Compiler Attributes: homogenize __must_be_array

Different definitions of __must_be_array:

  * gcc: disabled for __CHECKER__

  * clang: same definition as gcc's, but without __CHECKER__

  * intel: the comment claims __builtin_types_compatible_p()
    is unsupported; but icc seems to support it since 13.0.1
    (released in 2012). See https://godbolt.org/z/S0l6QQ

Therefore, we can remove all of them and have a single definition
in compiler.h

Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # on top of v4.19-rc5, clang 7
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Signed-off-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index ec4a28bad2c6..165b1d5683ed 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -357,4 +357,11 @@ static inline void *offset_to_ptr(const int *off)
         compiletime_assert(__native_word(t),                            \
                 "Need native word sized stores/loads for atomicity.")
 
+#ifdef __CHECKER__
+#define __must_be_array(a)      0
+#else
+/* &a[0] degrades to a pointer: a different type from an array */
+#define __must_be_array(a)      BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0]))
+#endif
+
 #endif /* __LINUX_COMPILER_H */