cmake: iar: Don't assume C compiler is gcc.

Let's not assume everyone takes gcc parameters.
Currently IAR do use gcc for DTS preprocessing.
This should be fixed nicer, but with this fix
we can start testing other things.

Signed-off-by: Robin Kastberg <[email protected]>

Author: RobinKastberg

subsys/partition_manager/CMakeLists.txt

@@ -16,18 +16,22 @@ endif()
 set_shared(IMAGE ${IMAGE_NAME} PROPERTY ZEPHYR_BINARY_DIR ${ZEPHYR_BINARY_DIR})
 
 function(preprocess_pm_yml in_file out_file)
-  execute_process(
-    COMMAND ${CMAKE_C_COMPILER}
-    -x assembler-with-cpp
-    -nostdinc
-    -I${ZEPHYR_BINARY_DIR}/include/generated
-    ${NOSYSDEF_CFLAG}
-    -P
-    -E ${in_file}
-    -o ${out_file}
+
+  if(DEFINED CMAKE_DTS_PREPROCESSOR)
+    set(dts_preprocessor ${CMAKE_DTS_PREPROCESSOR})
+  else()
+    set(dts_preprocessor ${CMAKE_C_COMPILER})
+  endif()
+
+
+  zephyr_dt_preprocess(CPP ${dts_preprocessor}
+    INCLUDE_DIRECTORIES ${ZEPHYR_BINARY_DIR}/include/generated
+    EXTRA_CPPFLAGS -P ${NOSYSDEF_CFLAG}
+    SOURCE_FILES ${in_file}
+    OUT_FILE ${out_file}
     WORKING_DIRECTORY ${ZEPHYR_BINARY_DIR}
-    RESULT_VARIABLE ret
     )
+
   if(NOT "${ret}" STREQUAL "0")
     message(FATAL_ERROR "command failed with return code: ${ret}")
   endif()