Experimental objdiff-cli (WIP)

objdiff-cli/src/argp_version.rs

@@ -0,0 +1,64 @@
+// Originally from https://gist.github.com/suluke/e0c672492126be0a4f3b4f0e1115d77c
+//! Extend `argp` to be better integrated with the `cargo` ecosystem
+//!
+//! For now, this only adds a --version/-V option which causes early-exit.
+use std::ffi::OsStr;
+
+use argp::{parser::ParseGlobalOptions, EarlyExit, FromArgs, TopLevelCommand};
+
+struct ArgsOrVersion<T>(T)
+where T: FromArgs;
+
+impl<T> TopLevelCommand for ArgsOrVersion<T> where T: FromArgs {}
+
+impl<T> FromArgs for ArgsOrVersion<T>
+where T: FromArgs
+{
+    fn _from_args(
+        command_name: &[&str],
+        args: &[&OsStr],
+        parent: Option<&mut dyn ParseGlobalOptions>,
+    ) -> Result<Self, EarlyExit> {
+        /// Also use argp for catching `--version`-only invocations
+        #[derive(FromArgs)]
+        struct Version {
+            /// Print version information and exit.
+            #[argp(switch, short = 'V')]
+            pub version: bool,
+        }
+
+        match Version::from_args(command_name, args) {
+            Ok(v) => {
+                if v.version {
+                    println!(
+                        "{} {} {}",
+                        command_name.first().unwrap_or(&""),
+                        env!("CARGO_PKG_VERSION"),
+                        env!("GIT_COMMIT_SHA"),
+                    );
+                    std::process::exit(0);
+                } else {
+                    // Pass through empty arguments
+                    T::_from_args(command_name, args, parent).map(Self)
+                }
+            }
+            Err(exit) => match exit {
+                EarlyExit::Help(_help) => {
+                    // TODO: Chain help info from Version
+                    // For now, we just put the switch on T as well
+                    T::from_args(command_name, &["--help"]).map(Self)
+                }
+                EarlyExit::Err(_) => T::_from_args(command_name, args, parent).map(Self),
+            },
+        }
+    }
+}
+
+/// Create a `FromArgs` type from the current process’s `env::args`.
+///
+/// This function will exit early from the current process if argument parsing was unsuccessful or if information like `--help` was requested.
+/// Error messages will be printed to stderr, and `--help` output to stdout.
+pub fn from_env<T>() -> T
+where T: TopLevelCommand {
+    argp::parse_args_or_exit::<ArgsOrVersion<T>>(argp::DEFAULT).0
+}