Reorganize CMake and minimize configuration for non-top-level builds.upstream-master

4 files changed, 581 insertions, 553 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 314c72fe8..21f054656 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,12 +1,18 @@
-# cmake_minimum_require must be the first command of the file
 cmake_minimum_required(VERSION 3.10.0)
 
+#==============================================================================
+# CMake Policy issues.
+#==============================================================================
+# Allow overriding options in a parent project via `set` before including Eigen.
+if (POLICY CMP0077)
+  cmake_policy (SET CMP0077 NEW)
+endif (POLICY CMP0077)
+
 # NOTE Remove setting the policy once the minimum required CMake version is
 # increased to at least 3.15. Retain enabling the export to package registry.
 if (POLICY CMP0090)
   # The export command does not populate package registry by default
   cmake_policy (SET CMP0090 NEW)
-
   # Unless otherwise specified, always export to package registry to ensure
   # backwards compatibility.
   if (NOT DEFINED CMAKE_EXPORT_PACKAGE_REGISTRY)
@@ -23,48 +29,73 @@ if (POLICY CMP0146)
   cmake_policy(SET CMP0146 OLD)
 endif ()
 
+#==============================================================================
+# CMake Project.
+#==============================================================================
+
 project(Eigen3)
 
 # Remove this block after bumping CMake to v3.21.0
 # PROJECT_IS_TOP_LEVEL is defined then by default
 if(CMAKE_VERSION VERSION_LESS 3.21.0)
   if(CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
-    set(PROJECT_IS_TOP_LEVEL TRUE)
+    set(PROJECT_IS_TOP_LEVEL ON)
   else()
-    set(PROJECT_IS_TOP_LEVEL FALSE)
+    set(PROJECT_IS_TOP_LEVEL OFF)
   endif()
 endif()
 
-if(PROJECT_IS_TOP_LEVEL)
-  set(CMAKE_CXX_STANDARD 14 CACHE STRING "Default C++ standard")
-  set(CMAKE_CXX_STANDARD_REQUIRED ON CACHE BOOL "Require C++ standard")
-  set(CMAKE_CXX_EXTENSIONS OFF CACHE BOOL "Allow C++ extensions")
+#==============================================================================
+# Build ON/OFF Settings.
+#==============================================================================
+# Determine if we should build tests.
+include(CMakeDependentOption)
+cmake_dependent_option(BUILD_TESTING "Enable creation of tests." ON "PROJECT_IS_TOP_LEVEL" OFF)
+option(EIGEN_BUILD_TESTING "Enable creation of Eigen tests." ${BUILD_TESTING})
+option(EIGEN_LEAVE_TEST_IN_ALL_TARGET "Leaves tests in the all target, needed by ctest for automatic building." OFF)
+
+# Determine if we should build BLAS/LAPACK implementations.
+option(EIGEN_BUILD_BLAS "Toggles the building of the Eigen Blas library" ${PROJECT_IS_TOP_LEVEL})
+option(EIGEN_BUILD_LAPACK "Toggles the building of the included Eigen LAPACK library" ${PROJECT_IS_TOP_LEVEL})
+if (EIGEN_BUILD_BLAS OR EIGEN_BUILD_LAPACK)
+  # BLAS and LAPACK currently need a fortran compiler.
+  include(CMakeDetermineFortranCompiler)
+  if (NOT CMAKE_Fortran_COMPILER)
+    set(EIGEN_BUILD_BLAS OFF)
+    set(EIGEN_BUILD_LAPACK OFF)
+  else()
+    # Determine if we should build shared libraries for BLAS/LAPACK on this platform.
+    get_cmake_property(EIGEN_BUILD_SHARED_LIBS TARGET_SUPPORTS_SHARED_LIBS)
+  endif()
 endif()
 
-# guard against in-source builds
-
-if(${CMAKE_SOURCE_DIR} STREQUAL ${CMAKE_BINARY_DIR})
-  message(FATAL_ERROR "In-source builds not allowed. Please make a new directory (called a build directory) and run CMake from there. You may need to remove CMakeCache.txt. ")
+option(EIGEN_BUILD_BTL "Build benchmark suite" OFF)
+option(EIGEN_BUILD_SPBENCH "Build sparse benchmark suite" OFF)
+# Avoid building docs if included from another project.
+# Building documentation requires creating and running executables on the host
+# platform.  We shouldn't do this if cross-compiling.
+if (PROJECT_IS_TOP_LEVEL AND NOT CMAKE_CROSSCOMPILING)
+  set(EIGEN_BUILD_DOC_DEFAULT ON)
 endif()
+option(EIGEN_BUILD_DOC "Enable creation of Eigen documentation" ${EIGEN_BUILD_DOC_DEFAULT})
 
+option(EIGEN_BUILD_DEMOS "Toggles the building of the Eigen demos" ${PROJECT_IS_TOP_LEVEL})
 
-# Alias Eigen_*_DIR to Eigen3_*_DIR:
-
-set(Eigen_SOURCE_DIR ${Eigen3_SOURCE_DIR})
-set(Eigen_BINARY_DIR ${Eigen3_BINARY_DIR})
-
-# guard against bad build-type strings
-
-if (NOT CMAKE_BUILD_TYPE)
-  set(CMAKE_BUILD_TYPE "Release")
+# Disable pkgconfig only for native Windows builds
+if(NOT WIN32 OR NOT CMAKE_HOST_SYSTEM_NAME MATCHES Windows)
+  option(EIGEN_BUILD_PKGCONFIG "Build pkg-config .pc file for Eigen" ${PROJECT_IS_TOP_LEVEL})
 endif()
+option(EIGEN_BUILD_CMAKE_PACKAGE "Enables the creation of EigenConfig.cmake and related files" ${PROJECT_IS_TOP_LEVEL})
 
+if (EIGEN_BUILD_TESTING OR EIGEN_BUILD_BLAS OR EIGEN_BUILD_LAPACK OR EIGEN_BUILT_BTL OR EIGEN_BUILD_BTL OR EIGEN_BUILD_SPBENCH OR EIGEN_BUILD_DOC OR EIGEN_BUILD_DEMOS)
+  set(EIGEN_IS_BUILDING_ ON)
+endif()
 
-#############################################################################
-# retrieve version information                                              #
-#############################################################################
+#==============================================================================
+# Version Info.
+#==============================================================================
 
-# automatically parse the version number
+# Automatically parse the version number from header files.
 file(READ "${PROJECT_SOURCE_DIR}/Eigen/src/Core/util/Macros.h" _eigen_version_header)
 string(REGEX MATCH "define[ \t]+EIGEN_WORLD_VERSION[ \t]+([0-9]+)" _eigen_world_version_match "${_eigen_version_header}")
 set(EIGEN_WORLD_VERSION "${CMAKE_MATCH_1}")
@@ -74,13 +105,12 @@ string(REGEX MATCH "define[ \t]+EIGEN_MINOR_VERSION[ \t]+([0-9]+)" _eigen_minor_
 set(EIGEN_MINOR_VERSION "${CMAKE_MATCH_1}")
 set(EIGEN_VERSION_NUMBER ${EIGEN_WORLD_VERSION}.${EIGEN_MAJOR_VERSION}.${EIGEN_MINOR_VERSION})
 
-# if we are not in a git clone
+# If we are in a git repo, extract a changeset.
 if(IS_DIRECTORY ${CMAKE_SOURCE_DIR}/.git)
   # if the git program is absent or this will leave the EIGEN_GIT_REVNUM string empty,
   # but won't stop CMake.
   execute_process(COMMAND git ls-remote --refs -q ${CMAKE_SOURCE_DIR} HEAD OUTPUT_VARIABLE EIGEN_GIT_OUTPUT)
 endif()
-
 # extract the git rev number from the git output...
 if(EIGEN_GIT_OUTPUT)
 string(REGEX MATCH "^([0-9;a-f]+).*" EIGEN_GIT_CHANGESET_MATCH "${EIGEN_GIT_OUTPUT}")
@@ -93,547 +123,609 @@ else()
   set(EIGEN_VERSION "${EIGEN_VERSION_NUMBER}")
 endif()
 
-include(CheckCXXCompilerFlag)
-include(GNUInstallDirs)
-include(CMakeDependentOption)
-
-set(CMAKE_MODULE_PATH ${PROJECT_SOURCE_DIR}/cmake)
+#==============================================================================
+# Eigen Library.
+#==============================================================================
 
-macro(ei_add_cxx_compiler_flag FLAG)
-  string(REGEX REPLACE "-" "" SFLAG1 ${FLAG})
-  string(REGEX REPLACE "\\+" "p" SFLAG ${SFLAG1})
-  check_cxx_compiler_flag(${FLAG} COMPILER_SUPPORT_${SFLAG})
-  if(COMPILER_SUPPORT_${SFLAG})
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${FLAG}")
-  endif()
-endmacro()
-
-function(ei_maybe_separate_arguments variable mode args)
-  # Use separate_arguments if the input is a single string containing a space.
-  # Otherwise, if it is already a list or doesn't have a space, just propagate
-  # the original value.  This is to better support multi-argument lists.
-  list(LENGTH args list_length)
-  if (${list_length} EQUAL 1)
-    string(FIND "${args}" " " has_space)
-    if (${has_space} GREATER -1)
-      separate_arguments(args ${mode} "${args}")
-    endif()
-  endif()
-  set(${variable} ${args} PARENT_SCOPE)
-endfunction(ei_maybe_separate_arguments)
-
-# Determine if we should build shared libraries on this platform.
-get_cmake_property(EIGEN_BUILD_SHARED_LIBS TARGET_SUPPORTS_SHARED_LIBS)
-
-#############################################################################
-# find how to link to the standard libraries                                #
-#############################################################################
-
-find_package(StandardMathLibrary)
-
-
-set(EIGEN_TEST_CUSTOM_LINKER_FLAGS  "" CACHE STRING "Additional linker flags when linking unit tests.")
-set(EIGEN_TEST_CUSTOM_CXX_FLAGS     "" CACHE STRING "Additional compiler flags when compiling unit tests.")
+set ( EIGEN_VERSION_STRING ${EIGEN_VERSION_NUMBER} )
+set ( EIGEN_VERSION_MAJOR  ${EIGEN_WORLD_VERSION} )
+set ( EIGEN_VERSION_MINOR  ${EIGEN_MAJOR_VERSION} )
+set ( EIGEN_VERSION_PATCH  ${EIGEN_MINOR_VERSION} )
 
-# Convert space-separated arguments into CMake lists for downstream consumption.
-ei_maybe_separate_arguments(EIGEN_TEST_CUSTOM_LINKER_FLAGS NATIVE_COMMAND "${EIGEN_TEST_CUSTOM_LINKER_FLAGS}")
-ei_maybe_separate_arguments(EIGEN_TEST_CUSTOM_CXX_FLAGS NATIVE_COMMAND "${EIGEN_TEST_CUSTOM_CXX_FLAGS}")
+# Imported target support
+add_library (eigen INTERFACE)
+add_library (Eigen3::Eigen ALIAS eigen)
+target_include_directories (eigen INTERFACE
+  $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}>
+  $<INSTALL_INTERFACE:${INCLUDE_INSTALL_DIR}>
+)
 
+# Export as title case Eigen
+set_target_properties (eigen PROPERTIES EXPORT_NAME Eigen)
 
-set(EIGEN_STANDARD_LIBRARIES_TO_LINK_TO "")
+# Alias Eigen_*_DIR to Eigen3_*_DIR:
+set(Eigen_SOURCE_DIR ${Eigen3_SOURCE_DIR})
+set(Eigen_BINARY_DIR ${Eigen3_BINARY_DIR})
 
-if(NOT STANDARD_MATH_LIBRARY_FOUND)
+#==============================================================================
+# Install Configuration.
+#==============================================================================
 
-  message(FATAL_ERROR
-    "Can't link to the standard math library. Please report to the Eigen developers, telling them about your platform.")
+# Unconditionally allow install of targets to support nested dependency
+# installations.
+#
+# Note: projects that depend on Eigen should _probably_ exclude installing
+# Eigen by default (e.g. by using EXCLUDE_FROM_ALL when using
+# FetchContent_Declare or add_subdirectory) to avoid overwriting a previous
+# installation.
 
-else()
-  if(EIGEN_STANDARD_LIBRARIES_TO_LINK_TO)
-    set(EIGEN_STANDARD_LIBRARIES_TO_LINK_TO "${EIGEN_STANDARD_LIBRARIES_TO_LINK_TO} ${STANDARD_MATH_LIBRARY}")
-  else()
-    set(EIGEN_STANDARD_LIBRARIES_TO_LINK_TO "${STANDARD_MATH_LIBRARY}")
-  endif()
+include(GNUInstallDirs)
+# Backward compatibility support for EIGEN_INCLUDE_INSTALL_DIR
+if(EIGEN_INCLUDE_INSTALL_DIR)
+  message(WARNING "EIGEN_INCLUDE_INSTALL_DIR is deprecated. Use INCLUDE_INSTALL_DIR instead.")
 endif()
 
-if(EIGEN_STANDARD_LIBRARIES_TO_LINK_TO)
-  message(STATUS "Standard libraries to link to explicitly: ${EIGEN_STANDARD_LIBRARIES_TO_LINK_TO}")
+if(EIGEN_INCLUDE_INSTALL_DIR AND NOT INCLUDE_INSTALL_DIR)
+  set(INCLUDE_INSTALL_DIR ${EIGEN_INCLUDE_INSTALL_DIR}
+      CACHE PATH "The directory relative to CMAKE_INSTALL_PREFIX where Eigen header files are installed")
 else()
-  message(STATUS "Standard libraries to link to explicitly: none")
-endif()
-
-option(EIGEN_BUILD_BTL "Build benchmark suite" OFF)
-option(EIGEN_BUILD_SPBENCH "Build sparse benchmark suite" OFF)
-
-# Disable pkgconfig only for native Windows builds
-if(NOT WIN32 OR NOT CMAKE_HOST_SYSTEM_NAME MATCHES Windows)
-  option(EIGEN_BUILD_PKGCONFIG "Build pkg-config .pc file for Eigen" ON)
+  set(INCLUDE_INSTALL_DIR
+      "${CMAKE_INSTALL_INCLUDEDIR}/eigen3"
+      CACHE PATH "The directory relative to CMAKE_INSTALL_PREFIX where Eigen header files are installed"
+      )
 endif()
+set(CMAKEPACKAGE_INSTALL_DIR
+    "${CMAKE_INSTALL_DATADIR}/eigen3/cmake"
+    CACHE PATH "The directory relative to CMAKE_INSTALL_PREFIX where Eigen3Config.cmake is installed"
+    )
+set(PKGCONFIG_INSTALL_DIR
+    "${CMAKE_INSTALL_DATADIR}/pkgconfig"
+    CACHE PATH "The directory relative to CMAKE_INSTALL_PREFIX where eigen3.pc is installed"
+    )
 
-set(CMAKE_INCLUDE_CURRENT_DIR OFF)
+foreach(var INCLUDE_INSTALL_DIR CMAKEPACKAGE_INSTALL_DIR PKGCONFIG_INSTALL_DIR)
+  # If an absolute path is specified, make it relative to "{CMAKE_INSTALL_PREFIX}".
+  if(IS_ABSOLUTE "${${var}}")
+    file(RELATIVE_PATH "${var}" "${CMAKE_INSTALL_PREFIX}" "${${var}}")
+  endif()
+endforeach()
 
-option(EIGEN_SPLIT_LARGE_TESTS "Split large tests into smaller executables" ON)
+install(FILES
+  signature_of_eigen3_matrix_library
+  DESTINATION ${INCLUDE_INSTALL_DIR} COMPONENT Devel
+  )
 
-option(EIGEN_DEFAULT_TO_ROW_MAJOR "Use row-major as default matrix storage order" OFF)
-if(EIGEN_DEFAULT_TO_ROW_MAJOR)
-  add_definitions("-DEIGEN_DEFAULT_TO_ROW_MAJOR")
+if(EIGEN_BUILD_PKGCONFIG)
+    configure_file(eigen3.pc.in eigen3.pc @ONLY)
+    install(FILES ${CMAKE_CURRENT_BINARY_DIR}/eigen3.pc
+        DESTINATION ${PKGCONFIG_INSTALL_DIR})
 endif()
 
-set(EIGEN_TEST_MAX_SIZE "320" CACHE STRING "Maximal matrix/vector size, default is 320")
+install(DIRECTORY Eigen DESTINATION ${INCLUDE_INSTALL_DIR} COMPONENT Devel)
 
-if(NOT MSVC)
-  # We assume that other compilers are partly compatible with GNUCC
+install(TARGETS eigen EXPORT Eigen3Targets)
 
-  # clang outputs some warnings for unknown flags that are not caught by check_cxx_compiler_flag
-  # adding -Werror turns such warnings into errors
-  check_cxx_compiler_flag("-Werror" COMPILER_SUPPORT_WERROR)
-  if(COMPILER_SUPPORT_WERROR)
-    set(CMAKE_REQUIRED_FLAGS "-Werror")
-  endif()
-  ei_add_cxx_compiler_flag("-pedantic")
-  ei_add_cxx_compiler_flag("-Wall")
-  ei_add_cxx_compiler_flag("-Wextra")
-  #ei_add_cxx_compiler_flag("-Weverything")              # clang
-
-  ei_add_cxx_compiler_flag("-Wundef")
-  ei_add_cxx_compiler_flag("-Wcast-align")
-  ei_add_cxx_compiler_flag("-Wchar-subscripts")
-  ei_add_cxx_compiler_flag("-Wnon-virtual-dtor")
-  ei_add_cxx_compiler_flag("-Wunused-local-typedefs")
-  ei_add_cxx_compiler_flag("-Wpointer-arith")
-  ei_add_cxx_compiler_flag("-Wwrite-strings")
-  ei_add_cxx_compiler_flag("-Wformat-security")
-  ei_add_cxx_compiler_flag("-Wshorten-64-to-32")
-  ei_add_cxx_compiler_flag("-Wlogical-op")
-  ei_add_cxx_compiler_flag("-Wenum-conversion")
-  ei_add_cxx_compiler_flag("-Wc++11-extensions")
-  ei_add_cxx_compiler_flag("-Wdouble-promotion")
-#  ei_add_cxx_compiler_flag("-Wconversion")
-
-  ei_add_cxx_compiler_flag("-Wshadow")
-
-  ei_add_cxx_compiler_flag("-Wno-psabi")
-  ei_add_cxx_compiler_flag("-Wno-variadic-macros")
-  ei_add_cxx_compiler_flag("-Wno-long-long")
-
-  ei_add_cxx_compiler_flag("-fno-check-new")
-  ei_add_cxx_compiler_flag("-fno-common")
-  ei_add_cxx_compiler_flag("-fstrict-aliasing")
-  ei_add_cxx_compiler_flag("-wd981")                    # disable ICC's "operands are evaluated in unspecified order" remark
-  ei_add_cxx_compiler_flag("-wd2304")                   # disable ICC's "warning #2304: non-explicit constructor with single argument may cause implicit type conversion" produced by -Wnon-virtual-dtor
-
-  if(ANDROID_NDK)
-    ei_add_cxx_compiler_flag("-pie")
-    ei_add_cxx_compiler_flag("-fPIE")
-  endif()
+if(EIGEN_BUILD_CMAKE_PACKAGE)
+  include (CMakePackageConfigHelpers)
+  configure_package_config_file (
+    ${CMAKE_CURRENT_SOURCE_DIR}/cmake/Eigen3Config.cmake.in
+    ${CMAKE_CURRENT_BINARY_DIR}/Eigen3Config.cmake
+    INSTALL_DESTINATION ${CMAKEPACKAGE_INSTALL_DIR}
+    NO_SET_AND_CHECK_MACRO # Eigen does not provide legacy style defines
+    NO_CHECK_REQUIRED_COMPONENTS_MACRO # Eigen does not provide components
+  )
 
-  set(CMAKE_REQUIRED_FLAGS "")
+  # NOTE Remove the first code path once the minimum required CMake version is
+  # bumped to 3.14 or above.
+  if (CMAKE_VERSION VERSION_LESS 3.14)
+    # Remove CMAKE_SIZEOF_VOID_P from Eigen3ConfigVersion.cmake since Eigen does
+    # not depend on architecture specific settings or libraries. More
+    # specifically, an Eigen3Config.cmake generated from a 64 bit target can be
+    # used for 32 bit targets as well (and vice versa).
+    set (_Eigen3_CMAKE_SIZEOF_VOID_P ${CMAKE_SIZEOF_VOID_P})
+    unset (CMAKE_SIZEOF_VOID_P)
+    write_basic_package_version_file (Eigen3ConfigVersion.cmake
+                                      VERSION ${EIGEN_VERSION_NUMBER}
+                                      COMPATIBILITY SameMajorVersion)
+    set (CMAKE_SIZEOF_VOID_P ${_Eigen3_CMAKE_SIZEOF_VOID_P})
+  else (CMAKE_VERSION VERSION_LESS 3.14)
+    write_basic_package_version_file (Eigen3ConfigVersion.cmake
+                                      VERSION ${EIGEN_VERSION_NUMBER}
+                                      COMPATIBILITY SameMajorVersion
+                                      ARCH_INDEPENDENT)
+  endif (CMAKE_VERSION VERSION_LESS 3.14)
+
+  # The Eigen target will be located in the Eigen3 namespace. Other CMake
+  # targets can refer to it using Eigen3::Eigen.
+  export (TARGETS eigen NAMESPACE Eigen3:: FILE Eigen3Targets.cmake)
+  # Export Eigen3 package to CMake registry such that it can be easily found by
+  # CMake even if it has not been installed to a standard directory.
+  export (PACKAGE Eigen3)
+
+  install (EXPORT Eigen3Targets NAMESPACE Eigen3:: DESTINATION ${CMAKEPACKAGE_INSTALL_DIR})
+
+  install (FILES ${CMAKE_CURRENT_BINARY_DIR}/Eigen3Config.cmake
+                ${CMAKE_CURRENT_BINARY_DIR}/Eigen3ConfigVersion.cmake
+          DESTINATION ${CMAKEPACKAGE_INSTALL_DIR})
+
+  # Add uninstall target
+  if(NOT TARGET uninstall)
+    add_custom_target ( uninstall
+        COMMAND ${CMAKE_COMMAND} -P ${CMAKE_CURRENT_SOURCE_DIR}/cmake/EigenUninstall.cmake)
+  endif()
+endif()
+
+#==============================================================================
+# General Build Configuration.
+#==============================================================================
+
+# Avoid setting the standard in a parent if unset.
+if(PROJECT_IS_TOP_LEVEL)
+  set(CMAKE_CXX_STANDARD 14 CACHE STRING "Default C++ standard")
+  set(CMAKE_CXX_STANDARD_REQUIRED ON CACHE BOOL "Require C++ standard")
+  set(CMAKE_CXX_EXTENSIONS OFF CACHE BOOL "Allow C++ extensions")
+endif()
 
-  option(EIGEN_TEST_SSE2 "Enable/Disable SSE2 in tests/examples" OFF)
-  if(EIGEN_TEST_SSE2)
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -msse2")
-    message(STATUS "Enabling SSE2 in tests/examples")
-  endif()
+# Guard against in-source builds
+if(${CMAKE_SOURCE_DIR} STREQUAL ${CMAKE_BINARY_DIR})
+  message(FATAL_ERROR "In-source builds not allowed. Please make a new directory (called a build directory) and run CMake from there. You may need to remove CMakeCache.txt. ")
+endif()
 
-  option(EIGEN_TEST_SSE3 "Enable/Disable SSE3 in tests/examples" OFF)
-  if(EIGEN_TEST_SSE3)
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -msse3")
-    message(STATUS "Enabling SSE3 in tests/examples")
-  endif()
+# Guard against bad build-type strings
+if (PROJECT_IS_TOP_LEVEL AND NOT CMAKE_BUILD_TYPE)
+  set(CMAKE_BUILD_TYPE "Release")
+endif()
 
-  option(EIGEN_TEST_SSSE3 "Enable/Disable SSSE3 in tests/examples" OFF)
-  if(EIGEN_TEST_SSSE3)
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -mssse3")
-    message(STATUS "Enabling SSSE3 in tests/examples")
-  endif()
+# Only try to figure out how to link the math library if we are building something.
+# Otherwise, let the parent project deal with dependencies.
+if (EIGEN_IS_BUILDING_)
+  # Use Eigen's cmake files.
+  set(CMAKE_MODULE_PATH ${PROJECT_SOURCE_DIR}/cmake)
 
-  option(EIGEN_TEST_SSE4_1 "Enable/Disable SSE4.1 in tests/examples" OFF)
-  if(EIGEN_TEST_SSE4_1)
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -msse4.1")
-    message(STATUS "Enabling SSE4.1 in tests/examples")
-  endif()
+  set(CMAKE_INCLUDE_CURRENT_DIR OFF)
 
-  option(EIGEN_TEST_SSE4_2 "Enable/Disable SSE4.2 in tests/examples" OFF)
-  if(EIGEN_TEST_SSE4_2)
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -msse4.2")
-    message(STATUS "Enabling SSE4.2 in tests/examples")
+  find_package(StandardMathLibrary)
+  set(EIGEN_STANDARD_LIBRARIES_TO_LINK_TO "")
+  if(NOT STANDARD_MATH_LIBRARY_FOUND)
+    message(FATAL_ERROR
+      "Can't link to the standard math library. Please report to the Eigen developers, telling them about your platform.")
+  else()
+    if(EIGEN_STANDARD_LIBRARIES_TO_LINK_TO)
+      set(EIGEN_STANDARD_LIBRARIES_TO_LINK_TO "${EIGEN_STANDARD_LIBRARIES_TO_LINK_TO} ${STANDARD_MATH_LIBRARY}")
+    else()
+      set(EIGEN_STANDARD_LIBRARIES_TO_LINK_TO "${STANDARD_MATH_LIBRARY}")
+    endif()
   endif()
-
-  option(EIGEN_TEST_AVX "Enable/Disable AVX in tests/examples" OFF)
-  if(EIGEN_TEST_AVX)
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -mavx")
-    message(STATUS "Enabling AVX in tests/examples")
+  if(EIGEN_STANDARD_LIBRARIES_TO_LINK_TO)
+    message(STATUS "Standard libraries to link to explicitly: ${EIGEN_STANDARD_LIBRARIES_TO_LINK_TO}")
+  else()
+    message(STATUS "Standard libraries to link to explicitly: none")
   endif()
 
-  option(EIGEN_TEST_FMA "Enable/Disable FMA in tests/examples" OFF)
-  if(EIGEN_TEST_FMA AND NOT EIGEN_TEST_NEON)
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -mfma")
-    message(STATUS "Enabling FMA in tests/examples")
+  # Default tests/examples/libraries to row-major.
+  option(EIGEN_DEFAULT_TO_ROW_MAJOR "Use row-major as default matrix storage order" OFF)
+  if(EIGEN_DEFAULT_TO_ROW_MAJOR)
+    add_definitions("-DEIGEN_DEFAULT_TO_ROW_MAJOR")
   endif()
+endif()
 
-  option(EIGEN_TEST_AVX2 "Enable/Disable AVX2 in tests/examples" OFF)
-  if(EIGEN_TEST_AVX2)
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -mavx2 -mfma")
-    message(STATUS "Enabling AVX2 in tests/examples")
-  endif()
+#==============================================================================
+# Test Configuration.
+#==============================================================================
 
-  option(EIGEN_TEST_AVX512 "Enable/Disable AVX512 in tests/examples" OFF)
-  if(EIGEN_TEST_AVX512)
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -mavx512f -mfma")
-    message(STATUS "Enabling AVX512 in tests/examples")
-  endif()
+if (EIGEN_BUILD_TESTING)
+  function(ei_maybe_separate_arguments variable mode args)
+    # Use separate_arguments if the input is a single string containing a space.
+    # Otherwise, if it is already a list or doesn't have a space, just propagate
+    # the original value.  This is to better support multi-argument lists.
+    list(LENGTH args list_length)
+    if (${list_length} EQUAL 1)
+      string(FIND "${args}" " " has_space)
+      if (${has_space} GREATER -1)
+        separate_arguments(args ${mode} "${args}")
+      endif()
+    endif()
+    set(${variable} ${args} PARENT_SCOPE)
+  endfunction(ei_maybe_separate_arguments)
+
+  include(CheckCXXCompilerFlag)
+  macro(ei_add_cxx_compiler_flag FLAG)
+    string(REGEX REPLACE "-" "" SFLAG1 ${FLAG})
+    string(REGEX REPLACE "\\+" "p" SFLAG ${SFLAG1})
+    check_cxx_compiler_flag(${FLAG} COMPILER_SUPPORT_${SFLAG})
+    if(COMPILER_SUPPORT_${SFLAG})
+      set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${FLAG}")
+    endif()
+  endmacro()
+
+  set(EIGEN_TEST_CUSTOM_LINKER_FLAGS  "" CACHE STRING "Additional linker flags when linking unit tests.")
+  set(EIGEN_TEST_CUSTOM_CXX_FLAGS     "" CACHE STRING "Additional compiler flags when compiling unit tests.")
+  # Convert space-separated arguments into CMake lists for downstream consumption.
+  ei_maybe_separate_arguments(EIGEN_TEST_CUSTOM_LINKER_FLAGS NATIVE_COMMAND "${EIGEN_TEST_CUSTOM_LINKER_FLAGS}")
+  ei_maybe_separate_arguments(EIGEN_TEST_CUSTOM_CXX_FLAGS NATIVE_COMMAND "${EIGEN_TEST_CUSTOM_CXX_FLAGS}")
+
+  option(EIGEN_SPLIT_LARGE_TESTS "Split large tests into smaller executables" ON)
+  set(EIGEN_TEST_MAX_SIZE "320" CACHE STRING "Maximal matrix/vector size, default is 320")
+
+  # Flags for tests.
+  if(NOT MSVC)
+    # We assume that other compilers are partly compatible with GNUCC
+
+    # clang outputs some warnings for unknown flags that are not caught by check_cxx_compiler_flag
+    # adding -Werror turns such warnings into errors
+    check_cxx_compiler_flag("-Werror" COMPILER_SUPPORT_WERROR)
+    if(COMPILER_SUPPORT_WERROR)
+      set(CMAKE_REQUIRED_FLAGS "-Werror")
+    endif()
+    ei_add_cxx_compiler_flag("-pedantic")
+    ei_add_cxx_compiler_flag("-Wall")
+    ei_add_cxx_compiler_flag("-Wextra")
+    # ei_add_cxx_compiler_flag("-Weverything") # clang
+    ei_add_cxx_compiler_flag("-Wundef")
+    ei_add_cxx_compiler_flag("-Wcast-align")
+    ei_add_cxx_compiler_flag("-Wchar-subscripts")
+    ei_add_cxx_compiler_flag("-Wnon-virtual-dtor")
+    ei_add_cxx_compiler_flag("-Wunused-local-typedefs")
+    ei_add_cxx_compiler_flag("-Wpointer-arith")
+    ei_add_cxx_compiler_flag("-Wwrite-strings")
+    ei_add_cxx_compiler_flag("-Wformat-security")
+    ei_add_cxx_compiler_flag("-Wshorten-64-to-32")
+    ei_add_cxx_compiler_flag("-Wlogical-op")
+    ei_add_cxx_compiler_flag("-Wenum-conversion")
+    ei_add_cxx_compiler_flag("-Wc++11-extensions")
+    ei_add_cxx_compiler_flag("-Wdouble-promotion")
+    # ei_add_cxx_compiler_flag("-Wconversion")
+    ei_add_cxx_compiler_flag("-Wshadow")
+    ei_add_cxx_compiler_flag("-Wno-psabi")
+    ei_add_cxx_compiler_flag("-Wno-variadic-macros")
+    ei_add_cxx_compiler_flag("-Wno-long-long")
+    ei_add_cxx_compiler_flag("-fno-check-new")
+    ei_add_cxx_compiler_flag("-fno-common")
+    ei_add_cxx_compiler_flag("-fstrict-aliasing")
+    ei_add_cxx_compiler_flag("-wd981")                    # disable ICC's "operands are evaluated in unspecified order" remark
+    ei_add_cxx_compiler_flag("-wd2304")                   # disable ICC's "warning #2304: non-explicit constructor with single argument may cause implicit type conversion" produced by -Wnon-virtual-dtor
+
+    if(ANDROID_NDK)
+      ei_add_cxx_compiler_flag("-pie")
+      ei_add_cxx_compiler_flag("-fPIE")
+    endif()
 
-  option(EIGEN_TEST_AVX512DQ "Enable/Disable AVX512DQ in tests/examples" OFF)
-  if(EIGEN_TEST_AVX512DQ)
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -mavx512dq -mfma")
-    message(STATUS "Enabling AVX512DQ in tests/examples")
-  endif()
+    set(CMAKE_REQUIRED_FLAGS "")
 
-  option(EIGEN_TEST_AVX512FP16 "Enable/Disable AVX512-FP16 in tests/examples" OFF)
-  if(EIGEN_TEST_AVX512FP16)
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -mavx512f -mfma -mavx512vl -mavx512fp16")
-	message(STATUS "Enabling AVX512-FP16 in tests/examples")
-  endif()
+    option(EIGEN_TEST_SSE2 "Enable/Disable SSE2 in tests/examples" OFF)
+    if(EIGEN_TEST_SSE2)
+      set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -msse2")
+      message(STATUS "Enabling SSE2 in tests/examples")
+    endif()
 
-  option(EIGEN_TEST_F16C "Enable/Disable F16C in tests/examples" OFF)
-  if(EIGEN_TEST_F16C)
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -mf16c")
-    message(STATUS "Enabling F16C in tests/examples")
-  endif()
+    option(EIGEN_TEST_SSE3 "Enable/Disable SSE3 in tests/examples" OFF)
+    if(EIGEN_TEST_SSE3)
+      set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -msse3")
+      message(STATUS "Enabling SSE3 in tests/examples")
+    endif()
 
-  option(EIGEN_TEST_ALTIVEC "Enable/Disable AltiVec in tests/examples" OFF)
-  if(EIGEN_TEST_ALTIVEC)
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -maltivec -mabi=altivec")
-    message(STATUS "Enabling AltiVec in tests/examples")
-  endif()
+    option(EIGEN_TEST_SSSE3 "Enable/Disable SSSE3 in tests/examples" OFF)
+    if(EIGEN_TEST_SSSE3)
+      set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -mssse3")
+      message(STATUS "Enabling SSSE3 in tests/examples")
+    endif()
 
-  option(EIGEN_TEST_VSX "Enable/Disable VSX in tests/examples" OFF)
-  if(EIGEN_TEST_VSX)
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -m64 -mvsx")
-    message(STATUS "Enabling VSX in tests/examples")
-  endif()
+    option(EIGEN_TEST_SSE4_1 "Enable/Disable SSE4.1 in tests/examples" OFF)
+    if(EIGEN_TEST_SSE4_1)
+      set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -msse4.1")
+      message(STATUS "Enabling SSE4.1 in tests/examples")
+    endif()
 
-  option(EIGEN_TEST_MSA "Enable/Disable MSA in tests/examples" OFF)
-  if(EIGEN_TEST_MSA)
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -mmsa")
-    message(STATUS "Enabling MSA in tests/examples")
-  endif()
+    option(EIGEN_TEST_SSE4_2 "Enable/Disable SSE4.2 in tests/examples" OFF)
+    if(EIGEN_TEST_SSE4_2)
+      set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -msse4.2")
+      message(STATUS "Enabling SSE4.2 in tests/examples")
+    endif()
 
-  option(EIGEN_TEST_NEON "Enable/Disable Neon in tests/examples" OFF)
-  if(EIGEN_TEST_NEON)
-    if(EIGEN_TEST_FMA)
-      set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -mfpu=neon-vfpv4")
-    else()
-      set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -mfpu=neon")
+    option(EIGEN_TEST_AVX "Enable/Disable AVX in tests/examples" OFF)
+    if(EIGEN_TEST_AVX)
+      set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -mavx")
+      message(STATUS "Enabling AVX in tests/examples")
     endif()
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -mfloat-abi=hard")
-    message(STATUS "Enabling NEON in tests/examples")
-  endif()
 
-  option(EIGEN_TEST_NEON64 "Enable/Disable Neon in tests/examples" OFF)
-  if(EIGEN_TEST_NEON64)
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
-    message(STATUS "Enabling NEON in tests/examples")
-  endif()
+    option(EIGEN_TEST_FMA "Enable/Disable FMA in tests/examples" OFF)
+    if(EIGEN_TEST_FMA AND NOT EIGEN_TEST_NEON)
+      set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -mfma")
+      message(STATUS "Enabling FMA in tests/examples")
+    endif()
 
-  option(EIGEN_TEST_Z13 "Enable/Disable S390X(zEC13) ZVECTOR in tests/examples" OFF)
-  if(EIGEN_TEST_Z13)
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -march=z13 -mzvector")
-    message(STATUS "Enabling S390X(zEC13) ZVECTOR in tests/examples")
-  endif()
+    option(EIGEN_TEST_AVX2 "Enable/Disable AVX2 in tests/examples" OFF)
+    if(EIGEN_TEST_AVX2)
+      set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -mavx2 -mfma")
+      message(STATUS "Enabling AVX2 in tests/examples")
+    endif()
 
-  option(EIGEN_TEST_Z14 "Enable/Disable S390X(zEC14) ZVECTOR in tests/examples" OFF)
-  if(EIGEN_TEST_Z14)
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -march=z14 -mzvector")
-    message(STATUS "Enabling S390X(zEC13) ZVECTOR in tests/examples")
-  endif()
+    option(EIGEN_TEST_AVX512 "Enable/Disable AVX512 in tests/examples" OFF)
+    if(EIGEN_TEST_AVX512)
+      set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -mavx512f -mfma")
+      message(STATUS "Enabling AVX512 in tests/examples")
+    endif()
 
-  check_cxx_compiler_flag("-fopenmp" COMPILER_SUPPORT_OPENMP)
-  if(COMPILER_SUPPORT_OPENMP)
-    option(EIGEN_TEST_OPENMP "Enable/Disable OpenMP in tests/examples" OFF)
-    if(EIGEN_TEST_OPENMP)
-      set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fopenmp")
-      message(STATUS "Enabling OpenMP in tests/examples")
+    option(EIGEN_TEST_AVX512DQ "Enable/Disable AVX512DQ in tests/examples" OFF)
+    if(EIGEN_TEST_AVX512DQ)
+      set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -mavx512dq -mfma")
+      message(STATUS "Enabling AVX512DQ in tests/examples")
     endif()
-  endif()
 
-else()
+    option(EIGEN_TEST_AVX512FP16 "Enable/Disable AVX512-FP16 in tests/examples" OFF)
+    if(EIGEN_TEST_AVX512FP16)
+      set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -mavx512f -mfma -mavx512vl -mavx512fp16")
+    message(STATUS "Enabling AVX512-FP16 in tests/examples")
+    endif()
 
-  # C4127 - conditional expression is constant
-  # C4714 - marked as __forceinline not inlined (I failed to deactivate it selectively)
-  #         We can disable this warning in the unit tests since it is clear that it occurs
-  #         because we are oftentimes returning objects that have a destructor or may
-  #         throw exceptions - in particular in the unit tests we are throwing extra many
-  #         exceptions to cover indexing errors.
-  # C4505 - unreferenced local function has been removed (impossible to deactivate selectively)
-  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /EHsc /wd4127 /wd4505 /wd4714")
-
-  # replace all /Wx by /W4
-  string(REGEX REPLACE "/W[0-9]" "/W4" CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
-
-  check_cxx_compiler_flag("/openmp" COMPILER_SUPPORT_OPENMP)
-  if(COMPILER_SUPPORT_OPENMP)
-    option(EIGEN_TEST_OPENMP "Enable/Disable OpenMP in tests/examples" OFF)
-    if(EIGEN_TEST_OPENMP)
-      set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /openmp")
-      message(STATUS "Enabling OpenMP in tests/examples")
+    option(EIGEN_TEST_F16C "Enable/Disable F16C in tests/examples" OFF)
+    if(EIGEN_TEST_F16C)
+      set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -mf16c")
+      message(STATUS "Enabling F16C in tests/examples")
     endif()
-  endif()
 
-  option(EIGEN_TEST_SSE2 "Enable/Disable SSE2 in tests/examples" OFF)
-  if(EIGEN_TEST_SSE2)
-    if(NOT CMAKE_CL_64)
-      # arch is not supported on 64 bit systems, SSE is enabled automatically.
-      set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /arch:SSE2")
+    option(EIGEN_TEST_ALTIVEC "Enable/Disable AltiVec in tests/examples" OFF)
+    if(EIGEN_TEST_ALTIVEC)
+      set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -maltivec -mabi=altivec")
+      message(STATUS "Enabling AltiVec in tests/examples")
     endif()
-    message(STATUS "Enabling SSE2 in tests/examples")
-  endif()
 
-  option(EIGEN_TEST_AVX "Enable/Disable AVX in tests/examples" OFF)
-  if(EIGEN_TEST_AVX)
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /arch:AVX")
-    message(STATUS "Enabling AVX in tests/examples")
-  endif()
+    option(EIGEN_TEST_VSX "Enable/Disable VSX in tests/examples" OFF)
+    if(EIGEN_TEST_VSX)
+      set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -m64 -mvsx")
+      message(STATUS "Enabling VSX in tests/examples")
+    endif()
 
-  option(EIGEN_TEST_FMA "Enable/Disable FMA/AVX2 in tests/examples" OFF)
-  option(EIGEN_TEST_AVX2 "Enable/Disable FMA/AVX2 in tests/examples" OFF)
-  if((EIGEN_TEST_FMA AND NOT EIGEN_TEST_NEON) OR EIGEN_TEST_AVX2)
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /arch:AVX2")
-    message(STATUS "Enabling FMA/AVX2 in tests/examples")
-  endif()
+    option(EIGEN_TEST_MSA "Enable/Disable MSA in tests/examples" OFF)
+    if(EIGEN_TEST_MSA)
+      set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -mmsa")
+      message(STATUS "Enabling MSA in tests/examples")
+    endif()
 
-  option(EIGEN_TEST_AVX512 "Enable/Disable AVX512 in tests/examples" OFF)
-  option(EIGEN_TEST_AVX512DQ "Enable/Disable AVX512DQ in tests/examples" OFF)
-  if(EIGEN_TEST_AVX512 OR EIGEN_TEST_AVX512DQ)
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /arch:AVX512")
-    message(STATUS "Enabling AVX512 in tests/examples")
-  endif()
+    option(EIGEN_TEST_NEON "Enable/Disable Neon in tests/examples" OFF)
+    if(EIGEN_TEST_NEON)
+      if(EIGEN_TEST_FMA)
+        set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -mfpu=neon-vfpv4")
+      else()
+        set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -mfpu=neon")
+      endif()
+      set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -mfloat-abi=hard")
+      message(STATUS "Enabling NEON in tests/examples")
+    endif()
 
-endif()
+    option(EIGEN_TEST_NEON64 "Enable/Disable Neon in tests/examples" OFF)
+    if(EIGEN_TEST_NEON64)
+      set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
+      message(STATUS "Enabling NEON in tests/examples")
+    endif()
 
-option(EIGEN_TEST_NO_EXPLICIT_VECTORIZATION "Disable explicit vectorization in tests/examples" OFF)
-option(EIGEN_TEST_X87 "Force using X87 instructions. Implies no vectorization." OFF)
-option(EIGEN_TEST_32BIT "Force generating 32bit code." OFF)
+    option(EIGEN_TEST_Z13 "Enable/Disable S390X(zEC13) ZVECTOR in tests/examples" OFF)
+    if(EIGEN_TEST_Z13)
+      set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -march=z13 -mzvector")
+      message(STATUS "Enabling S390X(zEC13) ZVECTOR in tests/examples")
+    endif()
 
-if(EIGEN_TEST_X87)
-  set(EIGEN_TEST_NO_EXPLICIT_VECTORIZATION ON)
-  if(CMAKE_COMPILER_IS_GNUCXX)
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -mfpmath=387")
-    message(STATUS "Forcing use of x87 instructions in tests/examples")
-  else()
-    message(STATUS "EIGEN_TEST_X87 ignored on your compiler")
-  endif()
-endif()
+    option(EIGEN_TEST_Z14 "Enable/Disable S390X(zEC14) ZVECTOR in tests/examples" OFF)
+    if(EIGEN_TEST_Z14)
+      set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -march=z14 -mzvector")
+      message(STATUS "Enabling S390X(zEC13) ZVECTOR in tests/examples")
+    endif()
 
-if(EIGEN_TEST_32BIT)
-  if(CMAKE_COMPILER_IS_GNUCXX)
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -m32")
-    message(STATUS "Forcing generation of 32-bit code in tests/examples")
-  else()
-    message(STATUS "EIGEN_TEST_32BIT ignored on your compiler")
-  endif()
-endif()
+    check_cxx_compiler_flag("-fopenmp" COMPILER_SUPPORT_OPENMP)
+    if(COMPILER_SUPPORT_OPENMP)
+      option(EIGEN_TEST_OPENMP "Enable/Disable OpenMP in tests/examples" OFF)
+      if(EIGEN_TEST_OPENMP)
+        set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fopenmp")
+        message(STATUS "Enabling OpenMP in tests/examples")
+      endif()
+    endif()
 
-if(EIGEN_TEST_NO_EXPLICIT_VECTORIZATION)
-  add_definitions(-DEIGEN_DONT_VECTORIZE=1)
-  message(STATUS "Disabling vectorization in tests/examples")
-endif()
+  else()
+    # C4127 - conditional expression is constant
+    # C4714 - marked as __forceinline not inlined (I failed to deactivate it selectively)
+    #         We can disable this warning in the unit tests since it is clear that it occurs
+    #         because we are oftentimes returning objects that have a destructor or may
+    #         throw exceptions - in particular in the unit tests we are throwing extra many
+    #         exceptions to cover indexing errors.
+    # C4505 - unreferenced local function has been removed (impossible to deactivate selectively)
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /EHsc /wd4127 /wd4505 /wd4714")
+
+    # replace all /Wx by /W4
+    string(REGEX REPLACE "/W[0-9]" "/W4" CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
+
+    check_cxx_compiler_flag("/openmp" COMPILER_SUPPORT_OPENMP)
+    if(COMPILER_SUPPORT_OPENMP)
+      option(EIGEN_TEST_OPENMP "Enable/Disable OpenMP in tests/examples" OFF)
+      if(EIGEN_TEST_OPENMP)
+        set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /openmp")
+        message(STATUS "Enabling OpenMP in tests/examples")
+      endif()
+    endif()
 
-option(EIGEN_TEST_NO_EXPLICIT_ALIGNMENT "Disable explicit alignment (hence vectorization) in tests/examples" OFF)
-if(EIGEN_TEST_NO_EXPLICIT_ALIGNMENT)
-  add_definitions(-DEIGEN_DONT_ALIGN=1)
-  message(STATUS "Disabling alignment in tests/examples")
-endif()
+    option(EIGEN_TEST_SSE2 "Enable/Disable SSE2 in tests/examples" OFF)
+    if(EIGEN_TEST_SSE2)
+      if(NOT CMAKE_CL_64)
+        # arch is not supported on 64 bit systems, SSE is enabled automatically.
+        set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /arch:SSE2")
+      endif()
+      message(STATUS "Enabling SSE2 in tests/examples")
+    endif()
 
-option(EIGEN_TEST_NO_EXCEPTIONS "Disables C++ exceptions" OFF)
-if(EIGEN_TEST_NO_EXCEPTIONS)
-  ei_add_cxx_compiler_flag("-fno-exceptions")
-  message(STATUS "Disabling exceptions in tests/examples")
-endif()
+    option(EIGEN_TEST_AVX "Enable/Disable AVX in tests/examples" OFF)
+    if(EIGEN_TEST_AVX)
+      set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /arch:AVX")
+      message(STATUS "Enabling AVX in tests/examples")
+    endif()
 
-set(EIGEN_CUDA_CXX_FLAGS "" CACHE STRING "Additional flags to pass to the cuda compiler.")
-set(EIGEN_CUDA_COMPUTE_ARCH 30 CACHE STRING "The CUDA compute architecture(s) to target when compiling CUDA code")
+    option(EIGEN_TEST_FMA "Enable/Disable FMA/AVX2 in tests/examples" OFF)
+    option(EIGEN_TEST_AVX2 "Enable/Disable FMA/AVX2 in tests/examples" OFF)
+    if((EIGEN_TEST_FMA AND NOT EIGEN_TEST_NEON) OR EIGEN_TEST_AVX2)
+      set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /arch:AVX2")
+      message(STATUS "Enabling FMA/AVX2 in tests/examples")
+    endif()
 
-include_directories(${CMAKE_CURRENT_SOURCE_DIR})
+    option(EIGEN_TEST_AVX512 "Enable/Disable AVX512 in tests/examples" OFF)
+    option(EIGEN_TEST_AVX512DQ "Enable/Disable AVX512DQ in tests/examples" OFF)
+    if(EIGEN_TEST_AVX512 OR EIGEN_TEST_AVX512DQ)
+      set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /arch:AVX512")
+      message(STATUS "Enabling AVX512 in tests/examples")
+    endif()
 
-# Backward compatibility support for EIGEN_INCLUDE_INSTALL_DIR
-if(EIGEN_INCLUDE_INSTALL_DIR)
-  message(WARNING "EIGEN_INCLUDE_INSTALL_DIR is deprecated. Use INCLUDE_INSTALL_DIR instead.")
-endif()
+  endif(NOT MSVC)
 
-if(EIGEN_INCLUDE_INSTALL_DIR AND NOT INCLUDE_INSTALL_DIR)
-  set(INCLUDE_INSTALL_DIR ${EIGEN_INCLUDE_INSTALL_DIR}
-      CACHE PATH "The directory relative to CMAKE_INSTALL_PREFIX where Eigen header files are installed")
-else()
-  set(INCLUDE_INSTALL_DIR
-      "${CMAKE_INSTALL_INCLUDEDIR}/eigen3"
-      CACHE PATH "The directory relative to CMAKE_INSTALL_PREFIX where Eigen header files are installed"
-      )
-endif()
-set(CMAKEPACKAGE_INSTALL_DIR
-    "${CMAKE_INSTALL_DATADIR}/eigen3/cmake"
-    CACHE PATH "The directory relative to CMAKE_INSTALL_PREFIX where Eigen3Config.cmake is installed"
-    )
-set(PKGCONFIG_INSTALL_DIR
-    "${CMAKE_INSTALL_DATADIR}/pkgconfig"
-    CACHE PATH "The directory relative to CMAKE_INSTALL_PREFIX where eigen3.pc is installed"
-    )
+  option(EIGEN_TEST_NO_EXPLICIT_VECTORIZATION "Disable explicit vectorization in tests/examples" OFF)
+  option(EIGEN_TEST_X87 "Force using X87 instructions. Implies no vectorization." OFF)
+  option(EIGEN_TEST_32BIT "Force generating 32bit code." OFF)
 
-foreach(var INCLUDE_INSTALL_DIR CMAKEPACKAGE_INSTALL_DIR PKGCONFIG_INSTALL_DIR)
-  # If an absolute path is specified, make it relative to "{CMAKE_INSTALL_PREFIX}".
-  if(IS_ABSOLUTE "${${var}}")
-    file(RELATIVE_PATH "${var}" "${CMAKE_INSTALL_PREFIX}" "${${var}}")
+  if(EIGEN_TEST_X87)
+    set(EIGEN_TEST_NO_EXPLICIT_VECTORIZATION ON)
+    if(CMAKE_COMPILER_IS_GNUCXX)
+      set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -mfpmath=387")
+      message(STATUS "Forcing use of x87 instructions in tests/examples")
+    else()
+      message(STATUS "EIGEN_TEST_X87 ignored on your compiler")
+    endif()
   endif()
-endforeach()
-
-install(FILES
-  signature_of_eigen3_matrix_library
-  DESTINATION ${INCLUDE_INSTALL_DIR} COMPONENT Devel
-  )
-
-if(EIGEN_BUILD_PKGCONFIG)
-    configure_file(eigen3.pc.in eigen3.pc @ONLY)
-    install(FILES ${CMAKE_CURRENT_BINARY_DIR}/eigen3.pc
-        DESTINATION ${PKGCONFIG_INSTALL_DIR}
-        )
-endif()
 
-install(DIRECTORY Eigen DESTINATION ${INCLUDE_INSTALL_DIR} COMPONENT Devel)
-
-
-# Avoid building docs if included from another project.
-# Building documentation requires creating and running executables on the host
-# platform.  We shouldn't do this if cross-compiling.
-if (${PROJECT_IS_TOP_LEVEL} AND NOT ${CMAKE_CROSSCOMPILING})
-  set(EIGEN_BUILD_DOC_DEFAULT ON)
-else()
-  set(EIGEN_BUILD_DOC_DEFAULT OFF)
-endif()
-option(EIGEN_BUILD_DOC "Enable creation of Eigen documentation" ${EIGEN_BUILD_DOC_DEFAULT})
-if(EIGEN_BUILD_DOC)
-  add_subdirectory(doc EXCLUDE_FROM_ALL)
-endif()
+  if(EIGEN_TEST_32BIT)
+    if(CMAKE_COMPILER_IS_GNUCXX)
+      set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -m32")
+      message(STATUS "Forcing generation of 32-bit code in tests/examples")
+    else()
+      message(STATUS "EIGEN_TEST_32BIT ignored on your compiler")
+    endif()
+  endif()
 
-# add SYCL
-option(EIGEN_TEST_SYCL "Add Sycl support." OFF)
-if(EIGEN_TEST_SYCL)
-  option(EIGEN_SYCL_DPCPP "Use the DPCPP Sycl implementation (DPCPP is default SYCL-Compiler)." ON)
-  option(EIGEN_SYCL_TRISYCL "Use the triSYCL Sycl implementation." OFF)
-  option(EIGEN_SYCL_ComputeCpp "Use the ComputeCPP Sycl implementation." OFF)
-
-  # Building options
-  # https://developer.codeplay.com/products/computecpp/ce/2.11.0/guides/eigen-overview/options-for-building-eigen-sycl
-  option(EIGEN_SYCL_USE_DEFAULT_SELECTOR "Use sycl default selector to select the preferred device." OFF)
-  option(EIGEN_SYCL_NO_LOCAL_MEM "Build for devices without dedicated shared memory." OFF)
-  option(EIGEN_SYCL_LOCAL_MEM "Allow the use of local memory (enabled by default)." ON)
-  option(EIGEN_SYCL_LOCAL_THREAD_DIM0 "Set work group size for dimension 0." 16)
-  option(EIGEN_SYCL_LOCAL_THREAD_DIM1 "Set work group size for dimension 1." 16)
-  option(EIGEN_SYCL_ASYNC_EXECUTION "Allow asynchronous execution (enabled by default)." ON)
-  option(EIGEN_SYCL_DISABLE_SKINNY "Disable optimization for tall/skinny matrices." OFF)
-  option(EIGEN_SYCL_DISABLE_DOUBLE_BUFFER "Disable double buffer." OFF)
-  option(EIGEN_SYCL_DISABLE_SCALAR "Disable scalar contraction." OFF)
-  option(EIGEN_SYCL_DISABLE_GEMV "Disable GEMV and create a single kernel to calculate contraction instead." OFF)
-
-  set(EIGEN_SYCL ON)
-  set(CMAKE_CXX_STANDARD 17)
-  set(CMAKE_CXX_FLAGS  "${CMAKE_CXX_FLAGS} -Wno-deprecated-declarations -Wno-shorten-64-to-32 -Wno-cast-align")
-  set(CMAKE_CXX_FLAGS  "${CMAKE_CXX_FLAGS} -Wno-deprecated-copy-with-user-provided-copy -Wno-unused-variable")
-  set (CMAKE_MODULE_PATH "${CMAKE_ROOT}/Modules" "cmake/Modules/" "${CMAKE_MODULE_PATH}")
-  find_package(Threads REQUIRED)
-  if(EIGEN_SYCL_TRISYCL)
-    message(STATUS "Using triSYCL")
-    include(FindTriSYCL)
-  elseif(EIGEN_SYCL_ComputeCpp)
-    message(STATUS "Using ComputeCPP SYCL")
-    include(FindComputeCpp)
-    set(COMPUTECPP_DRIVER_DEFAULT_VALUE OFF)
-    if (NOT MSVC)
-      set(COMPUTECPP_DRIVER_DEFAULT_VALUE ON)
-    endif()
-    option(COMPUTECPP_USE_COMPILER_DRIVER
-            "Use ComputeCpp driver instead of a 2 steps compilation"
-            ${COMPUTECPP_DRIVER_DEFAULT_VALUE}
-            )
-  else() #Default SYCL compiler is DPCPP (EIGEN_SYCL_DPCPP)
-    set(DPCPP_SYCL_TARGET "spir64" CACHE STRING "Default target for Intel CPU/GPU")
-    message(STATUS "Using DPCPP")
-    find_package(DPCPP)
-    add_definitions(-DSYCL_COMPILER_IS_DPCPP)
-  endif(EIGEN_SYCL_TRISYCL)
-  if(EIGEN_DONT_VECTORIZE_SYCL)
-    message(STATUS "Disabling SYCL vectorization in tests/examples")
-    # When disabling SYCL vectorization, also disable Eigen default vectorization
+  if(EIGEN_TEST_NO_EXPLICIT_VECTORIZATION)
     add_definitions(-DEIGEN_DONT_VECTORIZE=1)
-    add_definitions(-DEIGEN_DONT_VECTORIZE_SYCL=1)
+    message(STATUS "Disabling vectorization in tests/examples")
+  endif()
+
+  option(EIGEN_TEST_NO_EXPLICIT_ALIGNMENT "Disable explicit alignment (hence vectorization) in tests/examples" OFF)
+  if(EIGEN_TEST_NO_EXPLICIT_ALIGNMENT)
+    add_definitions(-DEIGEN_DONT_ALIGN=1)
+    message(STATUS "Disabling alignment in tests/examples")
+  endif()
+
+  option(EIGEN_TEST_NO_EXCEPTIONS "Disables C++ exceptions" OFF)
+  if(EIGEN_TEST_NO_EXCEPTIONS)
+    ei_add_cxx_compiler_flag("-fno-exceptions")
+    message(STATUS "Disabling exceptions in tests/examples")
+  endif()
+
+  set(EIGEN_CUDA_CXX_FLAGS "" CACHE STRING "Additional flags to pass to the cuda compiler.")
+  set(EIGEN_CUDA_COMPUTE_ARCH 30 CACHE STRING "The CUDA compute architecture(s) to target when compiling CUDA code")
+
+  option(EIGEN_TEST_SYCL "Add Sycl support." OFF)
+  if(EIGEN_TEST_SYCL)
+    option(EIGEN_SYCL_DPCPP "Use the DPCPP Sycl implementation (DPCPP is default SYCL-Compiler)." ON)
+    option(EIGEN_SYCL_TRISYCL "Use the triSYCL Sycl implementation." OFF)
+    option(EIGEN_SYCL_ComputeCpp "Use the ComputeCPP Sycl implementation." OFF)
+
+    # Building options
+    # https://developer.codeplay.com/products/computecpp/ce/2.11.0/guides/eigen-overview/options-for-building-eigen-sycl
+    option(EIGEN_SYCL_USE_DEFAULT_SELECTOR "Use sycl default selector to select the preferred device." OFF)
+    option(EIGEN_SYCL_NO_LOCAL_MEM "Build for devices without dedicated shared memory." OFF)
+    option(EIGEN_SYCL_LOCAL_MEM "Allow the use of local memory (enabled by default)." ON)
+    option(EIGEN_SYCL_LOCAL_THREAD_DIM0 "Set work group size for dimension 0." 16)
+    option(EIGEN_SYCL_LOCAL_THREAD_DIM1 "Set work group size for dimension 1." 16)
+    option(EIGEN_SYCL_ASYNC_EXECUTION "Allow asynchronous execution (enabled by default)." ON)
+    option(EIGEN_SYCL_DISABLE_SKINNY "Disable optimization for tall/skinny matrices." OFF)
+    option(EIGEN_SYCL_DISABLE_DOUBLE_BUFFER "Disable double buffer." OFF)
+    option(EIGEN_SYCL_DISABLE_SCALAR "Disable scalar contraction." OFF)
+    option(EIGEN_SYCL_DISABLE_GEMV "Disable GEMV and create a single kernel to calculate contraction instead." OFF)
+
+    set(EIGEN_SYCL ON)
+    set(CMAKE_CXX_STANDARD 17)
+    set(CMAKE_CXX_FLAGS  "${CMAKE_CXX_FLAGS} -Wno-deprecated-declarations -Wno-shorten-64-to-32 -Wno-cast-align")
+    set(CMAKE_CXX_FLAGS  "${CMAKE_CXX_FLAGS} -Wno-deprecated-copy-with-user-provided-copy -Wno-unused-variable")
+    set (CMAKE_MODULE_PATH "${CMAKE_ROOT}/Modules" "cmake/Modules/" "${CMAKE_MODULE_PATH}")
+    find_package(Threads REQUIRED)
+    if(EIGEN_SYCL_TRISYCL)
+      message(STATUS "Using triSYCL")
+      include(FindTriSYCL)
+    elseif(EIGEN_SYCL_ComputeCpp)
+      message(STATUS "Using ComputeCPP SYCL")
+      include(FindComputeCpp)
+      set(COMPUTECPP_DRIVER_DEFAULT_VALUE OFF)
+      if (NOT MSVC)
+        set(COMPUTECPP_DRIVER_DEFAULT_VALUE ON)
+      endif()
+      option(COMPUTECPP_USE_COMPILER_DRIVER
+              "Use ComputeCpp driver instead of a 2 steps compilation"
+              ${COMPUTECPP_DRIVER_DEFAULT_VALUE}
+              )
+    else() #Default SYCL compiler is DPCPP (EIGEN_SYCL_DPCPP)
+      set(DPCPP_SYCL_TARGET "spir64" CACHE STRING "Default target for Intel CPU/GPU")
+      message(STATUS "Using DPCPP")
+      find_package(DPCPP)
+      add_definitions(-DSYCL_COMPILER_IS_DPCPP)
+    endif(EIGEN_SYCL_TRISYCL)
+    if(EIGEN_DONT_VECTORIZE_SYCL)
+      message(STATUS "Disabling SYCL vectorization in tests/examples")
+      # When disabling SYCL vectorization, also disable Eigen default vectorization
+      add_definitions(-DEIGEN_DONT_VECTORIZE=1)
+      add_definitions(-DEIGEN_DONT_VECTORIZE_SYCL=1)
+    endif()
   endif()
-endif()
 
-cmake_dependent_option(BUILD_TESTING "Enable creation of tests." ON "PROJECT_IS_TOP_LEVEL" OFF)
-option(EIGEN_BUILD_TESTING "Enable creation of Eigen tests." ${BUILD_TESTING})
-if(EIGEN_BUILD_TESTING)
   include(EigenConfigureTesting)
 
   if(EIGEN_LEAVE_TEST_IN_ALL_TARGET)
-    add_subdirectory(test) # can't do EXCLUDE_FROM_ALL here, breaks CTest
+    # CTest automatic test building relies on the "all" target.
+    add_subdirectory(test)
+    add_subdirectory(failtest)
   else()
     add_subdirectory(test EXCLUDE_FROM_ALL)
+    add_subdirectory(failtest EXCLUDE_FROM_ALL)
   endif()
 
-  add_subdirectory(failtest)
-endif()
+  ei_testing_print_summary()
 
-include(CMakeDetermineFortranCompiler)
-option(EIGEN_BUILD_BLAS "Toggles the building of the Eigen Blas library" ${CMAKE_Fortran_COMPILER})
-option(EIGEN_BUILD_LAPACK "Toggles the building of the included Eigen LAPACK library" ${CMAKE_Fortran_COMPILER})
-if(EIGEN_LEAVE_TEST_IN_ALL_TARGET)
-  add_subdirectory(blas)
-  add_subdirectory(lapack)
-else()
-  add_subdirectory(blas EXCLUDE_FROM_ALL)
-  add_subdirectory(lapack EXCLUDE_FROM_ALL)
-endif()
+  if (EIGEN_SPLIT_TESTSUITE)
+    ei_split_testsuite("${EIGEN_SPLIT_TESTSUITE}")
+  endif()
+endif(EIGEN_BUILD_TESTING)
 
+#==============================================================================
+# Other Build Configurations.
+#==============================================================================
 add_subdirectory(unsupported)
 
-add_subdirectory(demos EXCLUDE_FROM_ALL)
+if(EIGEN_BUILD_BLAS)
+  add_subdirectory(blas)
+endif()
+
+if (EIGEN_BUILD_LAPACK)
+  add_subdirectory(lapack)
+endif()
 
-# must be after test and unsupported, for configuring buildtests.in
-add_subdirectory(scripts EXCLUDE_FROM_ALL)
+if(EIGEN_BUILD_DOC)
+  add_subdirectory(doc EXCLUDE_FROM_ALL)
+endif()
 
 # TODO: consider also replacing EIGEN_BUILD_BTL by a custom target "make btl"?
 if(EIGEN_BUILD_BTL)
   add_subdirectory(bench/btl EXCLUDE_FROM_ALL)
 endif()
 
-find_package(CLANG_FORMAT 9 EXACT)
-if(CLANG_FORMAT_FOUND)
-set(FORMAT_SOURCES)
-list(APPEND FORMAT_SUBDIRS blas bench demos "doc" Eigen include lapack scripts share unsupported test failtest)
-foreach(DIR ${FORMAT_SUBDIRS})
-    set(ABS_DIR ${CMAKE_CURRENT_SOURCE_DIR}/${DIR})
-    file(GLOB_RECURSE ${DIR}_SOURCES ${ABS_DIR}/*.cc ${ABS_DIR}/*.h ${ABS_DIR}/*.cpp ${ABS_DIR}/*.hpp ${ABS_DIR}/*.c)
-    list(APPEND FORMAT_SOURCES ${${DIR}_SOURCES})
-  endforeach()
-    file(GLOB FORMAT_SOURCES_WITHOUTENDING LIST_DIRECTORIES false ${CMAKE_CURRENT_SOURCE_DIR}/Eigen/* ${CMAKE_CURRENT_SOURCE_DIR}/Eigen/CXX11/* ${CMAKE_CURRENT_SOURCE_DIR}/unsupported/Eigen/* ${CMAKE_CURRENT_SOURCE_DIR}/unsupported/Eigen/CXX11/*)
-    list(FILTER FORMAT_SOURCES_WITHOUTENDING EXCLUDE REGEX ".*.txt$")
-    list (APPEND FORMAT_SOURCES ${FORMAT_SOURCES_WITHOUTENDING})
-    add_custom_target(format
-    COMMAND ${CLANG_FORMAT_EXECUTABLE} -i -style=file ${FORMAT_SOURCES}
-    DEPENDS ${FORMAT_SOURCES})
-endif()
-
 if(NOT WIN32 AND EIGEN_BUILD_SPBENCH)
   add_subdirectory(bench/spbench EXCLUDE_FROM_ALL)
 endif()
 
-configure_file(scripts/cdashtesting.cmake.in cdashtesting.cmake @ONLY)
+if (EIGEN_BUILD_DEMOS)
+  add_subdirectory(demos EXCLUDE_FROM_ALL)
+endif()
 
-if(EIGEN_BUILD_TESTING)
-  ei_testing_print_summary()
+if (PROJECT_IS_TOP_LEVEL)
+  # must be after test and unsupported, for configuring buildtests.in
+  add_subdirectory(scripts EXCLUDE_FROM_ALL)
+  configure_file(scripts/cdashtesting.cmake.in cdashtesting.cmake @ONLY)
 endif()
 
-message(STATUS "")
-message(STATUS "Configured Eigen ${EIGEN_VERSION_NUMBER}")
-message(STATUS "")
+#==============================================================================
+# Summary.
+#==============================================================================
 
 if(PROJECT_IS_TOP_LEVEL)
   string(TOLOWER "${CMAKE_GENERATOR}" cmake_generator_tolower)
@@ -654,90 +746,24 @@ if(PROJECT_IS_TOP_LEVEL)
   message(STATUS "         |     cmake . -DCMAKE_INSTALL_PREFIX=yourprefix")
   message(STATUS "         |   Or:")
   message(STATUS "         |     cmake . -DINCLUDE_INSTALL_DIR=yourdir")
-  message(STATUS "doc      | Generate the API documentation, requires Doxygen & LaTeX")
+  message(STATUS "uninstall| Remove files installed by the install target")
+  if (EIGEN_BUILD_DOC)
+    message(STATUS "doc      | Generate the API documentation, requires Doxygen & LaTeX")
+  endif()
   if(EIGEN_BUILD_TESTING)
     message(STATUS "check    | Build and run the unit-tests. Read this page:")
     message(STATUS "         |   http://eigen.tuxfamily.org/index.php?title=Tests")
   endif()
-  if(CLANG_FORMAT_FOUND)
-    message(STATUS "format   | Formats the source code according to .clang-format file")
+  if (EIGEN_BUILD_BLAS)
+    message(STATUS "blas     | Build BLAS library (not the same thing as Eigen)")
+  endif()
+  if (EIGEN_BUILD_LAPACK)
+    message(STATUS "lapack   | Build LAPACK subset library (not the same thing as Eigen)")
   endif()
-  message(STATUS "blas     | Build BLAS library (not the same thing as Eigen)")
-  message(STATUS "uninstall| Remove files installed by the install target")
   message(STATUS "---------+--------------------------------------------------------------")
   message(STATUS "")
 endif()
 
-set ( EIGEN_VERSION_STRING ${EIGEN_VERSION_NUMBER} )
-set ( EIGEN_VERSION_MAJOR  ${EIGEN_WORLD_VERSION} )
-set ( EIGEN_VERSION_MINOR  ${EIGEN_MAJOR_VERSION} )
-set ( EIGEN_VERSION_PATCH  ${EIGEN_MINOR_VERSION} )
-
-include (CMakePackageConfigHelpers)
-
-# Imported target support
-add_library (eigen INTERFACE)
-add_library (Eigen3::Eigen ALIAS eigen)
-target_include_directories (eigen INTERFACE
-  $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}>
-  $<INSTALL_INTERFACE:${INCLUDE_INSTALL_DIR}>
-)
-
-# Export as title case Eigen
-set_target_properties (eigen PROPERTIES EXPORT_NAME Eigen)
-
-install (TARGETS eigen EXPORT Eigen3Targets)
-
-option(EIGEN_BUILD_CMAKE_PACKAGE "Enables the creation of EigenConfig.cmake and related files" ON)
-if(EIGEN_BUILD_CMAKE_PACKAGE)
-configure_package_config_file (
-  ${CMAKE_CURRENT_SOURCE_DIR}/cmake/Eigen3Config.cmake.in
-  ${CMAKE_CURRENT_BINARY_DIR}/Eigen3Config.cmake
-  INSTALL_DESTINATION ${CMAKEPACKAGE_INSTALL_DIR}
-  NO_SET_AND_CHECK_MACRO # Eigen does not provide legacy style defines
-  NO_CHECK_REQUIRED_COMPONENTS_MACRO # Eigen does not provide components
-)
-
-# NOTE Remove the first code path once the minimum required CMake version is
-# bumped to 3.14 or above.
-if (CMAKE_VERSION VERSION_LESS 3.14)
-  # Remove CMAKE_SIZEOF_VOID_P from Eigen3ConfigVersion.cmake since Eigen does
-  # not depend on architecture specific settings or libraries. More
-  # specifically, an Eigen3Config.cmake generated from a 64 bit target can be
-  # used for 32 bit targets as well (and vice versa).
-  set (_Eigen3_CMAKE_SIZEOF_VOID_P ${CMAKE_SIZEOF_VOID_P})
-  unset (CMAKE_SIZEOF_VOID_P)
-  write_basic_package_version_file (Eigen3ConfigVersion.cmake
-                                    VERSION ${EIGEN_VERSION_NUMBER}
-                                    COMPATIBILITY SameMajorVersion)
-  set (CMAKE_SIZEOF_VOID_P ${_Eigen3_CMAKE_SIZEOF_VOID_P})
-else (CMAKE_VERSION VERSION_LESS 3.14)
-  write_basic_package_version_file (Eigen3ConfigVersion.cmake
-                                    VERSION ${EIGEN_VERSION_NUMBER}
-                                    COMPATIBILITY SameMajorVersion
-                                    ARCH_INDEPENDENT)
-endif (CMAKE_VERSION VERSION_LESS 3.14)
-
-# The Eigen target will be located in the Eigen3 namespace. Other CMake
-# targets can refer to it using Eigen3::Eigen.
-export (TARGETS eigen NAMESPACE Eigen3:: FILE Eigen3Targets.cmake)
-# Export Eigen3 package to CMake registry such that it can be easily found by
-# CMake even if it has not been installed to a standard directory.
-export (PACKAGE Eigen3)
-
-install (EXPORT Eigen3Targets NAMESPACE Eigen3:: DESTINATION ${CMAKEPACKAGE_INSTALL_DIR})
-
-install (FILES ${CMAKE_CURRENT_BINARY_DIR}/Eigen3Config.cmake
-               ${CMAKE_CURRENT_BINARY_DIR}/Eigen3ConfigVersion.cmake
-         DESTINATION ${CMAKEPACKAGE_INSTALL_DIR})
-
-# Add uninstall target
-if(NOT TARGET uninstall)
-  add_custom_target ( uninstall
-      COMMAND ${CMAKE_COMMAND} -P ${CMAKE_CURRENT_SOURCE_DIR}/cmake/EigenUninstall.cmake)
-endif()
-endif()
-
-if (EIGEN_SPLIT_TESTSUITE)
-  ei_split_testsuite("${EIGEN_SPLIT_TESTSUITE}")
-endif()
+message(STATUS "")
+message(STATUS "Configured Eigen ${EIGEN_VERSION_NUMBER}")
+message(STATUS "")
diff --git a/cmake/EigenTesting.cmake b/cmake/EigenTesting.cmake
index 2f6f89e33..9f75c1b8a 100644
--- a/cmake/EigenTesting.cmake
+++ b/cmake/EigenTesting.cmake
@@ -91,6 +91,7 @@ macro(ei_add_test_internal testname testname_with_suffix)
   if(EIGEN_TEST_CUSTOM_LINKER_FLAGS)
     target_link_libraries(${targetname} ${EIGEN_TEST_CUSTOM_LINKER_FLAGS})
   endif()
+  target_link_libraries(${targetname} Eigen3::Eigen)
 
   if(${ARGC} GREATER 3)
     set(libs_to_link ${ARGV3})
diff --git a/lapack/CMakeLists.txt b/lapack/CMakeLists.txt
index 1babd136a..e61c99b2c 100644
--- a/lapack/CMakeLists.txt
+++ b/lapack/CMakeLists.txt
@@ -110,6 +110,7 @@ foreach(target IN LISTS EIGEN_LAPACK_TARGETS)
   if(EIGEN_STANDARD_LIBRARIES_TO_LINK_TO)
     target_link_libraries(${target} ${EIGEN_STANDARD_LIBRARIES_TO_LINK_TO})
   endif()
+  target_link_libraries(${target} Eigen3::Eigen)
   add_dependencies(lapack ${target})
   install(TARGETS ${target}
           RUNTIME DESTINATION bin
diff --git a/unsupported/CMakeLists.txt b/unsupported/CMakeLists.txt
index 67d1f6262..390460181 100644
--- a/unsupported/CMakeLists.txt
+++ b/unsupported/CMakeLists.txt
@@ -4,7 +4,7 @@ if(EIGEN_BUILD_DOC)
 endif()
 if(EIGEN_BUILD_TESTING)
   if(EIGEN_LEAVE_TEST_IN_ALL_TARGET)
-    add_subdirectory(test) # can't do EXCLUDE_FROM_ALL here, breaks CTest
+    add_subdirectory(test) # CTest automatic test building relies on the "all" target.
   else()
     add_subdirectory(test EXCLUDE_FROM_ALL)
   endif()