[PATCH] D158218: [CMake] Deprecate DEFAULT_SYSROOT and GCC_INSTALL_PREFIX

[Fangrui Song via Phabricator via cfe-commits]

MaskRay created this revision.
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Specifying DEFAULT_SYSROOT and GCC_INSTALL_PREFIX can cause many
clang/test/Driver failures, e.g. non-empty DEFAULT_SYSROOT causes:

  Failed Tests (14):
    Clang :: Driver/baremetal.cpp
    Clang :: Driver/csky-toolchain.c
    Clang :: Driver/freebsd-include-paths.c
    Clang :: Driver/hexagon-toolchain-elf.c
    Clang :: Driver/hexagon-toolchain-linux.c
    Clang :: Driver/mips-cs.cpp
    Clang :: Driver/mips-fsf.cpp
    Clang :: Driver/mips-img-v2.cpp
    Clang :: Driver/mips-img.cpp
    Clang :: Driver/riscv32-toolchain-extra.c
    Clang :: Driver/riscv64-toolchain-extra.c
    Clang :: Driver/rocm-detect.hip
    Clang :: Driver/solaris-ld.c
    Clang :: Driver/sysroot.c

The two CMake variables are partially responsible for many
`--sysroot=`/ `--sysroot=""/`--gcc-toolchain=`/`--gcc-toolchain=""` in
clang/test/Driver: some contributors add them to fix tests and some just
do cargo culting.
This is not healthy for contributors adding cross compilation support.

Configuration files are perfect replacement.

Link: https://discourse.llvm.org/t/add-gcc-install-dir-deprecate-gcc-toolchain-and-remove-gcc-install-prefix/65091
Link: https://discourse.llvm.org/t/correct-cmake-parameters-for-building-clang-and-lld-for-riscv/72833

I hope that people can help port some docs:
clang/cmake/caches/CrossWinToARMLinux.cmake
libc/docs/full_host_build.rst


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D158218

Files:
  clang/CMakeLists.txt


Index: clang/CMakeLists.txt
===================================================================
--- clang/CMakeLists.txt
+++ clang/CMakeLists.txt
@@ -176,6 +176,17 @@
 set(GCC_INSTALL_PREFIX "" CACHE PATH "Directory where gcc is installed." )
 set(DEFAULT_SYSROOT "" CACHE STRING
   "Default <path> to all compiler invocations for --sysroot=<path>." )
+if(DEFAULT_SYSROOT)
+  message(WARNING "DEFAULT_SYSROOT is deprecated and will be removed. Use "
+    "configuration files (https://clang.llvm.org/docs/UsersManual.html#configuration-files)"
+    "to specify the default --sysroot=")
+endif()
+if(GCC_INSTALL_PREFIX)
+  message(WARNING "GCC_INSTALL_PREFIX is deprecated and will be removed. Use "
+    "configuration files (https://clang.llvm.org/docs/UsersManual.html#configuration-files)"
+    "to specify the default --gcc-install-dir=. --gcc-toolchain= is discouraged. "
+    "The option is often unneeded or better replaced with --gcc-install-dir=.")
+endif()
 
 set(ENABLE_LINKER_BUILD_ID OFF CACHE BOOL "pass --build-id to ld")
 


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