cmake: Fix bug where -Wno- flags could not be compatbility-checked
It turns out that 'check_compiler_flag' has not been working for flags
that start with -Wno-. This has caused old compilers to accidentally
use flags that they do not support.
To fix this we check for compatibility with the appropriate -W flag
instead and infer the -Wno- compatibility from this check.
The root cause of this problem is explained well here:
https://github.com/zephyrproject-rtos/zephyr/pull/18922#discussion_r321537098
Signed-off-by: Sebastian Bøe <sebastian.boe@nordicsemi.no>
diff --git a/cmake/extensions.cmake b/cmake/extensions.cmake
index e28f416..cbb640c 100644
--- a/cmake/extensions.cmake
+++ b/cmake/extensions.cmake
@@ -747,8 +747,17 @@
return()
endif()
- # Test the flag
- check_compiler_flag(${lang} "${option}" inner_check)
+ # Flags that start with -Wno-<warning> can not be tested by
+ # check_compiler_flag, they will always pass, but -W<warning> can be
+ # tested, so to test -Wno-<warning> flags we test -W<warning>
+ # instead.
+ if("${option}" MATCHES "-Wno-(.*)")
+ set(possibly_translated_option -W${CMAKE_MATCH_1})
+ else()
+ set(possibly_translated_option ${option})
+ endif()
+
+ check_compiler_flag(${lang} "${possibly_translated_option}" inner_check)
set(${check} ${inner_check} PARENT_SCOPE)
