Repository: clap-rs/clap
Pull request #1901 (2020-05-03 06:33:07)

implement Arg::short_alias and Arg::short_aliases
This should resolve https://github.com/clap-rs/clap/issues/1896

I wasn't totally sure which test cases would be good

@kbknapp

pksunkara: Looks good, but I think the shell completions also need support for this.
connorskees: @pksunkara is there a reason to prefer `short_alias` over `short_aliases` here https://github.com/clap-rs/clap/pull/1901/commits/bbc2bea45bf477aecf0ab34c3f9197b243be6153? It seems like `short_aliases` would be simpler choice?
pksunkara: Yes, to be consistent. See the line above.

```rust
"aliases" => yaml_vec_or_str!(v, a, alias)
```
connorskees: @pksunkara I think that consistency of 2 characters comes at the cost of simplicity with regard to the macros.

Using `short_aliases` we can get away with something like
```rust
#[cfg(feature = "yaml")]
macro_rules! yaml_chars {
    ($v:expr) => {{
        &$v.as_str()
            .unwrap_or_else(|| panic!("failed to convert YAML {:?} value to a string", $v))
            .split_whitespace()
            .map(|s| {
                let mut chars = s.chars();
                let c = chars.next().expect("short aliases must be a single char");
                if chars.next().is_some() {
                    panic!("short aliases must be a single char");
                }
                c
            })
            .collect::<Vec<char>>()
    }};
}
```

but with `short_alias` the macro would presumably become more complex as this is the macro for `alias`

```rust
#[cfg(feature = "yaml")]
macro_rules! yaml_vec_or_str {
    ($v:ident, $a:ident, $c:ident) => {{
        let maybe_vec = $v.as_vec();
        if let Some(vec) = maybe_vec {
            for ys in vec {
                if let Some(s) = ys.as_str() {
                    $a = $a.$c(s);
                } else {
                    panic!("Failed to convert YAML value {:?} to a string", ys);
                }
            }
        } else {
            if let Some(s) = $v.as_str() {
                $a = $a.$c(s);
            } else {
                panic!(
                    "Failed to convert YAML value {:?} to either a vec or string",
                    $v
                );
            }
        }
        $a
    }};
}
```
connorskees: @pksunkara I have pushed a commit using the code from my comment above. If you disagree please feel free to flag it in review. Though I understand your viewpoint, believe the consistency is not worth it in this case.
pksunkara: Hmm.. You are right. Would you change the `yaml_vec_or_str` for alias also then?
connorskees: @pksunkara I think it makes sense to similarly refactor `yaml_vec_to_str!`, but I think that may fall out of the scope of this pull request.
pksunkara: I agree. Let's finish this PR by adding short aliases support for the completions. The logic should be similar to normal aliases.
CreepySkeleton: @connorskees could you please apply `cargo fmt --all` (latest stable) and squash the commits? I think we can merge it as is, support for completions can be added later.

Patch:
diff --git a/.travis.yml b/.travis.yml
index 8f46f5ed..246eabdd 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -32,9 +32,6 @@ jobs:
     - rust: beta
     - rust: nightly
       cache: false
-      script:
-        - cargo test --no-default-features --features "std cargo" -p clap:3.0.0-beta.1
-        - cargo test --features "yaml unstable doc"
     - name: Linting (fmt + clippy)
       before_script:
         - rustup component add clippy
@@ -42,7 +39,7 @@ jobs:
       script:
         - echo "Checking codebase with Clippy release `cargo clippy --version`."
         - cargo clippy --lib --features "yaml unstable" -- -D warnings
-        - cargo clippy --tests --examples --features "yaml unstable" -- -D warnings
+        - cargo clippy --tests --examples --features "yaml unstable"
         - cargo fmt -- --check
     - name: Coverage
       addons:
diff --git a/Cargo.toml b/Cargo.toml
index 69e35358..016a7a47 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -32,32 +32,26 @@ bench = false
 [[bench]]
 harness = false
 name = "01_default"
-path = "benches/01_default.rs"
 
 [[bench]]
 harness = false
 name = "02_simple"
-path = "benches/02_simple.rs"
 
 [[bench]]
 harness = false
 name = "03_complex"
-path = "benches/03_complex.rs"
 
 [[bench]]
 harness = false
 name = "04_new_help"
-path = "benches/04_new_help.rs"
 
 [[bench]]
 harness = false
 name = "05_ripgrep"
-path = "benches/05_ripgrep.rs"
 
 [[bench]]
 harness = false
 name = "06_rustup"
-path = "benches/06_rustup.rs"
 
 [badges]
 is-it-maintained-issue-resolution = { repository = "clap-rs/clap" }
diff --git a/FAQ.md b/FAQ.md
deleted file mode 100644
index 33fb99bb..00000000
--- a/FAQ.md
+++ /dev/null
@@ -1,90 +0,0 @@
-1. [Comparisons](#comparisons)
-   1. [How does `clap` compare to structopt?](#how-does-clap-compare-to-structopt)
-   2. [How does `clap` compare to getopts?](#how-does-clap-compare-to-getopts)
-   3. [How does `clap` compare to docopt.rs?](#how-does-clap-compare-to-docoptrs)
-   4. [What are some reasons to use `clap`? (The Pitch)](#what-are-some-reasons-to-use-clap-the-pitch)
-   5. [What are some reasons *not* to use `clap`? (The Anti Pitch)](#what-are-some-reasons-not-to-use-clap-the-anti-pitch)
-   6. [Reasons to use `clap`](#reasons-to-use-clap)
-   7. [Reasons to `docopt`](#reasons-to-docopt)
-   8. [Reasons to use `getopts`](#reasons-to-use-getopts)
-2. [How many methods are there to create an App/Arg?](#how-many-methods-are-there-to-create-an-apparg)
-3. [Why is there a default subcommand of help?](#why-is-there-a-default-subcommand-of-help)
-
-### Comparisons
-
-First, let me say that these comparisons are highly subjective, and not meant in a critical or harsh manner. All the argument parsing libraries out there (to include `clap`) have their own strengths and weaknesses. Sometimes it just comes down to personal taste when all other factors are equal. When in doubt, try them all and pick one that you enjoy :) There's plenty of room in the Rust community for multiple implementations!
-
-#### How does `clap` compare to [structopt](https://github.com/TeXitoi/structopt)?
-
-Simple! `clap` *is* `structopt`. With the 3.0 release, `clap` imported the `structopt` code into it's own codebase as the [`clap_derive`](https://github.com/clap-rs/clap/tree/master/clap_derive) crate. Since `structopt` already used `clap` under the hood, the transition was nearly painless, and is 100% feature compatible.
-
-If you were using `structopt` before, you have to change the attributes from `#[structopt(...)]` to `#[clap(...)]`.
-
-Also the derive statements changed from `#[derive(Structopt)]` to `#[derive(Clap)]`. There is also some additional functionality and breaking changes that's been added to the `clap_derive` crate. See the documentation for that crate, for more details.
-
-#### How does `clap` compare to [getopts](https://github.com/rust-lang-nursery/getopts)?
-
-`getopts` is a very basic, fairly minimalist argument parsing library. This isn't a bad thing, sometimes you don't need tons of features, you just want to parse some simple arguments, and have some help text generated for you based on valid arguments you specify. The downside to this approach is that you must manually implement most of the common features (such as checking to display help messages, usage strings, etc.). If you want a highly custom argument parser, and don't mind writing the majority of the functionality yourself, `getopts` is an excellent base.
-
-`getopts` also doesn't allocate much, or at all. This gives it a very small performance boost. Although, as you start implementing additional features, that boost quickly disappears.
-
-Personally, I find many, many uses of `getopts` are manually implementing features that `clap` provides by default. Using `clap` simplifies your codebase allowing you to focus on your application, and not argument parsing.
-
-#### How does `clap` compare to [docopt.rs](https://github.com/docopt/docopt.rs)?
-
-I first want to say I'm a big a fan of BurntSushi's work, the creator of `Docopt.rs`. I aspire to produce the quality of libraries that this man does! When it comes to comparing these two libraries they are very different. `docopt` tasks you with writing a help message, and then it parses that message for you to determine all valid arguments and their use. Some people LOVE this approach, others do not. If you're willing to write a detailed help message, it's nice that you can stick that in your program and have `docopt` do the rest. On the downside, it's far less flexible.
-
-`docopt` is also excellent at translating arguments into Rust types automatically. There is even a syntax extension which will do all this for you, if you're willing to use a nightly compiler (use of a stable compiler requires you to somewhat manually translate from arguments to Rust types). To use BurntSushi's words, `docopt` is also a sort of black box. You get what you get, and it's hard to tweak implementation or customize the experience for your use case.
-
-Because `docopt` is doing a ton of work to parse your help messages and determine what you were trying to communicate as valid arguments, it's also one of the more heavy weight parsers performance-wise. For most applications this isn't a concern and this isn't to say `docopt` is slow, in fact far from it. This is just something to keep in mind while comparing.
-
-#### What are some reasons to use `clap`? (The Pitch)
-
-`clap` is as fast, and as lightweight as possible while still giving all the features you'd expect from a modern argument parser. In fact, for the amount and type of features `clap` offers it remains about as fast as `getopts`. If you use `clap` when just need some simple arguments parsed, you'll find it's a walk in the park. `clap` also makes it possible to represent extremely complex, and advanced requirements, without too much thought. `clap` aims to be intuitive, easy to use, and fully capable for wide variety use cases and needs.
-
-#### What are some reasons *not* to use `clap`? (The Anti Pitch)
-
-Depending on the style in which you choose to define the valid arguments, `clap` can be very verbose. `clap` also offers so many finetuning knobs and dials, that learning everything can seem overwhelming. I strive to keep the simple cases simple, but when turning all those custom dials it can get complex. `clap` is also opinionated about parsing. Even though so much can be tweaked and tuned with `clap` (and I'm adding more all the time), there are still certain features which `clap` implements in specific ways which may be contrary to some users use-cases.
-
-#### Reasons to use `clap`
-
- * You want all the nice CLI features your users may expect, yet you don't want to implement them all yourself. You'd like to focus your application, not argument parsing.
- * In addition to the point above; you don't want to sacrifice performance to get all those nice features
- * You have complex requirements/conflicts between your various valid args.
- * You want to use subcommands (although other libraries also support subcommands, they are not nearly as feature rich as those provided by `clap`)
- * You want some sort of custom validation built into the argument parsing process, instead of as part of your application (which allows for earlier failures, better error messages, more cohesive experience, etc.)
- * You need more performance than `docopt` provides
-
-#### Reasons to `docopt`
-
- * You want *automatic* serialization of your arguments into Rust types (Although `clap` can do this, docopt is better at it)
- * You are on nightly Rust and want the library to automatically generate an "arguments struct" from the matched args
- * You are porting an application which uses docopt and already have the usage string already defined
-
-#### Reasons to use `getopts`
-
- * You need absolutely as few allocations as possible and don't mind implementing nearly everything yourself
- * You want a portion of the arg parsing process to be very custom (again, implementing the details yourself)
-
-
-### How many methods are there to create an App/Arg?
-
-To build an `App` there are three:
-
-* Derive Macros
-* Builder Pattern
-* Yaml
-
-To build an `Arg` there are four:
-
-* Derive Macros
-* Builder Pattern
-* Usage Strings
-* Yaml
-
-### Why is there a default subcommand of help?
-
-There is only a default subcommand of `help` when other subcommands have been defined manually. So it's opt-in(ish), being that you only get a `help` subcommand if you're actually using subcommands.
-
-Also, if the user defined a `help` subcommand themselves, the auto-generated one wouldn't be added (meaning it's only generated if the user hasn't defined one themselves).
-
diff --git a/README.md b/README.md
index f0bac9db..e8e7e464 100644
--- a/README.md
+++ b/README.md
@@ -1,49 +1,61 @@
-<!-- omit in TOC -->
-# clap
+clap
+====
 
-[![Crates.io](https://img.shields.io/crates/v/clap?style=flat-square)](https://crates.io/crates/clap)
-[![Crates.io](https://img.shields.io/crates/d/clap?style=flat-square)](https://crates.io/crates/clap)
-[![License](https://img.shields.io/badge/license-Apache%202.0-blue?style=flat-square)](https://github.com/clap-rs/clap/blob/master/LICENSE-APACHE)
-[![License](https://img.shields.io/badge/license-MIT-blue?style=flat-square)](https://github.com/clap-rs/clap/blob/master/LICENSE-MIT)
-[![Coverage Status](https://img.shields.io/coveralls/github/clap-rs/clap/master?style=flat-square)](https://coveralls.io/github/clap-rs/clap?branch=master)
-[![Linux Build Status](https://img.shields.io/travis/clap-rs/clap/master?style=flat-square&logo=linux&logoColor=fff)](https://travis-ci.org/clap-rs/clap)
-[![Windows Build Status](https://img.shields.io/azure-devops/build/clap-rs/3b9343e1-29b0-47be-acec-1edcdab69de9/1/master?style=flat-square&logo=windows)](https://dev.azure.com/clap-rs/clap/_build/latest?definitionId=1&branchName=master)
+[![Crates.io](https://img.shields.io/crates/v/clap.svg)](https://crates.io/crates/clap) [![Crates.io](https://img.shields.io/crates/d/clap.svg)](https://crates.io/crates/clap) [![license](https://img.shields.io/badge/license-Apache%202.0-blue.svg)](https://github.com/clap-rs/clap/blob/master/LICENSE-APACHE) [![license](http://img.shields.io/badge/license-MIT-blue.svg)](https://github.com/clap-rs/clap/blob/master/LICENSE-MIT) [![Coverage Status](https://coveralls.io/repos/clap-rs/clap/badge.svg?branch=master&service=github)](https://coveralls.io/github/clap-rs/clap?branch=master)
+
+Linux: [![Build Status](https://travis-ci.org/clap-rs/clap.svg?branch=master)](https://travis-ci.org/clap-rs/clap)
+Windows: [![Build Status](https://dev.azure.com/clap-rs/clap/_apis/build/status/clap-rs.clap?branchName=master)](https://dev.azure.com/clap-rs/clap/_build/latest?definitionId=1&branchName=master)
 
 Command Line Argument Parser for Rust
 
-It is a simple-to-use, efficient, and full-featured library for parsing command line arguments and subcommands when writing command line, console or terminal applications.
+It is a simple-to-use, efficient, and full-featured library for parsing command line arguments and subcommands when writing console/terminal applications.
 
-* [Documentation][docs]
+* [Documentation](https://docs.rs/clap/)
 * [Questions & Discussions](https://github.com/clap-rs/clap/discussions)
 * [Website](https://clap.rs/)
-
-We are currently hard at work trying to release `3.0`. We have a `3.0.0-beta.1` prerelease out but we do not give any guarantees that it's API is stable. We do not have a changelog yet which will be written down after we are sure about the API stability. We recommend users to not update to the prerelease version yet and to wait for the official `3.0`.
-
-> If you're looking for the readme & examples for `clap v2.33` - find it on [github](https://github.com/clap-rs/clap/tree/v2.33.0), [crates.io](https://crates.io/crates/clap/2.33.0), [docs.rs](https://docs.rs/clap/2.33.0/clap/).
-
-1. [About](#about)
-2. [FAQ](#faq)
-3. [Features](#features)
-4. [Quick Example](#quick-example)
-      1. [Using Derive Macros](#using-derive-macros)
-      2. [Using Builder Pattern](#using-builder-pattern)
-      3. [Using YAML](#using-yaml)
-      4. [Using Macros](#using-macros)
-      5. [Running it](#running-it)
-5. [Try it!](#try-it)
-   1. [Pre-Built Test](#pre-built-test)
-   2. [Build Your Own Binary](#build-your-own-binary)
-6. [Usage](#usage)
-   1. [Optional Dependencies / Features](#optional-dependencies--features)
-      1. [Features enabled by default](#features-enabled-by-default)
-      2. [Opt-in features](#opt-in-features)
-   2. [More Information](#more-information)
-7. [Contributing](#contributing)
-   1. [Compatibility Policy](#compatibility-policy)
-      1. [Minimum Supported Version of Rust (MSRV)](#minimum-supported-version-of-rust-msrv)
-      2. [Breaking Changes](#breaking-changes)
-8. [License](#license)
-9. [Related Crates](#related-crates)
+* [Video tutorials](https://www.youtube.com/playlist?list=PLza5oFLQGTl2Z5T8g1pRkIynR3E0_pc7U)
+
+> **IMPORTANT!**
+> This readme describes `clap v3.0.0` which is still under development and will be published soon-ish.
+> It was not published on crates.io yet, and if you want to use this preview anyway, use
+> ```toml,no_sync
+> clap = { git = "https://github.com/clap-rs/clap/" }
+> ```
+>
+> If you're looking for the readme for `clap v2.33` - find it on [github](https://github.com/clap-rs/clap/tree/v2.33.0), [crates.io](https://crates.io/crates/clap/2.33.0), [docs.rs](https://docs.rs/clap/2.33.0/clap/).
+
+
+Table of Contents
+=================
+
+* [What's New](#whats-new)
+* [About](#about)
+* [FAQ](#faq)
+* [Features](#features)
+* [Quick Example](#quick-example)
+* [Try it!](#try-it)
+  * [Pre-Built Test](#pre-built-test)
+  * [BYOB (Build Your Own Binary)](#byob-build-your-own-binary)
+* [Usage](#usage)
+  * [Optional Dependencies / Features](#optional-dependencies--features)
+  * [Dependencies Tree](#dependencies-tree)
+  * [More Information](#more-information)
+    * [Video Tutorials](#video-tutorials)
+* [How to Contribute](#how-to-contribute)
+  * [Compatibility Policy](#compatibility-policy)
+    * [Minimum Version of Rust](#minimum-version-of-rust)
+* [Related Crates](#related-crates)
+* [License](#license)
+* [Recent Breaking Changes](#recent-breaking-changes)
+  * [Deprecations](#deprecations)
+
+Created by [gh-md-toc](https://github.com/ekalinin/github-markdown-toc)
+
+## What's New
+
+Here's whats new in 3.0.0-alpha.1:
+
+For full details, see [CHANGELOG.md](https://github.com/clap-rs/clap/blob/master/CHANGELOG.md)
 
 ## About
 
@@ -55,11 +67,47 @@ Once `clap` parses the user provided string of arguments, it returns the matches
 
 ## FAQ
 
-For a full FAQ, see [this](FAQ.md)
+For a full FAQ and more in depth details, see [the wiki page](https://github.com/clap-rs/clap/wiki/FAQ)
+
+### Comparisons
+
+First, let me say that these comparisons are highly subjective, and not meant in a critical or harsh manner. All the argument parsing libraries out there (to include `clap`) have their own strengths and weaknesses. Sometimes it just comes down to personal taste when all other factors are equal. When in doubt, try them all and pick one that you enjoy :) There's plenty of room in the Rust community for multiple implementations!
+
+#### How does `clap` compare to [structopt](https://github.com/TeXitoi/structopt)?
+
+Simple! `clap` *is* `structopt`. With the 3.0 release, `clap` imported the `structopt` code into it's own codebase as the [`clap_derive`](https://github.com/clap-rs/clap_derive) crate. Since `structopt` already used `clap` under the hood, the transition was nearly painless, and is 100% feature compatible.
+
+If you were using `structopt` before, the only thing you should have to do is change the attributes from `#[structopt(...)]` to `#[clap(...)]`.
+
+Also the derive statements changed from `#[derive(Structopt)]` to `#[derive(Clap)]`. There is also some additional functionality that's been added to the `clap_derive` crate. See the documentation for that crate, for more details.
+
+#### How does `clap` compare to [getopts](https://github.com/rust-lang-nursery/getopts)?
+
+`getopts` is a very basic, fairly minimalist argument parsing library. This isn't a bad thing, sometimes you don't need tons of features, you just want to parse some simple arguments, and have some help text generated for you based on valid arguments you specify. The downside to this approach is that you must manually implement most of the common features (such as checking to display help messages, usage strings, etc.). If you want a highly custom argument parser, and don't mind writing the majority of the functionality yourself, `getopts` is an excellent base.
+
+`getopts` also doesn't allocate much, or at all. This gives it a very small performance boost. Although, as you start implementing additional features, that boost quickly disappears.
+
+Personally, I find many, many uses of `getopts` are manually implementing features that `clap` provides by default. Using `clap` simplifies your codebase allowing you to focus on your application, and not argument parsing.
+
+#### How does `clap` compare to [docopt.rs](https://github.com/docopt/docopt.rs)?
+
+I first want to say I'm a big a fan of BurntSushi's work, the creator of `Docopt.rs`. I aspire to produce the quality of libraries that this man does! When it comes to comparing these two libraries they are very different. `docopt` tasks you with writing a help message, and then it parses that message for you to determine all valid arguments and their use. Some people LOVE this approach, others do not. If you're willing to write a detailed help message, it's nice that you can stick that in your program and have `docopt` do the rest. On the downside, it's far less flexible.
+
+`docopt` is also excellent at translating arguments into Rust types automatically. There is even a syntax extension which will do all this for you, if you're willing to use a nightly compiler (use of a stable compiler requires you to somewhat manually translate from arguments to Rust types). To use BurntSushi's words, `docopt` is also a sort of black box. You get what you get, and it's hard to tweak implementation or customize the experience for your use case.
+
+Because `docopt` is doing a ton of work to parse your help messages and determine what you were trying to communicate as valid arguments, it's also one of the more heavy weight parsers performance-wise. For most applications this isn't a concern and this isn't to say `docopt` is slow, in fact far from it. This is just something to keep in mind while comparing.
+
+#### All else being equal, what are some reasons to use `clap`? (The Pitch)
+
+`clap` is as fast, and as lightweight as possible while still giving all the features you'd expect from a modern argument parser. In fact, for the amount and type of features `clap` offers it remains about as fast as `getopts`. If you use `clap` when just need some simple arguments parsed, you'll find it's a walk in the park. `clap` also makes it possible to represent extremely complex, and advanced requirements, without too much thought. `clap` aims to be intuitive, easy to use, and fully capable for wide variety use cases and needs.
+
+#### All else being equal, what are some reasons *not* to use `clap`? (The Anti Pitch)
+
+Depending on the style in which you choose to define the valid arguments, `clap` can be very verbose. `clap` also offers so many finetuning knobs and dials, that learning everything can seem overwhelming. I strive to keep the simple cases simple, but when turning all those custom dials it can get complex. `clap` is also opinionated about parsing. Even though so much can be tweaked and tuned with `clap` (and I'm adding more all the time), there are still certain features which `clap` implements in specific ways which may be contrary to some users use-cases. Finally, `clap` is "stringly typed" when referring to arguments which can cause typos in code. This particular paper-cut is being actively worked on, and should be gone in v3.x.
 
 ## Features
 
-Below are a few of the features which `clap` supports, full descriptions and usage can be found in the [documentation][docs] and [examples][examples] directory
+Below are a few of the features which `clap` supports, full descriptions and usage can be found in the [documentation](https://docs.rs/clap/) and [examples/](examples) directory
 
 * Generate a CLI simply by defining a struct!
 * **Auto-generated Help, Version, and Usage information**
@@ -114,22 +162,13 @@ Below are a few of the features which `clap` supports, full descriptions and usa
 
 ## Quick Example
 
-The following examples show a quick example of some of the very basic functionality of `clap`. For more advanced usage, such as requirements, conflicts, groups, multiple values and occurrences see the [documentation][docs], [examples][examples] directory of this repository.
+The following examples show a quick example of some of the very basic functionality of `clap`. For more advanced usage, such as requirements, conflicts, groups, multiple values and occurrences see the [documentation](https://docs.rs/clap/), [examples/](examples) directory of this repository or the [video tutorials](https://www.youtube.com/playlist?list=PLza5oFLQGTl2Z5T8g1pRkIynR3E0_pc7U).
 
  **NOTE:** All of these examples are functionally the same, but show different styles in which to use `clap`. These different styles are purely a matter of personal preference.
 
-Add `clap` to your `Cargo.toml`
-
-```toml
-[dependencies]
-clap = "3.0.0-beta.1"
-```
-
-#### Using Derive Macros
-
 The first example shows the simplest way to use `clap`, by defining a struct. If you're familiar with the `structopt` crate you're in luck, it's the same! (In fact it's the exact same code running under the covers!)
 
-```rust,no_run
+```rust
 // (Full example with detailed comments in examples/01d_quick_example.rs)
 //
 // This example demonstrates clap's full 'custom derive' style of creating arguments which is the
@@ -139,15 +178,15 @@ use clap::Clap;
 /// This doc string acts as a help message when the user runs '--help'
 /// as do all doc strings on fields
 #[derive(Clap)]
-#[clap(version = "1.0", author = "Kevin K. <kbknapp@gmail.com>")]
+#[clap(version = "1.0", author = "Kevin K.")]
 struct Opts {
     /// Sets a custom config file. Could have been an Option<T> with no default too
-    #[clap(short, long, default_value = "default.conf")]
+    #[clap(short = "c", long = "config", default_value = "default.conf")]
     config: String,
     /// Some input. Because this isn't an Option<T> it's required to be used
     input: String,
     /// A level of verbosity, and can be used multiple times
-    #[clap(short, long, parse(from_occurrences))]
+    #[clap(short = "v", long = "verbose", parse(from_occurrences))]
     verbose: i32,
     #[clap(subcommand)]
     subcmd: SubCommand,
@@ -155,7 +194,8 @@ struct Opts {
 
 #[derive(Clap)]
 enum SubCommand {
-    #[clap(version = "1.3", author = "Someone E. <someone_else@other.com>")]
+    /// A help message for the Test subcommand
+    #[clap(name = "test", version = "1.3", author = "Someone Else")]
     Test(Test),
 }
 
@@ -163,7 +203,7 @@ enum SubCommand {
 #[derive(Clap)]
 struct Test {
     /// Print debug info
-    #[clap(short)]
+    #[clap(short = "d")]
     debug: bool
 }
 
@@ -199,44 +239,42 @@ fn main() {
 }
 ```
 
-#### Using Builder Pattern
-
 This second method shows a method using the 'Builder Pattern' which allows more advanced configuration options (not shown in this small example), or even dynamically generating arguments when desired. The downside is it's more verbose.
 
-```rust,no_run
+```rust
 // (Full example with detailed comments in examples/01a_quick_example.rs)
 //
 // This example demonstrates clap's "builder pattern" method of creating arguments
 // which the most flexible, but also most verbose.
-use clap::{Arg, App};
+use clap::{Arg, App, SubCommand};
 
 fn main() {
     let matches = App::new("My Super Program")
-        .version("1.0")
-        .author("Kevin K. <kbknapp@gmail.com>")
-        .about("Does awesome things")
-        .arg(Arg::with_name("config")
-            .short('c')
-            .long("config")
-            .value_name("FILE")
-            .about("Sets a custom config file")
-            .takes_value(true))
-        .arg(Arg::with_name("INPUT")
-            .about("Sets the input file to use")
-            .required(true)
-            .index(1))
-        .arg(Arg::with_name("v")
-            .short('v')
-            .multiple(true)
-            .about("Sets the level of verbosity"))
-        .subcommand(App::new("test")
-            .about("controls testing features")
-            .version("1.3")
-            .author("Someone E. <someone_else@other.com>")
-            .arg(Arg::with_name("debug")
-                .short('d')
-                .about("print debug information verbosely")))
-        .get_matches();
+                          .version("1.0")
+                          .author("Kevin K. <kbknapp@gmail.com>")
+                          .about("Does awesome things")
+                          .arg(Arg::with_name("config")
+                               .short('c')
+                               .long("config")
+                               .value_name("FILE")
+                               .help("Sets a custom config file")
+                               .takes_value(true))
+                          .arg(Arg::with_name("INPUT")
+                               .help("Sets the input file to use")
+                               .required(true)
+                               .index(1))
+                          .arg(Arg::with_name("v")
+                               .short('v')
+                               .multiple(true)
+                               .help("Sets the level of verbosity"))
+                          .subcommand(SubCommand::with_name("test")
+                                      .about("controls testing features")
+                                      .version("1.3")
+                                      .author("Someone E. <someone_else@other.com>")
+                                      .arg(Arg::with_name("debug")
+                                          .short('d')
+                                          .help("print debug information verbosely")))
+                          .get_matches();
 
     // Same as above examples...
 }
@@ -244,34 +282,33 @@ fn main() {
 
 The next example shows a far less verbose method, but sacrifices some of the advanced configuration options (not shown in this small example). This method also takes a *very* minor runtime penalty.
 
-```rust,no_run
+```rust
 // (Full example with detailed comments in examples/01a_quick_example.rs)
 //
 // This example demonstrates clap's "usage strings" method of creating arguments
 // which is less verbose
-use clap::{Arg, App};
+use clap::{Arg, App, SubCommand};
 
 fn main() {
     let matches = App::new("myapp")
-        .version("1.0")
-        .author("Kevin K. <kbknapp@gmail.com>")
-        .about("Does awesome things")
-        .arg("-c, --config=[FILE] 'Sets a custom config file'")
-        .arg("<INPUT>              'Sets the input file to use'")
-        .arg("-v...                'Sets the level of verbosity'")
-        .subcommand(App::new("test")
-            .about("controls testing features")
-            .version("1.3")
-            .author("Someone E. <someone_else@other.com>")
-            .arg("-d, --debug 'Print debug information'"))
-        .get_matches();
+                          .version("1.0")
+                          .author("Kevin K. <kbknapp@gmail.com>")
+                          .about("Does awesome things")
+                          .args_from_usage(
+                              "-c, --config=[FILE] 'Sets a custom config file'
+                              <INPUT>              'Sets the input file to use'
+                              -v...                'Sets the level of verbosity'")
+                          .subcommand(SubCommand::with_name("test")
+                                      .about("controls testing features")
+                                      .version("1.3")
+                                      .author("Someone E. <someone_else@other.com>")
+                                      .arg("-d, --debug 'Print debug information'"))
+                          .get_matches();
 
     // Same as previous example...
 }
 ```
 
-#### Using YAML
-
 This third method shows how you can use a YAML file to build your CLI and keep your Rust source tidy
 or support multiple localized translations by having different YAML files for each localization.
 
@@ -287,16 +324,16 @@ args:
         short: c
         long: config
         value_name: FILE
-        about: Sets a custom config file
+        help: Sets a custom config file
         takes_value: true
     - INPUT:
-        about: Sets the input file to use
+        help: Sets the input file to use
         required: true
         index: 1
     - verbose:
         short: v
         multiple: true
-        about: Sets the level of verbosity
+        help: Sets the level of verbosity
 subcommands:
     - test:
         about: controls testing features
@@ -305,21 +342,16 @@ subcommands:
         args:
             - debug:
                 short: d
-                about: print debug information
+                help: print debug information
 ```
 
 Since this feature requires additional dependencies that not everyone may want, it is *not* compiled in by default and we need to enable a feature flag in Cargo.toml:
 
-Simply add the `yaml` feature flag to your `Cargo.toml`.
-
-```toml
-[dependencies]
-clap = { version = "3.0.0-beta.1", features = ["yaml"] }
-```
+Simply change your `clap = "3.0.0-beta.1"` to `clap = {version = "3.0.0-beta.1", features = ["yaml"]}`.
 
 Finally we create our `main.rs` file just like we would have with the previous two examples:
 
-```rust,ignore
+```rust
 // (Full example with detailed comments in examples/17_yaml.rs)
 //
 // This example demonstrates clap's building from YAML style of creating arguments which is far
@@ -335,39 +367,9 @@ fn main() {
 }
 ```
 
-#### Using Macros
-
-Finally there is a macro version, which is like a hybrid approach offering the speed of the
-builder pattern (the first example), but without all the verbosity.
-
-```rust,no_run
-use clap::clap_app;
-
-fn main() {
-    let matches = clap_app!(myapp =>
-        (version: "1.0")
-        (author: "Kevin K. <kbknapp@gmail.com>")
-        (about: "Does awesome things")
-        (@arg CONFIG: -c --config +takes_value "Sets a custom config file")
-        (@arg INPUT: +required "Sets the input file to use")
-        (@arg debug: -d ... "Sets the level of debugging information")
-        (@subcommand test =>
-            (about: "controls testing features")
-            (version: "1.3")
-            (author: "Someone E. <someone_else@other.com>")
-            (@arg verbose: -v --verbose "Print test information verbosely")
-        )
-    ).get_matches();
-
-    // Same as previous examples...
-}
-```
-
-#### Running it
-
 If you were to compile any of the above programs and run them with the flag `--help` or `-h` (or `help` subcommand, since we defined `test` as a subcommand) the following would be output (except the first example where the help message sort of explains the Rust code).
 
-```bash
+```sh
 $ myprog --help
 My Super Program 1.0
 Kevin K. <kbknapp@gmail.com>
@@ -398,7 +400,7 @@ SUBCOMMANDS:
 
 ### Pre-Built Test
 
-To try out the pre-built [examples][examples], use the following steps:
+To try out the pre-built examples, use the following steps:
 
 * Clone the repository `$ git clone https://github.com/clap-rs/clap && cd clap/`
 * Compile the example `$ cargo build --example <EXAMPLE>`
@@ -406,24 +408,49 @@ To try out the pre-built [examples][examples], use the following steps:
 * Play with the arguments!
 * You can also do a onetime run via `$ cargo run --example <EXAMPLE> -- [args to example]`
 
-### Build Your Own Binary
+### BYOB (Build Your Own Binary)
 
 To test out `clap`'s default auto-generated help/version follow these steps:
 * Create a new cargo project `$ cargo new fake --bin && cd fake`
-* Writer your program as described in the quick example section.
+* Add `clap` to your `Cargo.toml`
+
+```toml
+[dependencies]
+clap = "3.0.0-beta.1"
+```
+
+* Add the following to your `src/main.rs`
+
+```rust
+use clap::{App, Clap};
+
+#[derive(Clap)]
+#[clap(version = "v1.0-beta")]
+/// My First clap CLI!
+struct Opts;
+
+fn main() {
+    Opts::parse();
+}
+```
+
 * Build your program `$ cargo build --release`
 * Run with help or version `$ ./target/release/fake --help` or `$ ./target/release/fake --version`
 
 ## Usage
 
-For full usage, add `clap` as a dependency in your `Cargo.toml` to use from crates.io:
+For full usage, add `clap` as a dependency in your `Cargo.toml` () to use from crates.io:
 
 ```toml
 [dependencies]
-clap = "3.0.0-beta.1"
+clap = "~3.0.0-beta.1"
 ```
 
-Define a list of valid arguments for your program (see the [documentation][docs] or [examples][examples] directory of this repo)
+(**note**: If you are concerned with supporting a minimum version of Rust that is *older* than the current stable Rust minus 2 stable releases, it's recommended to use the `~major.minor.patch` style versions in your `Cargo.toml` which will only update the patch version automatically. For more information see the [Compatibility Policy](#compatibility-policy))
+
+Then add `extern crate clap;` to your crate root.
+
+Define a list of valid arguments for your program (see the [documentation](https://docs.rs/clap/) or [examples/](examples) directory of this repo)
 
 Then run `cargo build` or `cargo update && cargo build` for your project.
 
@@ -433,7 +460,8 @@ Then run `cargo build` or `cargo update && cargo build` for your project.
 
 * **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. (builds dependency `termcolor`)
+* **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`:
 
@@ -460,13 +488,23 @@ features = [ "suggestions", "color" ]
 * **"unstable"**: Enables unstable `clap` features that may change from release to release
 * **"wrap_help"**: Turns on the help text wrapping feature, based on the terminal size. (builds dependency `term-size`)
 
+### Dependencies Tree
+
+@TODO-v3-beta: update
+
 ### More Information
 
-You can find complete documentation on the [docs.rs][docs] for this project.
+You can find complete documentation on the [docs.rs](https://docs.rs/clap/) for this project.
+
+You can also find usage examples in the [examples/](examples) directory of this repo.
+
+#### Video Tutorials
 
-You can also find usage examples in the [examples][examples] directory of this repo.
+There's also the video tutorial series [Argument Parsing with Rust v2](https://www.youtube.com/playlist?list=PLza5oFLQGTl2Z5T8g1pRkIynR3E0_pc7U).
 
-## Contributing
+These videos slowly trickle out as I finish them and currently a work in progress.
+
+## How to Contribute
 
 Details on how to contribute can be found in the [CONTRIBUTING.md](CONTRIBUTING.md) file.
 
@@ -485,24 +523,79 @@ clap = "~3.0.0-beta.1"
 
 This will cause *only* the patch version to be updated upon a `cargo update` call, and therefore cannot break due to new features, or bumped minimum versions of Rust.
 
+#### Warning about '~' Dependencies
+
+Using `~` can cause issues in certain circumstances.
+
+From @alexcrichton:
+
+Right now Cargo's version resolution is pretty naive, it's just a brute-force search of the solution space, returning the first resolvable graph. This also means that it currently won't terminate until it proves there is not possible resolvable graph. This leads to situations where workspaces with multiple binaries, for example, have two different dependencies such as:
+
+```toml,no_sync
+
+# In one Cargo.toml
+[dependencies]
+clap = "~3.0.0-beta.1"
+
+# In another Cargo.toml
+[dependencies]
+clap = "3.0.0-beta.1"
+```
+
+This is inherently an unresolvable crate graph in Cargo right now. Cargo requires there's only one major version of a crate, and being in the same workspace these two crates must share a version. This is impossible in this location, though, as these version constraints cannot be met.
+
 #### Minimum Supported Version of Rust (MSRV)
 
 `clap` will officially support current stable Rust, minus two releases, but may work with prior releases as well. For example, current stable Rust at the time of this writing is 1.38.0, meaning `clap` is guaranteed to compile with 1.36.0 and beyond.
 
 At the 1.39.0 stable release, `clap` will be guaranteed to compile with 1.37.0 and beyond, etc.
 
-The following is a list of the minimum required version of Rust to compile `clap` by our `MAJOR.MINOR` version number:
-
-|  clap  |  MSRV  |
-| :----: | :----: |
-| >=3.0  | 1.40.0 |
-| >=2.21 | 1.24.0 |
-| >=2.2  | 1.12.0 |
-| >=2.1  | 1.6.0  |
-| >=1.5  | 1.4.0  |
-| >=1.4  | 1.2.0  |
-| >=1.2  | 1.1.0  |
-| >=1.0  | 1.0.0  |
+Upon bumping the minimum version of Rust (assuming it's within the stable-2 range), it *must* be clearly annotated in the `CHANGELOG.md`
+
+The following is a list of the minimum required version of Rust to compile `clap` by our `MAJOR.MINOR` version number (generated by [`cargo-msrv-table`](https://github.com/kbknapp/cargo-msrv-table)):
+
+|clap| MSRV |
+|---| --- |
+|2.33|	1.24.1|
+|2.32|	1.24.1|
+|2.31|	1.24.1|
+|2.30|	1.24.1|
+|2.29|	1.24.1|
+|2.28|	1.24.1|
+|2.27|	1.24.1|
+|2.26|	1.24.1|
+|2.25|	1.24.1|
+|2.24|	1.24.1|
+|2.23|	1.24.1|
+|2.22|	1.24.1|
+|2.21|	1.24.1|
+|2.20|	1.21.0|
+|2.19|	1.12.1|
+|2.18|	1.12.1|
+|2.17|	1.12.1|
+|2.16|	1.12.1|
+|2.15|	1.12.1|
+|2.14|	1.12.1|
+|2.13|	1.12.1|
+|2.12|	1.12.1|
+|2.11|	1.12.1|
+|2.10|	1.12.1|
+|2.9|	1.12.1|
+|2.8|	1.12.1|
+|2.7|	1.12.1|
+|2.6|	1.12.1|
+|2.5|	1.12.1|
+|2.4|	1.12.1|
+|2.3|	1.12.1|
+|2.2|	1.12.1|
+|2.1|	1.6.0|
+|2.0|	1.4.0|
+|1.5|	1.4.0|
+|1.4|	1.2.0|
+|1.3|	1.1.0|
+|1.2|	1.1.0|
+|1.1|	1.0.0|
+|1.0|	1.0.0|
 
 #### Breaking Changes
 
@@ -522,7 +615,61 @@ See the [LICENSE-APACHE](LICENSE-APACHE) and [LICENSE-MIT](LICENSE-MIT) files in
 
 There are several excellent crates which can be used with `clap`, I recommend checking them all out! If you've got a crate that would be a good fit to be used with `clap` open an issue and let me know, I'd love to add it!
 
+* [`structopt`](https://github.com/TeXitoi/structopt) - This crate allows you to define a struct, and build a CLI from it! No more "stringly typed" and it uses `clap` behind the scenes! (*Note*: There is work underway to pull this crate into mainline `clap`).
 * [`assert_cmd`](https://github.com/assert-rs/assert_cmd) - This crate allows you test your CLIs in a very intuitive and functional way!
 
-[docs]: https://docs.rs/clap
-[examples]: examples
+## Recent Breaking Changes
+
+`clap` follows semantic versioning, so breaking changes should only happen upon major version bumps. The only exception to this rule is breaking changes that happen due to implementation that was deemed to be a bug, security concerns, or it can be reasonably proved to affect no code. For the full details, see [CHANGELOG.md](./CHANGELOG.md).
+
+As of 2.27.0:
+
+* Argument values now take precedence over subcommand names. This only arises by using unrestrained multiple values and subcommands together where the subcommand name can coincide with one of the multiple values. Such as `$ prog <files>... <subcommand>`. The fix is to place restraints on number of values, or disallow the use of `$ prog <prog-args> <subcommand>` structure.
+
+As of 2.0.0 (From 1.x)
+
+* **Fewer lifetimes! Yay!**
+ * `App<'a, 'b, 'c, 'd, 'e, 'f>` => `App<'a, 'b>`
+ * `Arg<'a, 'b, 'c, 'd, 'e, 'f>` => `Arg<'a, 'b>`
+ * `ArgMatches<'a, 'b>` => `ArgMatches<'a>`
+* **Simply Renamed**
+ * `App::arg_group` => `App::group`
+ * `App::arg_groups` => `App::groups`
+ * `ArgGroup::add` => `ArgGroup::arg`
+ * `ArgGroup::add_all` => `ArgGroup::args`
+ * `ClapError` => `Error`
+  * struct field `ClapError::error_type` => `Error::kind`
+ * `ClapResult` => `Result`
+ * `ClapErrorType` => `ErrorKind`
+* **Removed Deprecated Functions and Methods**
+ * `App::subcommands_negate_reqs`
+ * `App::subcommand_required`
+ * `App::arg_required_else_help`
+ * `App::global_version(bool)`
+ * `App::versionless_subcommands`
+ * `App::unified_help_messages`
+ * `App::wait_on_error`
+ * `App::subcommand_required_else_help`
+ * `SubCommand::new`
+ * `App::error_on_no_subcommand`
+ * `Arg::new`
+ * `Arg::mutually_excludes`
+ * `Arg::mutually_excludes_all`
+ * `Arg::mutually_overrides_with`
+ * `simple_enum!`
+* **Renamed Error Variants**
+ * `InvalidUnicode` => `InvalidUtf8`
+ * `InvalidArgument` => `UnknownArgument`
+* **Usage Parser**
+ * Value names can now be specified inline, i.e. `-o, --option <FILE> <FILE2> 'some option which takes two files'`
+ * **There is now a priority of order to determine the name** - This is perhaps the biggest breaking change. See the documentation for full details. Prior to this change, the value name took precedence. **Ensure your args are using the proper names (i.e. typically the long or short and NOT the value name) throughout the code**
+* `ArgMatches::values_of` returns an `Values` now which implements `Iterator` (should not break any code)
+* `crate_version!` returns `&'static str` instead of `String`
+
+### Deprecations
+
+Old method names will be left around for several minor version bumps, or one major version bump.
+
+As of 2.27.0:
+
+* **AppSettings::PropagateGlobalValuesDown:**  this setting deprecated and is no longer required to propagate values down or up
diff --git a/clap_derive/Cargo.toml b/clap_derive/Cargo.toml
index ede7a3ef..a5498a1d 100644
--- a/clap_derive/Cargo.toml
+++ b/clap_derive/Cargo.toml
@@ -43,7 +43,7 @@ heck = "0.3.0"
 proc-macro-error = "0.4.9"
 
 [dev-dependencies]
-clap = { path = "../" }
+clap = { path = "../", version = "3.0.0-beta.1" }
 trybuild = "1.0"
 rustversion = "1"
 version-sync = "0.8"
diff --git a/clap_generate/Cargo.toml b/clap_generate/Cargo.toml
index 3e19d38a..b4104837 100644
--- a/clap_generate/Cargo.toml
+++ b/clap_generate/Cargo.toml
@@ -21,6 +21,7 @@ keywords = [
 	"generate",
 	"completion",
 	"manpage",
+	"parse"
 ]
 categories = ["command-line-interface"]
 license = "MIT OR Apache-2.0"
diff --git a/examples/01a_quick_example.rs b/examples/01a_quick_example.rs
index 548bf4fd..2311bf80 100644
--- a/examples/01a_quick_example.rs
+++ b/examples/01a_quick_example.rs
@@ -58,7 +58,7 @@ fn main() {
         0 => println!("Debug mode is off"),
         1 => println!("Debug mode is kind of on"),
         2 => println!("Debug mode is on"),
-        _ => println!("Don't be crazy"),
+        3 | _ => println!("Don't be crazy"),
     }
 
     // You can check for the existence of subcommands, and if found use their
diff --git a/examples/01b_quick_example.rs b/examples/01b_quick_example.rs
index 3eac6a3d..dd2d924c 100644
--- a/examples/01b_quick_example.rs
+++ b/examples/01b_quick_example.rs
@@ -76,7 +76,7 @@ fn main() {
         0 => println!("Debug mode is off"),
         1 => println!("Debug mode is kind of on"),
         2 => println!("Debug mode is on"),
-        _ => println!("Don't be crazy"),
+        3 | _ => println!("Don't be crazy"),
     }
 
     // You can check for the existence of subcommands, and if found use their
diff --git a/examples/01c_quick_example.rs b/examples/01c_quick_example.rs
index 937dfb57..73cacb9d 100644
--- a/examples/01c_quick_example.rs
+++ b/examples/01c_quick_example.rs
@@ -58,7 +58,7 @@ fn main() {
         0 => println!("Debug mode is off"),
         1 => println!("Debug mode is kind of on"),
         2 => println!("Debug mode is on"),
-        _ => println!("Don't be crazy"),
+        3 | _ => println!("Don't be crazy"),
     }
 
     // You can information about subcommands by requesting their matches by name
diff --git a/examples/05_flag_args.rs b/examples/05_flag_args.rs
index ee1b02e0..e800d77d 100644
--- a/examples/05_flag_args.rs
+++ b/examples/05_flag_args.rs
@@ -47,7 +47,7 @@ fn main() {
         0 => println!("Nothing is awesome"),
         1 => println!("Some things are awesome"),
         2 => println!("Lots of things are awesome"),
-        _ => println!("EVERYTHING is awesome!"),
+        3 | _ => println!("EVERYTHING is awesome!"),
     }
 
     // Continued program logic goes here...
diff --git a/examples/18_builder_macro.rs b/examples/18_builder_macro.rs
index 01ce0ab6..38bc2973 100644
--- a/examples/18_builder_macro.rs
+++ b/examples/18_builder_macro.rs
@@ -63,7 +63,7 @@ fn main() {
         0 => println!("Debug mode is off"),
         1 => println!("Debug mode is kind of on"),
         2 => println!("Debug mode is on"),
-        _ => println!("Don't be crazy"),
+        3 | _ => println!("Don't be crazy"),
     }
 
     // You can check for the existence of subcommands, and if found use their
diff --git a/src/build/app/mod.rs b/src/build/app/mod.rs
index ba8b4166..8a38feff 100644
--- a/src/build/app/mod.rs
+++ b/src/build/app/mod.rs
@@ -31,12 +31,11 @@ use crate::{
 
 // FIXME (@CreepySkeleton): some of these variants are never constructed
 #[derive(Clone, Debug, PartialEq, Eq)]
+#[allow(unused)]
 pub(crate) enum Propagation {
     To(Id),
     Full,
-    #[cfg_attr(not(test), allow(unused))]
     NextLevel,
-    #[allow(unused)]
     None,
 }
 
@@ -1583,7 +1582,6 @@ impl<'b> App<'b> {
         }
     }
 
-    #[cfg(debug_assertions)]
     fn two_args_of<F>(&self, condition: F) -> Option<(&Arg, &Arg)>
     where
         F: Fn(&Arg<'_>) -> bool,
@@ -1602,7 +1600,6 @@ impl<'b> App<'b> {
 
     // Perform some expensive assertions on the Parser itself
     #[allow(clippy::cognitive_complexity)]
-    #[cfg(debug_assertions)]
     fn _debug_asserts(&self) {
         debug!("App::_debug_asserts");
 
@@ -2009,7 +2006,6 @@ impl<'b> App<'b> {
             .any(|sc| !sc.is_set(AppSettings::Hidden))
     }
 
-    #[cfg(debug_assertions)]
     pub(crate) fn id_exists(&self, id: &Id) -> bool {
         self.args.args.iter().any(|x| x.id == *id) || self.groups.iter().any(|x| x.id == *id)
     }
diff --git a/src/build/arg/mod.rs b/src/build/arg/mod.rs
index 7a92a037..17d4b5c1 100644
--- a/src/build/arg/mod.rs
+++ b/src/build/arg/mod.rs
@@ -67,6 +67,7 @@ pub struct Arg<'help> {
     pub(crate) short: Option<char>,
     pub(crate) long: Option<&'help str>,
     pub(crate) aliases: Option<Vec<(&'help str, bool)>>, // (name, visible)
+    pub(crate) short_aliases: Vec<(char, bool)>,         // (name, visible)
     pub(crate) disp_ord: usize,
     pub(crate) unified_ord: usize,
     pub(crate) possible_vals: Option<Vec<&'help str>>,
@@ -195,6 +196,7 @@ impl<'help> Arg<'help> {
                 "short" => yaml_to_char!(a, v, short),
                 "long" => yaml_to_str!(a, v, long),
                 "aliases" => yaml_vec_or_str!(v, a, alias),
+                "short_aliases" => yaml_to_chars!(a, v, short_aliases),
                 "about" => yaml_to_str!(a, v, about),
                 "long_about" => yaml_to_str!(a, v, long_about),
                 "help" => yaml_to_str!(a, v, about),
@@ -364,6 +366,36 @@ impl<'help> Arg<'help> {
         self
     }
 
+    /// Allows adding a [`Arg`] alias, which function as "hidden" arguments that
+    /// automatically dispatch as if this argument was used. This is more efficient, and easier
+    /// than creating multiple hidden arguments as one only needs to check for the existence of
+    /// this command, and not all variants.
+    ///
+    /// # Examples
+    ///
+    /// ```rust
+    /// # use clap::{App, Arg};
+    /// let m = App::new("prog")
+    ///             .arg(Arg::with_name("test")
+    ///             .short('t')
+    ///             .short_alias('e')
+    ///             .takes_value(true))
+    ///        .get_matches_from(vec![
+    ///             "prog", "-e", "cool"
+    ///         ]);
+    /// assert!(m.is_present("test"));
+    /// assert_eq!(m.value_of("test"), Some("cool"));
+    /// ```
+    /// [`Arg`]: ./struct.Arg.html
+    pub fn short_alias(mut self, name: char) -> Self {
+        if name == '-' {
+            panic!("short alias name cannot be `-`");
+        }
+
+        self.short_aliases.push((name, false));
+        self
+    }
+
     /// Allows adding [`Arg`] aliases, which function as "hidden" arguments that
     /// automatically dispatch as if this argument was used. This is more efficient, and easier
     /// than creating multiple hidden subcommands as one only needs to check for the existence of
@@ -396,6 +428,37 @@ impl<'help> Arg<'help> {
         self
     }
 
+    /// Allows adding [`Arg`] aliases, which function as "hidden" arguments that
+    /// automatically dispatch as if this argument was used. This is more efficient, and easier
+    /// than creating multiple hidden subcommands as one only needs to check for the existence of
+    /// this command, and not all variants.
+    ///
+    /// # Examples
+    ///
+    /// ```rust
+    /// # use clap::{App, Arg};
+    /// let m = App::new("prog")
+    ///             .arg(Arg::with_name("test")
+    ///                     .short('t')
+    ///                     .short_aliases(&['e', 's'])
+    ///                     .help("the file to add")
+    ///                     .required(false))
+    ///             .get_matches_from(vec![
+    ///                 "prog", "-s"
+    ///             ]);
+    /// assert!(m.is_present("test"));
+    /// ```
+    /// [`Arg`]: ./struct.Arg.html
+    pub fn short_aliases(mut self, names: &[char]) -> Self {
+        for s in names {
+            if s == &'-' {
+                panic!("short alias name cannot be `-`");
+            }
+            self.short_aliases.push((*s, false));
+        }
+        self
+    }
+
     /// Allows adding a [`Arg`] alias that functions exactly like those defined with
     /// [`Arg::alias`], except that they are visible inside the help message.
     ///
@@ -425,6 +488,35 @@ impl<'help> Arg<'help> {
         self
     }
 
+    /// Allows adding a [`Arg`] alias that functions exactly like those defined with
+    /// [`Arg::alias`], except that they are visible inside the help message.
+    ///
+    /// # Examples
+    ///
+    /// ```rust
+    /// # use clap::{App, Arg};
+    /// let m = App::new("prog")
+    ///             .arg(Arg::with_name("test")
+    ///                 .long("test")
+    ///                 .visible_short_alias('t')
+    ///                 .takes_value(true))
+    ///        .get_matches_from(vec![
+    ///             "prog", "-t", "coffee"
+    ///         ]);
+    /// assert!(m.is_present("test"));
+    /// assert_eq!(m.value_of("test"), Some("coffee"));
+    /// ```
+    /// [`Arg`]: ./struct.Arg.html
+    /// [`App::alias`]: ./struct.Arg.html#method.short_alias
+    pub fn visible_short_alias(mut self, name: char) -> Self {
+        if name == '-' {
+            panic!("short alias name cannot be `-`");
+        }
+
+        self.short_aliases.push((name, true));
+        self
+    }
+
     /// Allows adding multiple [`Arg`] aliases that functions exactly like those defined
     /// with [`Arg::aliases`], except that they are visible inside the help message.
     ///
@@ -454,6 +546,34 @@ impl<'help> Arg<'help> {
         self
     }
 
+    /// Allows adding multiple [`Arg`] aliases that functions exactly like those defined
+    /// with [`Arg::aliases`], except that they are visible inside the help message.
+    ///
+    /// # Examples
+    ///
+    /// ```rust
+    /// # use clap::{App, Arg};
+    /// let m = App::new("prog")
+    ///             .arg(Arg::with_name("test")
+    ///                 .long("test")
+    ///                 .visible_short_aliases(&['t', 'e']))
+    ///        .get_matches_from(vec![
+    ///             "prog", "-t"
+    ///         ]);
+    /// assert!(m.is_present("test"));
+    /// ```
+    /// [`Arg`]: ./struct.Arg.html
+    /// [`App::aliases`]: ./struct.Arg.html#method.short_aliases
+    pub fn visible_short_aliases(mut self, names: &[char]) -> Self {
+        for n in names {
+            if n == &'-' {
+                panic!("short alias name cannot be `-`");
+            }
+            self.short_aliases.push((*n, true));
+        }
+        self
+    }
+
     /// See [`Arg::about`](./struct.Arg.html#method.about)
     #[deprecated(since = "3.0.0", note = "Please use `about` method instead")]
     #[inline]
@@ -4363,10 +4483,10 @@ impl<'help> fmt::Debug for Arg<'help> {
             "Arg {{ id: {:X?}, name: {:?}, help: {:?}, long_help: {:?}, conflicts_with: {:?}, \
              settings: {:?}, required_unless: {:?}, overrides_with: {:?}, groups: {:?}, \
              requires: {:?}, requires_ifs: {:?}, short: {:?}, index: {:?}, long: {:?}, \
-             aliases: {:?}, possible_values: {:?}, value_names: {:?}, number_of_values: {:?}, \
-             max_values: {:?}, min_values: {:?}, value_delimiter: {:?}, default_value_ifs: {:?}, \
-             value_terminator: {:?}, display_order: {:?}, env: {:?}, unified_ord: {:?}, \
-             default_value: {:?}, validator: {}, validator_os: {} \
+             aliases: {:?}, short_aliases: {:?}, possible_values: {:?}, value_names: {:?}, \
+             number_of_values: {:?}, max_values: {:?}, min_values: {:?}, value_delimiter: {:?}, \
+             default_value_ifs: {:?}, value_terminator: {:?}, display_order: {:?}, env: {:?}, \
+             unified_ord: {:?}, default_value: {:?}, validator: {}, validator_os: {} \
              }}",
             self.id,
             self.name,
@@ -4383,6 +4503,7 @@ impl<'help> fmt::Debug for Arg<'help> {
             self.index,
             self.long,
             self.aliases,
+            self.short_aliases,
             self.possible_vals,
             self.val_names,
             self.num_vals,
@@ -4444,6 +4565,23 @@ mod test {
         assert_eq!(&*format!("{}", f), "-f");
     }
 
+    #[test]
+    fn flag_display_single_short_alias() {
+        let mut f = Arg::with_name("flg");
+        f.short = Some('a');
+        f.short_aliases = vec![('b', true)];
+
+        assert_eq!(&*format!("{}", f), "-a")
+    }
+
+    #[test]
+    fn flag_display_multiple_short_aliases() {
+        let mut f = Arg::with_name("flg");
+        f.short = Some('a');
+        f.short_aliases = vec![('b', false), ('c', true), ('d', true), ('e', true)];
+        assert_eq!(&*format!("{}", f), "-a");
+    }
+
     // Options
 
     #[test]
@@ -4496,6 +4634,27 @@ mod test {
         assert_eq!(&*format!("{}", o), "--option <opt>");
     }
 
+    #[test]
+    fn option_display_single_short_alias() {
+        let o = Arg::with_name("opt")
+            .takes_value(true)
+            .short('a')
+            .visible_short_alias('b');
+
+        assert_eq!(&*format!("{}", o), "-a <opt>");
+    }
+
+    #[test]
+    fn option_display_multiple_short_aliases() {
+        let o = Arg::with_name("opt")
+            .short('a')
+            .takes_value(true)
+            .visible_short_aliases(&['b', 'c', 'd'])
+            .short_alias('e');
+
+        assert_eq!(&*format!("{}", o), "-a <opt>");
+    }
+
     // Positionals
 
     #[test]
diff --git a/src/build/macros.rs b/src/build/macros.rs
index da241dfa..a4c2f8fe 100644
--- a/src/build/macros.rs
+++ b/src/build/macros.rs
@@ -87,6 +87,28 @@ macro_rules! yaml_char {
     }};
 }
 
+#[cfg(feature = "yaml")]
+macro_rules! yaml_chars {
+    ($v:expr) => {{
+        &$v.as_vec()
+            .unwrap_or_else(|| panic!("failed to convert YAML {:?} value to a list", $v))
+            .into_iter()
+            .map(|s| {
+                s.as_str()
+                    .unwrap_or_else(|| panic!("failed to convert YAML {:?} value to a string", s))
+            })
+            .map(|s| {
+                let mut chars = s.chars();
+                let c = chars.next().expect("short aliases must be a single char");
+                if chars.next().is_some() {
+                    panic!("short aliases must be a single char");
+                }
+                c
+            })
+            .collect::<Vec<char>>()
+    }};
+}
+
 #[cfg(feature = "yaml")]
 macro_rules! yaml_str {
     ($v:expr) => {{
@@ -102,6 +124,13 @@ macro_rules! yaml_to_char {
     }};
 }
 
+#[cfg(feature = "yaml")]
+macro_rules! yaml_to_chars {
+    ($a:ident, $v:ident, $c:ident) => {{
+        $a.$c(yaml_chars!($v))
+    }};
+}
+
 #[cfg(feature = "yaml")]
 macro_rules! yaml_to_str {
     ($a:ident, $v:ident, $c:ident) => {{
diff --git a/src/lib.rs b/src/lib.rs
index 997cbd02..1f10865b 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,13 +1,438 @@
-// Copyright ⓒ 2015-2016 Kevin B. Knapp and [`clap-rs` contributors](https://github.com/clap-rs/clap/graphs/contributors).
+// Copyright ⓒ 2015-2016 Kevin B. Knapp and [`clap-rs` contributors](https://github.com/kbknapp/clap-rs/blob/master/CONTRIBUTORS.md).
 // Licensed under the MIT license
 // (see LICENSE or <http://opensource.org/licenses/MIT>) All files in the project carrying such
 // notice may not be copied, modified, or distributed except according to those terms.
 
-#![cfg_attr(feature = "doc", feature(external_doc))]
-#![doc(html_root_url = "https://docs.rs/clap/3.0.0-beta.1")]
-#![cfg_attr(feature = "doc", doc(include = "../README.md"))]
-//! https://github.com/clap-rs/clap
+//! `clap` is a simple-to-use, efficient, and full-featured library for parsing command line
+//! arguments and subcommands when writing console/terminal applications.
+//!
+//! ## About
+//!
+//! `clap` is used to parse *and validate* the string of command line arguments provided by the user
+//! at runtime. You provide the list of valid possibilities, and `clap` handles the rest. This means
+//! you focus on your *applications* functionality, and less on the parsing and validating of
+//! arguments.
+//!
+//! `clap` also provides the traditional version and help switches (or flags) 'for free' meaning
+//! automatically with no configuration. It does this by checking the list of valid possibilities you
+//! supplied and adding only the ones you haven't already defined. If you are using subcommands,
+//! `clap` will also auto-generate a `help` subcommand for you in addition to the traditional flags.
+//!
+//! Once `clap` parses the user provided string of arguments, it returns the matches along with any
+//! applicable values. If the user made an error or typo, `clap` informs them of the mistake and
+//! exits gracefully (or returns a `Result` type and allows you to perform any clean up prior to
+//! exit). Because of this, you can make reasonable assumptions in your code about the validity of
+//! the arguments.
+//!
+//!
+//! ## Quick Example
+//!
+//! The following examples show a quick example of some of the very basic functionality of `clap`.
+//! For more advanced usage, such as requirements, conflicts, groups, multiple values and
+//! occurrences see the [documentation](https://docs.rs/clap/), [examples/] directory of
+//! this repository or the [video tutorials].
+//!
+//! **NOTE:** All of these examples are functionally the same, but show different styles in which to
+//! use `clap`
+//!
+//! The first example shows a method that allows more advanced configuration options (not shown in
+//! this small example), or even dynamically generating arguments when desired. The downside is it's
+//! more verbose.
+//!
+//! ```no_run
+//! // (Full example with detailed comments in examples/01b_quick_example.rs)
+//! //
+//! // This example demonstrates clap's full 'builder pattern' style of creating arguments which is
+//! // more verbose, but allows easier editing, and at times more advanced options, or the possibility
+//! // to generate arguments dynamically.
+//! use clap::{Arg, App, };
+//!
+//! fn main() {
+//!     let matches = App::new("My Super Program")
+//!                           .version("1.0")
+//!                           .author("Kevin K. <kbknapp@gmail.com>")
+//!                           .about("Does awesome things")
+//!                           .arg(Arg::with_name("config")
+//!                                .short('c')
+//!                                .long("config")
+//!                                .value_name("FILE")
+//!                                .help("Sets a custom config file")
+//!                                .takes_value(true))
+//!                           .arg(Arg::with_name("INPUT")
+//!                                .help("Sets the input file to use")
+//!                                .required(true)
+//!                                .index(1))
+//!                           .arg(Arg::with_name("v")
+//!                                .short('v')
+//!                                .multiple(true)
+//!                                .help("Sets the level of verbosity"))
+//!                           .subcommand(App::new("test")
+//!                                       .about("controls testing features")
+//!                                       .version("1.3")
+//!                                       .author("Someone E. <someone_else@other.com>")
+//!                                       .arg(Arg::with_name("debug")
+//!                                           .short('d')
+//!                                           .help("print debug information verbosely")))
+//!                           .get_matches();
+//!
+//!     // Gets a value for config if supplied by user, or defaults to "default.conf"
+//!     let config = matches.value_of("config").unwrap_or("default.conf");
+//!     println!("Value for config: {}", config);
+//!
+//!     // Calling .unwrap() is safe here because "INPUT" is required (if "INPUT" wasn't
+//!     // required we could have used an 'if let' to conditionally get the value)
+//!     println!("Using input file: {}", matches.value_of("INPUT").unwrap());
+//!
+//!     // Vary the output based on how many times the user used the "verbose" flag
+//!     // (i.e. 'myprog -v -v -v' or 'myprog -vvv' vs 'myprog -v'
+//!     match matches.occurrences_of("v") {
+//!         0 => println!("No verbose info"),
+//!         1 => println!("Some verbose info"),
+//!         2 => println!("Tons of verbose info"),
+//!         3 | _ => println!("Don't be crazy"),
+//!     }
+//!
+//!     // You can handle information about subcommands by requesting their matches by name
+//!     // (as below), requesting just the name used, or both at the same time
+//!     if let Some(matches) = matches.subcommand_matches("test") {
+//!         if matches.is_present("debug") {
+//!             println!("Printing debug info...");
+//!         } else {
+//!             println!("Printing normally...");
+//!         }
+//!     }
+//!
+//!     // more program logic goes here...
+//! }
+//! ```
+//!
+//! The next example shows a far less verbose method, but sacrifices some of the advanced
+//! configuration options (not shown in this small example). This method also takes a *very* minor
+//! runtime penalty.
+//!
+//! ```no_run
+//! // (Full example with detailed comments in examples/01a_quick_example.rs)
+//! //
+//! // This example demonstrates clap's "usage strings" method of creating arguments
+//! // which is less verbose
+//! use clap::{Arg, App, };
+//!
+//! fn main() {
+//!     let matches = App::new("myapp")
+//!                           .version("1.0")
+//!                           .author("Kevin K. <kbknapp@gmail.com>")
+//!                           .about("Does awesome things")
+//!                           .arg("-c, --config=[FILE] 'Sets a custom config file'")
+//!                           .arg("<INPUT>              'Sets the input file to use'")
+//!                           .arg("-v...                'Sets the level of verbosity'")
+//!                           .subcommand(App::new("test")
+//!                                       .about("controls testing features")
+//!                                       .version("1.3")
+//!                                       .author("Someone E. <someone_else@other.com>")
+//!                                       .arg("-d, --debug 'Print debug information'"))
+//!                           .get_matches();
+//!
+//!     // Same as previous example...
+//! }
+//! ```
+//!
+//! This third method shows how you can use a YAML file to build your CLI and keep your Rust source
+//! tidy or support multiple localized translations by having different YAML files for each
+//! localization.
+//!
+//! First, create the `cli.yml` file to hold your CLI options, but it could be called anything we
+//! like:
+//!
+//! ```yaml
+//! name: myapp
+//! version: "1.0"
+//! author: Kevin K. <kbknapp@gmail.com>
+//! about: Does awesome things
+//! args:
+//!     - config:
+//!         short: c
+//!         long: config
+//!         value_name: FILE
+//!         help: Sets a custom config file
+//!         takes_value: true
+//!     - INPUT:
+//!         help: Sets the input file to use
+//!         required: true
+//!         index: 1
+//!     - verbose:
+//!         short: v
+//!         multiple: true
+//!         help: Sets the level of verbosity
+//! subcommands:
+//!     - test:
+//!         about: controls testing features
+//!         version: "1.3"
+//!         author: Someone E. <someone_else@other.com>
+//!         args:
+//!             - debug:
+//!                 short: d
+//!                 help: print debug information
+//! ```
+//!
+//! Since this feature requires additional dependencies that not everyone may want, it is *not*
+//! compiled in by default and we need to enable a feature flag in Cargo.toml:
+//!
+//! Simply change your `clap = "~2.27.0"` to `clap = {version = "~2.27.0", features = ["yaml"]}`.
+//!
+//! At last we create our `main.rs` file just like we would have with the previous two examples:
+//!
+//! ```ignore
+//! // (Full example with detailed comments in examples/17_yaml.rs)
+//! //
+//! // This example demonstrates clap's building from YAML style of creating arguments which is far
+//! // more clean, but takes a very small performance hit compared to the other two methods.
+//! use clap::App;
+//!
+//! fn main() {
+//!     // The YAML file is found relative to the current file, similar to how modules are found
+//!     let yaml = load_yaml!("cli.yml");
+//!     let matches = App::from_yaml(yaml).get_matches();
+//!
+//!     // Same as previous examples...
+//! }
+//! ```
+//!
+//! Finally there is a macro version, which is like a hybrid approach offering the speed of the
+//! builder pattern (the first example), but without all the verbosity.
+//!
+//! ```no_run
+//! use clap::clap_app;
+//! fn main() {
+//!     let matches = clap_app!(myapp =>
+//!         (version: "1.0")
+//!         (author: "Kevin K. <kbknapp@gmail.com>")
+//!         (about: "Does awesome things")
+//!         (@arg CONFIG: -c --config +takes_value "Sets a custom config file")
+//!         (@arg INPUT: +required "Sets the input file to use")
+//!         (@arg debug: -d ... "Sets the level of debugging information")
+//!         (@subcommand test =>
+//!             (about: "controls testing features")
+//!             (version: "1.3")
+//!             (author: "Someone E. <someone_else@other.com>")
+//!             (@arg verbose: -v --verbose "Print test information verbosely")
+//!         )
+//!     ).get_matches();
+//!
+//!     // Same as before...
+//! }
+//! ```
+//!
+//! If you were to compile any of the above programs and run them with the flag `--help` or `-h` (or
+//! `help` subcommand, since we defined `test` as a subcommand) the following would be output
+//!
+//! ```text
+//! $ myprog --help
+//! My Super Program 1.0
+//! Kevin K. <kbknapp@gmail.com>
+//! Does awesome things
+//!
+//! USAGE:
+//!     MyApp [FLAGS] [OPTIONS] <INPUT> [SUBCOMMAND]
+//!
+//! FLAGS:
+//!     -h, --help       Prints this message
+//!     -v               Sets the level of verbosity
+//!     -V, --version    Prints version information
+//!
+//! OPTIONS:
+//!     -c, --config <FILE>    Sets a custom config file
+//!
+//! ARGS:
+//!     INPUT    The input file to use
+//!
+//! SUBCOMMANDS:
+//!     help    Prints this message
+//!     test    Controls testing features
+//! ```
+//!
+//! **NOTE:** You could also run `myapp test --help` to see similar output and options for the
+//! `test` subcommand.
+//!
+//! ## Try it!
+//!
+//! ### Pre-Built Test
+//!
+//! To try out the pre-built example, use the following steps:
+//!
+//! * Clone the repository `$ git clone https://github.com/kbknapp/clap-rs && cd clap-rs/tests`
+//! * Compile the example `$ cargo build --release`
+//! * Run the help info `$ ./target/release/claptests --help`
+//! * Play with the arguments!
+//!
+//! ### BYOB (Build Your Own Binary)
+//!
+//! To test out `clap`'s default auto-generated help/version follow these steps:
+//!
+//! * Create a new cargo project `$ cargo new fake --bin && cd fake`
+//! * Add `clap` to your `Cargo.toml`
+//!
+//! ```toml
+//! [dependencies]
+//! clap = "2"
+//! ```
+//!
+//! * Add the following to your `src/main.rs`
+//!
+//! ```no_run
+//! use clap::App;
+//!
+//! fn main() {
+//!   App::new("fake").version("v1.0-beta").get_matches();
+//! }
+//! ```
+//!
+//! * Build your program `$ cargo build --release`
+//! * Run with help or version `$ ./target/release/fake --help` or `$ ./target/release/fake
+//! --version`
+//!
+//! ## Usage
+//!
+//! For full usage, add `clap` as a dependency in your `Cargo.toml` (it is **highly** recommended to
+//! use the `~major.minor.patch` style versions in your `Cargo.toml`, for more information see
+//! [Compatibility Policy](#compatibility-policy)) to use from crates.io:
+//!
+//! ```toml
+//! [dependencies]
+//! clap = "~2.27.0"
+//! ```
+//!
+//! Or get the latest changes from the master branch at github:
+//!
+//! ```toml
+//! [dependencies.clap]
+//! git = "https://github.com/kbknapp/clap-rs.git"
+//! ```
+//!
+//! Define a list of valid arguments for your program (see the
+//! [documentation](https://docs.rs/clap/) or [examples/] directory of this repo)
+//!
+//! Then run `cargo build` or `cargo update && cargo build` for your project.
+//!
+//! ### Optional Dependencies / Features
+//!
+//! #### Features enabled by default
+//!
+//! * `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`)
+//!
+//! To disable these, add this to your `Cargo.toml`:
+//!
+//! ```toml
+//! [dependencies.clap]
+//! version = "~2.27.0"
+//! default-features = false
+//! ```
+//!
+//! You can also selectively enable only the features you'd like to include, by adding:
+//!
+//! ```toml
+//! [dependencies.clap]
+//! version = "~2.27.0"
+//! default-features = false
+//!
+//! # Cherry-pick the features you'd like to use
+//! features = [ "suggestions", "color" ]
+//! ```
+//!
+//! #### Opt-in features
+//!
+//! * **"yaml"**: Enables building CLIs from YAML documents. (builds dependency `yaml-rust`)
+//! * **"unstable"**: Enables unstable `clap` features that may change from release to release
+//! * **"wrap_help"**: Turns on the help text wrapping feature, based on the terminal size. (builds dependency `term-size`)
+//!
+//! ### Dependencies Tree
+//!
+//! The following graphic depicts `clap`s dependency graph (generated using
+//! [cargo-graph](https://github.com/kbknapp/cargo-graph)).
+//!
+//!  * **Dashed** Line: Optional dependency
+//!  * **Red** Color: **NOT** included by default (must use cargo `features` to enable)
+//!  * **Blue** Color: Dev dependency, only used while developing.
+//!
+//! ![clap dependencies](https://raw.githubusercontent.com/kbknapp/clap-rs/master/clap_dep_graph.png)
+//!
+//! ### More Information
+//!
+//! You can find complete documentation on the [docs.rs](https://docs.rs/clap/) for this project.
+//!
+//! You can also find usage examples in the [examples/] directory of this repo.
+//!
+//! #### Video Tutorials
+//!
+//! There's also the video tutorial series [Argument Parsing with Rust v2][video tutorials].
+//!
+//! These videos slowly trickle out as I finish them and currently a work in progress.
+//!
+//! ## How to Contribute
+//!
+//! Please read [CONTRIBUTING.md](https://raw.githubusercontent.com/clap-rs/clap/master/.github/CONTRIBUTING.md) before you start contributing.
+//!
+//! ### Goals
+//!
+//! There are a few goals of `clap` that I'd like to maintain throughout contributions. If your
+//! proposed changes break, or go against any of these goals we'll discuss the changes further
+//! before merging (but will *not* be ignored, all contributes are welcome!). These are by no means
+//! hard-and-fast rules, as I'm no expert and break them myself from time to time (even if by
+//! mistake or ignorance).
+//!
+//! * Remain backwards compatible when possible
+//!   - If backwards compatibility *must* be broken, use deprecation warnings if at all possible before
+//!   removing legacy code - This does not apply for security concerns
+//! * Parse arguments quickly
+//!   - Parsing of arguments shouldn't slow down usage of the main program - This is also true of
+//!   generating help and usage information (although *slightly* less stringent, as the program is about
+//!   to exit)
+//! * Try to be cognizant of memory usage
+//!   - Once parsing is complete, the memory footprint of `clap` should be low since the  main program
+//!   is the star of the show
+//! * `panic!` on *developer* error, exit gracefully on *end-user* error
+//!
+//! ### Compatibility Policy
+//!
+//! Because `clap` takes `SemVer` and compatibility seriously, this is the official policy regarding
+//! breaking changes and previous versions of Rust.
+//!
+//! `clap` will pin the minimum required version of Rust to the CI builds. Bumping the minimum
+//! version of Rust is considered a minor breaking change, meaning *at a minimum* the minor version
+//! of `clap` will be bumped.
+//!
+//! In order to keep from being suprised of breaking changes, it is **highly** recommended to use
+//! the `~major.minor.patch` style in your `Cargo.toml`:
+//!
+//! ```toml
+//! [dependencies] clap = "~2.27.0"
+//! ```
+//!
+//! This will cause *only* the patch version to be updated upon a `cargo update` call, and therefore
+//! cannot break due to new features, or bumped minimum versions of Rust.
+//!
+//! #### Minimum Version of Rust
+//!
+//! `clap` will officially support current stable Rust, minus two releases, but may work with prior
+//! releases as well. For example, current stable Rust at the time of this writing is 1.21.0,
+//! meaning `clap` is guaranteed to compile with 1.19.0 and beyond. At the 1.22.0 release, `clap`
+//! will be guaranteed to compile with 1.20.0 and beyond, etc.
+//!
+//! Upon bumping the minimum version of Rust (assuming it's within the stable-2 range), it *must* be
+//! clearly annotated in the `CHANGELOG.md`
+//!
+//! ## License
+//!
+//! `clap` is licensed under the MIT license. Please read the [LICENSE-MIT][license] file in
+//! this repository for more information.
+//!
+//! [examples/]: https://github.com/kbknapp/clap-rs/tree/master/examples
+//! [video tutorials]: https://www.youtube.com/playlist?list=PLza5oFLQGTl2Z5T8g1pRkIynR3E0_pc7U
+//! [license]: https://raw.githubusercontent.com/kbknapp/clap-rs/master/LICENSE-MIT
+
 #![crate_type = "lib"]
+#![doc(html_root_url = "https://docs.rs/clap/3.0.0-beta.1")]
 #![deny(
     missing_docs,
     missing_debug_implementations,
diff --git a/src/macros.rs b/src/macros.rs
index 537dde03..82c18f47 100644
--- a/src/macros.rs
+++ b/src/macros.rs
@@ -113,7 +113,7 @@ macro_rules! crate_authors {
         use std::cell::Cell;
 
         #[allow(missing_copy_implementations)]
-        #[allow(unused)]
+        #[allow(dead_code)]
         struct CargoAuthors {
             authors: Cell<Option<&'static str>>,
             __private_field: (),
diff --git a/src/mkeymap.rs b/src/mkeymap.rs
index 51d7d9c3..828c4bfe 100644
--- a/src/mkeymap.rs
+++ b/src/mkeymap.rs
@@ -140,6 +140,9 @@ fn _get_keys(arg: &Arg) -> Vec<KeyType> {
     }
 
     let mut keys = vec![];
+    for short in arg.short_aliases.iter().map(|(c, _)| KeyType::Short(*c)) {
+        keys.push(short);
+    }
     if let Some(c) = arg.short {
         keys.push(KeyType::Short(c));
     }
diff --git a/src/output/help.rs b/src/output/help.rs
index d1654037..ccecfc1b 100644
--- a/src/output/help.rs
+++ b/src/output/help.rs
@@ -145,6 +145,11 @@ impl<'b, 'c, 'd, 'w> Help<'b, 'c, 'd, 'w> {
         write_method!(self, msg, warning)
     }
 
+    #[allow(dead_code)]
+    fn error(&mut self, msg: &str) -> io::Result<()> {
+        write_method!(self, msg, error)
+    }
+
     fn none(&mut self, msg: &str) -> io::Result<()> {
         write_method!(self, msg, none)
     }
@@ -500,6 +505,26 @@ impl<'b, 'c, 'd, 'w> Help<'b, 'c, 'd, 'w> {
                 spec_vals.push(format!(" [aliases: {}]", als));
             }
         }
+
+        if !a.short_aliases.is_empty() {
+            debug!(
+                "Help::spec_vals: Found short aliases...{:?}",
+                a.short_aliases
+            );
+
+            let als = a
+                .short_aliases
+                .iter()
+                .filter(|&als| als.1) // visible
+                .map(|&als| als.0.to_string()) // name
+                .collect::<Vec<_>>()
+                .join(", ");
+
+            if !als.is_empty() {
+                spec_vals.push(format!("[short aliases: {}]", als));
+            }
+        }
+
         if !self.hide_pv && !a.is_set(ArgSettings::HidePossibleValues) {
             if let Some(ref pv) = a.possible_vals {
                 debug!("Help::spec_vals: Found possible vals...{:?}", pv);
diff --git a/src/parse/arg_matcher.rs b/src/parse/arg_matcher.rs
index e4a520be..9dda0a8d 100644
--- a/src/parse/arg_matcher.rs
+++ b/src/parse/arg_matcher.rs
@@ -86,6 +86,13 @@ impl ArgMatcher {
         self.0.args.swap_remove(arg);
     }
 
+    #[allow(dead_code)]
+    pub(crate) fn remove_all(&mut self, args: &[Id]) {
+        for arg in args {
+            self.0.args.swap_remove(arg);
+        }
+    }
+
     pub(crate) fn insert(&mut self, name: &Id) {
         self.0.args.insert(name.clone(), MatchedArg::new());
     }


Test patch:
diff --git a/tests/app_settings.rs b/tests/app_settings.rs
index cbc50a32..50920567 100644
--- a/tests/app_settings.rs
+++ b/tests/app_settings.rs
@@ -470,8 +470,8 @@ fn unset_settings() {
     let m = m
         .unset_setting(AppSettings::AllowInvalidUtf8)
         .unset_setting(AppSettings::ColorAuto);
-    assert!(!m.is_set(AppSettings::AllowInvalidUtf8), "{:#?}", m);
-    assert!(!m.is_set(AppSettings::ColorAuto), "{:#?}", m);
+    assert!(!m.is_set(AppSettings::AllowInvalidUtf8), "{:#?}");
+    assert!(!m.is_set(AppSettings::ColorAuto));
 }
 
 #[test]
diff --git a/tests/arg_aliases_short.rs b/tests/arg_aliases_short.rs
new file mode 100644
index 00000000..ced33326
--- /dev/null
+++ b/tests/arg_aliases_short.rs
@@ -0,0 +1,204 @@
+mod utils;
+
+use clap::{App, Arg};
+
+static SC_VISIBLE_ALIAS_HELP: &str = "ct-test 1.2
+Some help
+
+USAGE:
+    ct test [FLAGS] [OPTIONS]
+
+FLAGS:
+    -f, --flag        [aliases: flag1] [short aliases: a, b, 🦆]
+    -h, --help       Prints help information
+    -V, --version    Prints version information
+
+OPTIONS:
+    -o, --opt <opt>    [short aliases: v]";
+
+static SC_INVISIBLE_ALIAS_HELP: &str = "ct-test 1.2
+Some help
+
+USAGE:
+    ct test [FLAGS] [OPTIONS]
+
+FLAGS:
+    -f, --flag       
+    -h, --help       Prints help information
+    -V, --version    Prints version information
+
+OPTIONS:
+    -o, --opt <opt>    ";
+
+#[test]
+fn single_short_alias_of_option() {
+    let a = App::new("single_alias")
+        .arg(
+            Arg::with_name("alias")
+                .long("alias")
+                .takes_value(true)
+                .about("single short alias")
+                .short_alias('a'),
+        )
+        .try_get_matches_from(vec!["", "-a", "cool"]);
+    assert!(a.is_ok());
+    let a = a.unwrap();
+    assert!(a.is_present("alias"));
+    assert_eq!(a.value_of("alias").unwrap(), "cool");
+}
+
+#[test]
+fn multiple_short_aliases_of_option() {
+    let a = App::new("multiple_aliases").arg(
+        Arg::with_name("aliases")
+            .long("aliases")
+            .takes_value(true)
+            .about("multiple aliases")
+            .short_aliases(&['1', '2', '3']),
+    );
+    let long = a
+        .clone()
+        .try_get_matches_from(vec!["", "--aliases", "value"]);
+    assert!(long.is_ok());
+    let long = long.unwrap();
+
+    let als1 = a.clone().try_get_matches_from(vec!["", "-1", "value"]);
+    assert!(als1.is_ok());
+    let als1 = als1.unwrap();
+
+    let als2 = a.clone().try_get_matches_from(vec!["", "-2", "value"]);
+    assert!(als2.is_ok());
+    let als2 = als2.unwrap();
+
+    let als3 = a.clone().try_get_matches_from(vec!["", "-3", "value"]);
+    assert!(als3.is_ok());
+    let als3 = als3.unwrap();
+
+    assert!(long.is_present("aliases"));
+    assert!(als1.is_present("aliases"));
+    assert!(als2.is_present("aliases"));
+    assert!(als3.is_present("aliases"));
+    assert_eq!(long.value_of("aliases").unwrap(), "value");
+    assert_eq!(als1.value_of("aliases").unwrap(), "value");
+    assert_eq!(als2.value_of("aliases").unwrap(), "value");
+    assert_eq!(als3.value_of("aliases").unwrap(), "value");
+}
+
+#[test]
+fn single_short_alias_of_flag() {
+    let a = App::new("test")
+        .arg(Arg::with_name("flag").long("flag").short_alias('f'))
+        .try_get_matches_from(vec!["", "-f"]);
+    assert!(a.is_ok());
+    let a = a.unwrap();
+    assert!(a.is_present("flag"));
+}
+
+#[test]
+fn multiple_short_aliases_of_flag() {
+    let a = App::new("test").arg(
+        Arg::with_name("flag")
+            .long("flag")
+            .short_aliases(&['a', 'b', 'c', 'd', 'e']),
+    );
+
+    let flag = a.clone().try_get_matches_from(vec!["", "--flag"]);
+    assert!(flag.is_ok());
+    let flag = flag.unwrap();
+
+    let als1 = a.clone().try_get_matches_from(vec!["", "-a"]);
+    assert!(als1.is_ok());
+    let als1 = als1.unwrap();
+
+    let als2 = a.clone().try_get_matches_from(vec!["", "-b"]);
+    assert!(als2.is_ok());
+    let als2 = als2.unwrap();
+
+    let als3 = a.clone().try_get_matches_from(vec!["", "-c"]);
+    assert!(als3.is_ok());
+    let als3 = als3.unwrap();
+
+    assert!(flag.is_present("flag"));
+    assert!(als1.is_present("flag"));
+    assert!(als2.is_present("flag"));
+    assert!(als3.is_present("flag"));
+}
+
+#[test]
+fn short_alias_on_a_subcommand_option() {
+    let m = App::new("test")
+        .subcommand(
+            App::new("some").arg(
+                Arg::with_name("test")
+                    .short('t')
+                    .long("test")
+                    .takes_value(true)
+                    .short_alias('o')
+                    .about("testing testing"),
+            ),
+        )
+        .arg(
+            Arg::with_name("other")
+                .long("other")
+                .short_aliases(&['1', '2', '3']),
+        )
+        .get_matches_from(vec!["test", "some", "-o", "awesome"]);
+
+    assert!(m.subcommand_matches("some").is_some());
+    let sub_m = m.subcommand_matches("some").unwrap();
+    assert!(sub_m.is_present("test"));
+    assert_eq!(sub_m.value_of("test").unwrap(), "awesome");
+}
+
+#[test]
+fn invisible_short_arg_aliases_help_output() {
+    let app = App::new("ct").author("Salim Afiune").subcommand(
+        App::new("test")
+            .about("Some help")
+            .version("1.2")
+            .arg(
+                Arg::with_name("opt")
+                    .long("opt")
+                    .short('o')
+                    .takes_value(true)
+                    .short_aliases(&['a', 'b', 'c']),
+            )
+            .arg(Arg::from("-f, --flag").short_aliases(&['a', 'b', 'c'])),
+    );
+    assert!(utils::compare_output(
+        app,
+        "ct test --help",
+        SC_INVISIBLE_ALIAS_HELP,
+        false
+    ));
+}
+
+#[test]
+fn visible_short_arg_aliases_help_output() {
+    let app = App::new("ct").author("Salim Afiune").subcommand(
+        App::new("test")
+            .about("Some help")
+            .version("1.2")
+            .arg(
+                Arg::with_name("opt")
+                    .long("opt")
+                    .short('o')
+                    .takes_value(true)
+                    .short_alias('i')
+                    .visible_short_alias('v'),
+            )
+            .arg(
+                Arg::with_name("flg")
+                    .long("flag")
+                    .short('f')
+                    .visible_alias("flag1")
+                    .visible_short_aliases(&['a', 'b', '🦆']),
+            ),
+    );
+    assert!(utils::compare_output(
+        app,
+        "ct test --help",
+        SC_VISIBLE_ALIAS_HELP,
+        false
+    ));
+}
diff --git a/tests/fixtures/app.yml b/tests/fixtures/app.yml
index 7c798c44..87b2e7ac 100644
--- a/tests/fixtures/app.yml
+++ b/tests/fixtures/app.yml
@@ -83,6 +83,16 @@ args:
         long: multaliases
         about: Tests mutliple aliases
         aliases: [als1, als2, als3]
+    - singleshortalias:
+        long: singleshortalias
+        about: Tests single short alias
+        short_aliases: [a]
+        required_if:
+            - [multvalsmo, two]
+    - multshortaliases:
+        long: multshortaliases
+        about: Tests mutliple short aliases
+        short_aliases: [a, b, c]
     - minvals2:
         long: minvals2
         multiple: true
diff --git a/tests/utf16.rs b/tests/utf16.rs
deleted file mode 100644
index 472644cb..00000000
--- a/tests/utf16.rs
+++ /dev/null
@@ -1,169 +0,0 @@
-//! These Windows-only tests are ported from the Unix-only tests in
-//! tests/utf16.rs. The tests that use StrictUtf8 mode are omitted here,
-//! because that's a Unix-only feature.
-
-#![cfg(windows)]
-
-use clap::{App, Arg};
-use std::ffi::OsString;
-use std::os::windows::ffi::OsStringExt;
-
-// Take a slice of ASCII bytes, convert them to UTF-16, and then append a
-// dangling surrogate character to make the result invalid UTF-16.
-fn bad_osstring(ascii: &[u8]) -> OsString {
-    let mut wide_chars: Vec<u16> = ascii.iter().map(|&c| c as u16).collect();
-    // UTF-16 surrogate characters are only valid in pairs.
-    let surrogate_char: u16 = 0xDC00;
-    wide_chars.push(surrogate_char);
-    let os = OsString::from_wide(&wide_chars);
-    assert!(os.to_str().is_none(), "invalid Unicode");
-    os
-}
-
-#[test]
-fn invalid_utf16_lossy_positional() {
-    let r = App::new("bad_utf16")
-        .arg(Arg::from("<arg> 'some arg'"))
-        .try_get_matches_from(vec![OsString::from(""), bad_osstring(b"")]);
-    assert!(r.is_ok());
-    let m = r.unwrap();
-    assert!(m.is_present("arg"));
-    assert_eq!(&*m.value_of_lossy("arg").unwrap(), "\u{FFFD}");
-}
-
-#[test]
-fn invalid_utf16_lossy_option_short_space() {
-    let r = App::new("bad_utf16")
-        .arg(Arg::from("-a, --arg <arg> 'some arg'"))
-        .try_get_matches_from(vec![
-            OsString::from(""),
-            OsString::from("-a"),
-            bad_osstring(b""),
-        ]);
-    assert!(r.is_ok());
-    let m = r.unwrap();
-    assert!(m.is_present("arg"));
-    assert_eq!(&*m.value_of_lossy("arg").unwrap(), "\u{FFFD}");
-}
-
-#[test]
-fn invalid_utf16_lossy_option_short_equals() {
-    let r = App::new("bad_utf16")
-        .arg(Arg::from("-a, --arg <arg> 'some arg'"))
-        .try_get_matches_from(vec![OsString::from(""), bad_osstring(b"-a=")]);
-    assert!(r.is_ok());
-    let m = r.unwrap();
-    assert!(m.is_present("arg"));
-    assert_eq!(&*m.value_of_lossy("arg").unwrap(), "\u{FFFD}");
-}
-
-#[test]
-fn invalid_utf16_lossy_option_short_no_space() {
-    let r = App::new("bad_utf16")
-        .arg(Arg::from("-a, --arg <arg> 'some arg'"))
-        .try_get_matches_from(vec![OsString::from(""), bad_osstring(b"-a")]);
-    assert!(r.is_ok());
-    let m = r.unwrap();
-    assert!(m.is_present("arg"));
-    assert_eq!(&*m.value_of_lossy("arg").unwrap(), "\u{FFFD}");
-}
-
-#[test]
-fn invalid_utf16_lossy_option_long_space() {
-    let r = App::new("bad_utf16")
-        .arg(Arg::from("-a, --arg <arg> 'some arg'"))
-        .try_get_matches_from(vec![
-            OsString::from(""),
-            OsString::from("--arg"),
-            bad_osstring(b""),
-        ]);
-    assert!(r.is_ok());
-    let m = r.unwrap();
-    assert!(m.is_present("arg"));
-    assert_eq!(&*m.value_of_lossy("arg").unwrap(), "\u{FFFD}");
-}
-
-#[test]
-fn invalid_utf16_lossy_option_long_equals() {
-    let r = App::new("bad_utf16")
-        .arg(Arg::from("-a, --arg <arg> 'some arg'"))
-        .try_get_matches_from(vec![OsString::from(""), bad_osstring(b"--arg=")]);
-    assert!(r.is_ok());
-    let m = r.unwrap();
-    assert!(m.is_present("arg"));
-    assert_eq!(&*m.value_of_lossy("arg").unwrap(), "\u{FFFD}");
-}
-
-#[test]
-fn invalid_utf16_positional() {
-    let r = App::new("bad_utf16")
-        .arg(Arg::from("<arg> 'some arg'"))
-        .try_get_matches_from(vec![OsString::from(""), bad_osstring(b"")]);
-    assert!(r.is_ok());
-    let m = r.unwrap();
-    assert!(m.is_present("arg"));
-    assert_eq!(&*m.value_of_os("arg").unwrap(), &*bad_osstring(b""));
-}
-
-#[test]
-fn invalid_utf16_option_short_space() {
-    let r = App::new("bad_utf16")
-        .arg(Arg::from("-a, --arg <arg> 'some arg'"))
-        .try_get_matches_from(vec![
-            OsString::from(""),
-            OsString::from("-a"),
-            bad_osstring(b""),
-        ]);
-    assert!(r.is_ok());
-    let m = r.unwrap();
-    assert!(m.is_present("arg"));
-    assert_eq!(&*m.value_of_os("arg").unwrap(), &*bad_osstring(b""));
-}
-
-#[test]
-fn invalid_utf16_option_short_equals() {
-    let r = App::new("bad_utf16")
-        .arg(Arg::from("-a, --arg <arg> 'some arg'"))
-        .try_get_matches_from(vec![OsString::from(""), bad_osstring(b"-a=")]);
-    assert!(r.is_ok());
-    let m = r.unwrap();
-    assert!(m.is_present("arg"));
-    assert_eq!(&*m.value_of_os("arg").unwrap(), &*bad_osstring(b""));
-}
-
-#[test]
-fn invalid_utf16_option_short_no_space() {
-    let r = App::new("bad_utf16")
-        .arg(Arg::from("-a, --arg <arg> 'some arg'"))
-        .try_get_matches_from(vec![OsString::from(""), bad_osstring(b"-a")]);
-    assert!(r.is_ok());
-    let m = r.unwrap();
-    assert!(m.is_present("arg"));
-    assert_eq!(&*m.value_of_os("arg").unwrap(), &*bad_osstring(b""));
-}
-
-#[test]
-fn invalid_utf16_option_long_space() {
-    let r = App::new("bad_utf16")
-        .arg(Arg::from("-a, --arg <arg> 'some arg'"))
-        .try_get_matches_from(vec![
-            OsString::from(""),
-            OsString::from("--arg"),
-            bad_osstring(b""),
-        ]);
-    assert!(r.is_ok());
-    let m = r.unwrap();
-    assert!(m.is_present("arg"));
-    assert_eq!(&*m.value_of_os("arg").unwrap(), &*bad_osstring(b""));
-}
-
-#[test]
-fn invalid_utf16_option_long_equals() {
-    let r = App::new("bad_utf16")
-        .arg(Arg::from("-a, --arg <arg> 'some arg'"))
-        .try_get_matches_from(vec![OsString::from(""), bad_osstring(b"--arg=")]);
-    assert!(r.is_ok());
-    let m = r.unwrap();
-    assert!(m.is_present("arg"));
-    assert_eq!(&*m.value_of_os("arg").unwrap(), &*bad_osstring(b""));
-}
diff --git a/tests/yaml.rs b/tests/yaml.rs
index f211d815..2852948e 100644
--- a/tests/yaml.rs
+++ b/tests/yaml.rs
@@ -25,9 +25,8 @@ fn help_message() {
     let mut help_buffer = Vec::new();
     app.write_help(&mut help_buffer).unwrap();
     let help_string = String::from_utf8(help_buffer).unwrap();
-    assert!(
-        help_string.contains("-h, --help             prints help with a nonstandard description\n")
-    );
+    assert!(help_string
+        .contains("-h, --help                prints help with a nonstandard description\n"));
 }
 
 #[test]