refactor: help the user find a transform

Author: fw-immunant

c2rust-refactor/src/command.rs

@@ -572,7 +572,14 @@ impl RefactorState {
                 s
             }));
 
-        let mut cmd = self.cmd_reg.get_command(cmd_name, &args)?;
+        let mut cmd = self.cmd_reg.get_command(cmd_name, &args).map_err(|mut e| {
+            e.push_str("\nValid commands:");
+            for c in self.cmd_reg.commands.keys() {
+                e.push_str("\n\t");
+                e.push_str(c);
+            }
+            e
+        })?;
         profile_start!(format!("Command {}", cmd_name));
         cmd.run(self);
         profile_end!(format!("Command {}", cmd_name));

c2rust-refactor/src/interact/main_thread.rs

@@ -194,7 +194,7 @@ impl InteractState {
                 match self.state.run(&name, &args) {
                     Ok(_) => {}
                     Err(e) => {
-                        eprintln!("{:?}", e);
+                        eprintln!("{e}");
                         panic!("Invalid command.");
                     }
                 }

c2rust-refactor/src/lib.rs

@@ -487,7 +487,7 @@ fn main_impl(opts: Options) -> interface::Result<()> {
                         match state.run(&cmd.name, &cmd.args) {
                             Ok(_) => {}
                             Err(e) => {
-                                eprintln!("{:?}", e);
+                                eprintln!("{e}");
                                 std::process::exit(1);
                             }
                         }