From: Michael Forney <mforney@mforney.org>
Date: Wed, 14 Apr 2021 07:41:27 +0000 (-0700)
Subject: libext2fs: use statement-expression for container_of only on GNU-compatible compilers
X-Git-Tag: v1.46.3~34
X-Git-Url: https://git.whamcloud.com/?a=commitdiff_plain;h=9d5fdcc5db1b5246028dc871e5f0fb908dd64771;p=tools%2Fe2fsprogs.git

libext2fs: use statement-expression for container_of only on GNU-compatible compilers

Functionally, the statement-expression is not necessary here; it
just gives a bit of type-safety to make sure the pointer really
does have a compatible type with the specified member of the struct.

When statement expressions are not available, we can just use a
portable fallback macro that skips this member type check.

Signed-off-by: Michael Forney <mforney@mforney.org>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
---

diff --git a/lib/ext2fs/compiler.h b/lib/ext2fs/compiler.h
index 9aa9b4e..03c35ab 100644
--- a/lib/ext2fs/compiler.h
+++ b/lib/ext2fs/compiler.h
@@ -14,9 +14,14 @@
 #define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
 #endif
 
+#ifdef __GNUC__
 #define container_of(ptr, type, member) ({			\
 	const __typeof__( ((type *)0)->member ) *__mptr = (ptr);	\
 	(type *)( (char *)__mptr - offsetof(type,member) );})
+#else
+#define container_of(ptr, type, member)				\
+	((type *)((char *)(ptr) - offsetof(type, member)))
+#endif
 
 
 #endif /* _EXT2FS_COMPILER_H */