[PATCH v2 3/8] qapi/error: Make QAPISourceError 'col' parameter optional

[John Snow <jsnow@redhat.com>]

It's already treated as optional, with some callers and subclasses
passing 'None'. Make it officially optional, which requires moving the
position of the argument to come after all required parameters.

QAPISemError becomes functionally identical to QAPISourceError. Keep the
name to preserve its semantic meaning and avoid code churn, but remove
the now-useless __init__ wrapper.

Signed-off-by: John Snow <jsnow@redhat.com>
---
 scripts/qapi/error.py  | 8 +++-----
 scripts/qapi/schema.py | 3 +--
 2 files changed, 4 insertions(+), 7 deletions(-)

diff --git a/scripts/qapi/error.py b/scripts/qapi/error.py
index 38bd7c4dd6..d179a3bd0c 100644
--- a/scripts/qapi/error.py
+++ b/scripts/qapi/error.py
@@ -18,11 +18,11 @@ class QAPIError(Exception):
 
 class QAPISourceError(QAPIError):
     """Error class for all exceptions identifying a source location."""
-    def __init__(self, info, col, msg):
+    def __init__(self, info, msg, col=None):
         super().__init__()
         self.info = info
-        self.col = col
         self.msg = msg
+        self.col = col
 
     def __str__(self):
         loc = str(self.info)
@@ -41,10 +41,8 @@ def __init__(self, parser, msg):
                 col = (col + 7) % 8 + 1
             else:
                 col += 1
-        super().__init__(parser.info, col, msg)
+        super().__init__(parser.info, msg, col)
 
 
 class QAPISemError(QAPISourceError):
     """Error class for semantic QAPI errors."""
-    def __init__(self, info, msg):
-        super().__init__(info, None, msg)
diff --git a/scripts/qapi/schema.py b/scripts/qapi/schema.py
index 1849c3e45f..dcf8a86139 100644
--- a/scripts/qapi/schema.py
+++ b/scripts/qapi/schema.py
@@ -878,8 +878,7 @@ def _def_entity(self, ent):
         other_ent = self._entity_dict.get(ent.name)
         if other_ent:
             if other_ent.info:
-                where = QAPISourceError(other_ent.info, None,
-                                        "previous definition")
+                where = QAPISourceError(other_ent.info, "previous definition")
                 raise QAPISemError(
                     ent.info,
                     "'%s' is already defined\n%s" % (ent.name, where))
-- 
2.30.2