Disable default smartquotes for zh_CN and zh_TW

CHANGES.rst

@@ -17,6 +17,7 @@ Incompatible changes
   Code-blokcs are unchanged as FreeMono is now loaded with ``Scale=0.9``.
   An adjustement to existing projects is needed only if they used a custom
   :ref:`fontpkg` configuration and did not set :ref:`fvset`.
+* #12875: Disable smartquotes for languages: ``zh_CN`` and ``zh_TW`` by default.
 
 Deprecated
 ----------

sphinx/config.py

@@ -271,7 +271,7 @@ class Config:
         'smartquotes': _Opt(True, 'env', ()),
         'smartquotes_action': _Opt('qDe', 'env', ()),
         'smartquotes_excludes': _Opt(
-            {'languages': ['ja'], 'builders': ['man', 'text']}, 'env', ()),
+            {'languages': ['ja', 'zh_CN', 'zh_TW'], 'builders': ['man', 'text']}, 'env', ()),
         'option_emphasise_placeholders': _Opt(False, 'env', ()),
     }
 

tests/test_markup/test_smartquotes.py

@@ -86,6 +86,32 @@ def test_ja_html_builder(app):
     assert '<p>-- &quot;Sphinx&quot; is a tool that makes it easy ...</p>' in content
 
 
+@pytest.mark.sphinx(
+    'html',
+    testroot='smartquotes',
+    freshenv=True,
+    confoverrides={'language': 'zh_CN'},
+)
+def test_zh_cn_html_builder(app):
+    app.build()
+
+    content = (app.outdir / 'index.html').read_text(encoding='utf8')
+    assert '<p>-- &quot;Sphinx&quot; is a tool that makes it easy ...</p>' in content
+
+
+@pytest.mark.sphinx(
+    'html',
+    testroot='smartquotes',
+    freshenv=True,
+    confoverrides={'language': 'zh_TW'},
+)
+def test_zh_tw_html_builder(app):
+    app.build()
+
+    content = (app.outdir / 'index.html').read_text(encoding='utf8')
+    assert '<p>-- &quot;Sphinx&quot; is a tool that makes it easy ...</p>' in content
+
+
 @pytest.mark.sphinx(
     'html',
     testroot='smartquotes',