[bpf-next v3 07/12] tools headers: Adopt compiletime_assert from kernel sources

[Krzesimir Nowak]

This will come in handy to verify that the hardcoded size of the
context data in bpf_test struct is high enough to hold some struct.

Signed-off-by: Krzesimir Nowak <krzesimir@xxxxxxxxxx>
---
 tools/include/linux/compiler.h | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/tools/include/linux/compiler.h b/tools/include/linux/compiler.h
index 1827c2f973f9..b4e97751000a 100644
--- a/tools/include/linux/compiler.h
+++ b/tools/include/linux/compiler.h
@@ -172,4 +172,32 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s
 # define __fallthrough
 #endif
 
+
+#ifdef __OPTIMIZE__
+# define __compiletime_assert(condition, msg, prefix, suffix)		\
+	do {								\
+		extern void prefix ## suffix(void) __compiletime_error(msg); \
+		if (!(condition))					\
+			prefix ## suffix();				\
+	} while (0)
+#else
+# define __compiletime_assert(condition, msg, prefix, suffix) do { } while (0)
+#endif
+
+#define _compiletime_assert(condition, msg, prefix, suffix) \
+	__compiletime_assert(condition, msg, prefix, suffix)
+
+/**
+ * compiletime_assert - break build and emit msg if condition is false
+ * @condition: a compile-time constant condition to check
+ * @msg:       a message to emit if condition is false
+ *
+ * In tradition of POSIX assert, this macro will break the build if the
+ * supplied condition is *false*, emitting the supplied error message if the
+ * compiler has support to do so.
+ */
+#define compiletime_assert(condition, msg) \
+	_compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)
+
+
 #endif /* _TOOLS_LINUX_COMPILER_H */
-- 
2.20.1