Hint when errors are hidden

Author: kornelski

src/cargo/lib.rs

@@ -146,9 +146,8 @@ fn _display_error(err: &Error, shell: &mut Shell, as_err: bool) -> bool {
     for (i, err) in err.chain().enumerate() {
         // If we're not in verbose mode then only print cause chain until one
         // marked as `VerboseError` appears.
-        //
-        // Generally the top error shouldn't be verbose, but check it anyways.
         if shell.verbosity() != Verbose && err.is::<VerboseError>() {
+            drop(shell.note("for more details, run again with '--verbose'"));
             return true;
         }
         if err.is::<AlreadyPrintedError>() {

tests/testsuite/check.rs

@@ -1281,6 +1281,7 @@ fn check_fixable_error_no_fix() {
 {}\
 [WARNING] `foo` (lib) generated 1 warning
 [ERROR] could not compile `foo` due to previous error; 1 warning emitted
+[NOTE] for more details, run again with '--verbose'
 ",
         rustc_message
     );

tests/testsuite/messages.rs

@@ -137,6 +137,7 @@ fn deduplicate_errors() {
             "\
 [COMPILING] foo v0.0.1 [..]
 {}error: could not compile `foo` due to previous error
+[NOTE] for more details, run again with '--verbose'
 ",
             rustc_message
         ))