fix: Loosen reflection lifetimes

Though we store a lot of values as `&'help str`, we return them as
`&'self str`, making it so they can not be used programmatically as part
of a `App::mut_arg` call.

This loosens the lifetimes so they can be used with `App::mut_arg`.
This also includes a test simulating the desired workflow described in #2966

I skipped `get_all_aliases`.  I ran into problems with lifetimes with
`all_subcommand_names`  and didn't quickly resolve it.  Rather than hold
this up, I punted on it for now.

We'll have to tighten these back up with #1041 but that will also enable
turning them into owned strings, so this will still be possible after
that issue is resolved, just the calls will be slightly different.

src/build/app/mod.rs

@@ -115,7 +115,7 @@ impl<'help> App<'help> {
 
     /// Get the long flag of the subcommand.
     #[inline]
-    pub fn get_long_flag(&self) -> Option<&str> {
+    pub fn get_long_flag(&self) -> Option<&'help str> {
         self.long_flag
     }
 
@@ -134,7 +134,7 @@ impl<'help> App<'help> {
     ///
     /// [`App::about`]: App::about()
     #[inline]
-    pub fn get_about(&self) -> Option<&str> {
+    pub fn get_about(&self) -> Option<&'help str> {
         self.about
     }
 
@@ -142,7 +142,7 @@ impl<'help> App<'help> {
     ///
     /// [`App::long_about`]: App::long_about()
     #[inline]
-    pub fn get_long_about(&self) -> Option<&str> {
+    pub fn get_long_about(&self) -> Option<&'help str> {
         self.long_about
     }
 
@@ -156,7 +156,7 @@ impl<'help> App<'help> {
 
     /// Iterate through the *visible* aliases for this subcommand.
     #[inline]
-    pub fn get_visible_aliases(&self) -> impl Iterator<Item = &str> {
+    pub fn get_visible_aliases(&self) -> impl Iterator<Item = &'help str> + '_ {
         self.aliases.iter().filter(|(_, vis)| *vis).map(|a| a.0)
     }
 
@@ -180,7 +180,7 @@ impl<'help> App<'help> {
 
     /// Iterate through the set of *all* the aliases for this subcommand, both visible and hidden.
     #[inline]
-    pub fn get_all_aliases(&self) -> impl Iterator<Item = &str> {
+    pub fn get_all_aliases(&self) -> impl Iterator<Item = &str> + '_ {
         self.aliases.iter().map(|a| a.0)
     }
 

src/build/arg/mod.rs

@@ -128,13 +128,13 @@ pub struct Arg<'help> {
 impl<'help> Arg<'help> {
     /// Get the name of the argument
     #[inline]
-    pub fn get_name(&self) -> &str {
+    pub fn get_name(&self) -> &'help str {
         self.name
     }
 
     /// Get the help specified for this argument, if any
     #[inline]
-    pub fn get_about(&self) -> Option<&str> {
+    pub fn get_about(&self) -> Option<&'help str> {
         self.about
     }
 
@@ -149,13 +149,13 @@ impl<'help> Arg<'help> {
     /// ```
     ///
     #[inline]
-    pub fn get_long_about(&self) -> Option<&str> {
+    pub fn get_long_about(&self) -> Option<&'help str> {
         self.long_about
     }
 
     /// Get the help heading specified for this argument, if any
     #[inline]
-    pub fn get_help_heading(&self) -> Option<&str> {
+    pub fn get_help_heading(&self) -> Option<&'help str> {
         self.help_heading.unwrap_or_default()
     }
 
@@ -196,13 +196,13 @@ impl<'help> Arg<'help> {
 
     /// Get the long option name for this argument, if any
     #[inline]
-    pub fn get_long(&self) -> Option<&str> {
+    pub fn get_long(&self) -> Option<&'help str> {
         self.long
     }
 
     /// Get visible aliases for this argument, if any
     #[inline]
-    pub fn get_visible_aliases(&self) -> Option<Vec<&str>> {
+    pub fn get_visible_aliases(&self) -> Option<Vec<&'help str>> {
         if self.aliases.is_empty() {
             None
         } else {
@@ -218,7 +218,7 @@ impl<'help> Arg<'help> {
 
     /// Get the long option name and its visible aliases, if any
     #[inline]
-    pub fn get_long_and_visible_aliases(&self) -> Option<Vec<&str>> {
+    pub fn get_long_and_visible_aliases(&self) -> Option<Vec<&'help str>> {
         let mut longs = match self.long {
             Some(long) => vec![long],
             None => return None,
@@ -241,7 +241,7 @@ impl<'help> Arg<'help> {
 
     /// Get the names of values for this argument.
     #[inline]
-    pub fn get_value_names(&self) -> Option<&[&str]> {
+    pub fn get_value_names(&self) -> Option<&[&'help str]> {
         if self.val_names.is_empty() {
             None
         } else {

tests/tests.rs

@@ -3,7 +3,7 @@ mod utils;
 use std::io::Write;
 use std::str;
 
-use clap::{App, Arg};
+use clap::{App, Arg, ArgSettings};
 
 static SCF2OP: &str = "flag present 2 times
 option NOT present
@@ -390,3 +390,17 @@ fn sc_short_flag_x2_short_opt_eq_pos() {
 fn sc_short_flag_x2_long_opt_eq_pos() {
     check_complex_output("clap-test subcmd value -f -f --option=some", SCF2OP);
 }
+
+#[test]
+fn mut_arg_all() {
+    let mut app = utils::complex_app();
+    let arg_names = app
+        .get_arguments()
+        .map(|a| a.get_name())
+        .filter(|a| *a != "version" && *a != "help")
+        .collect::<Vec<_>>();
+
+    for arg_name in arg_names {
+        app = app.mut_arg(arg_name, |arg| arg.setting(ArgSettings::HidePossibleValues));
+    }
+}