CI: install clang dependencies directly from LLVM (#5575)

I think this was a suggestion by @WeiqunZhang in the context of
debugging the clang sanitizer issue currently addressed in #5492. I'm
extracting all related changes from #5492 to implement and test the LLVM
installation separately here.

This effectively unifies the CI scripts to install clang dependencies
into one single script that reads the clang version number from the
command line.

I think all CI checks should pass here as a prerequisite for debugging
the clang sanitizer issue further in #5492.

.github/workflows/clang_sanitizers.yml

@@ -27,7 +27,7 @@ jobs:
     - uses: actions/checkout@v4
     - name: install dependencies
       run: |
-        .github/workflows/dependencies/clang17.sh
+        .github/workflows/dependencies/clang.sh 17
     - name: CCache Cache
       uses: actions/cache@v4
       with:
@@ -89,7 +89,7 @@ jobs:
     - uses: actions/checkout@v4
     - name: install dependencies
       run: |
-        .github/workflows/dependencies/clang17.sh
+        .github/workflows/dependencies/clang.sh 17
     - name: CCache Cache
       uses: actions/cache@v4
       with:

.github/workflows/clang_tidy.yml

@@ -26,7 +26,7 @@ jobs:
     - uses: actions/checkout@v4
     - name: install dependencies
       run: |
-        .github/workflows/dependencies/clang15.sh
+        .github/workflows/dependencies/clang.sh 15
     - name: set up cache
       uses: actions/cache@v4
       with:

.github/workflows/dependencies/clang17.sh → .github/workflows/dependencies/clang.sh

@@ -1,45 +1,50 @@
 #!/usr/bin/env bash
 #
-# Copyright 2024 The WarpX Community
+# Copyright 2025 The WarpX Community
 #
 # License: BSD-3-Clause-LBNL
-# Authors: Luca Fedeli
 
 set -eu -o pipefail
 
-# `man apt.conf`:
-#   Number of retries to perform. If this is non-zero APT will retry
-#   failed files the given number of times.
+# `man apt.conf`: number of retries to perform (if non-zero,
+# APT will retry failed files the given number of times).
 echo 'Acquire::Retries "3";' | sudo tee /etc/apt/apt.conf.d/80-retries
 
-# This dependency file is currently used within a docker container,
-# which does not come (among others) with wget, xz-utils, curl, git,
-# ccache, and pkg-config pre-installed.
-sudo apt-get -qqq update
+sudo apt-get update
 sudo apt-get install -y \
     cmake               \
-    clang-17            \
-    clang-tidy-17       \
     libblas-dev         \
-    libc++-17-dev       \
     libboost-math-dev   \
     libfftw3-dev        \
     libfftw3-mpi-dev    \
     libhdf5-openmpi-dev \
     liblapack-dev       \
     libopenmpi-dev      \
-    libomp-17-dev       \
-    ninja-build         \
-    wget                \
-    xz-utils            \
-    curl                \
-    git                 \
-    ccache              \
-    pkg-config
+    ninja-build
 
-# Use clang 17
-export CXX=$(which clang++-17)
-export CC=$(which clang-17)
+# parse clang version number from command line
+version_number=${1}
+
+# add LLVM repository and install clang tools
+wget https://apt.llvm.org/llvm.sh
+chmod +x llvm.sh
+sudo ./llvm.sh ${version_number}
+
+# install clang, clang-tidy, and
+# LLVM implementations of C++ standard library and OpenMP
+sudo apt-get update
+sudo apt-get install -y          \
+    clang-${version_number}      \
+    clang-tidy-${version_number} \
+    libc++-${version_number}-dev \
+    libomp-${version_number}-dev
+
+# export compiler flags
+export CXX=$(which clang++-${version_number})
+export CC=$(which clang-${version_number})
+
+# ccache
+$(dirname "$0")/ccache.sh
 
 # cmake-easyinstall
 #