Merge pull request #2954 from shrit/check_blas

Check for blas and Lapack before downloading armadillo

CMake/ConfigureCrossCompile.cmake

@@ -33,7 +33,7 @@ macro(search_openblas version)
       endif()
       file(GLOB OPENBLAS_LIBRARIES "${CMAKE_BINARY_DIR}/deps/OpenBLAS-${version}/libopenblas.a")
       set(BLAS_openblas_LIBRARY ${OPENBLAS_LIBRARIES})
-      set(LAPACK_openblas_LIBRARY ${OPENBLAS_LIBRARIES})  
+      set(LAPACK_openblas_LIBRARY ${OPENBLAS_LIBRARIES}) 
       set(BLA_VENDOR OpenBLAS)
       set(BLAS_FOUND ON)
     endif()

CMakeLists.txt

@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.3.2)
+cmake_minimum_required(VERSION 3.6)
 project(mlpack C CXX)
 
 include(CMake/cotire.cmake)
@@ -283,6 +283,13 @@ if (DISABLE_DOWNLOADS)
 else()
   find_package(Armadillo "${ARMADILLO_VERSION}")
   if (NOT ARMADILLO_FOUND)
+    if (NOT CMAKE_CROSSCOMPILING)
+      find_package(BLAS QUIET)
+      find_package(LAPACK QUIET)
+      if (NOT BLAS_FOUND AND NOT LAPACK_FOUND)
+        message(FATAL_ERROR "Can not find BLAS or LAPACK!  These are required for Armadillo.  Please install one of them---or install Armadillo---before installing mlpack.")
+      endif()
+    endif()
     get_deps(http://files.mlpack.org/armadillo-10.3.0.tar.gz armadillo armadillo-10.3.0.tar.gz)
     set(ARMADILLO_INCLUDE_DIR ${GENERIC_INCLUDE_DIR})
     find_package(Armadillo REQUIRED)

README.md

@@ -101,7 +101,7 @@ mlpack has the following dependencies:
 
       Armadillo      >= 8.400.0
       Boost (math_c99, spirit) >= 1.58.0
-      CMake          >= 3.2.2
+      CMake          >= 3.6
       ensmallen      >= 2.10.0
       cereal         >= 1.1.2