api(App): Adds version_about method to App.

Version about text is now customizable and propagates to subcommands. Closes #1640.

src/build/app/mod.rs

@@ -84,6 +84,7 @@ pub struct App<'help> {
     pub(crate) about: Option<&'help str>,
     pub(crate) long_about: Option<&'help str>,
     pub(crate) help_about: Option<&'help str>,
+    pub(crate) version_about: Option<&'help str>,
     pub(crate) before_help: Option<&'help str>,
     pub(crate) before_long_help: Option<&'help str>,
     pub(crate) after_help: Option<&'help str>,
@@ -444,6 +445,27 @@ impl<'help> App<'help> {
         self
     }
 
+    /// Sets the help text for the auto-generated version argument.
+    ///
+    /// By default clap sets this to "Prints versoin information" but if
+    /// you're using a different convention for your help messages and
+    /// would prefer a different phrasing you can override it.
+    ///
+    /// **NOTE:** This setting propagates to subcommands.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// # use clap::App;
+    /// App::new("myprog")
+    ///     .version_about("Print version information") // Impertive tone
+    /// # ;
+    /// ```
+    pub fn version_about<S: Into<&'help str>>(mut self, version_about: S) -> Self {
+        self.version_about = Some(version_about.into());
+        self
+    }
+
     /// (Re)Sets the program's name. This will be displayed when displaying help
     /// or version messages.
     ///
@@ -2274,6 +2296,9 @@ impl<'help> App<'help> {
                     if $sc.help_about.is_none() && $_self.help_about.is_some() {
                         $sc.help_about = $_self.help_about.clone();
                     }
+                    if $sc.version_about.is_none() && $_self.version_about.is_some() {
+                        $sc.version_about = $_self.version_about.clone();
+                    }
                 }
                 {
                     // FIXME: This doesn't belong here at all.
@@ -2347,7 +2372,7 @@ impl<'help> App<'help> {
             debug!("App::_create_help_and_version: Building --version");
             let mut version = Arg::new("version")
                 .long("version")
-                .about("Prints version information");
+                .about(self.version_about.unwrap_or("Prints version information"));
             if !self.args.args.iter().any(|x| x.short == Some('V')) {
                 version = version.short('V');
             }

tests/help.rs

@@ -1977,3 +1977,155 @@ fn help_about_multi_subcmd_override_long_flag() {
         false
     ));
 }
+
+static VERSION_ABOUT: &str = "myapp 1.0
+
+USAGE:
+    myapp
+
+FLAGS:
+    -h, --help       Prints help information
+    -V, --version    Print custom version about text";
+
+static VERSION_ABOUT_MULTI_SC: &str = "myapp-subcmd-multi 1.0
+
+USAGE:
+    myapp subcmd multi
+
+FLAGS:
+    -h, --help       Prints help information
+    -V, --version    Print custom version about text";
+
+static VERSION_ABOUT_MULTI_SC_OVERRIDE: &str = "myapp-subcmd-multi 1.0
+
+USAGE:
+    myapp subcmd multi
+
+FLAGS:
+    -h, --help       Prints help information
+    -V, --version    Print custom version about text from multi";
+
+#[test]
+fn version_about_short_flag() {
+    let app = App::new("myapp")
+        .version("1.0")
+        .version_about("Print custom version about text");
+
+    assert!(utils::compare_output(app, "myapp -h", VERSION_ABOUT, false));
+}
+
+#[test]
+fn version_about_long_flag() {
+    let app = App::new("myapp")
+        .version("1.0")
+        .version_about("Print custom version about text");
+
+    assert!(utils::compare_output(
+        app,
+        "myapp --help",
+        VERSION_ABOUT,
+        false
+    ));
+}
+
+#[test]
+fn version_about_multi_subcmd() {
+    let app = App::new("myapp")
+        .version_about("Print custom version about text")
+        .subcommand(App::new("subcmd").subcommand(App::new("multi").version("1.0")));
+
+    assert!(utils::compare_output(
+        app,
+        "myapp help subcmd multi",
+        VERSION_ABOUT_MULTI_SC,
+        false
+    ));
+}
+
+#[test]
+fn version_about_multi_subcmd_short_flag() {
+    let app = App::new("myapp")
+        .version_about("Print custom version about text")
+        .subcommand(App::new("subcmd").subcommand(App::new("multi").version("1.0")));
+
+    assert!(utils::compare_output(
+        app,
+        "myapp subcmd multi -h",
+        VERSION_ABOUT_MULTI_SC,
+        false
+    ));
+}
+
+#[test]
+fn version_about_multi_subcmd_long_flag() {
+    let app = App::new("myapp")
+        .version_about("Print custom version about text")
+        .subcommand(App::new("subcmd").subcommand(App::new("multi").version("1.0")));
+
+    assert!(utils::compare_output(
+        app,
+        "myapp subcmd multi --help",
+        VERSION_ABOUT_MULTI_SC,
+        false
+    ));
+}
+
+#[test]
+fn version_about_multi_subcmd_override() {
+    let app = App::new("myapp")
+        .version_about("Print custom version about text")
+        .subcommand(
+            App::new("subcmd").subcommand(
+                App::new("multi")
+                    .version("1.0")
+                    .version_about("Print custom version about text from multi"),
+            ),
+        );
+
+    assert!(utils::compare_output(
+        app,
+        "myapp help subcmd multi",
+        VERSION_ABOUT_MULTI_SC_OVERRIDE,
+        false
+    ));
+}
+
+#[test]
+fn version_about_multi_subcmd_override_short_flag() {
+    let app = App::new("myapp")
+        .version_about("Print custom version about text")
+        .subcommand(
+            App::new("subcmd").subcommand(
+                App::new("multi")
+                    .version("1.0")
+                    .version_about("Print custom version about text from multi"),
+            ),
+        );
+
+    assert!(utils::compare_output(
+        app,
+        "myapp subcmd multi -h",
+        VERSION_ABOUT_MULTI_SC_OVERRIDE,
+        false
+    ));
+}
+
+#[test]
+fn version_about_multi_subcmd_override_long_flag() {
+    let app = App::new("myapp")
+        .version_about("Print custom version about text")
+        .subcommand(
+            App::new("subcmd").subcommand(
+                App::new("multi")
+                    .version("1.0")
+                    .version_about("Print custom version about text from multi"),
+            ),
+        );
+
+    assert!(utils::compare_output(
+        app,
+        "myapp subcmd multi --help",
+        VERSION_ABOUT_MULTI_SC_OVERRIDE,
+        false
+    ));
+}