Merge tag 'auto-type-conversion-for-v6.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/hpa/linux-auto

Pull __auto_type to auto conversion from Peter Anvin:
 "Convert '__auto_type' to 'auto', defining a macro for 'auto' unless
  C23+ is in use"

* tag 'auto-type-conversion-for-v6.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/hpa/linux-auto:
  tools/virtio: replace "__auto_type" with "auto"
  selftests/bpf: replace "__auto_type" with "auto"
  arch/x86: replace "__auto_type" with "auto"
  arch/nios2: replace "__auto_type" and adjacent equivalent with "auto"
  fs/proc: replace "__auto_type" with "const auto"
  include/linux: change "__auto_type" to "auto"
  compiler_types.h: add "auto" as a macro for "__auto_type"

4 files changed, 20 insertions, 7 deletions

diff --git a/include/linux/cleanup.h b/include/linux/cleanup.h
index 0b55a8f6c59e..8d41b917c77d 100644
--- a/include/linux/cleanup.h
+++ b/include/linux/cleanup.h
@@ -212,10 +212,10 @@
 
 #define __free(_name)	__cleanup(__free_##_name)
 
-#define __get_and_null(p, nullvalue)   \
+#define __get_and_null(p, nullvalue)	    \
 	({                                  \
-		__auto_type __ptr = &(p);   \
-		__auto_type __val = *__ptr; \
+		auto __ptr = &(p);	    \
+		auto __val = *__ptr;	    \
 		*__ptr = nullvalue;         \
 		__val;                      \
 	})
diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index ff71bebe56f5..04487c9bd751 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -190,7 +190,7 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
 #define data_race(expr)							\
 ({									\
 	__kcsan_disable_current();					\
-	__auto_type __v = (expr);					\
+	auto __v = (expr);						\
 	__kcsan_enable_current();					\
 	__v;								\
 })
diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h
index 45875903960e..1280693766b9 100644
--- a/include/linux/compiler_types.h
+++ b/include/linux/compiler_types.h
@@ -18,6 +18,19 @@
 #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.
  */
diff --git a/include/linux/minmax.h b/include/linux/minmax.h
index eaaf5c008e4d..a0158db54a04 100644
--- a/include/linux/minmax.h
+++ b/include/linux/minmax.h
@@ -89,7 +89,7 @@
 	__cmp_once_unique(op, type, x, y, __UNIQUE_ID(x_), __UNIQUE_ID(y_))
 
 #define __careful_cmp_once(op, x, y, ux, uy) ({		\
-	__auto_type ux = (x); __auto_type uy = (y);	\
+	auto ux = (x); auto uy = (y);			\
 	BUILD_BUG_ON_MSG(!__types_ok(ux, uy),		\
 		#op"("#x", "#y") signedness error");	\
 	__cmp(op, ux, uy); })
@@ -129,7 +129,7 @@
 	__careful_cmp(max, (x) + 0u + 0ul + 0ull, (y) + 0u + 0ul + 0ull)
 
 #define __careful_op3(op, x, y, z, ux, uy, uz) ({			\
-	__auto_type ux = (x); __auto_type uy = (y);__auto_type uz = (z);\
+	auto ux = (x); auto uy = (y); auto uz = (z);			\
 	BUILD_BUG_ON_MSG(!__types_ok3(ux, uy, uz),			\
 		#op"3("#x", "#y", "#z") signedness error");		\
 	__cmp(op, ux, __cmp(op, uy, uz)); })
@@ -203,7 +203,7 @@
  * This macro checks @val/@lo/@hi to make sure they have compatible
  * signedness.
  */
-#define clamp(val, lo, hi) __careful_clamp(__auto_type, val, lo, hi)
+#define clamp(val, lo, hi) __careful_clamp(auto, val, lo, hi)
 
 /**
  * clamp_t - return a value clamped to a given range using a given type