[llvm] [Github] Add flang docs to Github actions (PR #70530)

[Aiden Grossman via llvm-commits]

https://github.com/boomanaiden154 created https://github.com/llvm/llvm-project/pull/70530

This patch enables building the flang docs in Github actions to enable rapid iteration in PRs and to catch docs build failures more easily before merge/after merge. This patch currently doesn't fail for Sphinx warnings, but the intention is to enable this functionality once the flang docs are fixed to build without warnings after the transition to Myst.

>From 8949dac821f93aafc58a28a23283f1601a5009a9 Mon Sep 17 00:00:00 2001
From: Aiden Grossman <agrossman154 at yahoo.com>
Date: Fri, 27 Oct 2023 18:51:39 -0700
Subject: [PATCH] [Github] Add flang docs to Github actions

This patch enables building the flang docs in Github actions to enable
rapid iteration in PRs and to catch docs build failures more easily
before merge/after merge. This patch currently doesn't fail for Sphinx
warnings, but the intention is to enable this functionality once the
flang docs are fixed to build without warnings after the transition to
Myst.
---
 .github/workflows/docs.yml | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/.github/workflows/docs.yml b/.github/workflows/docs.yml
index e6af2f41167e0a1..40cd3da1f8120c3 100644
--- a/.github/workflows/docs.yml
+++ b/.github/workflows/docs.yml
@@ -21,6 +21,7 @@ on:
       - 'libcxx/docs/**'
       - 'libc/docs/**'
       - 'lld/docs/**'
+      - 'flang/docs/**'
   pull_request:
     paths:
       - 'llvm/docs/**'
@@ -31,6 +32,7 @@ on:
       - 'libcxx/docs/**'
       - 'libc/docs/**'
       - 'lld/docs/**'
+      - 'flang/docs/**'
 
 jobs:
   check-docs-build:
@@ -67,6 +69,8 @@ jobs:
               - 'libc/docs/**'
             lld:
               - 'lld/docs/**'
+            flang:
+              - 'flang/docs/**'
       - name: Fetch LLVM sources (PR)
         if: ${{ github.event_name == 'pull_request' }}
         uses: actions/checkout at v4
@@ -125,4 +129,11 @@ jobs:
         run: |
           cmake -B lld-build -GNinja -DCMAKE_BUILD_TYPE=Release -DLLVM_ENABLE_PROJECTS="lld" -DLLVM_ENABLE_SPHINX=ON ./llvm
           TZ=UTC ninja -C lld-build docs-lld-html
+      - name: Build Flang docs
+        if: steps.docs-changed-subprojects.outputs.flang_any_changed == 'true'
+        # TODO(boomanaiden154): Remove the SPHINX_WARNINGS_AS_ERRORS from the
+        # CMake invocation once the warnings in the flang docs build are fixed.
+        run: |
+          cmake -B flang-build -GNinja -DCMAKE_BUILD_TYPE=Release -DLLVM_ENABLE_PROJECTS="clang;mlir;flang" -DLLVM_ENABLE_SPHINX=ON -DSPHINX_WARNINGS_AS_ERRORS=OFF ./llvm
+          TZ=UTC ninja -C flang-build docs-flang-html docs-flang-man