From 9ca55f4ba588211ece65d89891223d8a5d1ab407 Mon Sep 17 00:00:00 2001
From: Eric Blake <eblake@redhat.com>
Date: Mon, 19 Feb 2018 20:34:51 -0500
Subject: [PATCH] qapi: Don't let implicit enum MAX member collide

Now that we guarantee the user doesn't have any enum values
beginning with a single underscore, we can use that for our
own purposes. Renaming ENUM_MAX to ENUM__MAX makes it obvious
that the sentinel is generated.

This patch was mostly generated by applying a temporary patch:

|diff --git a/scripts/qapi.py b/scripts/qapi.py
|index e6d014b..b862ec9 100644
|--- a/scripts/qapi.py
|+++ b/scripts/qapi.py
|@@ -1570,6 +1570,7 @@ const char *const %(c_name)s_lookup[] = {
| max_index = c_enum_const(name, 'MAX', prefix)
| ret += mcgen('''
| [%(max_index)s] = NULL,
|+// %(max_index)s
| };
| ''',
| max_index=max_index)

then running:

$ cat qapi-{types,event}.c tests/test-qapi-types.c |
sed -n 's,^// \(.*\)MAX,s|\1MAX|\1_MAX|g,p' > list
$ git grep -l _MAX | xargs sed -i -f list

The only things not generated are the changes in scripts/qapi.py.

Rejecting enum members named 'MAX' is now useless, and will be dropped
in the next patch.

Backports commit 7fb1cf1606c78c9d5b538f29176fd5a101726a9d from qemu
---
 qemu/scripts/qapi.py | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/qemu/scripts/qapi.py b/qemu/scripts/qapi.py
index 41c4b4f4..5c5b73fc 100644
--- a/qemu/scripts/qapi.py
+++ b/qemu/scripts/qapi.py
@@ -920,7 +920,7 @@ class QAPISchemaEnumType(QAPISchemaType):
         return c_name(self.name)
 
     def c_null(self):
-        return c_enum_const(self.name, (self.values + ['MAX'])[0],
+        return c_enum_const(self.name, (self.values + ['_MAX'])[0],
                             self.prefix)
 
     def json_type(self):
@@ -1570,7 +1570,7 @@ const char *const %(c_name)s_lookup[] = {
     # Unicorn: We don't use C99 [ARRAY_INDICING] = Thing because
     # MSVC is still in the stone-age with this part of C compiler
     # support.
-    max_index = c_enum_const(name, 'MAX', prefix)
+    max_index = c_enum_const(name, '_MAX', prefix)
     ret += mcgen('''
     NULL,
 };
@@ -1581,7 +1581,7 @@ const char *const %(c_name)s_lookup[] = {
 
 def gen_enum(name, values, prefix=None):
     # append automatically generated _MAX value
-    enum_values = values + ['MAX']
+    enum_values = values + ['_MAX']
     ret = mcgen('''
 
 typedef enum %(c_name)s {