str,
     value_name: &'static str,
@@ -502,7 +506,7 @@ pub trait ArgMatchesExt {
             // As for cargo 0.50.0, this won't occur but if someone sneaks in
             // we can still provide this informative message for them.
             anyhow::bail!(
-                "\"--package <SPEC>\" requires a SPEC format value, \n\
+                "\"--package <SPEC>\" requires a SPEC format value, \
                 which can be any package ID specifier in the dependency graph.\n\
                 Run `cargo help pkgid` for more information about SPEC format."
             )