From 72e7d87b01d52968ca018e9b54f433abfb7994dd Mon Sep 17 00:00:00 2001
From: Dmitry Kalinkin <dmitry.kalinkin@gmail.com>
Date: Wed, 7 Oct 2020 22:41:30 -0400
Subject: [PATCH] pythia: add hepmc3 support

---
 pkgs/development/libraries/physics/pythia/default.nix | 11 +++++++----
 pkgs/top-level/all-packages.nix                       |  4 +++-
 2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/pkgs/development/libraries/physics/pythia/default.nix b/pkgs/development/libraries/physics/pythia/default.nix
index 3105476c8429..53b2889a25c8 100644
--- a/pkgs/development/libraries/physics/pythia/default.nix
+++ b/pkgs/development/libraries/physics/pythia/default.nix
@@ -1,4 +1,4 @@
-{ stdenv, fetchurl, boost, fastjet, hepmc2, lhapdf, rsync, zlib }:
+{ stdenv, fetchurl, boost, fastjet, hepmc, lhapdf, rsync, zlib }:
 
 stdenv.mkDerivation rec {
   pname = "pythia";
@@ -9,7 +9,7 @@ stdenv.mkDerivation rec {
     sha256 = "0gli6zf8931i7kyminppisc9d0q69xxnalvhld5fgnkh4q82nz6d";
   };
 
-  buildInputs = [ boost fastjet hepmc2 zlib rsync lhapdf ];
+  buildInputs = [ boost fastjet hepmc zlib rsync lhapdf ];
 
   preConfigure = ''
     patchShebangs ./configure
@@ -17,9 +17,12 @@ stdenv.mkDerivation rec {
 
   configureFlags = [
     "--enable-shared"
-    "--with-hepmc2=${hepmc2}"
     "--with-lhapdf6=${lhapdf}"
-  ];
+  ] ++ (if stdenv.lib.versions.major hepmc.version == "3" then [
+    "--with-hepmc3=${hepmc}"
+  ] else [
+    "--with-hepmc2=${hepmc}"
+  ]);
 
   enableParallelBuilding = true;
 
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index ab0a1cf5c2f5..c026c8b678c6 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -26755,7 +26755,9 @@ in
 
   nlojet = callPackage ../development/libraries/physics/nlojet { };
 
-  pythia = callPackage ../development/libraries/physics/pythia { };
+  pythia = callPackage ../development/libraries/physics/pythia {
+    hepmc = hepmc2;
+  };
 
   rivet = callPackage ../development/libraries/physics/rivet {
     hepmc = hepmc2;