[cmake] Make include(GNUInstallDirs) always below project(..)

[Ericson2314]

Summary

Its defaulting logic must go after project(..) to work correctly, but project(..) is often in a standalone condition making this
awkward, since the rest of the condition code may also need GNUInstallDirs.

The good thing is there are the various standalone booleans, which I had missed before. This makes splitting the conditional blocks less awkward.

[Ericson2314]

Don't forget compiler-rt

[arichardson]

I believe LLVM_LIBDIR_SUFFIX was added as a workaround for not being able to use GNUInstallDirs (which will automatically detect the right suffixed e.g. for SuSE) in rG46fed3b475ddd92d02d9b72d0d77c5a939f132d1. Would it be possible to move the include() below the project()/enable_language() calls so that CMake can detect the expected libdir suffix and then use something like the following:

# If LLVM_LIBDIR_SUFFIX is defined, we use that to override the libdir, otherwise GNUInstallDirs defaults should be correct.
if(DEFINED LLVM_LIBDIR_SUFFIX)
  message(DEPRECATION "LLVM_LIBDIR_SUFFIX is deprecated, set CMAKE_INSTALL_LIBDIR to lib${LLVM_LIBDIR_SUFFIX} instead")
  set(CMAKE_INSTALL_LIBDIR lib${LLVM_LIBDIR_SUFFIX})
endif()
include(GNUInstallDirs)

[arichardson]

I can't see anywhere where the GNUInstallDirs variables are used before project(), so can't we just move the includes further down?

[arichardson]

I see AddLLVM already includes GNUInstallDirs, can we add the LLVM_LIBDIR_SUFFIX check to that file and avoid including GNUInstallDirs explicitly in all the projects? The standalone builds will pull in GNUInstallDirs via AddLLVM, and the non-standalone builds should already have the variables defined?

[Ericson2314]

In D117639#3254065, @arichardson wrote:

I believe LLVM_LIBDIR_SUFFIX was added as a workaround for not being able to use GNUInstallDirs (which will automatically detect the right suffixed e.g. for SuSE) in rG46fed3b475ddd92d02d9b72d0d77c5a939f132d1. Would it be possible to move the include() below the project()/enable_language() calls so that CMake can detect the expected libdir suffix and then use something like the following:

# If LLVM_LIBDIR_SUFFIX is defined, we use that to override the libdir, otherwise GNUInstallDirs defaults should be correct.
if(DEFINED LLVM_LIBDIR_SUFFIX)
  message(DEPRECATION "LLVM_LIBDIR_SUFFIX is deprecated, set CMAKE_INSTALL_LIBDIR to lib${LLVM_LIBDIR_SUFFIX} instead")
  set(CMAKE_INSTALL_LIBDIR lib${LLVM_LIBDIR_SUFFIX})
endif()
include(GNUInstallDirs)

I would love to do this, but I was unsure whether that was acceptable.

It gets even more complicated downstream when other *_LIBDIR_SUFFIX variable are defaulted from LLVM_LIBDIR_SUFFIX. Can we deprecate that too?

[Ericson2314]

Just move them

@arichardson as the description now indicates, I found the STANDALONE variables, which made doing what was originally asked less awkard than I feared.

I do also prefer splitting the blocks to putting the logic further below. as I rather not get clever with questions of "does this include transitively reference gnu install dirs?" etc.

[Ericson2314]

Rebase after D117617 landed

[arichardson]

This LGTM, but please wait for someone else to review before committing it.

lldb/CMakeLists.txt

21

Could keep this in the first if then you won't have to duplicate setting LLDB_BUILT_STANDALONE?

[beanz]

LGTM.

[phosek]

LGTM

flang/CMakeLists.txt

 cmake_minimum_required(VERSION 3.13.4)
 
 set(CMAKE_BUILD_WITH_INSTALL_NAME_DIR ON)
 
 # Flang requires C++17.
 set(CMAKE_CXX_STANDARD 17)
 set(CMAKE_CXX_STANDARD_REQUIRED TRUE)
 set(CMAKE_CXX_EXTENSIONS OFF)
 
-include(GNUInstallDirs)
-
 set(FLANG_SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR})
 
 if (CMAKE_SOURCE_DIR STREQUAL CMAKE_BINARY_DIR AND NOT MSVC_IDE)
   message(FATAL_ERROR "In-source builds are not allowed. \
           Please create a directory and run cmake from there,\
           passing the path to this source directory as the last argument.\
           This process created the file `CMakeCache.txt' and the directory\
           `CMakeFiles'. Please delete them.")
 endif()
 
 option(FLANG_ENABLE_WERROR "Fail and stop building flang if a warning is triggered." OFF)
 
 # Check for a standalone build and configure as appropriate from
 # there.
 if (CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
   message("Building Flang as a standalone project.")
   project(Flang)
   set(FLANG_STANDALONE_BUILD ON)
+else()
+  set(FLANG_STANDALONE_BUILD OFF)
+endif()
 
+# Must go below project(..)
+include(GNUInstallDirs)
+
+if (FLANG_STANDALONE_BUILD)
   set(FLANG_BINARY_DIR ${CMAKE_CURRENT_BINARY_DIR})
   if (NOT MSVC_IDE)
     set(LLVM_ENABLE_ASSERTIONS ${ENABLE_ASSERTIONS}
       CACHE BOOL "Enable assertions")
     # Assertions follow llvm's configuration.
     mark_as_advanced(LLVM_ENABLE_ASSERTIONS)
   endif()
 
#LLVM_BUILD_MAIN_SRC_DIR - Path to llvm source when out-of-tree.
   else()
     add_custom_target(check-all DEPENDS check-flang )
   endif()
   if (LLVM_BUILD_DOCS)
     add_custom_target(doxygen ALL)
   endif()
 
 else()
-  set(FLANG_STANDALONE_BUILD OFF)
   option(FLANG_INCLUDE_TESTS
          "Generate build targets for the Flang unit tests."
          ${LLVM_INCLUDE_TESTS})
   set(FLANG_GTEST_AVAIL 1)
 
   if(FLANG_STANDALONE_BUILD)
     set(FLANG_BINARY_DIR ${CMAKE_BINARY_DIR}/tools/flang)
   else()

libcxx/CMakeLists.txt

 # See https://libcxx.llvm.org/docs/BuildingLibcxx.html for instructions on how
 # to build libcxx with CMake.
 
 if (NOT IS_DIRECTORY "${CMAKE_CURRENT_LIST_DIR}/../libcxxabi")
   message(FATAL_ERROR "libc++ now requires being built in a monorepo layout with libcxxabi available")
 endif()
 
 #===============================================================================
 # Setup Project
 #===============================================================================
 cmake_minimum_required(VERSION 3.13.4)
 
-include(GNUInstallDirs)
-
 set(LLVM_COMMON_CMAKE_UTILS "${CMAKE_CURRENT_SOURCE_DIR}/../cmake")
 
 # Add path for custom modules
 list(INSERT CMAKE_MODULE_PATH 0
   "${CMAKE_CURRENT_SOURCE_DIR}/cmake"
   "${CMAKE_CURRENT_SOURCE_DIR}/cmake/Modules"
   "${LLVM_COMMON_CMAKE_UTILS}"
   "${LLVM_COMMON_CMAKE_UTILS}/Modules"
if (CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR OR LIBCXX_STANDALONE_BUILD)
   set(PACKAGE_NAME libcxx)
   set(PACKAGE_VERSION 14.0.0git)
   set(PACKAGE_STRING "${PACKAGE_NAME} ${PACKAGE_VERSION}")
   set(PACKAGE_BUGREPORT "[e-mail]")
 
   # In a standalone build, we don't have llvm to automatically generate the
   # llvm-lit script for us.  So we need to provide an explicit directory that
   # the configurator should write the script into.
-  set(LIBCXX_STANDALONE_BUILD 1)
+  set(LIBCXX_STANDALONE_BUILD TRUE)
   set(LLVM_LIT_OUTPUT_DIR "${LIBCXX_BINARY_DIR}/bin")
+endif()
+
+# Must go below project(..)
+include(GNUInstallDirs)
 
+if (LIBCXX_STANDALONE_BUILD)
   # Find the LLVM sources and simulate LLVM CMake options.
   include(HandleOutOfTreeLLVM)
-endif()
 
-if (LIBCXX_STANDALONE_BUILD)
   find_package(Python3 COMPONENTS Interpreter)
   if(NOT Python3_Interpreter_FOUND)
     message(SEND_ERROR "Python3 not found. Python3 is required")
   endif()
 endif()
 
 # Require out of source build.
 include(MacroEnsureOutOfSourceBuild)

libcxxabi/CMakeLists.txt

 # See www/CMake.html for instructions on how to build libcxxabi with CMake.
 
 if (NOT IS_DIRECTORY "${CMAKE_CURRENT_LIST_DIR}/../libcxx")
   message(FATAL_ERROR "libc++abi now requires being built in a monorepo layout with libcxx available")
 endif()
 
 #===============================================================================
 # Setup Project
 #===============================================================================
 
 cmake_minimum_required(VERSION 3.13.4)
 
-include(GNUInstallDirs)
-
 set(LLVM_COMMON_CMAKE_UTILS "${CMAKE_CURRENT_SOURCE_DIR}/../cmake")
 
 # Add path for custom modules
 list(INSERT CMAKE_MODULE_PATH 0
   "${CMAKE_CURRENT_SOURCE_DIR}/cmake"
   "${CMAKE_CURRENT_SOURCE_DIR}/cmake/Modules"
   "${LLVM_COMMON_CMAKE_UTILS}"
   "${LLVM_COMMON_CMAKE_UTILS}/Modules"

 if (CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR OR LIBCXXABI_STANDALONE_BUILD)
   project(libcxxabi CXX C)
 
   set(PACKAGE_NAME libcxxabi)
   set(PACKAGE_VERSION 11.0.0git)
   set(PACKAGE_STRING "${PACKAGE_NAME} ${PACKAGE_VERSION}")
   set(PACKAGE_BUGREPORT "[e-mail]")
 
+  set(LIBCXXABI_STANDALONE_BUILD TRUE)
+
   # In a standalone build, we don't have llvm to automatically generate the
   # llvm-lit script for us.  So we need to provide an explicit directory that
   # the configurator should write the script into.
-  set(LIBCXXABI_STANDALONE_BUILD 1)
   set(LLVM_LIT_OUTPUT_DIR "${LIBCXXABI_BINARY_DIR}/bin")
+endif()
 
+# Must go below project(..)
+include(GNUInstallDirs)
+
+if (LIBCXXABI_STANDALONE_BUILD)
   # Find the LLVM sources and simulate LLVM CMake options.
   include(HandleOutOfTreeLLVM)
-endif()
 
-if (LIBCXXABI_STANDALONE_BUILD)
   find_package(Python3 COMPONENTS Interpreter)
   if(NOT Python3_Interpreter_FOUND)
     message(WARNING "Python3 not found, using python2 as a fallback")
     find_package(Python2 COMPONENTS Interpreter REQUIRED)
     if(Python2_VERSION VERSION_LESS 2.7)
       message(SEND_ERROR "Python 2.7 or newer is required")
     endif()
 

libunwind/CMakeLists.txt

 if (NOT IS_DIRECTORY "${CMAKE_CURRENT_LIST_DIR}/../libcxx")
   message(FATAL_ERROR "libunwind requires being built in a monorepo layout with libcxx available")
 endif()
 
 #===============================================================================
 # Setup Project
 #===============================================================================
 
 cmake_minimum_required(VERSION 3.13.4)
 
-include(GNUInstallDirs)
-
 set(LLVM_COMMON_CMAKE_UTILS "${CMAKE_CURRENT_SOURCE_DIR}/../cmake")
 
 # Add path for custom modules
 list(INSERT CMAKE_MODULE_PATH 0
   "${CMAKE_CURRENT_SOURCE_DIR}/cmake"
   "${CMAKE_CURRENT_SOURCE_DIR}/cmake/Modules"
   "${LLVM_COMMON_CMAKE_UTILS}"
   "${LLVM_COMMON_CMAKE_UTILS}/Modules"
   )
 
 set(LIBUNWIND_SOURCE_DIR  ${CMAKE_CURRENT_SOURCE_DIR})
 set(LIBUNWIND_BINARY_DIR  ${CMAKE_CURRENT_BINARY_DIR})
 set(LIBUNWIND_LIBCXX_PATH "${CMAKE_CURRENT_LIST_DIR}/../libcxx" CACHE PATH
         "Specify path to libc++ source.")
 
 if (CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR OR LIBUNWIND_STANDALONE_BUILD)
   # We may have an incomplete toolchain - do language support tests without
   # linking.
   include(EnableLanguageNolink)
   project(libunwind LANGUAGES NONE)
-  llvm_enable_language_nolink(C CXX ASM)
 
   set(PACKAGE_NAME libunwind)
   set(PACKAGE_VERSION 14.0.0git)
   set(PACKAGE_STRING "${PACKAGE_NAME} ${PACKAGE_VERSION}")
   set(PACKAGE_BUGREPORT "[e-mail]")
 
+  set(LIBUNWIND_STANDALONE_BUILD TRUE)
+endif()
+
+# Must go below project(..)
+include(GNUInstallDirs)
+
+if(LIBUNWIND_STANDALONE_BUILD)
+  llvm_enable_language_nolink(C CXX ASM)
+
+  # Find the LLVM sources and simulate LLVM CMake options.
+  include(HandleOutOfTreeLLVM)
+
   # In a standalone build, we don't have llvm to automatically generate the
   # llvm-lit script for us.  So we need to provide an explicit directory that
   # the configurator should write the script into.
-  set(LIBUNWIND_STANDALONE_BUILD 1)
   set(LLVM_LIT_OUTPUT_DIR "${LIBUNWIND_BINARY_DIR}/bin")
-
-  # Find the LLVM sources and simulate LLVM CMake options.
-  include(HandleOutOfTreeLLVM)
 else()
   set(LLVM_LIT "${CMAKE_SOURCE_DIR}/utils/lit/lit.py")
 endif()
 
 #===============================================================================
 # Setup CMake Options
 #===============================================================================
 include(CMakeDependentOption)

lld/CMakeLists.txt

 cmake_minimum_required(VERSION 3.13.4)
 
-include(GNUInstallDirs)
-
 # If we are not building as a part of LLVM, build LLD as an
 # standalone project, using LLVM as an external library:
 if(CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
   project(lld)
+  set(LLD_BUILT_STANDALONE TRUE)
+endif()
 
+# Must go below project(..)
+include(GNUInstallDirs)
+
+if(LLD_BUILT_STANDALONE)
   set(CMAKE_INCLUDE_CURRENT_DIR ON)
 
   # Rely on llvm-config.
   set(LLVM_CONFIG_OUTPUT)
   if(LLVM_CONFIG)
     set (LLVM_CONFIG_FOUND 1)
     message(STATUS "Found LLVM_CONFIG as ${LLVM_CONFIG}")
     message(DEPRECATION "Using llvm-config to detect the LLVM installation is \
if(LLVM_INCLUDE_TESTS)
     else()
       set(LLVM_INCLUDE_TESTS OFF)
     endif()
   endif()
 
   if(LLVM_HAVE_LIBXAR)
     set(XAR_LIB xar)
   endif()
-
-  set(LLD_BUILT_STANDALONE TRUE)
 endif() # standalone
 
 set(LLD_SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR})
 set(LLD_INCLUDE_DIR ${LLD_SOURCE_DIR}/include )
 set(LLD_BINARY_DIR ${CMAKE_CURRENT_BINARY_DIR})
 
 set(LLD_VENDOR ${PACKAGE_VENDOR} CACHE STRING
   "Vendor-specific text for showing with version information.")

lldb/CMakeLists.txt

 cmake_minimum_required(VERSION 3.13.4)
 
-include(GNUInstallDirs)
-
 # Add path for custom modules.
 set(CMAKE_MODULE_PATH
   ${CMAKE_MODULE_PATH}
   "${CMAKE_CURRENT_SOURCE_DIR}/cmake"
   "${CMAKE_CURRENT_SOURCE_DIR}/cmake/modules"
   )
 
 # If we are not building as part of LLVM, build LLDB as a standalone project,
 # using LLVM as an external library.
 if (CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
   project(lldb)
+  set(LLDB_BUILT_STANDALONE TRUE)
+endif()
+
+# Must go below project(..)
+include(GNUInstallDirs)
+
+if(LLDB_BUILT_STANDALONE)
   include(LLDBStandalone)
 
   set(CMAKE_CXX_STANDARD 14 CACHE STRING "C++ standard to conform to")
   set(CMAKE_CXX_STANDARD_REQUIRED YES)
   set(CMAKE_CXX_EXTENSIONS NO)
 endif()
 
 include(LLDBConfig)
 include(AddLLDB)

lldb/cmake/modules/LLDBStandalone.cmake

 include_directories(
   "${CMAKE_BINARY_DIR}/include"
   "${LLVM_INCLUDE_DIRS}"
   "${CLANG_INCLUDE_DIRS}")
 
 set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/bin)
 set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/lib${LLVM_LIBDIR_SUFFIX})
 set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/lib${LLVM_LIBDIR_SUFFIX})
-
-set(LLDB_BUILT_STANDALONE 1)

lldb/tools/debugserver/CMakeLists.txt

 cmake_minimum_required(VERSION 3.13.4)
 
 project(Debugserver LANGUAGES C CXX ASM-ATT)
 
+# Must go below project(..)
+include(GNUInstallDirs)
+
 if (CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
+  set(LLDB_BUILT_STANDALONE TRUE)
+
   set(CMAKE_MODULE_PATH
     ${CMAKE_MODULE_PATH}
     "${CMAKE_SOURCE_DIR}/../../cmake"
     "${CMAKE_SOURCE_DIR}/../../cmake/modules"
     )
 
   include(LLDBStandalone)
   include(debugserverConfig)

llvm/CMakeLists.txt

 # See docs/CMake.html for instructions about how to build LLVM with CMake.
 
 cmake_minimum_required(VERSION 3.13.4)
 
-include(GNUInstallDirs)
-
 # CMP0116: Ninja generators transform `DEPFILE`s from `add_custom_command()`
 # New in CMake 3.20. https://cmake.org/cmake/help/latest/policy/CMP0116.html
 if(POLICY CMP0116)
   cmake_policy(SET CMP0116 OLD)
 endif()
 
 set(CMAKE_BUILD_WITH_INSTALL_NAME_DIR ON)
 
if (CMAKE_GENERATOR STREQUAL "Xcode" AND NOT CMAKE_OSX_ARCHITECTURES)
   # explicitly specify an architecture setting with the Xcode generator.
   set(CMAKE_OSX_ARCHITECTURES "x86_64")
 endif()
 
 project(LLVM
   VERSION ${LLVM_VERSION_MAJOR}.${LLVM_VERSION_MINOR}.${LLVM_VERSION_PATCH}
   LANGUAGES C CXX ASM)
 
+# Must go after project(..)
+include(GNUInstallDirs)
+
 set(CMAKE_CXX_STANDARD 14 CACHE STRING "C++ standard to conform to")
 set(CMAKE_CXX_STANDARD_REQUIRED YES)
 if (CYGWIN)
   # Cygwin is a bit stricter and lack things like 'strdup', 'stricmp', etc in
   # c++xx mode.
   set(CMAKE_CXX_EXTENSIONS YES)
 else()
   set(CMAKE_CXX_EXTENSIONS NO)

mlir/CMakeLists.txt

 # MLIR project.
 
-include(GNUInstallDirs)
-
 # Check if MLIR is built as a standalone project.
 if(CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
   project(mlir)
+  set(MLIR_STANDALONE_BUILD TRUE)
+endif()
+
+# Must go below project(..)
+include(GNUInstallDirs)
+
+if(MLIR_STANDALONE_BUILD)
   cmake_minimum_required(VERSION 3.13.4)
 
   find_package(LLVM CONFIG REQUIRED)
   set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} ${LLVM_CMAKE_DIR})
   include(HandleLLVMOptions)
   include(AddLLVM)
   include(TableGen)
 

polly/CMakeLists.txt

-include(GNUInstallDirs)
-
 # Check if this is a in tree build.
 if (NOT DEFINED LLVM_MAIN_SRC_DIR)
   project(Polly)
   cmake_minimum_required(VERSION 3.13.4)
+  set(POLLY_STANDALONE_BUILD TRUE)
+endif()
+
+# Must go below project(..)
+include(GNUInstallDirs)
 
+if(POLLY_STANDALONE_BUILD)
   # Where is LLVM installed?
   find_package(LLVM CONFIG REQUIRED)
   set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} ${LLVM_CMAKE_DIR})
   include(HandleLLVMOptions)
   include(AddLLVM)
 
   # Add the llvm header path.
   include_directories(${LLVM_INCLUDE_DIRS})

pstl/CMakeLists.txt

 #===-- CMakeLists.txt ----------------------------------------------------===##
 #
 # Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 # See https://llvm.org/LICENSE.txt for license information.
 # SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 #
 #===----------------------------------------------------------------------===##
 cmake_minimum_required(VERSION 3.13.4)
 
-include(GNUInstallDirs)
-
 set(PARALLELSTL_VERSION_FILE "${CMAKE_CURRENT_SOURCE_DIR}/include/pstl/internal/pstl_config.h")
 file(STRINGS "${PARALLELSTL_VERSION_FILE}" PARALLELSTL_VERSION_SOURCE REGEX "#define _PSTL_VERSION .*$")
 string(REGEX REPLACE "#define _PSTL_VERSION (.*)$" "\\1" PARALLELSTL_VERSION_SOURCE "${PARALLELSTL_VERSION_SOURCE}")
 math(EXPR VERSION_MAJOR "(${PARALLELSTL_VERSION_SOURCE} / 1000)")
 math(EXPR VERSION_MINOR "((${PARALLELSTL_VERSION_SOURCE} % 1000) / 10)")
 math(EXPR VERSION_PATCH "(${PARALLELSTL_VERSION_SOURCE} % 10)")
 
 project(ParallelSTL VERSION ${VERSION_MAJOR}.${VERSION_MINOR}.${VERSION_PATCH} LANGUAGES CXX)
 
+# Must go below project(..)
+include(GNUInstallDirs)
+
 set(PSTL_PARALLEL_BACKEND "serial" CACHE STRING "Threading backend to use. Valid choices are 'serial', 'omp', and 'tbb'. The default is 'serial'.")
 set(PSTL_HIDE_FROM_ABI_PER_TU OFF CACHE BOOL "Whether to constrain ABI-unstable symbols to each translation unit (basically, mark them with C's static keyword).")
 set(_PSTL_HIDE_FROM_ABI_PER_TU ${PSTL_HIDE_FROM_ABI_PER_TU}) # For __pstl_config_site
 
 if (NOT TBB_DIR)
     get_filename_component(PSTL_DIR_NAME ${CMAKE_CURRENT_SOURCE_DIR} NAME)
     string(REPLACE pstl tbb TBB_DIR_NAME ${PSTL_DIR_NAME})
     if (EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/../${TBB_DIR_NAME}/cmake")