feat(no_cargo): add no_cargo feature to disable Cargo-env-var-depende…

…nt macros (#786)

Cargo.toml

@@ -39,6 +39,7 @@ unstable    = [] # for building with unstable clap features (doesn't require nig
 nightly     = [] # for building with unstable Rust features (currently none)
 lints       = ["clippy"] # Requires nightly Rust
 debug       = [] # Enables debug messages
+no_cargo    = [] # Enable if you're not using Cargo, disables Cargo-env-var-dependent macros
 
 [profile.release]
 opt-level = 3

src/app/mod.rs

@@ -104,8 +104,8 @@ impl<'a, 'b> App<'a, 'b> {
     #[deprecated(since="2.14.1", note="Can never work; use explicit App::author() and App::version() calls instead")]
     pub fn with_defaults<S: Into<String>>(n: S) -> Self {
         let mut a = App { p: Parser::with_name(n.into()) };
-        a.p.meta.author = Some(crate_authors!());
-        a.p.meta.version = Some(crate_version!());
+        a.p.meta.author = Some("Kevin K. <kbknapp@gmail.com>");
+        a.p.meta.version = Some("2.19.2");
         a
     }
 

src/macros.rs

@@ -385,6 +385,7 @@ macro_rules! arg_enum {
 ///                 .get_matches();
 /// # }
 /// ```
+#[cfg(not(feature="no_cargo"))]
 #[macro_export]
 macro_rules! crate_version {
     () => {
@@ -413,6 +414,7 @@ macro_rules! crate_version {
 ///             .get_matches();
 /// # }
 /// ```
+#[cfg(not(feature="no_cargo"))]
 #[macro_export]
 macro_rules! crate_authors {
     ($sep:expr) => {{