[PULL 06/13] qapi/parser: clarify _end_section() logic

[Markus Armbruster <armbru@redhat.com>]

From: John Snow <jsnow@redhat.com>

The "if self._section" clause in end_section is mysterious: In which
circumstances might we end a section when we don't have one?

QAPIDoc always expects there to be a "current section", only except
after a call to end_comment(). This actually *shouldn't* ever be 'None',
so let's remove that logic so I don't wonder why it's like this again in
three months.

Signed-off-by: John Snow <jsnow@redhat.com>
Message-Id: <20210930205716.1148693-7-jsnow@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
---
 scripts/qapi/parser.py | 22 +++++++++++++++-------
 1 file changed, 15 insertions(+), 7 deletions(-)

diff --git a/scripts/qapi/parser.py b/scripts/qapi/parser.py
index 23898ab1dc..82f1d952b1 100644
--- a/scripts/qapi/parser.py
+++ b/scripts/qapi/parser.py
@@ -718,13 +718,21 @@ def _start_section(self, name=None, indent=0):
         self.sections.append(self._section)
 
     def _end_section(self):
-        if self._section:
-            text = self._section.text = self._section.text.strip()
-            if self._section.name and (not text or text.isspace()):
-                raise QAPIParseError(
-                    self._parser,
-                    "empty doc section '%s'" % self._section.name)
-            self._section = None
+        assert self._section is not None
+
+        text = self._section.text = self._section.text.strip()
+
+        # Only the 'body' section is allowed to have an empty body.
+        # All other sections, including anonymous ones, must have text.
+        if self._section != self.body and not text:
+            # We do not create anonymous sections unless there is
+            # something to put in them; this is a parser bug.
+            assert self._section.name
+            raise QAPIParseError(
+                self._parser,
+                "empty doc section '%s'" % self._section.name)
+
+        self._section = None
 
     def _append_freeform(self, line):
         match = re.match(r'(@\S+:)', line)
-- 
2.31.1