From beac8a05dd8f4973ce0d9343b4403324e177a8aa Mon Sep 17 00:00:00 2001
From: Max Horn <max@quendi.de>
Date: Fri, 25 Aug 2023 11:46:11 +0200
Subject: [PATCH] Fix Agemo(G,p) for trivial G (#5494)

---
 lib/grp.gi                          | 4 ++++
 tst/testbugfix/2023-08-25-Agemo.tst | 5 +++++
 2 files changed, 9 insertions(+)
 create mode 100644 tst/testbugfix/2023-08-25-Agemo.tst

diff --git a/lib/grp.gi b/lib/grp.gi
index f2e6b620fb..5713761c35 100644
--- a/lib/grp.gi
+++ b/lib/grp.gi
@@ -2362,6 +2362,10 @@ InstallGlobalFunction( Agemo, function( arg )
     G := arg[1];
     p := arg[2];
 
+    if IsTrivial(G) then
+        return G;
+    fi;
+
     # <G> must be a <p>-group
     if not IsPGroup(G) or PrimePGroup(G)<>p then
         Error( "Agemo: <G> must be a p-group" );
diff --git a/tst/testbugfix/2023-08-25-Agemo.tst b/tst/testbugfix/2023-08-25-Agemo.tst
new file mode 100644
index 0000000000..1f525b5f70
--- /dev/null
+++ b/tst/testbugfix/2023-08-25-Agemo.tst
@@ -0,0 +1,5 @@
+# fix Agemo(G,p) for trivial G
+gap> Agemo(TrivialGroup(IsPcGroup), 2);
+<pc group of size 1 with 0 generators>
+gap> Agemo(TrivialGroup(IsPcGroup), 2, 1);
+<pc group of size 1 with 0 generators>