Merge pull request #5679 from epage/api

feat(complete): Make `Shells` more flexible

clap_complete/src/dynamic/env/mod.rs

@@ -232,7 +232,7 @@ pub struct Shells<'s>(pub &'s [&'s dyn EnvCompleter]);
 
 impl<'s> Shells<'s> {
     /// Select all of the built-in shells
-    pub fn builtins() -> Self {
+    pub const fn builtins() -> Self {
         Self(&[&Bash, &Elvish, &Fish, &Powershell, &Zsh])
     }
 
@@ -245,6 +245,11 @@ impl<'s> Shells<'s> {
     pub fn names(&self) -> impl Iterator<Item = &'static str> + 's {
         self.0.iter().map(|c| c.name())
     }
+
+    /// Iterate over [`EnvCompleter`]s
+    pub fn iter(&self) -> impl Iterator<Item = &dyn EnvCompleter> {
+        self.0.iter().copied()
+    }
 }
 
 /// Shell-integration for completions