[FLANG] Pick .md files when building sphinx documentation.

Need to build sphinx using below flags to Cmake `-DLLVM_ENABLE_SPHINX=ON -DSPHINX_WARNINGS_AS_ERRORS=OFF`. Generate html docs using cmake target `docs-flang-html` Generated html files should be at `build/tools/flang/docs/html`. Patch in series from the dicussion on review https://reviews.llvm.org/D85828 After this patch the markdown docmentation must be written using guide in- `llvm/docs/MarkdownQuickstartTemplate.md` Reviewed By: sscalpone Differential Revision: https://reviews.llvm.org/D86131
YuriPlyakhin · Aug 24, 2020 · bc9cdfa · bc9cdfa
1 parent 3cd8d7b
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diff --git a/flang/README.md b/flang/README.md
@@ -33,6 +33,9 @@ read the [style guide](docs/C++style.md)
 and
 also review [how flang uses modern C++ features](docs/C++17.md).
 
+If you are interested in writing new documentation, follow 
+[markdown style guide from LLVM](https://github.com/llvm/llvm-project/blob/master/llvm/docs/MarkdownQuickstartTemplate.md).
+
 ## Supported C++ compilers
 
 Flang is written in C++17.
@@ -216,3 +219,25 @@ It will generate html in
 
     <build-dir>/tools/flang/docs/doxygen/html # for flang docs
 ```
+## Generate Sphinx-based Documentation
+<!TODO: Add webpage once we have a website.
+!>
+Flang documentation should preferably be written in `markdown(.md)` syntax (they can be in `reStructuredText(.rst)` format as well but markdown is recommended in first place), it
+is mostly meant to be processed by the Sphinx documentation generation
+system to create HTML pages which would be hosted on the webpage of flang and
+updated periodically.
+
+If you would like to generate and view the HTML locally, install
+Sphinx <http://sphinx-doc.org/> and then:
+
+- Pass `-DLLVM_ENABLE_SPHINX=ON -DSPHINX_WARNINGS_AS_ERRORS=OFF` to the cmake command.
+
+```
+cd ~/llvm-project/build
+cmake -DLLVM_ENABLE_SPHINX=ON -DSPHINX_WARNINGS_AS_ERRORS=OFF ../llvm
+make docs-flang-html
+
+It will generate html in
+
+   $BROWSER <build-dir>/tools/flang/docs/html/
+```
diff --git a/flang/docs/conf.py b/flang/docs/conf.py
@@ -21,7 +21,6 @@
 
 # If your documentation needs a minimal Sphinx version, state it here.
 #needs_sphinx = '1.0'
-
 # Add any Sphinx extension module names here, as strings. They can be extensions
 # coming with Sphinx (named 'sphinx.ext.*') or your custom ones.
 extensions = ['sphinx.ext.todo', 'sphinx.ext.mathjax', 'sphinx.ext.intersphinx']
@@ -30,13 +29,29 @@
 templates_path = ['_templates']
 
 # The suffix of source filenames.
-source_suffix = '.rst'
+source_suffix = {
+    '.rst': 'restructuredtext',
+}
+try:
+  import recommonmark
+except ImportError:
+  # manpages do not use any .md sources
+  if not tags.has('builder-man'):
+    raise
+else:
+  import sphinx
+  if sphinx.version_info >= (3, 0):
+    # This requires 0.5 or later.
+    extensions.append('recommonmark')
+  else:
+    source_parsers = {'.md': 'recommonmark.parser.CommonMarkParser'}
+  source_suffix['.md'] = 'markdown'
 
 # The encoding of source files.
 #source_encoding = 'utf-8-sig'
 
 # The master toctree document.
-master_doc = 'ReleaseNotes'
+master_doc = 'Overview'
 
 # General information about the project.
 project = u'Flang'
@@ -196,7 +211,7 @@
 # Grouping the document tree into LaTeX files. List of tuples
 # (source start file, target name, title, author, documentclass [howto/manual]).
 latex_documents = [
-  ('ReleaseNotes', 'Flang.tex', u'Flang Documentation',
+  ('Overview', 'Flang.tex', u'Flang Documentation',
    u'The Flang Team', 'manual'),
 ]
 
@@ -237,8 +252,8 @@
 # (source start file, target name, title, author,
 #  dir menu entry, description, category)
 texinfo_documents = [
-  ('ReleaseNotes', 'Flang', u'Flang Documentation',
-   u'The Flang Team', 'Flang', 'One line description of project.',
+  ('Overview', 'Flang', u'Flang Documentation',
+   u'The Flang Team', 'Flang', 'A Fortran front end for LLVM.',
    'Miscellaneous'),
 ]