build grid synth if gmp is detected

CMakeLists.txt

@@ -17,14 +17,6 @@ add_compile_definitions(STAQ_VERSION_STR="${STAQ_VERSION_STR}")
 #### staq root directory
 add_compile_definitions(PROJECT_ROOT_DIR="${PROJECT_SOURCE_DIR}")
 
-#### grid synth
-option(BUILD_GRID_SYNTH "Builds staq_grid_synth, requires GMP" OFF)
-if (${BUILD_GRID_SYNTH})
-    message(STATUS "Builds staq_grid_synth - ON")
-else ()
-    message(STATUS "Builds staq_grid_synth - OFF")
-endif ()
-
 #### Force clang to use libc++
 if (${CMAKE_CXX_COMPILER_ID} MATCHES "Clang")
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -stdlib=libc++")

tools/CMakeLists.txt

@@ -2,16 +2,22 @@ file(GLOB FILENAMES *.cpp)
 
 add_custom_target(tools COMMENT "Build all binary tools.")
 
-if (${BUILD_GRID_SYNTH})
-    if (MSVC)
-        # gmp, gmpxx
-        find_package(PkgConfig REQUIRED)
+set(BUILD_GRID_SYNTH OFF)
+if (MSVC)
+    # gmp, gmpxx
+    find_package(PkgConfig REQUIRED)
+    if (PkgConfig_FOUND)
         pkg_check_modules(gmp REQUIRED IMPORTED_TARGET gmp)
         pkg_check_modules(gmpxx REQUIRED IMPORTED_TARGET gmpxx)
-    else ()
-        find_package(GMP REQUIRED)
+        set(BUILD_GRID_SYNTH ON)
+        add_compile_options("-DEXPR_GMP")
+    endif ()
+else ()
+    find_package(GMP REQUIRED)
+    if (GMP_FOUND)
+        set(BUILD_GRID_SYNTH ON)
+        add_compile_options("-DEXPR_GMP")
     endif ()
-    add_compile_options("-DEXPR_GMP")
 endif ()
 
 foreach (filename ${FILENAMES})