docs/sphinx: remove special parsing for freeform sections

Remove the QAPI doc section heading syntax, use plain rST section
headings instead.

Tests and documentation are updated to match.

Interestingly, Plain rST headings work fine before this patch, except
for over- and underlining with '=', which the doc parser rejected as
invalid QAPI doc section heading in free-form comments.

Signed-off-by: John Snow <jsnow@redhat.com>
Message-ID: <20250618165353.1980365-5-jsnow@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
[Add more detail to commit message]
Signed-off-by: Markus Armbruster <armbru@redhat.com>

docs/devel/qapi-code-gen.rst

@@ -876,25 +876,35 @@ structuring content.
 Headings and subheadings
 ~~~~~~~~~~~~~~~~~~~~~~~~
 
-A free-form documentation comment containing a line which starts with
-some ``=`` symbols and then a space defines a section heading::
+Free-form documentation does not start with ``@SYMBOL`` and can contain
+arbitrary rST markup. Headings can be marked up using the standard rST
+syntax::
 
     ##
-    # = This is a top level heading
+    # *************************
+    # This is a level 2 heading
+    # *************************
     #
     # This is a free-form comment which will go under the
     # top level heading.
     ##
 
     ##
-    # == This is a second level heading
+    # This is a third level heading
+    # ==============================
+    #
+    # Level 4
+    # _______
+    #
+    # Level 5
+    # ^^^^^^^
+    #
+    # Level 6
+    # """""""
     ##
 
-A heading line must be the first line of the documentation
-comment block.
-
-Section headings must always be correctly nested, so you can only
-define a third-level heading inside a second-level heading, and so on.
+Level 1 headings are reserved for use by the generated documentation
+page itself, leaving level 2 as the highest level that should be used.
 
 
 Documentation markup

docs/interop/firmware.json

@@ -11,7 +11,9 @@
 # later. See the COPYING file in the top-level directory.
 
 ##
-# = Firmware
+# ********
+# Firmware
+# ********
 ##
 
 { 'pragma': {

docs/interop/vhost-user.json

@@ -10,7 +10,9 @@
 # later. See the COPYING file in the top-level directory.
 
 ##
-# = vhost user backend discovery & capabilities
+# *******************************************
+# vhost user backend discovery & capabilities
+# *******************************************
 ##
 
 ##

docs/sphinx/qapidoc.py

@@ -399,44 +399,9 @@ class Transmogrifier:
         self.ensure_blank_line()
 
     def visit_freeform(self, doc: QAPIDoc) -> None:
-        # TODO: Once the old qapidoc transformer is deprecated, freeform
-        # sections can be updated to pure rST, and this transformed removed.
-        #
-        # For now, translate our micro-format into rST. Code adapted
-        # from Peter Maydell's freeform().
-
         assert len(doc.all_sections) == 1, doc.all_sections
         body = doc.all_sections[0]
-        text = self.reformat_arobase(body.text)
-        info = doc.info
-
-        if re.match(r"=+ ", text):
-            # Section/subsection heading (if present, will always be the
-            # first line of the block)
-            (heading, _, text) = text.partition("\n")
-            (leader, _, heading) = heading.partition(" ")
-            # Implicit +1 for heading in the containing .rst doc
-            level = len(leader) + 1
-
-            # https://www.sphinx-doc.org/en/master/usage/restructuredtext/basics.html#sections
-            markers = ' #*=_^"'
-            overline = level <= 2
-            marker = markers[level]
-
-            self.ensure_blank_line()
-            # This credits all 2 or 3 lines to the single source line.
-            if overline:
-                self.add_line(marker * len(heading), info)
-            self.add_line(heading, info)
-            self.add_line(marker * len(heading), info)
-            self.ensure_blank_line()
-
-            # Eat blank line(s) and advance info
-            trimmed = text.lstrip("\n")
-            text = trimmed
-            info = info.next_line(len(text) - len(trimmed) + 1)
-
-        self.add_lines(text, info)
+        self.add_lines(self.reformat_arobase(body.text), doc.info)
         self.ensure_blank_line()
 
     def visit_entity(self, ent: QAPISchemaDefinition) -> None:

qapi/acpi.json

@@ -6,7 +6,9 @@
 # SPDX-License-Identifier: GPL-2.0-or-later
 
 ##
-# = ACPI
+# ****
+# ACPI
+# ****
 ##
 
 ##

qapi/audio.json

@@ -7,7 +7,9 @@
 # See the COPYING file in the top-level directory.
 
 ##
-# = Audio
+# *****
+# Audio
+# *****
 ##
 
 ##

qapi/authz.json

@@ -2,7 +2,9 @@
 # vim: filetype=python
 
 ##
-# = User authorization
+# ******************
+# User authorization
+# ******************
 ##
 
 ##

qapi/block-core.json

@@ -2,7 +2,8 @@
 # vim: filetype=python
 
 ##
-# == Block core (VM unrelated)
+# Block core (VM unrelated)
+# =========================
 ##
 
 { 'include': 'common.json' }

qapi/block-export.json

@@ -2,7 +2,8 @@
 # vim: filetype=python
 
 ##
-# == Block device exports
+# Block device exports
+# ====================
 ##
 
 { 'include': 'sockets.json' }

qapi/block.json

@@ -2,13 +2,16 @@
 # vim: filetype=python
 
 ##
-# = Block devices
+# *************
+# Block devices
+# *************
 ##
 
 { 'include': 'block-core.json' }
 
 ##
-# == Additional block stuff (VM related)
+# Additional block stuff (VM related)
+# ===================================
 ##
 
 ##

qapi/char.json

@@ -3,7 +3,9 @@
 #
 
 ##
-# = Character devices
+# *****************
+# Character devices
+# *****************
 ##
 
 { 'include': 'sockets.json' }

qapi/common.json

@@ -2,7 +2,9 @@
 # vim: filetype=python
 
 ##
-# = Common data types
+# *****************
+# Common data types
+# *****************
 ##
 
 ##

qapi/compat.json

@@ -2,7 +2,9 @@
 # vim: filetype=python
 
 ##
-# = Compatibility policy
+# ********************
+# Compatibility policy
+# ********************
 ##
 
 ##

qapi/control.json

@@ -3,7 +3,9 @@
 #
 
 ##
-# = QMP monitor control
+# *******************
+# QMP monitor control
+# *******************
 ##
 
 ##

qapi/crypto.json

@@ -3,7 +3,9 @@
 #
 
 ##
-# = Cryptography
+# ************
+# Cryptography
+# ************
 ##
 
 ##

qapi/cryptodev.json

@@ -5,7 +5,9 @@
 # See the COPYING file in the top-level directory.
 
 ##
-# = Cryptography devices
+# ********************
+# Cryptography devices
+# ********************
 ##
 
 ##

qapi/cxl.json

@@ -2,7 +2,9 @@
 # vim: filetype=python
 
 ##
-# = CXL devices
+# ***********
+# CXL devices
+# ***********
 ##
 
 ##

qapi/dump.json

@@ -5,7 +5,9 @@
 # See the COPYING file in the top-level directory.
 
 ##
-# = Dump guest memory
+# *****************
+# Dump guest memory
+# *****************
 ##
 
 ##

qapi/ebpf.json

@@ -5,7 +5,9 @@
 # See the COPYING file in the top-level directory.
 
 ##
-# = eBPF Objects
+# ************
+# eBPF Objects
+# ************
 #
 # eBPF object is an ELF binary that contains the eBPF program and eBPF
 # map description(BTF).  Overall, eBPF object should contain the

qapi/error.json

@@ -2,7 +2,9 @@
 # vim: filetype=python
 
 ##
-# = QMP errors
+# **********
+# QMP errors
+# **********
 ##
 
 ##

qapi/introspect.json

@@ -10,7 +10,9 @@
 # See the COPYING file in the top-level directory.
 
 ##
-# = QMP introspection
+# *****************
+# QMP introspection
+# *****************
 ##
 
 ##

qapi/job.json

@@ -2,7 +2,9 @@
 # vim: filetype=python
 
 ##
-# = Background jobs
+# ***************
+# Background jobs
+# ***************
 ##
 
 ##

qapi/machine-common.json

@@ -5,7 +5,9 @@
 # See the COPYING file in the top-level directory.
 
 ##
-# = Common machine types
+# ********************
+# Common machine types
+# ********************
 ##
 
 ##

qapi/machine.json

@@ -5,7 +5,9 @@
 # See the COPYING file in the top-level directory.
 
 ##
-# = Machines
+# ********
+# Machines
+# ********
 ##
 
 { 'include': 'common.json' }

qapi/migration.json

@@ -3,7 +3,9 @@
 #
 
 ##
-# = Migration
+# *********
+# Migration
+# *********
 ##
 
 { 'include': 'common.json' }

qapi/misc.json

@@ -3,7 +3,9 @@
 #
 
 ##
-# = Miscellanea
+# ***********
+# Miscellanea
+# ***********
 ##
 
 { 'include': 'common.json' }

qapi/net.json

@@ -3,7 +3,9 @@
 #
 
 ##
-# = Net devices
+# ***********
+# Net devices
+# ***********
 ##
 
 { 'include': 'sockets.json' }

qapi/pci.json

@@ -6,7 +6,9 @@
 # SPDX-License-Identifier: GPL-2.0-or-later
 
 ##
-# = PCI
+# ***
+# PCI
+# ***
 ##
 
 ##

qapi/qapi-schema.json

@@ -1,7 +1,9 @@
 # -*- Mode: Python -*-
 # vim: filetype=python
 ##
-# = Introduction
+# ************
+# Introduction
+# ************
 #
 # This manual describes the commands and events supported by the QEMU
 # Monitor Protocol (QMP).

qapi/qdev.json

@@ -5,7 +5,9 @@
 # See the COPYING file in the top-level directory.
 
 ##
-# = Device infrastructure (qdev)
+# ****************************
+# Device infrastructure (qdev)
+# ****************************
 ##
 
 { 'include': 'qom.json' }

qapi/qom.json

@@ -10,7 +10,9 @@
 { 'include': 'crypto.json' }
 
 ##
-# = QEMU Object Model (QOM)
+# ***********************
+# QEMU Object Model (QOM)
+# ***********************
 ##
 
 ##

qapi/replay.json

@@ -3,7 +3,9 @@
 #
 
 ##
-# = Record/replay
+# *************
+# Record/replay
+# *************
 ##
 
 { 'include': 'common.json' }

qapi/rocker.json

@@ -2,7 +2,9 @@
 # vim: filetype=python
 
 ##
-# = Rocker switch device
+# ********************
+# Rocker switch device
+# ********************
 ##
 
 ##

qapi/run-state.json

@@ -3,7 +3,9 @@
 #
 
 ##
-# = VM run state
+# ************
+# VM run state
+# ************
 ##
 
 ##

qapi/sockets.json

@@ -2,7 +2,9 @@
 # vim: filetype=python
 
 ##
-# = Socket data types
+# *****************
+# Socket data types
+# *****************
 ##
 
 ##

qapi/stats.json

@@ -9,7 +9,9 @@
 # SPDX-License-Identifier: GPL-2.0-or-later
 
 ##
-# = Statistics
+# **********
+# Statistics
+# **********
 ##
 
 ##

qapi/tpm.json

@@ -3,7 +3,9 @@
 #
 
 ##
-# = TPM (trusted platform module) devices
+# *************************************
+# TPM (trusted platform module) devices
+# *************************************
 ##
 
 ##

qapi/trace.json

@@ -7,7 +7,9 @@
 # See the COPYING file in the top-level directory.
 
 ##
-# = Tracing
+# *******
+# Tracing
+# *******
 ##
 
 ##

qapi/transaction.json

@@ -3,7 +3,9 @@
 #
 
 ##
-# = Transactions
+# ************
+# Transactions
+# ************
 ##
 
 { 'include': 'block-core.json' }

qapi/uefi.json

@@ -3,7 +3,9 @@
 #
 
 ##
-# = UEFI Variable Store
+# *******************
+# UEFI Variable Store
+# *******************
 #
 # The QEMU efi variable store implementation (hw/uefi/) uses this to
 # store non-volatile variables in json format on disk.

qapi/ui.json

@@ -3,7 +3,9 @@
 #
 
 ##
-# = Remote desktop
+# **************
+# Remote desktop
+# **************
 ##
 
 { 'include': 'common.json' }
@@ -200,7 +202,8 @@
   'if': 'CONFIG_PIXMAN' }
 
 ##
-# == Spice
+# Spice
+# =====
 ##
 
 ##
@@ -461,7 +464,8 @@
   'if': 'CONFIG_SPICE' }
 
 ##
-# == VNC
+# VNC
+# ===
 ##
 
 ##
@@ -794,7 +798,9 @@
   'if': 'CONFIG_VNC' }
 
 ##
-# = Input
+# *****
+# Input
+# *****
 ##
 
 ##

qapi/vfio.json

@@ -3,7 +3,9 @@
 #
 
 ##
-# = VFIO devices
+# ************
+# VFIO devices
+# ************
 ##
 
 ##

qapi/virtio.json

@@ -3,7 +3,9 @@
 #
 
 ##
-# = Virtio devices
+# **************
+# Virtio devices
+# **************
 ##
 
 ##

qapi/yank.json

@@ -3,7 +3,9 @@
 #
 
 ##
-# = Yank feature
+# ************
+# Yank feature
+# ************
 ##
 
 ##

scripts/qapi/parser.py

@@ -597,22 +597,15 @@ class QAPISchemaParser:
             # Free-form documentation
             doc = QAPIDoc(info)
             doc.ensure_untagged_section(self.info)
-            first = True
             while line is not None:
                 if match := self._match_at_name_colon(line):
                     raise QAPIParseError(
                         self,
                         "'@%s:' not allowed in free-form documentation"
                         % match.group(1))
-                if line.startswith('='):
-                    if not first:
-                        raise QAPIParseError(
-                            self,
-                            "'=' heading must come first in a comment block")
                 doc.append_line(line)
                 self.accept(False)
                 line = self.get_doc_line()
-                first = False
 
         self.accept()
         doc.end()

storage-daemon/qapi/qapi-schema.json

@@ -14,7 +14,9 @@
 # storage daemon.
 
 ##
-# = Introduction
+# ************
+# Introduction
+# ************
 #
 # This manual describes the commands and events supported by the QEMU
 # storage daemon QMP.
@@ -51,7 +53,9 @@
 { 'include': '../../qapi/job.json' }
 
 ##
-# = Block devices
+# *************
+# Block devices
+# *************
 ##
 { 'include': '../../qapi/block-core.json' }
 { 'include': '../../qapi/block-export.json' }

tests/qapi-schema/doc-good.json

@@ -8,7 +8,9 @@
     'documentation-exceptions': [ 'Enum', 'Variant1', 'Alternate', 'cmd' ] } }
 
 ##
-# = Section
+# *******
+# Section
+# *******
 ##
 
 ##
@@ -16,7 +18,8 @@
 ##
 
 ##
-# == Subsection
+# Subsection
+# ==========
 #
 # *with emphasis*
 # @var {in braces}
@@ -144,7 +147,8 @@
   'if': { 'not': { 'any': [ 'IFONE', 'IFTWO' ] } } }
 
 ##
-# == Another subsection
+# Another subsection
+# ==================
 ##
 
 ##

tests/qapi-schema/doc-good.out

@@ -55,13 +55,16 @@ event EVT_BOXED Object
     feature feat3
 doc freeform
     body=
-= Section
+*******
+Section
+*******
 doc freeform
     body=
 Just text, no heading.
 doc freeform
     body=
-== Subsection
+Subsection
+==========
 
 *with emphasis*
 @var {in braces}
@@ -155,7 +158,8 @@ description starts on the same line
 a feature
 doc freeform
     body=
-== Another subsection
+Another subsection
+==================
 doc symbol=cmd
     body=