LAPACK requires CMake 3.11 or newer

[christoph-conrads]

Description

When building a BLAS shared library with cmake -DBUILD_SHARED_LIBS=ON with CMake releases before version 3.11, linking of the BLAS library will fail:

[ 27%] Linking Fortran shared library ../../lib/libblas.so
CMakeFiles/blas_64_obj.dir/blas_64_obj/isamax.f.o: In function `isamax_':
/tmp/build/BLAS/SRC/blas_64_obj/isamax.f:70: multiple definition of `isamax_'
CMakeFiles/blas_obj.dir/isamax.f.o:/home/docker/lapack/BLAS/SRC/isamax.f:70: first defined here
CMakeFiles/blas_64_obj.dir/blas_64_obj/lsame.f.o: In function `lsame_':
/tmp/build/BLAS/SRC/blas_64_obj/lsame.f:52: multiple definition of `lsame_'
CMakeFiles/blas_obj.dir/lsame.f.o:/home/docker/lapack/BLAS/SRC/lsame.f:52: first defined here
CMakeFiles/blas_64_obj.dir/blas_64_obj/sasum.f.o: In function `sasum_':
/tmp/build/BLAS/SRC/blas_64_obj/sasum.f:71: multiple definition of `sasum_'
CMakeFiles/blas_obj.dir/sasum.f.o:/home/docker/lapack/BLAS/SRC/sasum.f:71: first defined here
[snip]

The cause is an attempt to set the source file property COMPILE_OPTIONS:

lapack/BLAS/SRC/CMakeLists.txt

Lines 140 to 143 in d7ea9c5

	list(APPEND COPT_64_F "-D${FUNC}=${FUNC}_64")
	endforeach()
	list(REMOVE_DUPLICATES COPT_64_F)
	set_source_files_properties(${F} PROPERTIES COMPILE_OPTIONS "${COPT_64_F}")

This property exists only from CMake 3.11 onwards and these compiler options would avoid the name clash.

There are two possible fixes:

• Require at least CMake 3.11 for building LAPACK
• Use the COMPILE_FLAGS and COMPILE_DEFINITIONS properties

Checklist

• I've included a minimal example to reproduce the issue
• I'd be willing to make a PR to solve this issue

[christoph-conrads]

Suggested fix (will be PR'ed later) tested on Ubuntu 18.04 with CMake 3.10.2:

diff --git a/BLAS/SRC/CMakeLists.txt b/BLAS/SRC/CMakeLists.txt
index 9df128eb5..d90198f37 100644
--- a/BLAS/SRC/CMakeLists.txt
+++ b/BLAS/SRC/CMakeLists.txt
@@ -124,9 +124,9 @@ if(BUILD_INDEX64_EXT_API)
   #Add _64 suffix to all Fortran functions via macros
   foreach(F IN LISTS SOURCES_64_F)
     if(CMAKE_Fortran_COMPILER_ID STREQUAL "NAG")
-      set(COPT_64_F -fpp)
+               set_source_files_properties(${F} PROPERTIES COMPILE_FLAGS "-fpp")
     else()
-      set(COPT_64_F -cpp)
+               set_source_files_properties(${F} PROPERTIES COMPILE_FLAGS "-cpp")
     endif()
     file(STRINGS ${F} ${F}.lst)
     list(FILTER ${F}.lst INCLUDE REGEX "subroutine|SUBROUTINE|external|EXTERNAL|function|FUNCTION")
@@ -137,10 +137,10 @@ if(BUILD_INDEX64_EXT_API)
       string(REGEX REPLACE "^[a-zA-Z0-9_ *]*(subroutine|SUBROUTINE|external|EXTERNAL|function|FUNCTION)[ ]*[*]?" "" FUNC ${FUNC})
       string(REGEX REPLACE "[(][a-zA-Z0-9_, )]*$" "" FUNC ${FUNC})
       string(STRIP ${FUNC} FUNC)
-      list(APPEND COPT_64_F "-D${FUNC}=${FUNC}_64")
+      list(APPEND COPT_64_F "${FUNC}=${FUNC}_64")
     endforeach()
     list(REMOVE_DUPLICATES COPT_64_F)
-    set_source_files_properties(${F} PROPERTIES COMPILE_OPTIONS "${COPT_64_F}")
+        set_source_files_properties(${F} PROPERTIES COMPILE_DEFINITIONS "${COPT_64_F}")
   endforeach()
 endif()