From a0d16f0c6cfc1af0f4e3cf3e2c910515c0f7bdf3 Mon Sep 17 00:00:00 2001
From: Max Horn <max@quendi.de>
Date: Thu, 15 Apr 2021 02:12:53 +0200
Subject: [PATCH] Fix NewZeroMatrix for IsGF2MatrixRep with zero rows

---
 hpcgap/lib/vecmat.gi                     | 9 ++++-----
 lib/vecmat.gi                            | 9 ++++-----
 tst/testinstall/MatrixObj/ZeroMatrix.tst | 4 ++--
 3 files changed, 10 insertions(+), 12 deletions(-)

diff --git a/hpcgap/lib/vecmat.gi b/hpcgap/lib/vecmat.gi
index f28aa5e0b3a..8148a2b51e6 100644
--- a/hpcgap/lib/vecmat.gi
+++ b/hpcgap/lib/vecmat.gi
@@ -2480,12 +2480,11 @@ InstallMethod( NewZeroMatrix, "for IsGF2MatrixRep, GF(2), and two ints",
     if rows = 0 then
         Error("IsGF2MatrixRep with zero rows not yet supported");
     fi;
-    m := 0*[1..rows];
-    m[1] := NewZeroVector(IsGF2VectorRep,f,cols);
-    for i in [2..rows] do
-        m[i] := ShallowCopy(m[1]);
+    m := EmptyPlist(rows);
+    for i in [1..rows] do
+        m[i] := ZERO_GF2VEC_2(cols);
     od;
-    ConvertToMatrixRep(m,2);
+    ConvertToMatrixRepNC(m,2);
     return m;
   end );
 
diff --git a/lib/vecmat.gi b/lib/vecmat.gi
index ff011542c97..bfbc243f3cc 100644
--- a/lib/vecmat.gi
+++ b/lib/vecmat.gi
@@ -2473,12 +2473,11 @@ InstallMethod( NewZeroMatrix, "for IsGF2MatrixRep, GF(2), and two ints",
     if rows = 0 then
         Error("IsGF2MatrixRep with zero rows not yet supported");
     fi;
-    m := 0*[1..rows];
-    m[1] := NewZeroVector(IsGF2VectorRep,f,cols);
-    for i in [2..rows] do
-        m[i] := ShallowCopy(m[1]);
+    m := EmptyPlist(rows);
+    for i in [1..rows] do
+        m[i] := ZERO_GF2VEC_2(cols);
     od;
-    ConvertToMatrixRep(m,2);
+    ConvertToMatrixRepNC(m,2);
     return m;
   end );
 
diff --git a/tst/testinstall/MatrixObj/ZeroMatrix.tst b/tst/testinstall/MatrixObj/ZeroMatrix.tst
index a66f1231708..2affaa554b8 100644
--- a/tst/testinstall/MatrixObj/ZeroMatrix.tst
+++ b/tst/testinstall/MatrixObj/ZeroMatrix.tst
@@ -7,7 +7,7 @@ gap> ReadGapRoot("tst/testinstall/MatrixObj/testmatobj.g");
 gap> TestZeroMatrix(IsGF2MatrixRep, GF(2), 2, 3);
 <a 2x3 matrix over GF2>
 gap> TestZeroMatrix(IsGF2MatrixRep, GF(2), 2, 0);
-Error, Assertion failure
+<a 2x0 matrix over GF2>
 gap> TestZeroMatrix(IsGF2MatrixRep, GF(2), 0, 3); # TODO
 Error, IsGF2MatrixRep with zero rows not yet supported
 
@@ -106,7 +106,7 @@ gap> ZeroMatrix(GF(2), 2, 3);
 gap> ZeroMatrix(GF(2), 0, 3);
 Error, IsGF2MatrixRep with zero rows not yet supported
 gap> ZeroMatrix(GF(2), 2, 0);
-[ <a GF2 vector of length 0>, <a GF2 vector of length 0> ]
+<a 2x0 matrix over GF2>
 
 #
 gap> ZeroMatrix(GF(3), 2, 3);