Install builder: remove target file before copying to avoid errors due to overwriting read-only files - close #123

build_tests/build_dir/install_read_only.rb

@@ -0,0 +1,3 @@
+Rscons::Environment.new do |env|
+  env.Install("dest", "install.rb")
+end

lib/rscons/builders/install.rb

@@ -47,6 +47,7 @@ module Rscons
               printed_message = true
             end
             cache.mkdir_p(File.dirname(dest))
+            FileUtils.rm_f(dest)
             FileUtils.cp(src, dest, :preserve => true)
           end
           cache.register_build(dest, :Copy, [src], env)

spec/build_tests_spec.rb

@@ -1002,6 +1002,22 @@ EOF
       expect(lines(result.stdout)).to eq ["Install inst.exe"]
     end
 
+    it "overwrites a read-only file" do
+      test_dir("build_dir")
+
+      FileUtils.chmod("a=r", "install.rb")
+      result = run_test(rsconsfile: "install_read_only.rb")
+      expect(result.stderr).to eq ""
+      expect(lines(result.stdout)).to eq ["Install dest"]
+
+      FileUtils.rm_f("install.rb")
+      File.binwrite("install.rb", "hi")
+      FileUtils.chmod("a=r", "install.rb")
+      result = run_test(rsconsfile: "install_read_only.rb")
+      expect(result.stderr).to eq ""
+      expect(lines(result.stdout)).to eq ["Install dest"]
+    end
+
     it "operates the same as a Copy builder" do
       test_dir("build_dir")