[PATCH v4 16/17] doc/sphinx/hxtool.py: add optional label argument to SRST directive

[David Woodhouse <dwmw2@infradead.org>]

From: David Woodhouse <dwmw@amazon.co.uk>

We can't just embed labels directly into files like qemu-options.hx which
are included from multiple top-level RST files, because Sphinx sees the
labels as duplicate: https://github.com/sphinx-doc/sphinx/issues/9707

So add an 'emitrefs' option to the Sphinx hxtool-doc directive, which is
set only in invocation.rst and not from the HTML rendition of the man
page. Along with an argument to the SRST directive which causes a label
of the form '.. _LABEL-reference-label:' to be emitted when the emitrefs
option is set.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
---
 docs/sphinx/hxtool.py      | 18 +++++++++++++++++-
 docs/system/invocation.rst |  1 +
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/docs/sphinx/hxtool.py b/docs/sphinx/hxtool.py
index 9f6b9d87dc..bfb0929573 100644
--- a/docs/sphinx/hxtool.py
+++ b/docs/sphinx/hxtool.py
@@ -78,18 +78,28 @@ def parse_archheading(file, lnum, line):
         serror(file, lnum, "Invalid ARCHHEADING line")
     return match.group(1)
 
+def parse_srst(file, lnum, line):
+    """Handle an SRST directive"""
+    # The input should be "SRST(label)".
+    match = re.match(r'SRST\((.*?)\)', line)
+    if match is None:
+        serror(file, lnum, "Invalid SRST line")
+    return match.group(1)
+
 class HxtoolDocDirective(Directive):
     """Extract rST fragments from the specified .hx file"""
     required_argument = 1
     optional_arguments = 1
     option_spec = {
-        'hxfile': directives.unchanged_required
+        'hxfile': directives.unchanged_required,
+        'emitrefs': directives.flag
     }
     has_content = False
 
     def run(self):
         env = self.state.document.settings.env
         hxfile = env.config.hxtool_srctree + '/' + self.arguments[0]
+        emitrefs = "emitrefs" in self.options
 
         # Tell sphinx of the dependency
         env.note_dependency(os.path.abspath(hxfile))
@@ -113,6 +123,12 @@ def run(self):
                         serror(hxfile, lnum, 'expected ERST, found SRST')
                     else:
                         state = HxState.RST
+                        if emitrefs and line != "SRST":
+                            label = parse_srst(hxfile, lnum, line)
+                            if label != "":
+                                rstlist.append("", hxfile, lnum - 1)
+                                refline = ".. _" + label + "-reference-label:"
+                                rstlist.append(refline, hxfile, lnum - 1)
                 elif directive == 'ERST':
                     if state == HxState.CTEXT:
                         serror(hxfile, lnum, 'expected SRST, found ERST')
diff --git a/docs/system/invocation.rst b/docs/system/invocation.rst
index 4ba38fc23d..ef75dad2e2 100644
--- a/docs/system/invocation.rst
+++ b/docs/system/invocation.rst
@@ -11,6 +11,7 @@ disk_image is a raw hard disk image for IDE hard disk 0. Some targets do
 not need a disk image.
 
 .. hxtool-doc:: qemu-options.hx
+    :emitrefs:
 
 Device URL Syntax
 ~~~~~~~~~~~~~~~~~
-- 
2.34.1