diff options
| author | David Lamparter <equinox@diac24.net> | 2019-06-03 15:41:05 +0200 |
|---|---|---|
| committer | David Lamparter <equinox@diac24.net> | 2019-06-11 18:45:38 +0200 |
| commit | a7f20d4328092b382c26c6d738e575c1ead9dc91 (patch) | |
| tree | 32169265160a11e069dc58c9d08bae1d9c8593a5 /lib/compiler.h | |
| parent | 6aba4eeaecdb0307fda736d2bec968e5da0d5dfb (diff) | |
lib: const-unaware container_of for C++
This version of container_of() should work on C++, by ditching the
unavailable builtins (at the cost of no longer checking for "const"
violations.)
Signed-off-by: David Lamparter <equinox@diac24.net>
Diffstat (limited to 'lib/compiler.h')
| -rw-r--r-- | lib/compiler.h | 17 |
1 files changed, 14 insertions, 3 deletions
diff --git a/lib/compiler.h b/lib/compiler.h index 9ce91e3361..696fb0d040 100644 --- a/lib/compiler.h +++ b/lib/compiler.h @@ -173,6 +173,11 @@ extern "C" { #endif #endif +#ifdef container_of +#undef container_of +#endif + +#if !(defined(__cplusplus) || defined(test__cplusplus)) /* this variant of container_of() retains 'const' on pointers without needing * to be told to do so. The following will all work without warning: * @@ -191,9 +196,6 @@ extern "C" { * struct cont *x = container_of(cp, const struct cont, member); * struct cont *x = container_of(p, const struct cont, member); */ -#ifdef container_of -#undef container_of -#endif #define container_of(ptr, type, member) \ (__builtin_choose_expr( \ __builtin_types_compatible_p(typeof(&((type *)0)->member), \ @@ -209,6 +211,15 @@ extern "C" { offsetof(type, member)); \ }) \ )) +#else +/* current C++ compilers don't have the builtins used above; so this version + * of the macro doesn't do the const check. */ +#define container_of(ptr, type, member) \ + ({ \ + const typeof(((type *)0)->member) *__mptr = (ptr); \ + (type *)((char *)__mptr - offsetof(type, member)); \ + }) +#endif #define container_of_null(ptr, type, member) \ ({ \ |