Source: https://gitlab.archlinux.org/archlinux/packaging/packages/alure/-/blob/main/dumb-2.patch

diff -Naur a/src/codec_dumb.cpp b/src/codec_dumb.cpp
--- a/src/codec_dumb.cpp	2011-07-29 09:37:48.000000000 +0100
+++ b/src/codec_dumb.cpp	2020-05-10 15:59:48.502632496 +0100
@@ -272,7 +272,11 @@
 
 private:
     // DUMBFILE iostream callbacks
+#if DUMB_VERSION >= 2*10000
+    static int skip(void *user_data, dumb_off_t offset)
+#else
     static int skip(void *user_data, long offset)
+#endif
     {
         std::istream *stream = static_cast<dumbStream*>(user_data)->fstream;
         stream->clear();
@@ -282,7 +286,11 @@
         return -1;
     }
 
+#if DUMB_VERSION >= 2*10000
+    static dumb_ssize_t read(char *ptr, size_t size, void *user_data)
+#else
     static long read(char *ptr, long size, void *user_data)
+#endif
     {
         std::istream *stream = static_cast<dumbStream*>(user_data)->fstream;
         stream->clear();