Improve CI

Improve CI build times by using a dummy builder for (empty) output, dropping LaTeX, and disabling some Sphinx extensions when building for CI (GDScript lexing, creating a search index, and generating HTML description tags).

In my tests, this improves Travis CI build times: from up to 30 minutes down to 2 minutes.

.travis.yml

@@ -1,12 +1,12 @@
 os: linux
 dist: bionic
-language: python
+language: python - "3.8"
 
-python:
-  - "3.8"
-
-stages:
-  - build
+env:
+  global:
+    - SPHINX_NO_GDSCRIPT=1
+    - SPHINX_NO_SEARCH=1
+    - SPHINX_NO_DESCRIPTIONS=1
 
 matrix:
   include:
@@ -18,16 +18,17 @@ matrix:
           packages:
             - dos2unix
             - recode
-            - texlive-full
+
+install:
+  - pip install -r requirements.txt
+  - pip install codespell
 
 script:
   - bash ./format.sh
 
   # Check for possible typos
-  - pip install codespell
   - codespell -I codespell-ignore.txt {about,community,development,getting_started,tutorials}/**/*.rst
 
-  - pip install -r requirements.txt
   # TODO: Add `-W` to turn warnings into errors.
   # This can only be done once all warnings have been fixed.
-  - sphinx-build --color -b html -d _build/doctrees . _build/html
+  - sphinx-build --color -b dummy -d _build/doctrees . _build/html

Makefile

@@ -52,6 +52,7 @@ help:
 	@echo "  linkcheck  to check all external links for integrity"
 	@echo "  doctest    to run all doctests embedded in the documentation (if enabled)"
 	@echo "  coverage   to run coverage check of the documentation (if enabled)"
+	@echo "  dummy      to run only the parse steps without generating output"
 
 clean:
 	rm -rf $(BUILDDIR)/*
@@ -195,3 +196,8 @@ pseudoxml:
 	$(SPHINXBUILD) -b pseudoxml $(ALLSPHINXOPTS) $(BUILDDIR)/pseudoxml
 	@echo
 	@echo "Build finished. The pseudo-XML files are in $(BUILDDIR)/pseudoxml."
+
+dummy:
+	$(SPHINXBUILD) -b dummy $(ALLSPHINXOPTS) $(BUILDDIR)/html
+	@echo
+	@echo "Build finished. No output."

conf.py

@@ -13,13 +13,24 @@ needs_sphinx = "1.3"
 # Sphinx extension module names and templates location
 sys.path.append(os.path.abspath("_extensions"))
 extensions = [
-    "gdscript",
-    "godot_descriptions",
-    "sphinx_search.extension",
     "sphinx_tabs.tabs",
     "sphinx.ext.imgmath",
 ]
 
+# Warning when the Sphinx Tabs extension is used with unknown
+# builders (like the dummy builder) - as it doesn't cause errors,
+# we can ignore this so we still can treat other warnings as errors.
+sphinx_tabs_nowarn = True
+
+if not os.getenv("SPHINX_NO_GDSCRIPT"):
+    extensions.append("gdscript")
+
+if not os.getenv("SPHINX_NO_SEARCH"):
+    extensions.append("sphinx_search.extension")
+
+if not os.getenv("SPHINX_NO_DESCRIPTIONS"):
+    extensions.append("godot_descriptions")
+
 templates_path = ["_templates"]
 
 # You can specify multiple suffix as a list of string: ['.rst', '.md']