See https://groups.google.com/forum/#!topic/minisat/FCocZsC8oMQ
This seems to only be a problem with newer versions of g++, and
upstream development seems to have stopped in 2013.

diff -rupN minisat-2.2.0/core/SolverTypes.h minisat-2.2.0.patched/core/SolverTypes.h
--- a/minisat/core/SolverTypes.h	2010-07-10 17:07:36.000000000 +0100
+++ b/minisat/core/SolverTypes.h	2014-03-29 11:57:49.000000000 +0000
@@ -47,7 +47,7 @@ struct Lit {
     int     x;

     // Use this as a constructor:
-    friend Lit mkLit(Var var, bool sign = false);
+    //friend Lit mkLit(Var var, bool sign = false);

     bool operator == (Lit p) const { return x == p.x; }
     bool operator != (Lit p) const { return x != p.x; }
@@ -55,7 +55,7 @@ struct Lit {
 };


-inline  Lit  mkLit     (Var var, bool sign) { Lit p; p.x = var + var + (int)sign; return p; }
+inline  Lit  mkLit     (Var var, bool sign = false) { Lit p; p.x = var + var + (int)sign; return p; }
 inline  Lit  operator ~(Lit p)              { Lit q; q.x = p.x ^ 1; return q; }
 inline  Lit  operator ^(Lit p, bool b)      { Lit q; q.x = p.x ^ (unsigned int)b; return q; }
 inline  bool sign      (Lit p)              { return p.x & 1; }
/system/examples'>log</a><a href='/guix/tree/gnu/system/examples?id=8d615398831ebe47ae861b3580d49b64ca50bc82'>tree</a><a href='/guix/commit/gnu/system/examples?id=8d615398831ebe47ae861b3580d49b64ca50bc82'>commit</a><a href='/guix/diff/gnu/system/examples?id=8d615398831ebe47ae861b3580d49b64ca50bc82'>diff</a></td><td class='form'><form class='right' method='get' action='/guix/log/gnu/system/examples'>
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<div class='path'>path: <a href='/guix/log/?id=8d615398831ebe47ae861b3580d49b64ca50bc82'>root</a>/<a href='/guix/log/gnu?id=8d615398831ebe47ae861b3580d49b64ca50bc82'>gnu</a>/<a href='/guix/log/gnu/system?id=8d615398831ebe47ae861b3580d49b64ca50bc82'>system</a>/<a href='/guix/log/gnu/system/examples?id=8d615398831ebe47ae861b3580d49b64ca50bc82'>examples</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/gnu/system/examples?id=8d615398831ebe47ae861b3580d49b64ca50bc82&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2021-01-19 17:16:56 +0100'>2021-01-19</span></td><td><a href='/guix/comm<tr><td><span title='2022-07-03 14:12:32 +0200'>2022-07-03</span></td><td><a href='/guix/commit/.gitignore?id=4eaf90470f466b3fdab87f6961cb18bb348d433f'>etc: Add teams.scm.</a><span class='msg-avail'>...<span class='msg-tooltip'>* etc/teams.scm.in: New file.
* configure.ac: Generate executable.
* .gitignore: Ignore generated file.
</span></span></td><td>Ricardo Wurmus</td></tr>
ts/guix-system.sh: Ditto.
* gnu/system/examples/bare-hurd.tmpl: Ditto.
* doc/guix.texi (Building the Installation Image,
Building the Installation Image for ARM Boards,
Invoking guix pack,
Invoking guix system): Adapt documentation.
</span></span></td><td>Mathieu Othacehe</td></tr>