scripts/qapi/parser.py: improve doc comment indent handling

Make the handling of indentation in doc comments more sophisticated,
so that when we see a section like:

Notes: some text
       some more text
          indented line 3

we save it for the doc-comment processing code as:

some text
some more text
   indented line 3

and when we see a section with the heading on its own line:

Notes:

some text
some more text
   indented text

we also accept that and save it in the same form.

If we detect that the comment document text is not indented as much
as we expect it to be, we throw a parse error.  (We don't complain
about over-indented sections, because for rST this can be legitimate
markup.)

The golden reference for the doc comment text is updated to remove
the two 'wrong' indents; these now form a test case that we correctly
stripped leading whitespace from an indented multi-line argument
definition.

We update the documentation in docs/devel/qapi-code-gen.txt to
describe the new indentation rules.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-Id: <20200925162316.21205-6-peter.maydell@linaro.org>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
[Whitespace between sentences tweaked]
Signed-off-by: Markus Armbruster <armbru@redhat.com>

1 files changed, 23 insertions, 0 deletions

diff --git a/docs/devel/qapi-code-gen.txt b/docs/devel/qapi-code-gen.txt
index 9eede44350..2a09d4d292 100644
--- a/docs/devel/qapi-code-gen.txt
+++ b/docs/devel/qapi-code-gen.txt
@@ -901,6 +901,22 @@ commands and events), member (for structs and unions), branch (for
 alternates), or value (for enums), and finally optional tagged
 sections.
 
+Descriptions of arguments can span multiple lines.  The description
+text can start on the line following the '@argname:', in which case it
+must not be indented at all.  It can also start on the same line as
+the '@argname:'.  In this case if it spans multiple lines then second
+and subsequent lines must be indented to line up with the first
+character of the first line of the description:
+
+# @argone:
+# This is a two line description
+# in the first style.
+#
+# @argtwo: This is a two line description
+#          in the second style.
+
+The number of spaces between the ':' and the text is not significant.
+
 FIXME: the parser accepts these things in almost any order.
 FIXME: union branches should be described, too.
 
@@ -911,6 +927,13 @@ A tagged section starts with one of the following words:
 "Note:"/"Notes:", "Since:", "Example"/"Examples", "Returns:", "TODO:".
 The section ends with the start of a new section.
 
+The text of a section can start on a new line, in
+which case it must not be indented at all.  It can also start
+on the same line as the 'Note:', 'Returns:', etc tag.  In this
+case if it spans multiple lines then second and subsequent
+lines must be indented to match the first, in the same way as
+multiline argument descriptions.
+
 A 'Since: x.y.z' tagged section lists the release that introduced the
 definition.