cmake: compiler/xt-clang: add -Wno-unknown-warning-option

xt-clang is usually based on older version of clang, and
Zephyr main targets more recent versions. Because of this,
some newer compiler flags may cause warnings where twister
would mark as test being failed. To workaround that,
add -Wno-unknown-warning-option to suppress those warnings.

Fixes #84138

Signed-off-by: Daniel Leung <[email protected]>

Author: dcpleung

cmake/compiler/xt-clang/compiler_flags.cmake

@@ -34,3 +34,12 @@ set_compiler_property(PROPERTY no_position_independent "")
 
 # Remove after testing that -Wshadow works
 set_compiler_property(PROPERTY warning_shadow_variables)
+
+# xt-clang is usually based on older version of clang, and
+# Zephyr main targets more recent versions. Because of this,
+# some newer compiler flags may cause warnings where twister
+# would mark as test being failed. To workaround that,
+# add -Wno-unknown-warning-option to suppress those warnings.
+check_set_compiler_property(APPEND PROPERTY warning_extended
+                            -Wno-unknown-warning-option
+)