When the first letter of a comment is !, the comment will be interp…

…olated

and always rendered into css output even in compressed output modes.
This is useful for adding Copyright notices to your generated CSS.

doc-src/SASS_CHANGELOG.md

@@ -25,6 +25,12 @@
   The imported file will be treated as though it were nested within the rule.
   Files with mixins may not be imported in nested contexts.
 
+* If a comment starts with `!`, that comment will now be interpolated
+  (`#{...}` will be replaced with the resulting value of the expression
+  inside) and the comment will always be printed out in the generated CSS
+  file -- even with compressed output. This is useful for adding copyright
+  notices to your stylesheets.
+
 ### Keyword Arguments
 
 Both mixins and Sass functions now support the ability to pass in keyword arguments.

doc-src/SASS_REFERENCE.md

@@ -541,6 +541,9 @@ is compiled to:
     a {
       color: green; }
 
+When the first letter of a comment is `!`, the comment will be interpolated
+and always rendered into css output even in compressed output modes. This is useful for adding Copyright notices to your generated CSS.
+
 ## SassScript {#sassscript}
 
 In addition to the plain CSS property syntax,

lib/sass/tree/comment_node.rb

@@ -10,6 +10,14 @@ class CommentNode < Node
     # @return [String]
     attr_accessor :value
 
+    # Whether the comment is loud.
+    #
+    # Loud comments start with ! and force the comment to be generated
+    # irrespective of compilation settings or the comment syntax used.
+    #
+    # @return [Boolean]
+    attr_accessor :loud
+
     # Whether or not the comment is silent (that is, doesn't output to CSS).
     #
     # @return [Boolean]
@@ -19,8 +27,10 @@ class CommentNode < Node
     # @param silent [Boolean] See \{#silent}
     def initialize(value, silent)
       @lines = []
-      @value = normalize_indentation value
       @silent = silent
+      @value = normalize_indentation value
+      @loud = @value =~ %r{^(/[\/\*])?!}
+      @value.sub!("#{$1}!", $1.to_s) if @loud
       super()
     end
 
@@ -36,9 +46,20 @@ def ==(other)
     # Returns `true` if this is a silent comment
     # or the current style doesn't render comments.
     #
+    # Comments starting with ! are never invisible (and the ! is removed from the output.)
+    #
     # @return [Boolean]
     def invisible?
-      style == :compressed || @silent
+      if @loud
+        return false
+      else
+        @silent || (style == :compressed)
+      end
+    end
+
+    # Returns whether this comment should be interpolated for dynamic comment generation.
+    def evaluated?
+      @loud
     end
 
     private

lib/sass/tree/visitors/perform.rb

@@ -52,7 +52,14 @@ def visit_root(node)
 
   # Removes this node from the tree if it's a silent comment.
   def visit_comment(node)
-    node.silent ? [] : node
+    return [] if node.invisible?
+    if node.evaluated?
+      node.value.gsub!(/(^|[^\\])\#{([^}]*)}/) do |md|
+        $1+Sass::Script.parse($2, node.line, 0, node.options).perform(@environment).to_s
+      end
+      node.value = run_interp([Sass::Script::String.new(node.value)])
+    end
+    node
   end
 
   # Prints the expression to STDERR.

lib/sass/tree/visitors/to_css.rb

@@ -59,8 +59,10 @@ def visit_comment(node)
     return if node.invisible?
     spaces = ('  ' * [@tabs - node.value[/^ */].size, 0].max)
 
-    content = node.value.gsub(/^/, spaces)
-    content.gsub!(/\n +(\* *(?!\/))?/, ' ') if node.style == :compact
+    content = node.value.gsub(/^/, spaces).gsub(%r{^(\s*)//(.*)$}) do |md|
+      "#{$1}/*#{$2} */"
+    end
+    content.gsub!(/\n +(\* *(?!\/))?/, ' ') if (node.style == :compact || node.style == :compressed) && !node.loud
     content
   end
 

test/sass/engine_test.rb

@@ -1715,6 +1715,47 @@ def test_loud_comment_with_separate_line_close
 SASS
   end
 
+  def test_loud_comment_in_compressed_mode
+    assert_equal <<CSS, render(<<SASS, :style => :compressed)
+foo{color:blue;/* foo
+ * bar
+ */}
+CSS
+foo
+  color: blue
+  /*! foo
+   * bar
+   */
+SASS
+  end
+  def test_loud_comment_in_silent_comment
+    assert_equal <<CSS, render(<<SASS, :style => :compressed)
+foo{color:blue;/* foo */
+/* bar */
+/* */
+/* bip */
+/* baz */}
+CSS
+foo
+  color: blue
+  //! foo
+  //! bar
+  //!
+    bip
+    baz
+SASS
+  end
+
+  def test_loud_comment_is_evaluated
+    assert_equal <<CSS, render(<<SASS)
+/*
+ * Hue: 327.216deg */
+CSS
+/*!
+  Hue: \#{hue(#f836a0)}
+SASS
+  end
+
   def test_attribute_selector_with_spaces
     assert_equal(<<CSS, render(<<SASS))
 a b[foo=bar] {