From 5f37684ab1a3452b8e548861bac46e04a895346d Mon Sep 17 00:00:00 2001
From: Andreas Buhr <andreas@andreasbuhr.de>
Date: Thu, 15 Jan 2026 10:37:24 +0100
Subject: [PATCH 1/3] Add an ARM flavour to CI

---
 .github/workflows/cmake.yml | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/.github/workflows/cmake.yml b/.github/workflows/cmake.yml
index e7e6004e..59a190ec 100644
--- a/.github/workflows/cmake.yml
+++ b/.github/workflows/cmake.yml
@@ -105,6 +105,13 @@ jobs:
             cxx: "g++-14",
             cxxver: 20,
           }
+          - {
+            name: "Linux g++ 14 C++20 ARM",
+            os: ubuntu-24.04-arm,
+            buildtype: Release,
+            cxx: "g++-14",
+            cxxver: 20,
+          }
           - {
             name: "Linux g++ 15 (Debian) C++17",
             os: ubuntu-24.04,

From 583c5c5d9e14df21990bbdb53a32fc088b8e6cd9 Mon Sep 17 00:00:00 2001
From: Andreas Buhr <andreas@andreasbuhr.de>
Date: Thu, 15 Jan 2026 11:32:21 +0100
Subject: [PATCH 2/3] Add an Clang 21 and C++23, C++26 to CI

---
 .github/workflows/cmake.yml | 43 +++++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)

diff --git a/.github/workflows/cmake.yml b/.github/workflows/cmake.yml
index 59a190ec..e4adb341 100644
--- a/.github/workflows/cmake.yml
+++ b/.github/workflows/cmake.yml
@@ -128,6 +128,22 @@ jobs:
             cxx: "g++-15",
             cxxver: 20,
           }
+          - {
+            name: "Linux g++ 15 (Debian) C++23",
+            os: ubuntu-24.04,
+            container: debian:testing,
+            buildtype: Release,
+            cxx: "g++-15",
+            cxxver: 23,
+          }
+          - {
+            name: "Linux g++ 15 (Debian) C++26",
+            os: ubuntu-24.04,
+            container: debian:testing,
+            buildtype: Release,
+            cxx: "g++-15",
+            cxxver: 26,
+          }
           - {
             name: "Linux clang-13 C++17",
             os: ubuntu-22.04,
@@ -254,6 +270,33 @@ jobs:
             exe_linker_flags: -lc++,
             cxxver: 20,
           }
+          - {
+            name: "Linux clang-21 C++20",
+            os: ubuntu-24.04,
+            buildtype: Release,
+            cxx: "clang++-21",
+            cxx_flags: -stdlib=libc++,
+            exe_linker_flags: -lc++,
+            cxxver: 20,
+          }
+          - {
+            name: "Linux clang-21 C++23",
+            os: ubuntu-24.04,
+            buildtype: Release,
+            cxx: "clang++-21",
+            cxx_flags: -stdlib=libc++,
+            exe_linker_flags: -lc++,
+            cxxver: 23,
+          }
+          - {
+            name: "Linux clang-21 C++26",
+            os: ubuntu-24.04,
+            buildtype: Release,
+            cxx: "clang++-21",
+            cxx_flags: -stdlib=libc++,
+            exe_linker_flags: -lc++,
+            cxxver: 26,
+          }
           - {
             name: "Windows MSVC 2017 (x64) C++17",
             os: windows-2019,

From ee3bfc7a23d77b29158475f742f3a276de24fb3d Mon Sep 17 00:00:00 2001
From: Andreas Buhr <andreas@andreasbuhr.de>
Date: Thu, 15 Jan 2026 11:34:30 +0100
Subject: [PATCH 3/3] Add step to install Clang21 to CI script

---
 .github/workflows/cmake.yml | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/.github/workflows/cmake.yml b/.github/workflows/cmake.yml
index e4adb341..d86f3d9c 100644
--- a/.github/workflows/cmake.yml
+++ b/.github/workflows/cmake.yml
@@ -514,6 +514,17 @@ jobs:
         sudo ./llvm.sh 20
         sudo apt-get install libc++-20-dev libc++abi-20-dev libunwind-20-dev
 
+    - name: Install Clang 21
+      id: install_clang_21
+      if: startsWith(matrix.config.os, 'ubuntu') && ( matrix.config.cxx == 'clang++-21' )
+      shell: bash
+      working-directory: ${{ env.HOME }}
+      run: |
+        wget https://apt.llvm.org/llvm.sh
+        chmod +x llvm.sh
+        sudo ./llvm.sh 21
+        sudo apt-get install libc++-21-dev libc++abi-21-dev libunwind-21-dev
+
     - name: Install g++ 10
       id: install_gcc_10
       if: startsWith(matrix.config.os, 'ubuntu') && ( matrix.config.cxx == 'g++-10' )