rubyMinimal: ruby with all options disabled by default

Similar to `gitMinimal` or `pythonMinimal`, this is useful for scripts
which don’t use anything but the standard library and want a small
footprint.

pkgs/development/interpreters/ruby/default.nix

@@ -149,14 +149,14 @@ let
         postInstall = ''
           # Remove unnecessary groff reference from runtime closure, since it's big
           sed -i '/NROFF/d' $out/lib/ruby/*/*/rbconfig.rb
-
-          ${lib.optionalString removeReferenceToCC ''
+          ${
+            lib.optionalString removeReferenceToCC ''
               # Get rid of the CC runtime dependency
               ${removeReferencesTo}/bin/remove-references-to \
                 -t ${stdenv.cc} \
-                $out/lib/libruby.so.*
-          ''}
-
+                $out/lib/libruby*
+            ''
+          }
           # Bundler tries to create this directory
           mkdir -p $out/nix-support
           cat > $out/nix-support/setup-hook <<EOF

pkgs/top-level/all-packages.nix

@@ -9354,6 +9354,21 @@ in
     ruby_2_5
     ruby_2_6;
 
+  rubyMinimal = ruby.override {
+    # gem support is minimal overhead
+    rubygemsSupport = true;
+    useRailsExpress = false;
+    zlibSupport = false;
+    opensslSupport = false;
+    gdbmSupport = false;
+    cursesSupport = false;
+    docSupport = false;
+    yamlSupport = false;
+    fiddleSupport = false;
+    # remove gcc from runtime closure
+    removeReferenceToCC = true;
+  };
+
   ruby = ruby_2_6;
 
   rubyPackages_2_4 = recurseIntoAttrs ruby_2_4.gems;