Re-establish support for GAP 4.10

* Avoid 1-argument `First`/`Last` – instead use `list[1]`/`list[Length(list)]`
* Include compiled.h in GAP 4.10, since gap_all.h doesn't exist yet

Author: wilfwilson

gap/attr.gi

@@ -1814,12 +1814,12 @@ function(D, maxLength)
     # Extends a given chordless path if possible
     CCExtension := function(digraph, path, C, key, blocked)
         local v, extendedPath, data;
-        blocked := BlockNeighbours(digraph, Last(path), blocked);
-        for v in OutNeighboursOfVertex(digraph, Last(path)) do
+        blocked := BlockNeighbours(digraph, path[Length(path)], blocked);
+        for v in OutNeighboursOfVertex(digraph, path[Length(path)]) do
             if DigraphVertexLabel(digraph, v) > key and blocked[v] = 1
               and Length(path) < maxLength then
                 extendedPath := Concatenation(path, [v]);
-                if IsDigraphEdge(digraph, v, First(path)) then
+                if IsDigraphEdge(digraph, v, path[1]) then
                     Add(C, extendedPath);
                 else
                     data := CCExtension(digraph, extendedPath, C, key, blocked);
@@ -1828,7 +1828,7 @@ function(D, maxLength)
                 fi;
             fi;
         od;
-        blocked := UnblockNeighbours(digraph, Last(path), blocked);
+        blocked := UnblockNeighbours(digraph, path[Length(path)], blocked);
         return [C, blocked];
     end;
 

makedoc.g

@@ -53,7 +53,8 @@ for Pkg in Concatenation(PkgInfo.Dependencies.NeededOtherPackages,
 od;
 
 ARCHIVENAME := SplitString(PkgInfo.ArchiveURL, "/");
-ARCHIVENAME := Concatenation(Last(ARCHIVENAME), PkgInfo.ArchiveFormats);
+ARCHIVENAME := Concatenation(ARCHIVENAME[Length(ARCHIVENAME)],
+                             PkgInfo.ArchiveFormats);
 XMLEntities.ARCHIVENAME := ARCHIVENAME;
 
 XMLEntities.DIGRAPHS := PackageEntity("Digraphs");

read.g

@@ -30,6 +30,12 @@ BindGlobal("DIGRAPHS_NautyAvailable",
 
 Unbind(_NautyTracesInterfaceVersion);
 
+# Delete this when we no longer support GAP 4.10
+if not CompareVersionNumbers(ReplacedString(GAPInfo.Version, "dev", ""), "4.11")
+    and not IsBound(INTOBJ_MAX) then
+  BindGlobal("INTOBJ_MAX", 1152921504606846975);
+fi;
+
 ReadPackage("digraphs", "gap/utils.gi");
 ReadPackage("digraphs", "gap/digraph.gi");
 ReadPackage("digraphs", "gap/constructors.gi");

src/gap-includes.h

@@ -26,5 +26,9 @@
 #endif
 // GAP headers
 #include "gap_all.h"  // for Obj, Int
+                      //
+#ifdef GAP410_OR_OLDER
+#include "compiled.h"  // FIXME Remove include when we don't support GAP 4.10
+#endif
 
 #endif  // DIGRAPHS_SRC_GAP_INCLUDES_H_

src/gap_all.h

@@ -0,0 +1,20 @@
+/*******************************************************************************
+**
+*A  gap_all.h                   GAP package Digraphs          Julius Jonusas
+**                                                            James Mitchell
+**                                                            Wilf A. Wilson
+**                                                            Michael Young
+**
+**  Copyright (C) 2014-25 - Julius Jonusas, James Mitchell, Wilf A. Wilson,
+**  Michael Young
+**
+**  This file is free software, see the digraphs/LICENSE.
+**
+*******************************************************************************/
+
+#ifndef DIGRAPHS_SRC_GAP_ALL_H_
+#define DIGRAPHS_SRC_GAP_ALL_H_
+// Delete this file once we no longer support GAP 4.10.
+// This is a hack to get Digraphs to compile on GAP 4.10 still.
+#define GAP410_OR_OLDER
+#endif  // DIGRAPHS_SRC_GAP_ALL_H_