Fix #2030: automatic dedent support in code-block directive

CHANGES

@@ -30,6 +30,8 @@ Features added
 * #6241: mathjax: Include mathjax.js only on the document using equations
 * #8132: Add :confval:`project_copyright` as an alias of :confval:`copyright`
 * #207: Now :confval:`highlight_language` supports multiple languages
+* #2030: :rst:dir:`code-block` and :rst:dir:`literalinclude` supports automatic
+  dedent via no-argument ``:dedent:`` option
 
 Bugs fixed
 ----------

doc/usage/restructuredtext/directives.rst

@@ -572,9 +572,11 @@ __ http://pygments.org/docs/lexers
       .. versionadded:: 1.3
 
    .. rst:directive:option:: dedent: number
-      :type: number
+      :type: number or no value
 
-      Strip indentation characters from the code block. For example::
+      Strip indentation characters from the code block.  When number given,
+      leading N characters are removed.  When no argument given, leading spaces
+      are removed via :func:`textwrap.dedent()`.  For example::
 
          .. code-block:: ruby
             :dedent: 4
@@ -582,6 +584,8 @@ __ http://pygments.org/docs/lexers
                 some ruby code
 
       .. versionadded:: 1.3
+      .. versionchanged:: 3.5
+         Support automatic dedent.
 
    .. rst:directive:option:: force
       :type: no value
@@ -742,6 +746,9 @@ __ http://pygments.org/docs/lexers
    .. versionchanged:: 2.1
       Added the ``force`` option.
 
+   .. versionchanged:: 3.5
+      Support automatic dedent.
+
 .. _glossary-directive:
 
 Glossary

sphinx/directives/code.py

@@ -7,6 +7,7 @@
 """
 
 import sys
+import textwrap
 import warnings
 from difflib import unified_diff
 from typing import Any, Dict, List, Tuple
@@ -19,6 +20,7 @@ from docutils.statemachine import StringList
 from sphinx import addnodes
 from sphinx.config import Config
 from sphinx.deprecation import RemovedInSphinx40Warning
+from sphinx.directives import optional_int
 from sphinx.locale import __
 from sphinx.util import logging, parselinenos
 from sphinx.util.docutils import SphinxDirective
@@ -68,7 +70,7 @@ class HighlightLang(Highlight):
 
 def dedent_lines(lines: List[str], dedent: int, location: Tuple[str, int] = None) -> List[str]:
     if not dedent:
-        return lines
+        return textwrap.dedent(''.join(lines)).splitlines(True)
 
     if any(s[:dedent].strip() for s in lines):
         logger.warning(__('non-whitespace stripped by dedent'), location=location)
@@ -117,7 +119,7 @@ class CodeBlock(SphinxDirective):
     option_spec = {
         'force': directives.flag,
         'linenos': directives.flag,
-        'dedent': int,
+        'dedent': optional_int,
         'lineno-start': int,
         'emphasize-lines': directives.unchanged_required,
         'caption': directives.unchanged_required,
@@ -391,7 +393,7 @@ class LiteralInclude(SphinxDirective):
     optional_arguments = 0
     final_argument_whitespace = True
     option_spec = {
-        'dedent': int,
+        'dedent': optional_int,
         'linenos': directives.flag,
         'lineno-start': int,
         'lineno-match': directives.flag,

tests/test_directive_code.py

@@ -250,6 +250,14 @@ def test_LiteralIncludeReader_dedent(literal_inc_path):
                        "  pass\n"
                        "\n")
 
+    # dedent: None
+    options = {'lines': '9-11', 'dedent': None}
+    reader = LiteralIncludeReader(literal_inc_path, options, DUMMY_CONFIG)
+    content, lines = reader.read()
+    assert content == ("def baz():\n"
+                       "    pass\n"
+                       "\n")
+
 
 @pytest.mark.xfail(os.name != 'posix', reason="Not working on windows")
 def test_LiteralIncludeReader_tabwidth(testroot):