[RFC] util/error-report: Add "error: " prefix for error-level report

[Zhao Liu <zhao1.liu@linux.intel.com>]

From: Zhao Liu <zhao1.liu@intel.com>

When vreport() was introduced, there was no prefix for error-level
(REPORT_TYPE_ERROR) report. The original reason is "To maintain
compatibility we don't add anything here" as Alistair said in his
RFC v3 series [1].

This was done in the context of inheriting the original error_report()
interface without the prefix style. And it was also useful to have a
means of error handling, such as exit(), when error occurs, so that the
error message - the most serious level - can be noticed by the user.

Nowadays, however, error_report() and its variants have a tendency to be
"abused": it is used a lot just for the sake of logging something more
noticeable than the "warn" or "info" level, in the absence of
appropriate error handling logic.

But, in the use case above, due to the lack of a prefix, it is in fact
less informative to the user than warn_report()/info_report() (with
"warn:" or "info: " prfix), which does not match its highest level.

Therefore, add "error: " prefix for error-level report.

[1]: https://lore.kernel.org/qemu-devel/87r2xuay5h.fsf@dusky.pond.sub.org/#t

Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
---
 util/error-report.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/util/error-report.c b/util/error-report.c
index 6e44a5573217..e981c0b032f0 100644
--- a/util/error-report.c
+++ b/util/error-report.c
@@ -213,6 +213,7 @@ static void vreport(report_type type, const char *fmt, va_list ap)
 
     switch (type) {
     case REPORT_TYPE_ERROR:
+        error_printf("error: ");
         break;
     case REPORT_TYPE_WARNING:
         error_printf("warning: ");
-- 
2.34.1