Don't remove docs in block yielding of macro

spec/compiler/parser/to_s_spec.cr

@@ -1,8 +1,12 @@
 require "../../spec_helper"
 
-private def expect_to_s(original, expected = original, file = __FILE__, line = __LINE__)
+private def expect_to_s(original, expected = original, emit_doc = false, file = __FILE__, line = __LINE__)
   it "does to_s of #{original.inspect}", file, line do
-    Parser.parse(original).to_s.should eq(expected), file, line
+    str = IO::Memory.new expected.bytesize
+    parser = Parser.new original
+    parser.wants_doc = emit_doc
+    parser.parse.to_s(str, emit_doc: emit_doc)
+    str.to_s.should eq(expected), file, line
   end
 end
 
@@ -88,4 +92,5 @@ describe "ASTNode#to_s" do
   expect_to_s "macro foo\n{% @type %}\nend"
   expect_to_s "macro foo\n\\{%@type %}\nend"
   expect_to_s "enum A : B\nend"
+  expect_to_s "# doc\ndef foo\nend", emit_doc: true
 end

src/compiler/crystal/macros/interpreter.cr

@@ -103,7 +103,7 @@ module Crystal
         # are shown in the block instead of in the generated macro source
         is_yield = node.exp.is_a?(Yield) && !@last.is_a?(Nop)
         @str << " #<loc:push>begin " if is_yield
-        @last.to_s(@str, emit_loc_pragma: is_yield)
+        @last.to_s(@str, emit_loc_pragma: is_yield, emit_doc: is_yield)
         @str << " end#<loc:pop> " if is_yield
       end
 

src/compiler/crystal/syntax/ast.cr

@@ -40,6 +40,7 @@ module Crystal
       clone = clone_without_location
       clone.location = location
       clone.end_location = end_location
+      clone.doc = doc
       clone
     end
 

src/compiler/crystal/syntax/to_s.cr

@@ -7,37 +7,40 @@ module Crystal
       to_s(io)
     end
 
-    def to_s(io, emit_loc_pragma = false)
-      visitor = ToSVisitor.new(io, emit_loc_pragma: emit_loc_pragma)
+    def to_s(io, emit_loc_pragma = false, emit_doc = false)
+      visitor = ToSVisitor.new(io, emit_loc_pragma: emit_loc_pragma, emit_doc: emit_doc)
       self.accept visitor
     end
   end
 
   class ToSVisitor < Visitor
     @str : IO
 
-    def initialize(@str = IO::Memory.new, @emit_loc_pragma = false)
+    def initialize(@str = IO::Memory.new, @emit_loc_pragma = false, @emit_doc = false)
       @indent = 0
       @inside_macro = 0
       @inside_lib = false
     end
 
     def visit_any(node)
-      return true unless @emit_loc_pragma
-
-      location = node.location
-      return true unless location
-
-      filename = location.filename
-      return true unless filename.is_a?(String)
+      if @emit_doc && (doc = node.doc) && !doc.empty?
+        doc.each_line(chomp: false) do |line|
+          append_indent
+          @str << "# "
+          @str << line
+        end
+        @str.puts
+      end
 
-      @str << "#<loc:"
-      filename.inspect(@str)
-      @str << ","
-      @str << location.line_number
-      @str << ","
-      @str << location.column_number
-      @str << ">"
+      if @emit_loc_pragma && (loc = node.location) && loc.filename.is_a?(String)
+        @str << "#<loc:"
+        loc.filename.inspect(@str)
+        @str << ","
+        @str << loc.line_number
+        @str << ","
+        @str << loc.column_number
+        @str << ">"
+      end
 
       true
     end