RST: fix directive with fields (#16490) (#16493)

* RST: fix directive with fields (#16490)

* Update tests/stdlib/trstgen.nim

Co-authored-by: Clyybber <darkmine956@gmail.com>

lib/packages/docutils/rst.nim

@@ -1737,7 +1737,8 @@ proc parseDirective(p: var RstParser, flags: DirFlags,
   ##
   ## .. warning:: Any of the 3 children may be nil.
   result = parseDirective(p, flags)
-  if not isNil(contentParser):
+  if not isNil(contentParser) and
+      (currentTok(p).kind != tkIndent or indFollows(p)):
     var nextIndent = p.tok[tokenAfterNewline(p)-1].ival
     if nextIndent <= currInd(p):  # parse only this line
       nextIndent = currentTok(p).col

tests/stdlib/trstgen.nim

@@ -535,6 +535,17 @@ Test1
     doAssert count(output1, "<ul ") == 1
     doAssert count(output1, "</ul>") == 1
 
+  test "Nim (RST extension) code-block":
+    # check that presence of fields doesn't consume the following text as
+    # its code (which is a literal block)
+    let input0 = dedent """
+      .. code-block:: nim
+         :number-lines: 0
+
+      Paragraph1"""
+    let output0 = rstToHtml(input0, {roSupportMarkdown}, defaultConfig())
+    doAssert "<p>Paragraph1</p>" in output0
+
   test "RST admonitions":
     # check that all admonitions are implemented
     let input0 = dedent """