fix submodule headers detection

diff --git a/cmake/simde.cmake b/cmake/simde.cmake
index 5a7335bb393c2bbb6425d06fde47c81218326707..0ac52832f791c581949d3c22440101b7f82519ac 100644 (file)
--- a/cmake/simde.cmake
+++ b/cmake/simde.cmake
@@ -1,10 +1,11 @@
-include_directories(${PROJECT_SOURCE_DIR}/simde/simde)
+LIST(APPEND CMAKE_REQUIRED_INCLUDES ${PROJECT_SOURCE_DIR}/simde)
 
-CHECK_INCLUDE_FILES("simde/x86/sse4.2.h" SIMDE_SSE42_H_FOUND)
+CHECK_INCLUDE_FILES(simde/x86/sse4.2.h SIMDE_SSE42_H_FOUND)
 
 if (SIMDE_SSE42_H_FOUND)
   set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -DVS_SIMDE_BACKEND")
   set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -DVS_SIMDE_BACKEND")
+  include_directories(${PROJECT_SOURCE_DIR}/simde)
 
   if (CMAKE_COMPILER_IS_CLANG)
     set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -DSIMDE_NO_CHECK_IMMEDIATE_CONSTANT")