Merge pull request #3531 from epage/feature

fix: Reduce chance of missing `cargo` feature

Cargo.toml

@@ -187,7 +187,6 @@ required-features = ["cargo"]
 [[example]]
 name = "02_apps"
 path = "examples/tutorial_builder/02_apps.rs"
-required-features = ["cargo"]
 
 [[example]]
 name = "02_crate"

examples/tutorial_builder/01_quick.rs

@@ -1,3 +1,5 @@
+// Note: this requires the `cargo` feature
+
 use clap::{arg, command, Command};
 use std::path::Path;
 

examples/tutorial_builder/02_app_settings.rs

@@ -1,3 +1,5 @@
+// Note: this requires the `cargo` feature
+
 use clap::{arg, command, AppSettings};
 
 fn main() {

examples/tutorial_builder/02_crate.rs

@@ -1,3 +1,5 @@
+// Note: this requires the `cargo` feature
+
 use clap::{arg, command};
 
 fn main() {

examples/tutorial_builder/03_01_flag_bool.rs

@@ -1,3 +1,5 @@
+// Note: this requires the `cargo` feature
+
 use clap::{arg, command};
 
 fn main() {

examples/tutorial_builder/03_01_flag_count.rs

@@ -1,3 +1,5 @@
+// Note: this requires the `cargo` feature
+
 use clap::{arg, command};
 
 fn main() {

examples/tutorial_builder/03_02_option.rs

@@ -1,3 +1,5 @@
+// Note: this requires the `cargo` feature
+
 use clap::{arg, command};
 
 fn main() {

examples/tutorial_builder/03_03_positional.rs

@@ -1,3 +1,5 @@
+// Note: this requires the `cargo` feature
+
 use clap::{arg, command};
 
 fn main() {

examples/tutorial_builder/03_04_subcommands.rs

@@ -1,3 +1,5 @@
+// Note: this requires the `cargo` feature
+
 use clap::{arg, command, Command};
 
 fn main() {

examples/tutorial_builder/03_05_default_values.rs

@@ -1,3 +1,5 @@
+// Note: this requires the `cargo` feature
+
 use clap::{arg, command};
 
 fn main() {

examples/tutorial_builder/04_01_enum.rs

@@ -1,3 +1,5 @@
+// Note: this requires the `cargo` feature
+
 use clap::{arg, command, ArgEnum, PossibleValue};
 
 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, ArgEnum)]

examples/tutorial_builder/04_01_possible.rs

@@ -1,3 +1,5 @@
+// Note: this requires the `cargo` feature
+
 use clap::{arg, command};
 
 fn main() {

examples/tutorial_builder/04_02_parse.rs

@@ -1,3 +1,5 @@
+// Note: this requires the `cargo` feature
+
 use clap::{arg, command};
 
 fn main() {

examples/tutorial_builder/04_02_validate.rs

@@ -1,3 +1,5 @@
+// Note: this requires the `cargo` feature
+
 use clap::{arg, command};
 use std::ops::RangeInclusive;
 use std::str::FromStr;

examples/tutorial_builder/04_03_relations.rs

@@ -1,3 +1,5 @@
+// Note: this requires the `cargo` feature
+
 use clap::{arg, command, ArgGroup};
 
 fn main() {

examples/tutorial_builder/04_04_custom.rs

@@ -1,3 +1,5 @@
+// Note: this requires the `cargo` feature
+
 use clap::{arg, command, ErrorKind};
 
 fn main() {

examples/tutorial_builder/05_01_assert.rs

@@ -1,3 +1,5 @@
+// Note: this requires the `cargo` feature
+
 use clap::{arg, command};
 
 fn main() {

src/macros.rs

@@ -322,6 +322,18 @@ macro_rules! command {
     }};
 }
 
+/// Requires `cargo` feature flag to be enabled.
+#[cfg(not(feature = "cargo"))]
+#[macro_export]
+macro_rules! command {
+    () => {{
+        compile_error!("`cargo` feature flag is required");
+    }};
+    ($name:expr) => {{
+        compile_error!("`cargo` feature flag is required");
+    }};
+}
+
 /// Deprecated, replaced with [`clap::command!`][crate::command]
 #[cfg(feature = "cargo")]
 #[deprecated(since = "3.1.0", note = "Replaced with `clap::command!")]