Add support for Multicall executables as subcommands with a Multicall setting

.github/workflows/ci-pr.yml

@@ -41,7 +41,7 @@ jobs:
   test-full:
     name: Tests (Full)
     env:
-      FLAGS: --features 'wrap_help yaml regex unstable-replace'
+      FLAGS: --features 'wrap_help yaml regex unstable-replace unstable-multicall'
     strategy:
       fail-fast: false
       matrix:
@@ -80,7 +80,7 @@ jobs:
       - name: Default features
         run: cargo check --all-targets
       - name: All features + Debug
-        run: cargo check --all-targets --features "wrap_help yaml regex unstable-replace debug"
+        run: cargo check --all-targets --features "wrap_help yaml regex unstable-replace unstable-multicall debug"
       - name: No features
         run: cargo check --all-targets --no-default-features --features "std cargo"
       - name: UI Tests

.github/workflows/ci.yml

@@ -97,19 +97,19 @@ jobs:
         if: matrix.features == 'all'
         with:
           command: test
-          args: --target ${{ matrix.target }} --features "wrap_help yaml regex unstable-replace"
+          args: --target ${{ matrix.target }} --features "wrap_help yaml regex unstable-replace unstable-multicall"
       - name: Check debug
         uses: actions-rs/cargo@v1
         if: matrix.features == 'all'
         with:
           command: check
-          args: --target ${{ matrix.target }} --features "wrap_help yaml regex unstable-replace debug"
+          args: --target ${{ matrix.target }} --features "wrap_help yaml regex unstable-replace unstable-multicall debug"
       - name: Test release
         uses: actions-rs/cargo@v1
         if: matrix.features == 'release'
         with:
           command: test
-          args: --target ${{ matrix.target }} --features "wrap_help yaml regex unstable-replace" --release
+          args: --target ${{ matrix.target }} --features "wrap_help yaml regex unstable-replace unstable-multicall" --release
   nightly:
     name: Nightly Tests
     strategy:
@@ -139,19 +139,19 @@ jobs:
         if: matrix.features == 'all'
         with:
           command: test
-          args: --features "wrap_help yaml regex unstable-replace"
+          args: --features "wrap_help yaml regex unstable-replace unstable-multicall"
       - name: Check debug
         uses: actions-rs/cargo@v1
         if: matrix.features == 'all'
         with:
           command: check
-          args: --features "wrap_help yaml regex unstable-replace debug"
+          args: --features "wrap_help yaml regex unstable-replace unstable-multicall debug"
       - name: Test release
         uses: actions-rs/cargo@v1
         if: matrix.features == 'release'
         with:
           command: test
-          args: --features "wrap_help yaml regex unstable-replace" --release
+          args: --features "wrap_help yaml regex unstable-replace unstable-multicall" --release
   wasm:
     name: Wasm Check
     runs-on: ubuntu-latest
@@ -172,4 +172,4 @@ jobs:
         uses: actions-rs/cargo@v1
         with:
           command: check
-          args: --target ${{ matrix.target }} --features "yaml regex unstable-replace"
+          args: --target ${{ matrix.target }} --features "yaml regex unstable-replace unstable-multicall"

.github/workflows/coverage.yml

@@ -31,7 +31,7 @@ jobs:
         uses: actions-rs/cargo@v1
         with:
           command: llvm-cov
-          args: --features "wrap_help yaml regex unstable-replace" --lcov --output-path lcov.info
+          args: --features "wrap_help yaml regex unstable-replace unstable-multicall" --lcov --output-path lcov.info
       - name: Coveralls
         uses: coverallsapp/github-action@master
         with:

.github/workflows/lint.yml

@@ -32,7 +32,7 @@ jobs:
         uses: actions-rs/cargo@v1
         with:
           command: clippy
-          args: --features "wrap_help yaml regex unstable-replace" -- -D warnings
+          args: --features "wrap_help yaml regex unstable-replace unstable-multicall" -- -D warnings
       - name: Format check
         uses: actions-rs/cargo@v1
         with:

Cargo.toml

@@ -81,6 +81,14 @@ lazy_static = "1"
 version-sync = "0.9"
 criterion = "0.3.2"
 
+[[example]]
+name = "busybox"
+path = "examples/24a_multicall_busybox.rs"
+
+[[example]]
+name = "hostname"
+path = "examples/24b_multicall_hostname.rs"
+
 [features]
 default = [
 	"std",
@@ -108,6 +116,7 @@ yaml = ["yaml-rust"]
 
 # In-work features
 unstable-replace = []
+unstable-multicall = []
 
 [profile.test]
 opt-level = 1
@@ -117,7 +126,7 @@ lto = true
 codegen-units = 1
 
 [package.metadata.docs.rs]
-features = ["yaml", "regex", "unstable-replace"]
+features = ["yaml", "regex", "unstable-replace", "unstable-multicall"]
 targets = ["x86_64-unknown-linux-gnu"]
 
 [workspace]

README.md

@@ -508,6 +508,7 @@ features = ["std", "suggestions", "color"]
 These features are opt-in. But be wary that they can contain breaking changes between minor releases.
 
 * **unstable-replace**: Enable [`App::replace`](https://github.com/clap-rs/clap/issues/2836)
+* **unstable-multicall**: Enable [`AppSettings::Multicall`](https://github.com/clap-rs/clap/issues/2861)
 
 ### More Information
 

examples/24a_multicall_busybox.rs

@@ -0,0 +1,41 @@
+//! Example of a `busybox-style` multicall program
+//!
+//! See the documentation for clap::AppSettings::Multicall for rationale.
+//!
+//! This example omits every command except true and false,
+//! which are the most trivial to implement,
+//! but includes the `--install` option as an example of why it can be useful
+//! for the main program to take arguments that aren't applet subcommands.
+
+use std::process::exit;
+
+use clap::{App, AppSettings, Arg};
+
+fn main() {
+    let app = App::new(env!("CARGO_CRATE_NAME"))
+        .setting(AppSettings::ArgRequiredElseHelp)
+        .arg(
+            Arg::new("install")
+                .long("install")
+                .about("Install hardlinks for all subcommands in path")
+                .exclusive(true)
+                .takes_value(true)
+                .default_missing_value("/usr/local/bin")
+                .use_delimiter(false),
+        )
+        .subcommand(App::new("true").about("does nothing successfully"))
+        .subcommand(App::new("false").about("does nothing unsuccessfully"));
+
+    #[cfg(feature = "unstable-multicall")]
+    let app = app.setting(AppSettings::Multicall);
+    let matches = app.get_matches();
+    if matches.occurrences_of("install") > 0 {
+        unimplemented!("Make hardlinks to the executable here");
+    }
+
+    exit(match matches.subcommand_name() {
+        Some("true") => 0,
+        Some("false") => 1,
+        _ => 127,
+    })
+}

examples/24b_multicall_hostname.rs

@@ -0,0 +1,25 @@
+//! Example of a `hostname-style` multicall program
+//!
+//! See the documentation for clap::AppSettings::Multicall for rationale.
+//!
+//! This example omits the implementation of displaying address config
+
+use std::process::exit;
+
+use clap::{App, AppSettings};
+
+fn main() {
+    let app = App::new(env!("CARGO_CRATE_NAME"))
+        .setting(AppSettings::ArgRequiredElseHelp)
+        .subcommand(App::new("hostname").about("shot hostname part of FQDN"))
+        .subcommand(App::new("dnsdomainname").about("show domain name part of FQDN"));
+
+    #[cfg(feature = "unstable-multicall")]
+    let app = app.setting(AppSettings::Multicall);
+
+    match app.get_matches().subcommand_name() {
+        Some("hostname") => println!("www"),
+        Some("dnsdomainname") => println!("example.com"),
+        _ => exit(127),
+    }
+}

src/build/app/debug_asserts.rs

@@ -345,8 +345,25 @@ fn assert_app_flags(app: &App) {
                     panic!("{}", s)
                 }
             }
-        }
+        };
+        ($a:ident conflicts $($b:ident)|+) => {
+            if app.is_set($a) {
+                let mut s = String::new();
+
+                $(
+                    if app.is_set($b) {
+                        s.push_str(&format!("\nAppSettings::{} conflicts with AppSettings::{}.\n", std::stringify!($b), std::stringify!($a)));
+                    }
+                )+
+
+                if !s.is_empty() {
+                    panic!("{}", s)
+                }
+            }
+        };
     }
 
     checker!(AllowInvalidUtf8ForExternalSubcommands requires AllowExternalSubcommands);
+    #[cfg(feature = "unstable-multicall")]
+    checker!(Multicall conflicts NoBinaryName);
 }

src/build/app/mod.rs

@@ -1950,6 +1950,7 @@ impl<'help> App<'help> {
     ///     .get_matches();
     /// ```
     /// [`env::args_os`]: std::env::args_os()
+    /// [`App::try_get_matches_from_mut`]: App::try_get_matches_from_mut()
     #[inline]
     pub fn get_matches(self) -> ArgMatches {
         self.get_matches_from(&mut env::args_os())
@@ -2132,6 +2133,55 @@ impl<'help> App<'help> {
         T: Into<OsString> + Clone,
     {
         let mut it = Input::from(itr.into_iter());
+
+        #[cfg(feature = "unstable-multicall")]
+        if self.settings.is_set(AppSettings::Multicall) {
+            if let Some((argv0, _)) = it.next() {
+                let argv0 = Path::new(&argv0);
+                if let Some(command) = argv0.file_name().and_then(|f| f.to_str()) {
+                    // Stop borrowing command so we can get another mut ref to it.
+                    let command = command.to_owned();
+                    debug!(
+                        "App::try_get_matches_from_mut: Parsed command {} from argv",
+                        command
+                    );
+
+                    let subcommand = self
+                        .subcommands
+                        .iter_mut()
+                        .find(|subcommand| subcommand.aliases_to(&command));
+                    debug!(
+                        "App::try_get_matches_from_mut: Matched subcommand {:?}",
+                        subcommand
+                    );
+
+                    match subcommand {
+                        None if command == self.name => {
+                            debug!("App::try_get_matches_from_mut: no existing applet but matches name");
+                            debug!(
+                                "App::try_get_matches_from_mut: Setting bin_name to command name"
+                            );
+                            self.bin_name.get_or_insert(command);
+                            debug!(
+                                "App::try_get_matches_from_mut: Continuing with top-level parser."
+                            );
+                            return self._do_parse(&mut it);
+                        }
+                        _ => {
+                            debug!(
+                                "App::try_get_matches_from_mut: existing applet or no program name"
+                            );
+                            debug!("App::try_get_matches_from_mut: Reinserting command into arguments so subcommand parser matches it");
+                            it.insert(&[&command]);
+                            debug!("App::try_get_matches_from_mut: Clearing name and bin_name so that displayed command name starts with applet name");
+                            self.name.clear();
+                            self.bin_name = None;
+                            return self._do_parse(&mut it);
+                        }
+                    };
+                }
+            }
+        };
         // Get the name of the program (argument 1 of env::args()) and determine the
         // actual file
         // that was used to execute the program. This is because a program called