eigen{,2,_3_4_0}: migrate to by-name

--- a/CMakeLists.txt

+++ b/CMakeLists.txt

@@ -1,5 +1,5 @@

 # cmake_minimum_require must be the first command of the file

-cmake_minimum_required(VERSION 3.5.0)

+cmake_minimum_required(VERSION 3.7.0)

 project(Eigen3)

@@ -443,7 +443,7 @@ set(PKGCONFIG_INSTALL_DIR

     CACHE PATH "The directory relative to CMAKE_INSTALL_PREFIX where eigen3.pc is installed"

     )

-foreach(var INCLUDE_INSTALL_DIR CMAKEPACKAGE_INSTALL_DIR PKGCONFIG_INSTALL_DIR)

+foreach(var 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}}")

@@ -466,13 +466,6 @@ install(FILES

   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)

@@ -593,8 +586,15 @@ set ( EIGEN_VERSION_MAJOR  ${EIGEN_WORLD_VERSION} )

 set ( EIGEN_VERSION_MINOR  ${EIGEN_MAJOR_VERSION} )

 set ( EIGEN_VERSION_PATCH  ${EIGEN_MINOR_VERSION} )

 set ( EIGEN_DEFINITIONS "")

-set ( EIGEN_INCLUDE_DIR "${CMAKE_INSTALL_PREFIX}/${INCLUDE_INSTALL_DIR}" )

 set ( EIGEN_ROOT_DIR ${CMAKE_INSTALL_PREFIX} )

+GNUInstallDirs_get_absolute_install_dir(EIGEN_INCLUDE_DIR INCLUDE_INSTALL_DIR)

+

+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()

 include (CMakePackageConfigHelpers)

--- a/eigen3.pc.in

+++ b/eigen3.pc.in

@@ -6,4 +6,4 @@ Description: A C++ template library for linear algebra: vectors, matrices, and r

 Requires:

 Version: @EIGEN_VERSION_NUMBER@

 Libs:

-Cflags: -I${prefix}/@INCLUDE_INSTALL_DIR@

+Cflags: -I@EIGEN_INCLUDE_DIR@