From 0c82929fe4381528eb835f2313783ff9f5eaffe4 Mon Sep 17 00:00:00 2001
From: Zanie Blue <contact@zanie.dev>
Date: Mon, 8 Jul 2024 17:29:42 -0500
Subject: [PATCH] feat: show user defined help flags during help hints if
 present

---
 clap_builder/src/error/format.rs | 28 +++++++++++++++++++++++-----
 clap_builder/src/error/mod.rs    |  4 ++--
 tests/builder/help.rs            |  8 +++++++-
 3 files changed, 32 insertions(+), 8 deletions(-)

diff --git a/clap_builder/src/error/format.rs b/clap_builder/src/error/format.rs
index 0f8644f6adc..b1e3037411c 100644
--- a/clap_builder/src/error/format.rs
+++ b/clap_builder/src/error/format.rs
@@ -3,6 +3,8 @@
 #![cfg_attr(not(feature = "error-context"), allow(dead_code))]
 #![cfg_attr(not(feature = "error-context"), allow(unused_imports))]
 
+use std::borrow::Cow;
+
 use crate::builder::Command;
 use crate::builder::StyledStr;
 use crate::builder::Styles;
@@ -12,6 +14,7 @@ use crate::error::ContextKind;
 use crate::error::ContextValue;
 use crate::error::ErrorKind;
 use crate::output::TAB;
+use crate::ArgAction;
 
 /// Defines how to format an error for displaying to the user
 pub trait ErrorFormatter: Sized {
@@ -120,7 +123,7 @@ impl ErrorFormatter for RichFormatter {
             put_usage(&mut styled, usage);
         }
 
-        try_help(&mut styled, styles, error.inner.help_flag);
+        try_help(&mut styled, styles, error.inner.help_flag.as_deref());
 
         styled
     }
@@ -461,7 +464,7 @@ pub(crate) fn format_error_message(
         put_usage(&mut styled, usage);
     }
     if let Some(cmd) = cmd {
-        try_help(&mut styled, styles, get_help_flag(cmd));
+        try_help(&mut styled, styles, get_help_flag(cmd).as_deref());
     }
     styled
 }
@@ -480,16 +483,31 @@ fn put_usage(styled: &mut StyledStr, usage: &StyledStr) {
     styled.push_styled(usage);
 }
 
-pub(crate) fn get_help_flag(cmd: &Command) -> Option<&'static str> {
+pub(crate) fn get_help_flag(cmd: &Command) -> Option<Cow<'static, str>> {
     if !cmd.is_disable_help_flag_set() {
-        Some("--help")
+        Some(Cow::Borrowed("--help"))
+    } else if let Some(flag) = get_user_help_flag(cmd) {
+        Some(Cow::Owned(flag))
     } else if cmd.has_subcommands() && !cmd.is_disable_help_subcommand_set() {
-        Some("help")
+        Some(Cow::Borrowed("help"))
     } else {
         None
     }
 }
 
+fn get_user_help_flag(cmd: &Command) -> Option<String> {
+    let arg = cmd.get_arguments().find(|arg| {
+        matches!(
+            arg.get_action(),
+            ArgAction::Help | ArgAction::HelpShort | ArgAction::HelpLong
+        )
+    })?;
+
+    arg.get_long()
+        .map(|long| format!("--{long}"))
+        .or_else(|| arg.get_short().map(|short| format!("-{short}")))
+}
+
 fn try_help(styled: &mut StyledStr, styles: &Styles, help: Option<&str>) {
     if let Some(help) = help {
         use std::fmt::Write as _;
diff --git a/clap_builder/src/error/mod.rs b/clap_builder/src/error/mod.rs
index 1e8fcd57bab..cfba5a818b4 100644
--- a/clap_builder/src/error/mod.rs
+++ b/clap_builder/src/error/mod.rs
@@ -69,7 +69,7 @@ struct ErrorInner {
     context: FlatMap<ContextKind, ContextValue>,
     message: Option<Message>,
     source: Option<Box<dyn error::Error + Send + Sync>>,
-    help_flag: Option<&'static str>,
+    help_flag: Option<Cow<'static, str>>,
     styles: Styles,
     color_when: ColorChoice,
     color_help_when: ColorChoice,
@@ -319,7 +319,7 @@ impl<F: ErrorFormatter> Error<F> {
         self
     }
 
-    pub(crate) fn set_help_flag(mut self, help_flag: Option<&'static str>) -> Self {
+    pub(crate) fn set_help_flag(mut self, help_flag: Option<Cow<'static, str>>) -> Self {
         self.inner.help_flag = help_flag;
         self
     }
diff --git a/tests/builder/help.rs b/tests/builder/help.rs
index d1f53de4583..4b336031a01 100644
--- a/tests/builder/help.rs
+++ b/tests/builder/help.rs
@@ -374,6 +374,8 @@ fn try_help_custom_flag() {
 error: unexpected argument 'bar' found
 
 Usage: ctest
+
+For more information, try '--help'.
 ";
 
     let cmd = Command::new("ctest")
@@ -395,6 +397,8 @@ fn try_help_custom_flag_short() {
 error: unexpected argument 'bar' found
 
 Usage: ctest
+
+For more information, try '-h'.
 ";
 
     let cmd = Command::new("ctest")
@@ -411,6 +415,8 @@ fn try_help_custom_flag_long() {
 error: unexpected argument 'bar' found
 
 Usage: ctest
+
+For more information, try '--help'.
 ";
 
     let cmd = Command::new("ctest")
@@ -462,7 +468,7 @@ error: unrecognized subcommand 'bar'
 
 Usage: ctest [COMMAND]
 
-For more information, try 'help'.
+For more information, try '--help'.
 ";
 
     let cmd = Command::new("ctest")