imp(Aliases): improves readability of asliases in help messages

Aliases are now displayed after the help text inside a `[aliases: als1, als2, als3]` style box.

Closes #526
Closes #529

src/app/help.rs

@@ -461,6 +461,17 @@ impl<'a> Help<'a> {
                                    "".into()
                                }
                            });
+        } else if let Some(ref aliases) = a.aliases() {
+            debugln!("Writing aliases");
+            return format!(" [aliases: {}]",
+               if self.color {
+                   aliases.iter()
+                          .map(|v| format!("{}", self.cizer.good(v)))
+                          .collect::<Vec<_>>()
+                          .join(", ")
+               } else {
+                   aliases.join(", ")
+               });
         } else if !self.hide_pv {
             debugln!("Writing values");
             if let Some(ref pv) = a.possible_vals() {
@@ -548,21 +559,6 @@ impl<'a> Help<'a> {
 
         let mut ord_m = VecMap::new();
         for sc in parser.subcommands.iter().filter(|s| !s.p.is_set(AppSettings::Hidden)) {
-            let sc = if let Some(ref aliases) = sc.p.meta.aliases {
-                let mut a = App::new(format!("{}|{}", &*sc.p.meta.name, aliases.iter()
-                                                                               .filter(|&&(_, vis)| vis)
-                                                                               .map(|&(n, _)| n)
-                                                                               .collect::<Vec<_>>()
-                                                                               .join("|")));
-                a = if let Some(about) = sc.p.meta.about {
-                    a.about(about)
-                } else {
-                    a
-                };
-                a
-            } else {
-                sc.clone()
-            };
             let btm = ord_m.entry(sc.p.meta.disp_ord).or_insert(BTreeMap::new());
             longest = cmp::max(longest, sc.p.meta.name.len());
             btm.insert(sc.p.meta.name.clone(), sc.clone());

src/app/mod.rs

@@ -1261,6 +1261,18 @@ impl<'n, 'e> AnyArg<'n, 'e> for App<'n, 'e> {
     fn longest_filter(&self) -> bool {
         true
     }
+    fn aliases(&self) -> Option<Vec<&'e str>> {
+        if let Some(ref aliases) = self.p.meta.aliases {
+            let vis_aliases: Vec<_> = aliases.iter().filter_map(|&(n,v)| if v { Some(n) } else {None}).collect();
+            if vis_aliases.is_empty() {
+                None
+            } else {
+                Some(vis_aliases)
+            }
+        } else {
+            None
+        }
+    }
 }
 
 impl<'n, 'e> fmt::Display for App<'n, 'e> {

src/args/any_arg.rs

@@ -8,6 +8,7 @@ use args::settings::ArgSettings;
 pub trait AnyArg<'n, 'e> {
     fn name(&self) -> &'n str;
     fn overrides(&self) -> Option<&[&'e str]>;
+    fn aliases(&self) -> Option<Vec<&'e str>>;
     fn requires(&self) -> Option<&[&'e str]>;
     fn blacklist(&self) -> Option<&[&'e str]>;
     fn required_unless(&self) -> Option<&[&'e str]>;

src/args/arg_builder/flag.rs

@@ -166,6 +166,9 @@ impl<'n, 'e> AnyArg<'n, 'e> for FlagBuilder<'n, 'e> {
     fn longest_filter(&self) -> bool {
         self.long.is_some()
     }
+    fn aliases(&self) -> Option<Vec<&'e str>> {
+        None
+    }
 }
 
 impl<'n, 'e> DispOrder for FlagBuilder<'n, 'e> {

src/args/arg_builder/option.rs

@@ -248,6 +248,9 @@ impl<'n, 'e> AnyArg<'n, 'e> for OptBuilder<'n, 'e> {
     fn longest_filter(&self) -> bool {
         true
     }
+    fn aliases(&self) -> Option<Vec<&'e str>> {
+        None
+    }
 }
 
 impl<'n, 'e> DispOrder for OptBuilder<'n, 'e> {

src/args/arg_builder/positional.rs

@@ -238,6 +238,9 @@ impl<'n, 'e> AnyArg<'n, 'e> for PosBuilder<'n, 'e> {
     fn longest_filter(&self) -> bool {
         true
     }
+    fn aliases(&self) -> Option<Vec<&'e str>> {
+        None
+    }
 }
 
 impl<'n, 'e> DispOrder for PosBuilder<'n, 'e> {