build: enable SYCL warnings on Linux (#2096)

Some versions of DPC++ compiler pass paths to SYCL headers as user
include paths (`-I`) rather than system paths (`-isystem`). This makes
host compiler to report warnings encountered in the SYCL headers, such
as deprecated warnings, even if warned API is not actually used in the
program. We expect that this issue will be addressed in the later
version of DPC++ compiler. To workaround the issue we wrap paths to SYCL
headers in `-isystem`.

disable_ut
disable_e2e
disable_distributed

CC: @EikanWang @chuanqi129

Signed-off-by: Dmitry Rogozhkin <[email protected]>

Author: dvrogozh

cmake/BuildFlags.cmake

@@ -36,10 +36,16 @@ if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU" OR CMAKE_CXX_COMPILER_ID STREQUAL "MSVC"
     list(APPEND SYCL_HOST_FLAGS -fPIC)
     list(APPEND SYCL_HOST_FLAGS -std=c++17)
     list(APPEND SYCL_HOST_FLAGS -Wunused-variable)
-    # SYCL headers warnings
-    list(APPEND SYCL_HOST_FLAGS -Wno-deprecated-declarations)
-    list(APPEND SYCL_HOST_FLAGS -Wno-deprecated)
-    list(APPEND SYCL_HOST_FLAGS -Wno-attributes)
+    # Some versions of DPC++ compiler pass paths to SYCL headers as user include paths (`-I`) rather
+    # than system paths (`-isystem`). This makes host compiler to report warnings encountered in the
+    # SYCL headers, such as deprecated warnings, even if warned API is not actually used in the program.
+    # We expect that this issue will be addressed in the later version of DPC++ compiler. To workaround
+    # the issue we wrap paths to SYCL headers in `-isystem`.
+    foreach(FLAGS IN LISTS SYCL_INCLUDE_DIR)
+      list(APPEND SYCL_HOST_FLAGS "-isystem ${FLAGS}")
+    endforeach()
+    # Excluding warnings which flood the compilation output
+    # TODO: fix warnings in the source code and then reenable them in compilation
     list(APPEND SYCL_HOST_FLAGS -Wno-sign-compare)
   endif()