Taken from: https://gitweb.gentoo.org/repo/gentoo.git/tree/x11-libs/agg/files/agg-2.5-gcc8.patch.

diff -uprN agg-2.5/include/agg_renderer_outline_aa.h agg-2.5-fixed/include/agg_renderer_outline_aa.h
--- agg-2.5/include/agg_renderer_outline_aa.h	2018-08-25 02:02:52.507254241 +0800
+++ agg-2.5-fixed/include/agg_renderer_outline_aa.h	2018-08-25 02:04:15.291175316 +0800
@@ -1375,7 +1375,7 @@ namespace agg
         //---------------------------------------------------------------------
         void profile(const line_profile_aa& prof) { m_profile = &prof; }
         const line_profile_aa& profile() const { return *m_profile; }
-        line_profile_aa& profile() { return *m_profile; }
+        const line_profile_aa& profile() { return *m_profile; }
 
         //---------------------------------------------------------------------
         int subpixel_width() const { return m_profile->subpixel_width(); }
rm></td></tr>
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<tr><td><span title='2020-11-07 13:19:25 +0100'>2020-11-07</span></td><td><a href='/guix/commit/gnu/installer/steps.scm?id=8338d414b361e4fb961221642c1064e9dc89ba65'>installer: Limit listbox height.</a><span class='msg-avail'>...</span></td><td>Mathieu Othacehe</td></tr>
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<tr><td><span title='2020-03-05 23:40:22 +0100'>2020-03-05</span></td><td><a href='/guix/commit/gnu/installer/steps.scm?id=63b8c089c1596cd3e814ac13e1a8b3fa45bb2b54'>installer: Implement a dialog on /var/guix/installer-socket.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2020-02-22 00:45:42 +0100'>2020-02-22</span></td><td><a href='/guix/commit/gnu/installer/steps.scm?id=5c04b00cf463a543b8ffc9eb55991f6b4cc145dd'>installer: Log important bits to syslog.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
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<tr><td><span title='2019-04-07 18:02:39 +0200'>2019-04-07</span></td><td><a href='/guix/commit/gnu/installer/steps.scm?id=7d1030a63592aa2f94f6617786f22cfa83fb346f'>installer: Add dialog to select networking services.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>