qapi: Make section headings start a new doc comment block

Our current QAPI doc-comment markup allows section headers (introduced
with a leading '=' or '==') anywhere in a free-form documentation
comment.  This works for Texinfo because the generator simply prints a
Texinfo section command at that point in the output stream.  For rST
generation, since we're assembling a tree of docutils nodes, this is
awkward because a new section implies starting a new section node at
the top level of the tree and generating text into there.

Make section headers start a new free-form documentation block, so the
future rST document generator doesn't have to look at every line in
free-form blocks and handle headings in odd places.

This change makes no difference to the generated Texinfo.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20200320091805.5585-3-armbru@redhat.com>

scripts/qapi/parser.py

@@ -52,8 +52,8 @@ class QAPISchemaParser:
             info = self.info
             if self.tok == '#':
                 self.reject_expr_doc(cur_doc)
-                cur_doc = self.get_doc(info)
-                self.docs.append(cur_doc)
+                for cur_doc in self.get_doc(info):
+                    self.docs.append(cur_doc)
                 continue
 
             expr = self.get_expr(False)
@@ -270,7 +270,8 @@ class QAPISchemaParser:
             raise QAPIParseError(
                 self, "junk after '##' at start of documentation comment")
 
-        doc = QAPIDoc(self, info)
+        docs = []
+        cur_doc = QAPIDoc(self, info)
         self.accept(False)
         while self.tok == '#':
             if self.val.startswith('##'):
@@ -279,15 +280,20 @@ class QAPISchemaParser:
                     raise QAPIParseError(
                         self,
                         "junk after '##' at end of documentation comment")
-                doc.end_comment()
+                cur_doc.end_comment()
+                docs.append(cur_doc)
                 self.accept()
-                return doc
+                return docs
             if self.val.startswith('# ='):
-                if doc.symbol:
+                if cur_doc.symbol:
                     raise QAPIParseError(
                         self,
                         "unexpected '=' markup in definition documentation")
-            doc.append(self.val)
+                if cur_doc.body.text:
+                    cur_doc.end_comment()
+                    docs.append(cur_doc)
+                    cur_doc = QAPIDoc(self, info)
+            cur_doc.append(self.val)
             self.accept(False)
 
         raise QAPIParseError(self, "documentation comment must end with '##'")
@@ -316,7 +322,6 @@ class QAPIDoc:
         def __init__(self, name=None):
             # optional section name (argument/member or section name)
             self.name = name
-            # the list of lines for this section
             self.text = ''
 
         def append(self, line):

tests/qapi-schema/doc-good.out

@@ -69,7 +69,8 @@ event EVT-BOXED Object
 doc freeform
     body=
 = Section
-
+doc freeform
+    body=
 == Subsection
 
 *strong* _with emphasis_