[runtimes] Deprecate FOO_SYSROOT & friends

[ldionne]

Summary

As suggested in https://reviews.llvm.org/D112155.

[ldionne]

I will also cherry-pick this to release/14.x so we can move forward with D112155 in LLVM 15.

[ldionne]

@vvereschaka @broadwaylamb clang/cmake/caches/CrossWinToARMLinux.cmake is using those variables -- we should try to use the native CMake equivalents instead.

[ldionne]

Rebase onto main -- that should fix CI.

[vvereschaka]

@vvereschaka @broadwaylamb clang/cmake/caches/CrossWinToARMLinux.cmake is using those variables -- we should try to use the native CMake equivalents instead.

@ldionne , thank you. 'll update CrossWinToARMLinux.cmake accordingly.

[phosek]

libcxx/CMakeLists.txt

294

What's the motivation for checking if CMAKE_SYSROOT is unset and not just LIBCXX_SYSROOT?

[ldionne]

libcxx/CMakeLists.txt

294

If they are also setting CMAKE_SYSROOT, nothing will break when we remove LIBCXX_SYSROOT. I guess I could also just check for LIBCXX_SYSROOT if you have a preference for that.

[ldionne]

Rebase just to see CI passing.

[ldionne]

@phosek Please let me know if you care about dropping NOT CMAKE_SYSROOT AND and I can do it post-commit.

[phosek]

In D119836#3326197, @ldionne wrote:

@phosek Please let me know if you care about dropping NOT CMAKE_SYSROOT AND and I can do it post-commit.

I'm fine with the current solution.

libcxx/CMakeLists.txt

if(CMAKE_CXX_COMPILER_TARGET)
   set(LIBCXX_DEFAULT_TARGET_TRIPLE "${CMAKE_CXX_COMPILER_TARGET}")
 else()
   set(LIBCXX_DEFAULT_TARGET_TRIPLE "${LLVM_DEFAULT_TARGET_TRIPLE}")
 endif()
 set(LIBCXX_TARGET_TRIPLE "${LIBCXX_DEFAULT_TARGET_TRIPLE}" CACHE STRING "Use alternate target triple.")
 set(LIBCXX_SYSROOT "${CMAKE_SYSROOT}" CACHE STRING "Use alternate sysroot.")
 set(LIBCXX_GCC_TOOLCHAIN "${CMAKE_CXX_COMPILER_EXTERNAL_TOOLCHAIN}" CACHE STRING "Use alternate GCC toolchain.")
 
+if(NOT CMAKE_SYSROOT AND LIBCXX_SYSROOT)
+  message(WARNING "LIBCXX_SYSROOT is deprecated, please use CMAKE_SYSROOT instead")
+endif()
+if(NOT CMAKE_CXX_COMPILER_TARGET AND LIBCXX_TARGET_TRIPLE)
+  message(WARNING "LIBCXX_TARGET_TRIPLE is deprecated, please use CMAKE_CXX_COMPILER_TARGET instead")
+endif()
+if(NOT CMAKE_CXX_COMPILER_EXTERNAL_TOOLCHAIN AND LIBCXX_GCC_TOOLCHAIN)
+  message(WARNING "LIBCXX_GCC_TOOLCHAIN is deprecated, please use CMAKE_CXX_COMPILER_EXTERNAL_TOOLCHAIN instead")
+endif()
+
 # Feature options -------------------------------------------------------------
 option(LIBCXX_ENABLE_EXCEPTIONS "Use exceptions." ON)
 option(LIBCXX_ENABLE_RTTI "Use run time type information." ON)
 option(LIBCXX_ENABLE_THREADS "Build libc++ with support for threads." ON)
 option(LIBCXX_ENABLE_MONOTONIC_CLOCK
   "Build libc++ with support for a monotonic clock.
    This option may only be set to OFF when LIBCXX_ENABLE_THREADS=OFF." ON)
 option(LIBCXX_HAS_MUSL_LIBC "Build libc++ with support for the Musl C library" OFF)

libcxxabi/CMakeLists.txt

if(CMAKE_CXX_COMPILER_TARGET)
   set(LIBCXXABI_DEFAULT_TARGET_TRIPLE "${CMAKE_CXX_COMPILER_TARGET}")
 else()
   set(LIBCXXABI_DEFAULT_TARGET_TRIPLE "${LLVM_DEFAULT_TARGET_TRIPLE}")
 endif()
 set(LIBCXXABI_TARGET_TRIPLE "${LIBCXXABI_DEFAULT_TARGET_TRIPLE}" CACHE STRING "Target triple for cross compiling.")
 set(LIBCXXABI_GCC_TOOLCHAIN "${CMAKE_CXX_COMPILER_EXTERNAL_TOOLCHAIN}" CACHE PATH "GCC toolchain for cross compiling.")
 set(LIBCXXABI_SYSROOT "${CMAKE_SYSROOT}" CACHE PATH "Sysroot for cross compiling.")
 
+if(NOT CMAKE_SYSROOT AND LIBCXXABI_SYSROOT)
+  message(WARNING "LIBCXXABI_SYSROOT is deprecated, please use CMAKE_SYSROOT instead")
+endif()
+if(NOT CMAKE_CXX_COMPILER_TARGET AND LIBCXXABI_TARGET_TRIPLE)
+  message(WARNING "LIBCXXABI_TARGET_TRIPLE is deprecated, please use CMAKE_CXX_COMPILER_TARGET instead")
+endif()
+if(NOT CMAKE_CXX_COMPILER_EXTERNAL_TOOLCHAIN AND LIBCXXABI_GCC_TOOLCHAIN)
+  message(WARNING "LIBCXXABI_GCC_TOOLCHAIN is deprecated, please use CMAKE_CXX_COMPILER_EXTERNAL_TOOLCHAIN instead")
+endif()
+
 set(LIBCXXABI_LIBCXX_LIBRARY_PATH "" CACHE PATH "The path to libc++ library.")
 set(LIBCXXABI_LIBRARY_VERSION "1.0" CACHE STRING
 "Version of libc++abi. This will be reflected in the name of the shared \
 library produced. For example, -DLIBCXXABI_LIBRARY_VERSION=x.y will \
 result in the library being named libc++abi.x.y.dylib, along with the \
 usual symlinks pointing to that.")
 
 # Default to building a shared library so that the default options still test

libunwind/CMakeLists.txt

 set(LIBUNWIND_TARGET_TRIPLE "${LIBUNWIND_DEFAULT_TARGET_TRIPLE}" CACHE STRING "Target triple for cross compiling.")
 set(LIBUNWIND_GCC_TOOLCHAIN "${CMAKE_CXX_COMPILER_EXTERNAL_TOOLCHAIN}" CACHE PATH "GCC toolchain for cross compiling.")
 set(LIBUNWIND_SYSROOT "${CMAKE_SYSROOT}" CACHE PATH "Sysroot for cross compiling.")
 set(LIBUNWIND_TEST_LINKER_FLAGS "" CACHE STRING
     "Additional linker flags for test programs.")
 set(LIBUNWIND_TEST_COMPILER_FLAGS "" CACHE STRING
     "Additional compiler flags for test programs.")
 
+if(NOT CMAKE_SYSROOT AND LIBUNWIND_SYSROOT)
+  message(WARNING "LIBUNWIND_SYSROOT is deprecated, please use CMAKE_SYSROOT instead")
+endif()
+if(NOT CMAKE_CXX_COMPILER_TARGET AND LIBUNWIND_TARGET_TRIPLE)
+  message(WARNING "LIBUNWIND_TARGET_TRIPLE is deprecated, please use CMAKE_CXX_COMPILER_TARGET instead")
+endif()
+if(NOT CMAKE_CXX_COMPILER_EXTERNAL_TOOLCHAIN AND LIBUNWIND_GCC_TOOLCHAIN)
+  message(WARNING "LIBUNWIND_GCC_TOOLCHAIN is deprecated, please use CMAKE_CXX_COMPILER_EXTERNAL_TOOLCHAIN instead")
+endif()
+
 if (LIBUNWIND_ENABLE_SHARED)
   set(LIBUNWIND_DEFAULT_TEST_CONFIG "llvm-libunwind-shared.cfg.in")
 else()
   set(LIBUNWIND_DEFAULT_TEST_CONFIG "llvm-libunwind-static.cfg.in")
 endif()
 set(LIBUNWIND_TEST_CONFIG "${LIBUNWIND_DEFAULT_TEST_CONFIG}" CACHE STRING
   "The path to the Lit testing configuration to use when running the tests.
    If a relative path is provided, it is assumed to be relative to '<monorepo>/libunwind/test/configs'.")