Merge branch '3.1.x' into 7812_broken_stub_files

.github/workflows/builddoc.yml

@@ -0,0 +1,21 @@
+name: Build document
+
+on: [push, pull_request]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v2
+    - name: Set up Python
+      uses: actions/setup-python@v1
+      with:
+        python-version: 3.6
+    - name: Install dependencies
+      run:  |
+        sudo apt update
+        sudo apt install -y graphviz
+        pip install -U tox
+    - name: Run Tox
+      run:  tox -e docs

.travis.yml

@@ -27,8 +27,6 @@ jobs:
     - python: 'nightly'
       env:
         - TOXENV=du16
-    - python: '3.6'
-      env: TOXENV=docs
 
     - language: node_js
       node_js: '10.7'

CHANGES

@@ -23,6 +23,7 @@ Bugs fixed
   is 'description'
 * #7812: autosummary: generates broken stub files if the target code contains
   an attribute and module that are same name
+* #7806: viewcode: Failed to resolve viewcode references on 3rd party builders
 
 Testing
 --------

sphinx/ext/viewcode.py

@@ -131,10 +131,8 @@ def env_merge_info(app: Sphinx, env: BuildEnvironment, docnames: Iterable[str],
 
 def missing_reference(app: Sphinx, env: BuildEnvironment, node: Element, contnode: Node
                       ) -> Node:
-    if app.builder.format != 'html':
-        return None
-    elif node['reftype'] == 'viewcode':
-        # resolve our "viewcode" reference nodes -- they need special treatment
+    # resolve our "viewcode" reference nodes -- they need special treatment
+    if node['reftype'] == 'viewcode':
         return make_refnode(app.builder, node['refdoc'], node['reftarget'],
                             node['refid'], contnode)