macOS: Fix #3901 - CMake quirks on macOS wrt. CMAKE_C[XX]_COMPILER (#4926)

See https://cmake.org/cmake/help/latest/policy/CMP0132.html.

Author: kinke

.github/actions/helper-build-ldc/action.yml

@@ -36,8 +36,6 @@ runs:
           -DLLVM_ROOT_DIR="$PWD/../${{ inputs.llvm_dir }}" \
           -DD_COMPILER='${{ inputs.host_dc }}' \
           -DLDC_LINK_MANUALLY=OFF \
-          ${{ runner.os == 'macOS' && '-DCMAKE_C_COMPILER=/usr/bin/cc' || '' }} \
-          ${{ runner.os == 'macOS' && '-DCMAKE_CXX_COMPILER=/usr/bin/c++' || '' }} \
           ${{ inputs.specify_install_dir == 'true' && '-DCMAKE_INSTALL_PREFIX="$installDir"' || '' }} \
           ${{ inputs.specify_install_dir == 'true' && '-DINCLUDE_INSTALL_DIR="$installDir/import"' || '' }} \
           ${{ inputs.cmake_flags }}

.github/workflows/supported_llvm_versions.yml

@@ -28,17 +28,17 @@ jobs:
             os: macos-14
             host_dc: ldc-beta
             llvm_version: 17.0.5
-            cmake_flags: -DBUILD_SHARED_LIBS=ON -DRT_SUPPORT_SANITIZERS=ON -DCMAKE_EXE_LINKER_FLAGS=-L/opt/homebrew/opt/zstd/lib -DCMAKE_C_COMPILER=/usr/bin/cc -DCMAKE_CXX_COMPILER=/usr/bin/c++
+            cmake_flags: -DBUILD_SHARED_LIBS=ON -DRT_SUPPORT_SANITIZERS=ON -DCMAKE_EXE_LINKER_FLAGS=-L/opt/homebrew/opt/zstd/lib
           - job_name: macOS 14, LLVM 16, latest LDC beta
             os: macos-14
             host_dc: ldc-beta
             llvm_version: 16.0.5
-            cmake_flags: -DBUILD_SHARED_LIBS=OFF -DCMAKE_EXE_LINKER_FLAGS=-L/opt/homebrew/opt/zstd/lib -DCMAKE_C_COMPILER=/usr/bin/cc -DCMAKE_CXX_COMPILER=/usr/bin/c++
+            cmake_flags: -DBUILD_SHARED_LIBS=OFF -DCMAKE_EXE_LINKER_FLAGS=-L/opt/homebrew/opt/zstd/lib
           - job_name: Ubuntu 24.04, LLVM 15, latest DMD beta
             os: ubuntu-24.04
             host_dc: dmd-beta
             llvm_version: 15
-            cmake_flags: -DBUILD_SHARED_LIBS=ON -DRT_SUPPORT_SANITIZERS=ON -DLIB_SUFFIX=64 -DLDC_LINK_MANUALLY=ON
+            cmake_flags: -DBUILD_SHARED_LIBS=ON -DRT_SUPPORT_SANITIZERS=ON -DLIB_SUFFIX=64
     name: ${{ matrix.job_name }}
     runs-on: ${{ matrix.os }}
     env:
@@ -124,7 +124,6 @@ jobs:
           cmake -G Ninja . \
             -DCMAKE_BUILD_TYPE=Release \
             -DLLVM_ROOT_DIR=${{ runner.os == 'Linux' && format('/usr/lib/llvm-{0}', matrix.llvm_version) || '"$PWD/llvm"' }} \
-            -DLDC_LINK_MANUALLY=OFF \
             ${{ matrix.cmake_flags }}
           ninja obj/ldc2.o all ldc2-unittest all-test-runners
           bin/ldc2 --version

CMakeLists.txt

@@ -2,6 +2,10 @@ cmake_minimum_required(VERSION 3.16.0)
 if(POLICY CMP0025)
     cmake_policy(SET CMP0025 NEW)
 endif()
+if(POLICY CMP0132)
+    # see https://github.com/ldc-developers/ldc/issues/3901
+    cmake_policy(SET CMP0132 NEW)
+endif()
 if(${CMAKE_VERSION} VERSION_GREATER "3.26.9")
     # Prevent implicit dependencies for custom commands, e.g.,
     # `obj/ldc2.o` depending on `lib/libldc.a` with LDC_LINK_MANUALLY=ON.

cmake/Modules/BuildDExecutable.cmake

@@ -100,7 +100,12 @@ function(build_d_executable target_name output_exe d_src_files compiler_args lin
 
         # We need to link against the C++ runtime library.
         if(NOT MSVC AND "${D_COMPILER_ID}" STREQUAL "LDMD" AND NOT "${dflags}" MATCHES "(^|;)-gcc=")
-            set(translated_linker_args "-gcc=${CMAKE_CXX_COMPILER}" ${translated_linker_args})
+            if(CMAKE_VERSION VERSION_LESS "4.0.0" AND APPLE AND "${CMAKE_CXX_COMPILER}" MATCHES "/Developer/.+/usr/bin/c\\+\\+$")
+                # see https://github.com/ldc-developers/ldc/issues/3901
+                set(translated_linker_args "-gcc=/usr/bin/c++" ${translated_linker_args})
+            else()
+                set(translated_linker_args "-gcc=${CMAKE_CXX_COMPILER}" ${translated_linker_args})
+            endif()
         endif()
 
         # Use an extra custom target as dependency for the executable in

runtime/DRuntimeIntegrationTests.cmake

@@ -57,10 +57,19 @@ else()
     list(REMOVE_ITEM testnames uuid)
 endif()
 
+set(musl "")
 if(TARGET_SYSTEM MATCHES "musl")
     set(musl "IS_MUSL=1")
 endif()
 
+set(cc  "CC=${CMAKE_C_COMPILER}")
+set(cxx "CXX=${CMAKE_CXX_COMPILER}")
+if(CMAKE_VERSION VERSION_LESS "4.0.0" AND CMAKE_HOST_APPLE AND "${TARGET_SYSTEM}" MATCHES "APPLE")
+    # see https://github.com/ldc-developers/ldc/issues/3901
+    set(cc  "")
+    set(cxx "")
+endif()
+
 foreach(name ${testnames})
     foreach(build debug release)
         set(druntime_path_build ${druntime_path})
@@ -78,10 +87,9 @@ foreach(name ${testnames})
         add_test(NAME ${fullname}
             COMMAND ${GNU_MAKE_BIN} -C ${PROJECT_SOURCE_DIR}/druntime/test/${name}
                 ROOT=${outdir} DMD=${LDMD_EXE_FULL} BUILD=${build} SHARED=1
-                CC=${CMAKE_C_COMPILER} CXX=${CMAKE_CXX_COMPILER}
                 DRUNTIME=${druntime_path_build} DRUNTIMESO=${shared_druntime_path_build}
-                CFLAGS_BASE=${cflags_base} DFLAGS_BASE=${dflags_base} ${linkdl}
-		IN_LDC=1 ${musl}
+                ${cc} ${cxx} CFLAGS_BASE=${cflags_base} DFLAGS_BASE=${dflags_base} ${linkdl}
+                IN_LDC=1 ${musl}
         )
         set_tests_properties(${fullname} PROPERTIES DEPENDS clean-${fullname})
     endforeach()