switched to cmake options

CMakeLists.txt

@@ -12,6 +12,7 @@ OPTION(USE_GPU "Enable GPU-accelerated training" OFF)
 OPTION(USE_SWIG "Enable SWIG to generate Java API" OFF)
 OPTION(USE_HDFS "Enable HDFS support (EXPERIMENTAL)" OFF)
 OPTION(USE_R35 "Set to ON if your R version is not earlier than 3.5" OFF)
+OPTION(BUILD_FOR_R "Set to ON if building lib_lightgbm for use with the R package" OFF)
 
 if(APPLE)
     OPTION(APPLE_OUTPUT_DYLIB "Output dylib shared library" OFF)
@@ -68,6 +69,10 @@ if(USE_R35)
     ADD_DEFINITIONS(-DR_VER_ABOVE_35)
 endif(USE_R35)
 
+if(BUILD_FOR_R)
+    ADD_DEFINITIONS(-DLGB_BUILD_R)
+endif(BUILD_FOR_R)
+
 if(USE_TIMETAG)
     ADD_DEFINITIONS(-DTIMETAG)
 endif(USE_TIMETAG)

R-package/src/install.libs.R

@@ -43,6 +43,7 @@ if (!use_precompile) {
   if (R_ver >= 3.5) {
     cmake_cmd <- paste0(cmake_cmd, " -DUSE_R35=ON ")
   }
+  cmake_cmd <- paste0(cmake_cmd, " -DBUILD_FOR_R=ON ")
 
   # Check if Windows installation (for gcc vs Visual Studio)
   if (WINDOWS) {
@@ -77,15 +78,8 @@ if (!use_precompile) {
     }
   }
 
-  # Add R CXXFLAGS. Do this in one command with ';' since R
-  # system() call isn't guaranteed to preserve environment from call to call
-  cmake_cmd <- paste0(
-    "export CXXFLAGS=\"${CXXFLAGS} -DLGB_R_BUILD\";"
-    , paste0(cmake_cmd, " ..")
-  )
-
   # Install
-  system(cmake_cmd)
+  system(paste0(cmake_cmd, " .."))
 
   # R CMD check complains about the .NOTPARALLEL directive created in the cmake
   # Makefile. We don't need it here anyway since targets are built serially, so trying