fix: add an alias section to the help for subcommands (#545)

include/CLI/App.hpp

@@ -1834,7 +1834,21 @@ class App {
     }
 
     /// Get a display name for an app
-    std::string get_display_name() const { return (!name_.empty()) ? name_ : "[Option Group: " + get_group() + "]"; }
+    std::string get_display_name(bool with_aliases = false) const {
+        if(name_.empty()) {
+            return std::string("[Option Group: ") + get_group() + "]";
+        }
+        if(aliases_.empty() || !with_aliases || aliases_.empty()) {
+            return name_;
+        }
+        std::string dispname = name_;
+        for(const auto &lalias : aliases_) {
+            dispname.push_back(',');
+            dispname.push_back(' ');
+            dispname.append(lalias);
+        }
+        return dispname;
+    }
 
     /// Check the name, case insensitive and underscore insensitive if set
     bool check_name(std::string name_to_check) const {

include/CLI/Formatter.hpp

@@ -205,15 +205,18 @@ inline std::string Formatter::make_subcommands(const App *app, AppFormatMode mod
 
 inline std::string Formatter::make_subcommand(const App *sub) const {
     std::stringstream out;
-    detail::format_help(out, sub->get_name(), sub->get_description(), column_width_);
+    detail::format_help(out, sub->get_display_name(true), sub->get_description(), column_width_);
     return out.str();
 }
 
 inline std::string Formatter::make_expanded(const App *sub) const {
     std::stringstream out;
-    out << sub->get_display_name() << "\n";
+    out << sub->get_display_name(true) << "\n";
 
     out << make_description(sub);
+    if(sub->get_name().empty() && !sub->get_aliases().empty()) {
+        detail::format_aliases(out, sub->get_aliases(), column_width_ + 2);
+    }
     out << make_positionals(sub);
     out << make_groups(sub, AppFormatMode::Sub);
     out << make_subcommands(sub, AppFormatMode::Sub);

include/CLI/StringTools.hpp

@@ -159,7 +159,7 @@ inline std::string trim_copy(const std::string &str, const std::string &filter)
     return trim(s, filter);
 }
 /// Print a two part "help" string
-inline std::ostream &format_help(std::ostream &out, std::string name, std::string description, std::size_t wid) {
+inline std::ostream &format_help(std::ostream &out, std::string name, const std::string &description, std::size_t wid) {
     name = "  " + name;
     out << std::setw(static_cast<int>(wid)) << std::left << name;
     if(!description.empty()) {
@@ -176,6 +176,24 @@ inline std::ostream &format_help(std::ostream &out, std::string name, std::strin
     return out;
 }
 
+/// Print subcommand aliases
+inline std::ostream &format_aliases(std::ostream &out, const std::vector<std::string> &aliases, std::size_t wid) {
+    if(!aliases.empty()) {
+        out << std::setw(static_cast<int>(wid)) << "     aliases: ";
+        bool front = true;
+        for(const auto &alias : aliases) {
+            if(!front) {
+                out << ", ";
+            } else {
+                front = false;
+            }
+            out << alias;
+        }
+        out << "\n";
+    }
+    return out;
+}
+
 /// Verify the first character of an option
 template <typename T> bool valid_first_char(T c) {
     return std::isalnum(c, std::locale()) || c == '_' || c == '?' || c == '@';

tests/HelpTest.cpp

@@ -467,6 +467,36 @@ TEST(THelp, Subcom) {
     EXPECT_THAT(help, HasSubstr("Usage: ./myprogram sub2"));
 }
 
+TEST(THelp, Subcom_alias) {
+    CLI::App app{"My prog"};
+
+    auto sub1 = app.add_subcommand("sub1", "Subcommand1 description test");
+    sub1->alias("sub_alias1");
+    sub1->alias("sub_alias2");
+
+    app.add_subcommand("sub2", "Subcommand2 description test");
+
+    std::string help = app.help();
+    EXPECT_THAT(help, HasSubstr("Usage: [OPTIONS] [SUBCOMMAND]"));
+    EXPECT_THAT(help, HasSubstr("sub_alias1"));
+    EXPECT_THAT(help, HasSubstr("sub_alias2"));
+}
+
+TEST(THelp, Subcom_alias_group) {
+    CLI::App app{"My prog"};
+
+    auto sub1 = app.add_subcommand("", "Subcommand1 description test");
+    sub1->alias("sub_alias1");
+    sub1->alias("sub_alias2");
+
+    app.add_subcommand("sub2", "Subcommand2 description test");
+
+    std::string help = app.help();
+    EXPECT_THAT(help, HasSubstr("Usage: [OPTIONS] [SUBCOMMAND]"));
+    EXPECT_THAT(help, HasSubstr("sub_alias1"));
+    EXPECT_THAT(help, HasSubstr("sub_alias2"));
+}
+
 TEST(THelp, MasterName) {
     CLI::App app{"My prog", "MyRealName"};