clhep: patch for clang

Fixes Homebrew/homebrew#28514.

Formula/clhep.rb

@@ -1,14 +1,17 @@
-require 'formula'
+require "formula"
 
 class Clhep < Formula
-  homepage 'http://proj-clhep.web.cern.ch/proj-clhep/'
-  url 'http://proj-clhep.web.cern.ch/proj-clhep/DISTRIBUTION/tarFiles/clhep-2.1.3.1.tgz'
-  sha1 '3ef0b7410d71ca25bb2f5b5ba6d928a338e30e6e'
+  homepage "http://proj-clhep.web.cern.ch/proj-clhep/"
+  url "http://proj-clhep.web.cern.ch/proj-clhep/DISTRIBUTION/tarFiles/clhep-2.1.3.1.tgz"
+  sha1 "3ef0b7410d71ca25bb2f5b5ba6d928a338e30e6e"
 
-  depends_on 'cmake' => :build
+  depends_on "cmake" => :build
+
+  # Patch for clang compatibility, adapted from MacPorts
+  patch :DATA
 
   def install
-    mkdir 'clhep-build' do
+    mkdir "clhep-build" do
       system "cmake", "../CLHEP",
                       "-DCMAKE_PREFIX_PATH=#{prefix}",
                       *std_cmake_args
@@ -16,3 +19,23 @@ class Clhep < Formula
     end
   end
 end
+
+__END__
+# https://savannah.cern.ch/bugs/?104110
+# https://trac.macports.org/ticket/42841
+#
+--- a/CLHEP/Matrix/src/Vector.cc.orig
++++ b/CLHEP/Matrix/src/Vector.cc
+@@ -114,9 +114,9 @@ HepVector::HepVector(const HepMatrix &hm1)
+ 
+ // trivial methods
+ 
+-inline int HepVector::num_row() const {return nrow;} 
+-inline int HepVector::num_size() const {return nrow;} 
+-inline int HepVector::num_col() const { return 1; }
++int HepVector::num_row() const {return nrow;}
++int HepVector::num_size() const {return nrow;}
++int HepVector::num_col() const { return 1; }
+ 
+ // operator()
+