fix: Gracefully handle empty authors

CHANGELOG.md

@@ -267,11 +267,13 @@ On top of the clap 2 changes
 - `IgnoreCase` is now unicode aware (requires `unicode` feature flag)
 - Always respect `ColorChoice::Never`, even if that means we skip colors in some cases
 - `ArgMatches` panics on unknown arguments
+- Gracefully handle empty `authors` field in `Cargo.toml` with `app_from_crate`
 
 **From structopt 0.3.25**
 
 - Support `SubcommandsNegateReqs` by allowing required `Option<_>`s ([clap-rs/clap#2255](https://github.com/clap-rs/clap/issues/2255))
 - Infer `AllowInvalidUtf8` based on parser ([clap-rs/clap#751](https://github.com/clap-rs/clap/issues/2255))
+- Gracefully handle empty `authors` field in `Cargo.toml`
 
 On top of the clap 2 changes
 

clap_derive/src/attrs.rs

@@ -483,17 +483,19 @@ impl Attrs {
                 }
 
                 About(ident, about) => {
-                    let method = Method::from_lit_or_env(ident, about, "CARGO_PKG_DESCRIPTION");
+                    if let Some(method) =
-                    self.methods.push(method);
+                        Method::from_lit_or_env(ident, about, "CARGO_PKG_DESCRIPTION")
+                    {
+                        self.methods.push(method);
+                    }
                 }
 
                 Author(ident, author) => {
-                    self.author = Some(Method::from_lit_or_env(ident, author, "CARGO_PKG_AUTHORS"));
+                    self.author = Method::from_lit_or_env(ident, author, "CARGO_PKG_AUTHORS");
                 }
 
                 Version(ident, version) => {
-                    self.version =
+                    self.version = Method::from_lit_or_env(ident, version, "CARGO_PKG_VERSION");
-                        Some(Method::from_lit_or_env(ident, version, "CARGO_PKG_VERSION"));
                 }
 
                 NameLitStr(name, lit) => {
@@ -675,12 +677,17 @@ impl Method {
         Method { name, args }
     }
 
-    fn from_lit_or_env(ident: Ident, lit: Option<LitStr>, env_var: &str) -> Self {
+    fn from_lit_or_env(ident: Ident, lit: Option<LitStr>, env_var: &str) -> Option<Self> {
         let mut lit = match lit {
             Some(lit) => lit,
 
             None => match env::var(env_var) {
-                Ok(val) => LitStr::new(&val, ident.span()),
+                Ok(val) => {
+                    if val.is_empty() {
+                        return None;
+                    }
+                    LitStr::new(&val, ident.span())
+                }
                 Err(_) => {
                     abort!(ident,
                         "cannot derive `{}` from Cargo.toml", ident;
@@ -696,7 +703,7 @@ impl Method {
             lit = LitStr::new(&edited, lit.span());
         }
 
-        Method::new(ident, quote!(#lit))
+        Some(Method::new(ident, quote!(#lit)))
     }
 }
 

examples/demo.md

@@ -5,8 +5,6 @@ Used to validate README.md's content
 $ demo --help
 clap [..]
 
-
-
 A simple to use, efficient, and full-featured Command Line Argument Parser
 
 USAGE:

examples/escaped_positional.md

@@ -7,8 +7,6 @@ Let's see what this looks like in the help:
 $ escaped_positional --help
 clap [..]
 
-
-
 A simple to use, efficient, and full-featured Command Line Argument Parser
 
 USAGE:

examples/escaped_positional_derive.md

@@ -7,8 +7,6 @@ Let's see what this looks like in the help:
 $ escaped_positional_derive --help
 clap [..]
 
-
-
 A simple to use, efficient, and full-featured Command Line Argument Parser
 
 USAGE:

examples/tutorial_builder/README.md

@@ -26,8 +26,6 @@ You can create an application with several arguments using usage strings.
 $ 01_quick --help
 clap [..]
 
-
-
 A simple to use, efficient, and full-featured Command Line Argument Parser
 
 USAGE:
@@ -93,8 +91,6 @@ file.  **This requires the `cargo` feature flag.**
 $ 02_crate --help
 clap [..]
 
-
-
 A simple to use, efficient, and full-featured Command Line Argument Parser
 
 USAGE:
@@ -118,8 +114,6 @@ all subcommands (`app.global_setting()`).
 $ 02_app_settings --help
 clap [..]
 
-
-
 A simple to use, efficient, and full-featured Command Line Argument Parser
 
 USAGE:
@@ -146,8 +140,6 @@ Flags are switches that can be on/off:
 $ 03_01_flag_bool --help
 clap [..]
 
-
-
 A simple to use, efficient, and full-featured Command Line Argument Parser
 
 USAGE:
@@ -178,8 +170,6 @@ Or counted.
 $ 03_01_flag_count --help
 clap [..]
 
-
-
 A simple to use, efficient, and full-featured Command Line Argument Parser
 
 USAGE:
@@ -206,8 +196,6 @@ Flags can also accept a value.
 $ 03_02_option --help
 clap [..]
 
-
-
 A simple to use, efficient, and full-featured Command Line Argument Parser
 
 USAGE:
@@ -240,8 +228,6 @@ Or you can have users specify values by their position on the command-line:
 $ 03_03_positional --help
 clap [..]
 
-
-
 A simple to use, efficient, and full-featured Command Line Argument Parser
 
 USAGE:
@@ -271,8 +257,6 @@ $ 03_04_subcommands
 ? failed
 clap [..]
 
-
-
 A simple to use, efficient, and full-featured Command Line Argument Parser
 
 USAGE:
@@ -288,8 +272,6 @@ SUBCOMMANDS:
 $ 03_04_subcommands help
 clap [..]
 
-
-
 A simple to use, efficient, and full-featured Command Line Argument Parser
 
 USAGE:
@@ -339,8 +321,6 @@ set `Arg::default_value`.
 $ 03_05_default_values --help
 clap [..]
 
-
-
 A simple to use, efficient, and full-featured Command Line Argument Parser
 
 USAGE:
@@ -374,8 +354,6 @@ of the mistake, and what the possible valid values are
 $ 04_01_possible --help
 clap [..]
 
-
-
 A simple to use, efficient, and full-featured Command Line Argument Parser
 
 USAGE:
@@ -409,8 +387,6 @@ When enabling the `derive` feature, you can use `ArgEnum` to take care of the bo
 $ 04_01_enum --help
 clap [..]
 
-
-
 A simple to use, efficient, and full-featured Command Line Argument Parser
 
 USAGE:
@@ -446,8 +422,6 @@ More generally, you can validate and parse into any data type.
 $ 04_02_validate --help
 clap [..]
 
-
-
 A simple to use, efficient, and full-featured Command Line Argument Parser
 
 USAGE:
@@ -485,8 +459,6 @@ each other.
 $ 04_03_relations --help
 clap [..]
 
-
-
 A simple to use, efficient, and full-featured Command Line Argument Parser
 
 USAGE:
@@ -546,8 +518,6 @@ As a last resort, you can create custom errors with the basics of clap's formatt
 $ 04_04_custom --help
 clap [..]
 
-
-
 A simple to use, efficient, and full-featured Command Line Argument Parser
 
 USAGE:

examples/tutorial_derive/README.md

@@ -27,8 +27,6 @@ attributes.  **This requires enabling the `derive` feature flag.**
 $ 01_quick_derive --help
 clap [..]
 
-
-
 A simple to use, efficient, and full-featured Command Line Argument Parser
 
 USAGE:
@@ -93,8 +91,6 @@ You can use `app_from_crate!()` to fill these fields in from your `Cargo.toml` f
 $ 02_crate_derive --help
 clap [..]
 
-
-
 A simple to use, efficient, and full-featured Command Line Argument Parser
 
 USAGE:
@@ -118,8 +114,6 @@ all subcommands (`app.global_setting()`).
 $ 02_app_settings_derive --help
 clap [..]
 
-
-
 A simple to use, efficient, and full-featured Command Line Argument Parser
 
 USAGE:
@@ -146,8 +140,6 @@ Flags are switches that can be on/off:
 $ 03_01_flag_bool_derive --help
 clap [..]
 
-
-
 A simple to use, efficient, and full-featured Command Line Argument Parser
 
 USAGE:
@@ -178,8 +170,6 @@ Or counted.
 $ 03_01_flag_count_derive --help
 clap [..]
 
-
-
 A simple to use, efficient, and full-featured Command Line Argument Parser
 
 USAGE:
@@ -206,8 +196,6 @@ Flags can also accept a value.
 $ 03_02_option_derive --help
 clap [..]
 
-
-
 A simple to use, efficient, and full-featured Command Line Argument Parser
 
 USAGE:
@@ -240,8 +228,6 @@ Or you can have users specify values by their position on the command-line:
 $ 03_03_positional_derive --help
 clap [..]
 
-
-
 A simple to use, efficient, and full-featured Command Line Argument Parser
 
 USAGE:
@@ -271,8 +257,6 @@ $ 03_04_subcommands_derive
 ? failed
 clap [..]
 
-
-
 A simple to use, efficient, and full-featured Command Line Argument Parser
 
 USAGE:
@@ -288,8 +272,6 @@ SUBCOMMANDS:
 $ 03_04_subcommands_derive help
 clap [..]
 
-
-
 A simple to use, efficient, and full-featured Command Line Argument Parser
 
 USAGE:
@@ -339,8 +321,6 @@ set `Arg::default_value`.
 $ 03_05_default_values_derive --help
 clap [..]
 
-
-
 A simple to use, efficient, and full-featured Command Line Argument Parser
 
 USAGE:
@@ -374,8 +354,6 @@ of the mistake, and what the possible valid values are
 $ 04_01_enum_derive --help
 clap [..]
 
-
-
 A simple to use, efficient, and full-featured Command Line Argument Parser
 
 USAGE:
@@ -411,8 +389,6 @@ More generally, you can validate and parse into any data type.
 $ 04_02_validate_derive --help
 clap [..]
 
-
-
 A simple to use, efficient, and full-featured Command Line Argument Parser
 
 USAGE:
@@ -450,8 +426,6 @@ each other.
 $ 04_03_relations_derive --help
 clap [..]
 
-
-
 A simple to use, efficient, and full-featured Command Line Argument Parser
 
 USAGE:
@@ -511,8 +485,6 @@ As a last resort, you can create custom errors with the basics of clap's formatt
 $ 04_04_custom_derive --help
 clap [..]
 
-
-
 A simple to use, efficient, and full-featured Command Line Argument Parser
 
 USAGE:

src/macros.rs

@@ -301,18 +301,36 @@ macro_rules! crate_name {
 #[cfg(feature = "cargo")]
 #[macro_export]
 macro_rules! app_from_crate {
-    () => {
+    () => {{
-        $crate::App::new($crate::crate_name!())
+        let mut app = $crate::App::new($crate::crate_name!()).version($crate::crate_version!());
-            .version($crate::crate_version!())
+
-            .author($crate::crate_authors!(", "))
+        let author = $crate::crate_authors!(", ");
-            .about($crate::crate_description!())
+        if !author.is_empty() {
-    };
+            app = app.author(author)
-    ($sep:expr) => {
+        }
-        $crate::App::new($crate::crate_name!())
+
-            .version($crate::crate_version!())
+        let about = $crate::crate_description!();
-            .author($crate::crate_authors!($sep))
+        if !about.is_empty() {
-            .about($crate::crate_description!())
+            app = app.about(about)
-    };
+        }
+
+        app
+    }};
+    ($sep:expr) => {{
+        let mut app = $crate::App::new($crate::crate_name!()).version($crate::crate_version!());
+
+        let author = $crate::crate_authors!($sep);
+        if !author.is_empty() {
+            app = app.author(author)
+        }
+
+        let about = $crate::crate_description!();
+        if !about.is_empty() {
+            app = app.about(about)
+        }
+
+        app
+    }};
 }
 
 #[doc(hidden)]

tests/builder/app_from_crate.rs

@@ -4,8 +4,6 @@ use clap::{app_from_crate, ErrorKind};
 
 static EVERYTHING: &str = "clap {{version}}
 
-
-
 A simple to use, efficient, and full-featured Command Line Argument Parser
 
 USAGE: