Better suggestion for unsupported silent flag

Author: Rustin170506

src/cargo/util/command_prelude.rs

@@ -331,7 +331,15 @@ pub trait CommandExt: Sized {
     }
 
     fn arg_quiet(self) -> Self {
+        let unsupported_silent_arg = {
+            let value_parser = UnknownArgumentValueParser::suggest_arg("--quiet");
+            flag("silent", "")
+                .short('s')
+                .value_parser(value_parser)
+                .hide(true)
+        };
         self._arg(flag("quiet", "Do not print cargo log messages").short('q'))
+            ._arg(unsupported_silent_arg)
     }
 
     fn arg_timings(self) -> Self {

tests/testsuite/run.rs

@@ -46,9 +46,9 @@ fn unsupported_silent_arg() {
     p.cargo("run -s")
         .with_stderr(
             "\
-error: unexpected argument '-s' found
+error: unexpected argument '--silent' found
 
-  tip: to pass '-s' as a value, use '-- -s'
+  tip: a similar argument exists: '--quiet'
 
 Usage: cargo run [OPTIONS] [args]...
 
@@ -63,7 +63,7 @@ For more information, try '--help'.
             "\
 error: unexpected argument '--silent' found
 
-  tip: to pass '--silent' as a value, use '-- --silent'
+  tip: a similar argument exists: '--quiet'
 
 Usage: cargo run [OPTIONS] [args]...