1 files changed, 30 insertions, 7 deletions
diff --git a/Library/Formula/dmd.rb b/Library/Formula/dmd.rb
index 16a84ef1a..ebf53f68b 100644
--- a/Library/Formula/dmd.rb
+++ b/Library/Formula/dmd.rb
@@ -35,16 +35,16 @@ class Dmd < Formula
     prefix.install "samples"
     man.install Dir["docs/man/*"]
 
-    conf = etc/"dmd.conf"
-
-    if conf.exist?
-      inreplace conf, /^DFLAGS=.+$/, "DFLAGS=-I#{include}/d2 -L-L#{lib}"
-    else
-      conf.write <<-EOS.undent
+    # A proper dmd.conf is required for later build steps:
+    conf = buildpath/"dmd.conf"
+    # Can't use opt_include or opt_lib here because dmd won't have been
+    # linked into opt by the time this build runs:
+    conf.write <<-EOS.undent
         [Environment]
         DFLAGS=-I#{include}/d2 -L-L#{lib}
         EOS
-    end
+    etc.install conf
+    install_new_dmd_conf
 
     make_args.unshift "DMD=#{bin}/dmd"
 
@@ -65,6 +65,29 @@ class Dmd < Formula
     end
   end
 
+  # Previous versions of this formula may have left in place an incorrect
+  # dmd.conf.  If it differs from the newly generated one, move it out of place
+  # and warn the user.
+  # This must be idempotent because it may run from both install() and
+  # post_install() if the user is running `brew install --build-from-source`.
+  def install_new_dmd_conf
+    conf = etc/"dmd.conf"
+
+    # If the new file differs from conf, etc.install drops it here:
+    new_conf = etc/"dmd.conf.default"
+    # Else, we're already using the latest version:
+    return unless new_conf.exist?
+
+    backup = etc/"dmd.conf.old"
+    opoo "An old dmd.conf was found and will be moved to #{backup}."
+    mv conf, backup
+    mv new_conf, conf
+  end
+
+  def post_install
+    install_new_dmd_conf
+  end
+
   test do
     system bin/"dmd", prefix/"samples/hello.d"
     system "./hello"