Heuristic for .inc PHP files (#2980)

lib/linguist/heuristics.rb

@@ -187,6 +187,12 @@ module Linguist
       end
     end
 
+    disambiguate ".inc" do |data|
+      if /^<\?(?:php)?/.match(data)
+        Language["PHP"]
+      end
+    end
+
     disambiguate ".l" do |data|
       if /\(def(un|macro)\s/.match(data)
         Language["Common Lisp"]

test/test_heuristics.rb

@@ -122,6 +122,12 @@ class TestHeuristcs < Minitest::Test
     })
   end
 
+  def test_inc_by_heuristics
+    assert_heuristics({
+      "PHP" => all_fixtures("PHP", "*.inc")
+    })
+  end
+
   def test_ls_by_heuristics
     assert_heuristics({
       "LiveScript" => all_fixtures("LiveScript", "*.ls"),