Convert "__auto_type" to "auto", defining a macro for "auto"

unless C23+ is in use.
 
 ---
  arch/nios2/include/asm/uaccess.h                      |  8 ++++----
  arch/x86/include/asm/bug.h                            |  2 +-
  arch/x86/include/asm/string_64.h                      |  6 +++---
  arch/x86/include/asm/uaccess_64.h                     |  2 +-
  fs/proc/inode.c                                       | 19 +++++++++----------
  include/linux/cleanup.h                               |  6 +++---
  include/linux/compiler.h                              |  2 +-
  include/linux/compiler_types.h                        | 13 +++++++++++++
  include/linux/minmax.h                                |  6 +++---
  .../testing/selftests/bpf/prog_tests/socket_helpers.h |  9 +++++++--
  tools/virtio/linux/compiler.h                         |  2 +-
  11 files changed, 46 insertions(+), 29 deletions(-)
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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"

arch/nios2/include/asm/uaccess.h

@@ -172,15 +172,15 @@ do {									\
 
 #define __put_user(x, ptr)						\
 ({									\
-	__auto_type __pu_ptr = (ptr);					\
+	auto __pu_ptr = (ptr);						\
-	typeof(*__pu_ptr) __pu_val = (typeof(*__pu_ptr))(x);		\
+	auto __pu_val = (typeof(*__pu_ptr))(x);				\
 	__put_user_common(__pu_val, __pu_ptr);				\
 })
 
 #define put_user(x, ptr)						\
 ({									\
-	__auto_type __pu_ptr = (ptr);					\
+	auto __pu_ptr = (ptr);						\
-	typeof(*__pu_ptr) __pu_val = (typeof(*__pu_ptr))(x);		\
+	auto __pu_val = (typeof(*__pu_ptr))(x);				\
 	access_ok(__pu_ptr, sizeof(*__pu_ptr)) ?			\
 		__put_user_common(__pu_val, __pu_ptr) :			\
 		-EFAULT;						\

arch/x86/include/asm/bug.h

@@ -129,7 +129,7 @@ do {								\
 
 #define __WARN_FLAGS(cond_str, flags)					\
 do {									\
-	__auto_type __flags = BUGFLAG_WARNING|(flags);			\
+	auto __flags = BUGFLAG_WARNING|(flags);				\
 	instrumentation_begin();					\
 	_BUG_FLAGS(cond_str, ASM_UD2, __flags, ARCH_WARN_REACHABLE);	\
 	instrumentation_end();						\

arch/x86/include/asm/string_64.h

@@ -31,7 +31,7 @@ KCFI_REFERENCE(__memset);
 #define __HAVE_ARCH_MEMSET16
 static inline void *memset16(uint16_t *s, uint16_t v, size_t n)
 {
-	const __auto_type s0 = s;
+	const auto s0 = s;
 	asm volatile (
 		"rep stosw"
 		: "+D" (s), "+c" (n)
@@ -44,7 +44,7 @@ static inline void *memset16(uint16_t *s, uint16_t v, size_t n)
 #define __HAVE_ARCH_MEMSET32
 static inline void *memset32(uint32_t *s, uint32_t v, size_t n)
 {
-	const __auto_type s0 = s;
+	const auto s0 = s;
 	asm volatile (
 		"rep stosl"
 		: "+D" (s), "+c" (n)
@@ -57,7 +57,7 @@ static inline void *memset32(uint32_t *s, uint32_t v, size_t n)
 #define __HAVE_ARCH_MEMSET64
 static inline void *memset64(uint64_t *s, uint64_t v, size_t n)
 {
-	const __auto_type s0 = s;
+	const auto s0 = s;
 	asm volatile (
 		"rep stosq"
 		: "+D" (s), "+c" (n)

arch/x86/include/asm/uaccess_64.h

@@ -72,7 +72,7 @@ static inline void __user *mask_user_address(const void __user *ptr)
 	return ret;
 }
 #define masked_user_access_begin(x) ({				\
-	__auto_type __masked_ptr = (x);				\
+	auto __masked_ptr = (x);				\
 	__masked_ptr = mask_user_address(__masked_ptr);		\
 	__uaccess_begin(); __masked_ptr; })
 

fs/proc/inode.c

@@ -303,7 +303,7 @@ static ssize_t proc_reg_read_iter(struct kiocb *iocb, struct iov_iter *iter)
 
 static ssize_t pde_read(struct proc_dir_entry *pde, struct file *file, char __user *buf, size_t count, loff_t *ppos)
 {
-	__auto_type read = pde->proc_ops->proc_read;
+	const auto read = pde->proc_ops->proc_read;
 	if (read)
 		return read(file, buf, count, ppos);
 	return -EIO;
@@ -325,7 +325,7 @@ static ssize_t proc_reg_read(struct file *file, char __user *buf, size_t count,
 
 static ssize_t pde_write(struct proc_dir_entry *pde, struct file *file, const char __user *buf, size_t count, loff_t *ppos)
 {
-	__auto_type write = pde->proc_ops->proc_write;
+	const auto write = pde->proc_ops->proc_write;
 	if (write)
 		return write(file, buf, count, ppos);
 	return -EIO;
@@ -347,7 +347,7 @@ static ssize_t proc_reg_write(struct file *file, const char __user *buf, size_t
 
 static __poll_t pde_poll(struct proc_dir_entry *pde, struct file *file, struct poll_table_struct *pts)
 {
-	__auto_type poll = pde->proc_ops->proc_poll;
+	const auto poll = pde->proc_ops->proc_poll;
 	if (poll)
 		return poll(file, pts);
 	return DEFAULT_POLLMASK;
@@ -369,7 +369,7 @@ static __poll_t proc_reg_poll(struct file *file, struct poll_table_struct *pts)
 
 static long pde_ioctl(struct proc_dir_entry *pde, struct file *file, unsigned int cmd, unsigned long arg)
 {
-	__auto_type ioctl = pde->proc_ops->proc_ioctl;
+	const auto ioctl = pde->proc_ops->proc_ioctl;
 	if (ioctl)
 		return ioctl(file, cmd, arg);
 	return -ENOTTY;
@@ -392,7 +392,7 @@ static long proc_reg_unlocked_ioctl(struct file *file, unsigned int cmd, unsigne
 #ifdef CONFIG_COMPAT
 static long pde_compat_ioctl(struct proc_dir_entry *pde, struct file *file, unsigned int cmd, unsigned long arg)
 {
-	__auto_type compat_ioctl = pde->proc_ops->proc_compat_ioctl;
+	const auto compat_ioctl = pde->proc_ops->proc_compat_ioctl;
 	if (compat_ioctl)
 		return compat_ioctl(file, cmd, arg);
 	return -ENOTTY;
@@ -414,7 +414,7 @@ static long proc_reg_compat_ioctl(struct file *file, unsigned int cmd, unsigned
 
 static int pde_mmap(struct proc_dir_entry *pde, struct file *file, struct vm_area_struct *vma)
 {
-	__auto_type mmap = pde->proc_ops->proc_mmap;
+	const auto mmap = pde->proc_ops->proc_mmap;
 	if (mmap)
 		return mmap(file, vma);
 	return -EIO;
@@ -497,7 +497,7 @@ static int proc_reg_open(struct inode *inode, struct file *file)
 	if (!use_pde(pde))
 		return -ENOENT;
 
-	__auto_type release = pde->proc_ops->proc_release;
+	const auto release = pde->proc_ops->proc_release;
 	if (release) {
 		pdeo = kmem_cache_alloc(pde_opener_cache, GFP_KERNEL);
 		if (!pdeo) {
@@ -534,10 +534,9 @@ static int proc_reg_release(struct inode *inode, struct file *file)
 	struct pde_opener *pdeo;
 
 	if (pde_is_permanent(pde)) {
-		__auto_type release = pde->proc_ops->proc_release;
+		const auto release = pde->proc_ops->proc_release;
-		if (release) {
+		if (release)
 			return release(inode, file);
-		}
 		return 0;
 	}
 

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 __ptr = &(p);	    \
-		__auto_type __val = *__ptr; \
+		auto __val = *__ptr;	    \
 		*__ptr = nullvalue;         \
 		__val;                      \
 	})

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;								\
 })

include/linux/compiler_types.h

@@ -17,6 +17,19 @@
 
 #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.

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

tools/testing/selftests/bpf/prog_tests/socket_helpers.h

@@ -17,11 +17,16 @@
 #define VMADDR_CID_LOCAL 1
 #endif
 
+/* include/linux/compiler_types.h */
+#if __STDC_VERSION__ < 202311L && !defined(auto)
+# define auto __auto_type
+#endif
+
 /* include/linux/cleanup.h */
 #define __get_and_null(p, nullvalue)                                           \
 	({                                                                     \
-		__auto_type __ptr = &(p);                                      \
+		auto __ptr = &(p);					       \
-		__auto_type __val = *__ptr;                                    \
+		auto __val = *__ptr;                                           \
 		*__ptr = nullvalue;                                            \
 		__val;                                                         \
 	})

tools/virtio/linux/compiler.h

@@ -31,7 +31,7 @@
  */
 #define data_race(expr)							\
 ({									\
-	__auto_type __v = (expr);					\
+	auto __v = (expr);						\
 	__v;								\
 })