qapi: Add alias for ErrorClass

The qapi enum ErrorClass is unusual that it uses 'CamelCase' names,
contrary to our documented convention of preferring 'lower-case'.
However, this enum is entrenched in the API; we cannot change
what strings QMP outputs.  Meanwhile, we want to simplify how
c_enum_const() is used to generate enum constants, by moving away
from the heuristics of camel_to_upper() to a more straightforward
c_name(N).upper() - but doing so will rename all of the ErrorClass
constants and cause churn to all client files, where the new names
are aesthetically less pleasing (ERROR_CLASS_DEVICENOTFOUND looks
like we can't make up our minds on whether to break between words).

So as always in computer science, solve the problem by some more
indirection: rename the qapi type to QapiErrorClass, and add a
new enum ErrorClass in error.h whose members are aliases of the
qapi type, but with the spelling expected elsewhere in the tree.
Then, when c_enum_const() changes the munging, we only have to
adjust the one alias spot.

Suggested by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <1447836791-369-26-git-send-email-eblake@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>

1 files changed, 14 insertions, 0 deletions

diff --git a/include/qapi/error.h b/include/qapi/error.h
index 4d42cdc..3060b0c 100644
--- a/include/qapi/error.h
+++ b/include/qapi/error.h
@@ -91,6 +91,20 @@
 typedef struct Error Error;
 
 /*
+ * Overall category of an error.
+ * Based on the qapi type QapiErrorClass, but reproduced here for nicer
+ * enum names.
+ */
+typedef enum ErrorClass {
+    ERROR_CLASS_GENERIC_ERROR = QAPI_ERROR_CLASS_GENERIC_ERROR,
+    ERROR_CLASS_COMMAND_NOT_FOUND = QAPI_ERROR_CLASS_COMMAND_NOT_FOUND,
+    ERROR_CLASS_DEVICE_ENCRYPTED = QAPI_ERROR_CLASS_DEVICE_ENCRYPTED,
+    ERROR_CLASS_DEVICE_NOT_ACTIVE = QAPI_ERROR_CLASS_DEVICE_NOT_ACTIVE,
+    ERROR_CLASS_DEVICE_NOT_FOUND = QAPI_ERROR_CLASS_DEVICE_NOT_FOUND,
+    ERROR_CLASS_KVM_MISSING_CAP = QAPI_ERROR_CLASS_KVM_MISSING_CAP,
+} ErrorClass;
+
+/*
  * Get @err's human-readable error message.
  */
 const char *error_get_pretty(Error *err);