added the third_party_subcommands function in the cli.rs file

src/bin/cargo/cli.rs

@@ -15,6 +15,9 @@ use crate::command_prelude::*;
 use crate::util::is_rustup;
 use cargo::core::shell::ColorChoice;
 use cargo::util::style;
+use crate::third_party_subcommands;
+use clap_complete::engine::SubcommandCandidates;
+use clap_complete::CompletionCandidate;
 
 #[tracing::instrument(skip_all)]
 pub fn main(gctx: &mut GlobalContext) -> CliResult {
@@ -578,6 +581,10 @@ pub fn cli(gctx: &GlobalContext) -> Command {
         // We also want these to come before auto-generated `--help`
         .next_display_order(800)
         .allow_external_subcommands(true)
+        .add(SubcommandCandidates::new(|| {
+            let third_party = third_party_subcommands(gctx);
+            vec![CompletionCandidate::new(third_party)]
+        }))
         .color(color)
         .styles(styles)
         // Provide a custom help subcommand for calling into man pages

src/bin/cargo/main.rs

@@ -219,7 +219,7 @@ fn list_commands(gctx: &GlobalContext) -> BTreeMap<String, CommandInfo> {
     commands
 }
 
-fn third_party_subcommands(gctx: &GlobalContext) -> BTreeMap<String, CommandInfo> {
+pub fn third_party_subcommands(gctx: &GlobalContext) -> BTreeMap<String, CommandInfo> {
     let prefix = "cargo-";
     let suffix = env::consts::EXE_SUFFIX;
     let mut commands = BTreeMap::new();