gerbv: pull fix pending upstream inclusion for -fno-common toolchains

Without the change build fails on upstream gcc-10 as:

    ld: interface.o:/build/gerbv/src/callbacks.h:50: multiple definition of
      `toggle_layer'; callbacks.o:/build/gerbv/src/callbacks.h:50: first defined here
    ld: interface.o:/build/gerbv/src/callbacks.h:44: multiple definition of
      `CALLBACKS_SAVE_FILE_TYPE'; callbacks.o:/build/gerbv/src/callbacks.h:44: first defined here
    ld: render.o:/build/gerbv/src/callbacks.h:44: multiple definition of
      `CALLBACKS_SAVE_FILE_TYPE'; callbacks.o:/build/gerbv/src/callbacks.h:44: first defined here

1 files changed, 11 insertions, 1 deletions

diff --git a/pkgs/applications/science/electronics/gerbv/default.nix b/pkgs/applications/science/electronics/gerbv/default.nix
index a16d5f32e27..f83cfa1bf04 100644
--- a/pkgs/applications/science/electronics/gerbv/default.nix
+++ b/pkgs/applications/science/electronics/gerbv/default.nix
@@ -1,4 +1,4 @@
-{ lib, stdenv, fetchgit, pkg-config, gettext, libtool, automake, autoconf, cairo, gtk2, autoreconfHook }:
+{ lib, stdenv, fetchgit, fetchpatch, pkg-config, gettext, libtool, automake, autoconf, cairo, gtk2, autoreconfHook }:
 
 stdenv.mkDerivation {
   pname = "gerbv";
@@ -10,6 +10,16 @@ stdenv.mkDerivation {
     sha256 = "00jn1xhf6kblxc5gac1wvk8zm12fy6sk81nj3jwdag0z6wk3z446";
   };
 
+  patches = [
+    # Pull patch pending upstream inclusion for -fno-common toolchains:
+    #  https://sourceforge.net/p/gerbv/patches/84/
+    (fetchpatch {
+      name = "fnoc-mmon.patch";
+      url = "https://sourceforge.net/p/gerbv/patches/84/attachment/0001-gerbv-fix-build-on-gcc-10-fno-common.patch";
+      sha256 = "1avfbkqhxl7wxn1z19y30ilkwvdgpdkzhzawrs5y3damxmqq8ggk";
+    })
+  ];
+
   nativeBuildInputs = [ autoreconfHook pkg-config automake autoconf ];
   buildInputs = [ gettext libtool cairo gtk2 ];