Make vec_map required dependency - in fact, it already is

Cargo.toml

@@ -64,11 +64,11 @@ unicode-width         = "0.1"
 textwrap              = "0.11"
 indexmap              = "1.0"
 os_str_bytes          = "2.1"
+vec_map               = "0.8"
 strsim      = { version = "0.10",  optional = true }
 yaml-rust   = { version = "0.4.1",  optional = true }
 atty        = { version = "0.2",  optional = true }
 termcolor   = { version = "1.1", optional = true }
-vec_map     = { version = "0.8", optional = true }
 term_size   = { version = "1.0.0-beta1", optional = true }
 lazy_static = { version = "1", optional = true }
 clap_derive = { path = "./clap_derive", version = "3.0.0-beta.1", optional = true }
@@ -80,7 +80,7 @@ version-sync = "0.8"
 criterion = { git = "git://github.com/pksunkara/criterion.rs", version = "0.3" }
 
 [features]
-default     = ["suggestions", "color", "vec_map", "derive", "std", "cargo"]
+default     = ["suggestions", "color", "derive", "std", "cargo"]
 std         = [] # support for no_std in a backwards-compatible way
 suggestions = ["strsim"]
 color       = ["atty", "termcolor"]

src/lib.rs

@@ -320,7 +320,6 @@
 //! * `derive`: Enables the custom derive (i.e. `#[derive(Clap)]`). Without this you must use one of the other methods of creating a `clap` CLI listed above
 //! * `suggestions`: Turns on the `Did you mean '--myoption'?` feature for when users make typos. (builds dependency `strsim`)
 //! * `color`: Turns on colored error messages. This feature only works on non-Windows OSs. (builds dependency `ansi-term`)
-//! * `vec_map`: Use [`VecMap`](https://crates.io/crates/vec_map) internally instead of a [`BTreeMap`](https://doc.rust-lang.org/stable/std/collections/struct.BTreeMap.html). This feature provides a _slight_ performance improvement. (builds dependency `vec_map`)
 //!
 //! To disable these, add this to your `Cargo.toml`:
 //!

src/parse/parser.rs

@@ -127,16 +127,10 @@ where
         // Because you must wait until all arguments have been supplied, this is the first chance
         // to make assertions on positional argument indexes
         //
-        // Firt we verify that the index highest supplied index, is equal to the number of
+        // First we verify that the index highest supplied index, is equal to the number of
         // positional arguments to verify there are no gaps (i.e. supplying an index of 1 and 3
         // but no 2)
 
-        // #[cfg(feature = "vec_map")]
-        // fn _highest_idx(map: &VecMap<&str>) -> usize { map.keys().last().unwrap_or(0) }
-
-        // #[cfg(not(feature = "vec_map"))]
-        // fn _highest_idx(map: &VecMap<&str>) -> usize { *map.keys().last().unwrap_or(&0) }
-
         let highest_idx = *self
             .app
             .args

src/util/mod.rs

@@ -4,12 +4,12 @@ mod argstr;
 mod fnv;
 mod graph;
 mod id;
-mod map;
 mod strext;
 
 pub use self::fnv::Key;
 
-pub(crate) use self::{argstr::ArgStr, graph::ChildGraph, id::Id, map::VecMap};
+pub(crate) use self::{argstr::ArgStr, graph::ChildGraph, id::Id};
+pub(crate) use vec_map::VecMap;
 
 #[cfg(feature = "color")]
 pub(crate) use termcolor;