toolchain: introduce macros to ignore -Wshadow

This introduces two macros TOOLCHAIN_IGNORE_WSHADOW_BEGIN and
TOOLCHAIN_IGNORE_WSHADOW_END which can be used inside another
macro to ignore -Wshadow for certain block of code. This is
useful for common macros that may nest upon themselves
(for example, logging).

Signed-off-by: Daniel Leung <daniel.leung@intel.com>

include/zephyr/logging/log_msg.h

@@ -235,7 +235,9 @@ do { \
 		CBPRINTF_STATIC_PACKAGE(NULL, 0, _plen, Z_LOG_MSG_ALIGN_OFFSET, _options, \
 					__VA_ARGS__); \
 	} \
+	TOOLCHAIN_IGNORE_WSHADOW_BEGIN \
 	struct log_msg *_msg; \
+	TOOLCHAIN_IGNORE_WSHADOW_END \
 	Z_LOG_MSG_ON_STACK_ALLOC(_msg, Z_LOG_MSG_LEN(_plen, 0)); \
 	Z_LOG_ARM64_VLA_PROTECT(); \
 	if (_plen != 0) { \

include/zephyr/toolchain.h

@@ -115,6 +115,28 @@
 #define TOOLCHAIN_HAS_C_AUTO_TYPE 0
 #endif
 
+/**
+ * @def TOOLCHAIN_IGNORE_WSHADOW_BEGIN
+ * @brief Begin of block to ignore -Wshadow.
+ *
+ * To be used inside another macro.
+ * Only for toolchain supporting _Pragma("GCC diagnostic ...").
+ */
+#ifndef TOOLCHAIN_IGNORE_WSHADOW_BEGIN
+#define TOOLCHAIN_IGNORE_WSHADOW_BEGIN
+#endif
+
+/**
+ * @def TOOLCHAIN_IGNORE_WSHADOW_END
+ * @brief End of block to ignore -Wshadow.
+ *
+ * To be used inside another macro.
+ * Only for toolchain supporting _Pragma("GCC diagnostic ...").
+ */
+#ifndef TOOLCHAIN_IGNORE_WSHADOW_END
+#define TOOLCHAIN_IGNORE_WSHADOW_END
+#endif
+
 /*
  * Ensure that __BYTE_ORDER__ and related preprocessor definitions are defined,
  * and that they match the Kconfig option that is used in the code itself to

include/zephyr/toolchain/gcc.h

@@ -639,5 +639,12 @@ do {                                                                    \
 #define FUNC_NO_STACK_PROTECTOR
 #endif
 
+#define TOOLCHAIN_IGNORE_WSHADOW_BEGIN \
+	_Pragma("GCC diagnostic push") \
+	_Pragma("GCC diagnostic ignored \"-Wshadow\"")
+
+#define TOOLCHAIN_IGNORE_WSHADOW_END \
+	_Pragma("GCC diagnostic pop")
+
 #endif /* !_LINKER */
 #endif /* ZEPHYR_INCLUDE_TOOLCHAIN_GCC_H_ */