CI Add macos-15 runner regression tests

Author: jarzec

.github/workflows/regression-tests.yml

@@ -45,6 +45,16 @@ jobs:
             compiler: clang++-15
             cxx_std: c++20
             stdlib: libc++-15-dev
+          - os: macos-15
+            shortosname: mac-15
+            compiler: clang++
+            cxx_std: c++2b
+            stdlib: default
+          - os: macos-15
+            shortosname: mac-15
+            compiler: clang++-18
+            cxx_std: c++23
+            stdlib: default
           - os: macos-14
             shortosname: mac-14
             compiler: clang++

regression-tests/run-tests.sh

@@ -155,7 +155,9 @@ else
     compiler_version=$("$cxx_compiler" --version)
 
     if [[ "$compiler_version" == *"Apple clang version 14.0"* ||
-          "$compiler_version" == *"Homebrew clang version 15.0"* ]]; then
+          "$compiler_version" == *"Apple clang version 16.0"* ||
+          "$compiler_version" == *"Homebrew clang version 15.0"* ||
+          "$compiler_version" == *"Homebrew clang version 18.1"* ]]; then
         exec_out_dir="$expected_results_dir/apple-clang-14"
         # We share the expected results dir for these two compilers, but there is one
         # test which (as expected) fails to compile on both compilers, but has a slightly