[llvm] [Github] Add libcxx docs to CI (PR #69828)

[Aiden Grossman via llvm-commits]

https://github.com/boomanaiden154 created https://github.com/llvm/llvm-project/pull/69828

This patch adds a step to the documentation Github action to build the libc++ docs if they have changed. This enables easily diagnosing build failures/warnings in PRs.

>From ba4e7689aeed7e3054b74792924625bfd1965126 Mon Sep 17 00:00:00 2001
From: Aiden Grossman <agrossman154 at yahoo.com>
Date: Sat, 21 Oct 2023 02:44:46 -0700
Subject: [PATCH] [Github] Add libcxx docs to CI

This patch adds a step to the documentation Github action to build the
libc++ docs if they have changed. This enables easily diagnosing build
failures/warnings in PRs.
---
 .github/workflows/docs.yml | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/.github/workflows/docs.yml b/.github/workflows/docs.yml
index 2900f73c77c5a66..3ec55b7b5d14cc8 100644
--- a/.github/workflows/docs.yml
+++ b/.github/workflows/docs.yml
@@ -15,10 +15,12 @@ on:
     paths:
       - 'llvm/docs/**'
       - 'clang/docs/**'
+      - 'libcxx/docs/**'
   pull_request:
     paths:
       - 'llvm/docs/**'
       - 'clang/docs/**'
+      - 'libcxx/docs/**'
 
 jobs:
   check-docs-build:
@@ -47,6 +49,8 @@ jobs:
               - 'llvm/docs/**'
             clang:
               - 'clang/docs/**'
+            libcxx:
+              - 'libcxx/docs/**'
       - name: Setup Python env
         uses: actions/setup-python at v4
         with:
@@ -69,4 +73,9 @@ jobs:
         run: |
           cmake -B clang-build -GNinja -DCMAKE_BUILD_TYPE=Release -DLLVM_ENABLE_PROJECTS="clang" -DLLVM_ENABLE_SPHINX=ON ./llvm
           TZ=UTC ninja -C clang-build docs-clang-html docs-clang-man
+      - name: Build libcxx docs
+        if: steps.docs-changed-subprojects.outputs.libcxx_any_changed == 'true'
+        run: |
+          cmake -B libcxx-build -GNinja -DCMAKE_BUILD_TYPE=Release -DLLVM_ENABLE_RUNTIMES="libcxxabi;libcxx" -DLLVM_ENABLE_SPHINX=ON ./runtimes
+          TZ=UTC ninja -C libcxx-build docs-libcxx-html