From 01fb5c840124f4ffa13257900226106151823f8c Mon Sep 17 00:00:00 2001
From: David Fischer <david@readthedocs.org>
Date: Thu, 28 May 2020 17:14:19 -0700
Subject: [PATCH] Add feature flag to use the stock Sphinx builders

---
 readthedocs/doc_builder/backends/sphinx.py    |  6 ++
 readthedocs/projects/models.py                |  5 ++
 .../rtd_tests/tests/test_doc_builder.py       | 59 ++++++++++++++++++-
 3 files changed, 69 insertions(+), 1 deletion(-)

diff --git a/readthedocs/doc_builder/backends/sphinx.py b/readthedocs/doc_builder/backends/sphinx.py
index 20d43a076d5..4f49e5dd84e 100644
--- a/readthedocs/doc_builder/backends/sphinx.py
+++ b/readthedocs/doc_builder/backends/sphinx.py
@@ -316,6 +316,8 @@ class HtmlBuilder(BaseSphinx):
     def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
         self.sphinx_builder = 'readthedocs'
+        if self.project.has_feature(Feature.USE_SPHINX_BUILDERS):
+            self.sphinx_builder = 'html'
 
     def move(self, **__):
         super().move()
@@ -346,6 +348,8 @@ class HtmlDirBuilder(HtmlBuilder):
     def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
         self.sphinx_builder = 'readthedocsdirhtml'
+        if self.project.has_feature(Feature.USE_SPHINX_BUILDERS):
+            self.sphinx_builder = 'dirhtml'
 
 
 class SingleHtmlBuilder(HtmlBuilder):
@@ -354,6 +358,8 @@ class SingleHtmlBuilder(HtmlBuilder):
     def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
         self.sphinx_builder = 'readthedocssinglehtml'
+        if self.project.has_feature(Feature.USE_SPHINX_BUILDERS):
+            self.sphinx_builder = 'singlehtml'
 
 
 class LocalMediaBuilder(BaseSphinx):
diff --git a/readthedocs/projects/models.py b/readthedocs/projects/models.py
index 1bc6c38c93d..886cb6cf3dc 100644
--- a/readthedocs/projects/models.py
+++ b/readthedocs/projects/models.py
@@ -1595,6 +1595,7 @@ def add_features(sender, **kwargs):
     VCS_REMOTE_LISTING = 'vcs_remote_listing'
     STORE_PAGEVIEWS = 'store_pageviews'
     SPHINX_PARALLEL = 'sphinx_parallel'
+    USE_SPHINX_BUILDERS = 'use_sphinx_builders'
 
     FEATURES = (
         (USE_SPHINX_LATEST, _('Use latest version of Sphinx')),
@@ -1692,6 +1693,10 @@ def add_features(sender, **kwargs):
             SPHINX_PARALLEL,
             _('Use "-j auto" when calling sphinx-build'),
         ),
+        (
+            USE_SPHINX_BUILDERS,
+            _('Use regular sphinx builders instead of custom RTD builders'),
+        )
     )
 
     projects = models.ManyToManyField(
diff --git a/readthedocs/rtd_tests/tests/test_doc_builder.py b/readthedocs/rtd_tests/tests/test_doc_builder.py
index 05da75898bc..106a48fb037 100644
--- a/readthedocs/rtd_tests/tests/test_doc_builder.py
+++ b/readthedocs/rtd_tests/tests/test_doc_builder.py
@@ -13,12 +13,14 @@
 
 from readthedocs.builds.models import Version
 from readthedocs.doc_builder.backends.mkdocs import MkdocsHTML, yaml_load_safely
-from readthedocs.doc_builder.backends.sphinx import BaseSphinx
+from readthedocs.doc_builder.backends.sphinx import BaseSphinx, HtmlBuilder, HtmlDirBuilder, SingleHtmlBuilder
+from readthedocs.doc_builder.config import load_yaml_config
 from readthedocs.doc_builder.exceptions import MkDocsYAMLParseError
 from readthedocs.doc_builder.python_environments import Virtualenv
 from readthedocs.projects.constants import PRIVATE, PROTECTED, PUBLIC
 from readthedocs.projects.exceptions import ProjectConfigurationError
 from readthedocs.projects.models import Feature, Project
+from readthedocs.rtd_tests.tests.test_config_integration import create_load
 
 
 class SphinxBuilderTest(TestCase):
@@ -216,6 +218,61 @@ def test_multiple_conf_py(
         with pytest.raises(ProjectConfigurationError):
             base_sphinx.append_conf()
 
+    @mock.patch('readthedocs.doc_builder.config.load_config')
+    def test_use_sphinx_builders(self, load_config):
+        feature = get(
+            Feature,
+            feature_id=Feature.USE_SPHINX_BUILDERS,
+        )
+
+        config_data = {'version': 2, 'sphinx': {'configuration': 'docs/conf.py'}}
+        load_config.side_effect = create_load(config_data)
+        config = load_yaml_config(self.version)
+
+        python_env = Virtualenv(
+            version=self.version,
+            build_env=self.build_env,
+            config=config,
+        )
+        builder = HtmlBuilder(
+            build_env=self.build_env,
+            python_env=python_env,
+        )
+        self.assertEqual(builder.sphinx_builder, 'readthedocs')
+
+        builder = HtmlDirBuilder(
+            build_env=self.build_env,
+            python_env=python_env,
+        )
+        self.assertEqual(builder.sphinx_builder, 'readthedocsdirhtml')
+
+        builder = SingleHtmlBuilder(
+            build_env=self.build_env,
+            python_env=python_env,
+        )
+        self.assertEqual(builder.sphinx_builder, 'readthedocssinglehtml')
+
+        # Add the feature to use the regular builders
+        feature.projects.add(self.project)
+
+        builder = HtmlBuilder(
+            build_env=self.build_env,
+            python_env=python_env,
+        )
+        self.assertEqual(builder.sphinx_builder, 'html')
+
+        builder = HtmlDirBuilder(
+            build_env=self.build_env,
+            python_env=python_env,
+        )
+        self.assertEqual(builder.sphinx_builder, 'dirhtml')
+
+        builder = SingleHtmlBuilder(
+            build_env=self.build_env,
+            python_env=python_env,
+        )
+        self.assertEqual(builder.sphinx_builder, 'singlehtml')
+
 
 @override_settings(PRODUCTION_DOMAIN='readthedocs.org')
 class MkdocsBuilderTest(TestCase):