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| author | H. Peter Anvin <hpa@zytor.com> | 2025-07-18 11:35:00 -0700 |
|---|---|---|
| committer | H. Peter Anvin <hpa@zytor.com> | 2025-12-08 15:32:14 -0800 |
| commit | 2fb6915fa22dc5524d704afba58a13305dd9f533 (patch) | |
| tree | ff980b6be9cce4c46163a59d2647120c01de3ba2 | |
| parent | c2f2b01b74be8b40a2173372bcd770723f87e7b2 (diff) | |
| download | tip-2fb6915fa22dc5524d704afba58a13305dd9f533.tar.gz | |
compiler_types.h: add "auto" as a macro for "__auto_type"
"auto" was defined as a keyword back in the K&R days, but as a storage
type specifier. No one ever used it, since it was and is the default
storage type for local variables.
C++11 recycled the keyword to allow a type to be declared based on the
type of an initializer. This was finally adopted into standard C in
C23.
gcc and clang provide the "__auto_type" alias keyword as an extension
for pre-C23, however, there is no reason to pollute the bulk of the
source base with this temporary keyword; instead define "auto" as a
macro unless the compiler is running in C23+ mode.
This macro is added in <linux/compiler_types.h> because that header is
included in some of the tools headers, wheres <linux/compiler.h> is
not as it has a bunch of very kernel-specific things in it.
[ Cc: stable to reduce potential backporting burden. ]
Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com>
Acked-by: Miguel Ojeda <ojeda@kernel.org>
Cc: <stable@kernel.org>
| -rw-r--r-- | include/linux/compiler_types.h | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h index 3eac51d6842614..41172a28ce76d6 100644 --- a/include/linux/compiler_types.h +++ b/include/linux/compiler_types.h @@ -14,6 +14,19 @@ #ifndef __ASSEMBLY__ /* + * C23 introduces "auto" as a standard way to define type-inferred + * variables, but "auto" has been a (useless) keyword even since K&R C, + * so it has always been "namespace reserved." + * + * Until at some future time we require C23 support, we need the gcc + * extension __auto_type, but there is no reason to put that elsewhere + * in the source code. + */ +#if __STDC_VERSION__ < 202311L +# define auto __auto_type +#endif + +/* * Skipped when running bindgen due to a libclang issue; * see https://github.com/rust-lang/rust-bindgen/issues/2244. */ |