package/eigen: fix build without Fortran

Fix the following build failure without a working Fortran compiler:

CMake Error at /nvmedata/autobuild/instance-17/output-1/host/share/cmake-3.18/Modules/CMakeTestFortranCompiler.cmake:51 (message):
  The Fortran compiler

    "/usr/bin/f95"

  is not able to compile a simple test program.

Fixes:
 - http://autobuild.buildroot.org/results/37f3f40ee39739b5e557d634b71a448762107a4b

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>

package/eigen/0001-Adds-new-CMake-Options-for-controlling-build-components.patch

@@ -0,0 +1,85 @@
+From cf82186416d04ea5df2a397d8fe09dc78d40ca65 Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Antonio=20S=C3=A1nchez?= <cantonios@google.com>
+Date: Sat, 5 Mar 2022 05:49:45 +0000
+Subject: [PATCH] Adds new CMake Options for controlling build components.
+
+[Retrieved from:
+https://gitlab.com/libeigen/eigen/-/commit/cf82186416d04ea5df2a397d8fe09dc78d40ca65]
+Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
+---
+ CMakeLists.txt        | 6 ++++++
+ blas/CMakeLists.txt   | 3 ++-
+ lapack/CMakeLists.txt | 5 +++++
+ 3 files changed, 13 insertions(+), 1 deletion(-)
+
+diff --git a/CMakeLists.txt b/CMakeLists.txt
+index de1c23e91..0af36a53a 100644
+--- a/CMakeLists.txt
++++ b/CMakeLists.txt
+@@ -477,6 +477,9 @@ if(EIGEN_BUILD_TESTING)
+   add_subdirectory(failtest)
+ endif()
+ 
++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)
+@@ -611,6 +614,8 @@ 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
+@@ -655,6 +660,7 @@ install (FILES ${CMAKE_CURRENT_BINARY_DIR}/Eigen3Config.cmake
+ # Add uninstall target
+ add_custom_target ( uninstall
+     COMMAND ${CMAKE_COMMAND} -P ${CMAKE_CURRENT_SOURCE_DIR}/cmake/EigenUninstall.cmake)
++endif()
+ 
+ if (EIGEN_SPLIT_TESTSUITE)
+   ei_split_testsuite("${EIGEN_SPLIT_TESTSUITE}")
+diff --git a/blas/CMakeLists.txt b/blas/CMakeLists.txt
+index 8d3cb86dc..c530957fb 100644
+--- a/blas/CMakeLists.txt
++++ b/blas/CMakeLists.txt
+@@ -1,6 +1,7 @@
+ 
+ project(EigenBlas CXX)
+ 
++if(EIGEN_BUILD_BLAS)
+ include(CheckLanguage)
+ check_language(Fortran)
+ if(CMAKE_Fortran_COMPILER)
+@@ -59,4 +60,4 @@ if(EIGEN_BUILD_TESTING)
+ endif()
+ 
+ endif()
+-
++endif()
+diff --git a/lapack/CMakeLists.txt b/lapack/CMakeLists.txt
+index c8ca64001..8d6d75401 100644
+--- a/lapack/CMakeLists.txt
++++ b/lapack/CMakeLists.txt
+@@ -1,5 +1,7 @@
+ project(EigenLapack CXX)
+ 
++if(EIGEN_BUILD_LAPACK AND EIGEN_BUILD_BLAS)
++
+ include(CheckLanguage)
+ check_language(Fortran)
+ if(CMAKE_Fortran_COMPILER)
+@@ -457,3 +459,6 @@ if(EXISTS ${eigen_full_path_to_testing_lapack})
+ 
+ endif()
+ 
++elseif(EIGEN_BUILD_LAPACK AND NOT EIGEN_BUILD_BLAS)
++ message(FATAL_ERROR "EIGEN_BUILD_LAPACK requires EIGEN_BUILD_BLAS")
++endif() #EIGEN_BUILD_LAPACK
+-- 
+GitLab
+

package/eigen/eigen.mk

@@ -18,7 +18,14 @@ EIGEN_SUPPORTS_IN_SOURCE_BUILD = NO
 EIGEN_CONF_OPTS = -DPKGCONFIG_INSTALL_DIR=/usr/lib/pkgconfig
 
 ifeq ($(BR2_TOOLCHAIN_HAS_FORTRAN),y)
-EIGEN_CONF_OPTS += -DCMAKE_Fortran_COMPILER=$(TARGET_FC)
+EIGEN_CONF_OPTS += \
+	-DCMAKE_Fortran_COMPILER=$(TARGET_FC) \
+	-DEIGEN_BUILD_BLAS=ON \
+	-DEIGEN_BUILD_LAPACK=ON
+else
+EIGEN_CONF_OPTS += \
+	-DEIGEN_BUILD_BLAS=OFF \
+	-DEIGEN_BUILD_LAPACK=OFF
 endif
 
 $(eval $(cmake-package))