hmp: Allow for error message hints on HMP

Commits 7216ae3d and d2828429 disabled some error message hints,
all because a change to use modern error reporting meant that the
hint would be output prior to the actual error.  Fix this by making
hints a first-class member of Error.

For example, we are now back to the pleasant:

 $ qemu-system-x86_64 --nodefaults -S --vnc :0 --chardev null,id=,
 qemu-system-x86_64: --chardev null,id=,: Parameter 'id' expects an identifier
 Identifiers consist of letters, digits, '-', '.', '_', starting with a letter.

Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <1441901956-21991-1-git-send-email-eblake@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>

1 files changed, 4 insertions, 7 deletions

diff --git a/util/qemu-option.c b/util/qemu-option.c
index b1fb57c..a50ecea 100644
--- a/util/qemu-option.c
+++ b/util/qemu-option.c
@@ -205,10 +205,8 @@ void parse_option_size(const char *name, const char *value,
             break;
         default:
             error_setg(errp, QERR_INVALID_PARAMETER_VALUE, name, "a size");
-#if 0 /* conversion from qerror_report() to error_set() broke this: */
-            error_printf_unless_qmp("You may use k, M, G or T suffixes for "
-                    "kilobytes, megabytes, gigabytes and terabytes.\n");
-#endif
+            error_append_hint(errp, "You may use k, M, G or T suffixes for "
+                    "kilobytes, megabytes, gigabytes and terabytes.");
             return;
         }
     } else {
@@ -648,9 +646,8 @@ QemuOpts *qemu_opts_create(QemuOptsList *list, const char *id,
         if (!id_wellformed(id)) {
             error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "id",
                        "an identifier");
-#if 0 /* conversion from qerror_report() to error_set() broke this: */
-            error_printf_unless_qmp("Identifiers consist of letters, digits, '-', '.', '_', starting with a letter.\n");
-#endif
+            error_append_hint(errp, "Identifiers consist of letters, digits, "
+                              "'-', '.', '_', starting with a letter.");
             return NULL;
         }
         opts = qemu_opts_find(list, id);