From dbd996d27a0fbc59ebeaf3ce969c0ca3d364ab91 Mon Sep 17 00:00:00 2001
From: Jakob Lykke Andersen <Jakob@caput.dk>
Date: Sun, 28 Nov 2021 20:52:47 +0100
Subject: [PATCH] Fix friend functions for older Doxygen versions

---
 CHANGELOG.rst                      | 2 ++
 breathe/renderer/sphinxrenderer.py | 5 +++++
 2 files changed, 7 insertions(+)

diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index 51265498..c20388c6 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -24,6 +24,8 @@ Inspired by `Keepachangelog.com <http://keepachangelog.com/>`__.
   - Add :confval:`breathe_show_include` to control whether ``#include`` lines
     are shown. Defaults to ``True``.
     `#725 <https://github.com/michaeljones/breathe/pull/725>`__
+  - Fix friend functions for older Doxygen versions.
+    `#767 <https://github.com/michaeljones/breathe/issues/767>`__
 
 - 2021-09-14 - **Breathe v4.31.0**
 
diff --git a/breathe/renderer/sphinxrenderer.py b/breathe/renderer/sphinxrenderer.py
index 6c3d3887..0f3c289d 100644
--- a/breathe/renderer/sphinxrenderer.py
+++ b/breathe/renderer/sphinxrenderer.py
@@ -1923,6 +1923,11 @@ def visit_function(self, node) -> List[Node]:
                 # Doxygen sometimes leaves 'static' in the type,
                 # e.g., for "constexpr static auto f()"
                 typ = typ.replace("static ", "")
+                # In Doxygen up to somewhere between 1.8.17 to exclusive 1.9.1
+                # the 'friend' part is also left in the type.
+                # See also #767.
+                if typ.startswith("friend "):
+                    typ = typ[7:]
                 elements.append(typ)
                 elements.append(name)
                 elements.append(node.get_argsstring())