diff --git a/library/core/src/ffi/va_list.rs b/library/core/src/ffi/va_list.rs
index ca211fca1551..020ea4513078 100644
--- a/library/core/src/ffi/va_list.rs
+++ b/library/core/src/ffi/va_list.rs
@@ -204,7 +204,7 @@ struct VaListInner {
 /// unsafe fn vmy_func(count: u32, mut ap: VaList<'_>) -> i32 {
 ///     let mut sum = 0;
 ///     for _ in 0..count {
-///         sum += unsafe { ap.arg::<i32>() };
+///         sum += unsafe { ap.next_arg::<i32>() };
 ///     }
 ///     sum
 /// }
@@ -213,7 +213,7 @@ struct VaListInner {
 /// assert_eq!(unsafe { my_func(3, 42i32, -7i32, 20i32) }, 55);
 /// ```
 ///
-/// The [`VaList::arg`] method reads the next argument from the variable argument list,
+/// The [`VaList::next_arg`] method reads the next argument from the variable argument list,
 /// and is equivalent to C `va_arg`.
 ///
 /// Cloning a `VaList` performs the equivalent of C `va_copy`, producing an independent cursor
@@ -284,7 +284,7 @@ impl<T> Sealed for *mut T {}
     impl<T> Sealed for *const T {}
 }
 
-/// Types that are valid to read using [`VaList::arg`].
+/// Types that are valid to read using [`VaList::next_arg`].
 ///
 /// This trait is implemented for primitive types that have a variable argument application-binary
 /// interface (ABI) on the current platform. It is always implemented for:
@@ -391,7 +391,7 @@ impl<'f> VaList<'f> {
     /// are no more variable arguments, is unsound.
     #[inline] // Avoid codegen when not used to help backends that don't support VaList.
     #[rustc_const_unstable(feature = "const_c_variadic", issue = "151787")]
-    pub const unsafe fn arg<T: VaArgSafe>(&mut self) -> T {
+    pub const unsafe fn next_arg<T: VaArgSafe>(&mut self) -> T {
         // SAFETY: the caller must uphold the safety contract for `va_arg`.
         unsafe { va_arg(self) }
     }
diff --git a/src/doc/unstable-book/src/language-features/c-variadic.md b/src/doc/unstable-book/src/language-features/c-variadic.md
index 001c1bfa9ec0..72980ea91ba2 100644
--- a/src/doc/unstable-book/src/language-features/c-variadic.md
+++ b/src/doc/unstable-book/src/language-features/c-variadic.md
@@ -17,7 +17,7 @@ defined in Rust. They may be called both from within Rust and via FFI.
 pub unsafe extern "C" fn add(n: usize, mut args: ...) -> usize {
     let mut sum = 0;
     for _ in 0..n {
-        sum += args.arg::<usize>();
+        sum += args.next_arg::<usize>();
     }
     sum
 }
diff --git a/src/tools/miri/tests/fail/c-variadic.rs b/src/tools/miri/tests/fail/c-variadic.rs
index 38141c23d08d..d36dccec8d8d 100644
--- a/src/tools/miri/tests/fail/c-variadic.rs
+++ b/src/tools/miri/tests/fail/c-variadic.rs
@@ -4,7 +4,7 @@
 
 fn read_too_many() {
     unsafe extern "C" fn variadic(mut ap: ...) {
-        ap.arg::<i32>();
+        ap.next_arg::<i32>();
     }
 
     unsafe { variadic() };
diff --git a/src/tools/miri/tests/fail/c-variadic.stderr b/src/tools/miri/tests/fail/c-variadic.stderr
index 31695f1cab49..af145b0ed1e7 100644
--- a/src/tools/miri/tests/fail/c-variadic.stderr
+++ b/src/tools/miri/tests/fail/c-variadic.stderr
@@ -7,7 +7,7 @@ LL |         unsafe { va_arg(self) }
    = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
    = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
    = note: stack backtrace:
-           0: std::ffi::VaList::<'_>::arg
+           0: std::ffi::VaList::<'_>::next_arg
                at RUSTLIB/core/src/ffi/va_list.rs:LL:CC
            1: read_too_many::variadic
                at tests/fail/c-variadic.rs:LL:CC
diff --git a/src/tools/miri/tests/pass/c-variadic-ignored-argument.rs b/src/tools/miri/tests/pass/c-variadic-ignored-argument.rs
index b41e1b0f076a..fe09a03edfff 100644
--- a/src/tools/miri/tests/pass/c-variadic-ignored-argument.rs
+++ b/src/tools/miri/tests/pass/c-variadic-ignored-argument.rs
@@ -13,8 +13,8 @@
 
 fn main() {
     unsafe extern "C" fn variadic(mut ap: ...) {
-        ap.arg::<i32>();
-        ap.arg::<i32>();
+        ap.next_arg::<i32>();
+        ap.next_arg::<i32>();
     }
 
     unsafe { variadic(0i32, (), 1i32) }
diff --git a/src/tools/miri/tests/pass/c-variadic.rs b/src/tools/miri/tests/pass/c-variadic.rs
index 8b353885699e..61ff1303f328 100644
--- a/src/tools/miri/tests/pass/c-variadic.rs
+++ b/src/tools/miri/tests/pass/c-variadic.rs
@@ -11,7 +11,7 @@ fn ignores_arguments() {
 
 fn echo() {
     unsafe extern "C" fn variadic(mut ap: ...) -> i32 {
-        ap.arg()
+        ap.next_arg()
     }
 
     assert_eq!(unsafe { variadic(1) }, 1);
@@ -20,7 +20,7 @@ fn echo() {
 
 fn forward_by_val() {
     unsafe fn helper(mut ap: VaList) -> i32 {
-        ap.arg()
+        ap.next_arg()
     }
 
     unsafe extern "C" fn variadic(ap: ...) -> i32 {
@@ -33,7 +33,7 @@ unsafe fn helper(mut ap: VaList) -> i32 {
 
 fn forward_by_ref() {
     unsafe fn helper(ap: &mut VaList) -> i32 {
-        ap.arg()
+        ap.next_arg()
     }
 
     unsafe extern "C" fn variadic(mut ap: ...) -> i32 {
@@ -47,7 +47,7 @@ unsafe fn helper(ap: &mut VaList) -> i32 {
 #[allow(improper_ctypes_definitions)]
 fn nested() {
     unsafe fn helper(mut ap1: VaList, mut ap2: VaList) -> (i32, i32) {
-        (ap1.arg(), ap2.arg())
+        (ap1.next_arg(), ap2.next_arg())
     }
 
     unsafe extern "C" fn variadic2(ap1: VaList, ap2: ...) -> (i32, i32) {
@@ -83,13 +83,13 @@ unsafe fn compare_c_str(ptr: *const c_char, val: &str) -> bool {
             }
         }
 
-        continue_if!(ap.arg::<c_double>().floor() == 3.14f64.floor());
-        continue_if!(ap.arg::<c_long>() == 12);
-        continue_if!(ap.arg::<c_int>() == 'a' as c_int);
-        continue_if!(ap.arg::<c_double>().floor() == 6.18f64.floor());
-        continue_if!(compare_c_str(ap.arg::<*const c_char>(), "Hello"));
-        continue_if!(ap.arg::<c_int>() == 42);
-        continue_if!(compare_c_str(ap.arg::<*const c_char>(), "World"));
+        continue_if!(ap.next_arg::<c_double>().floor() == 3.14f64.floor());
+        continue_if!(ap.next_arg::<c_long>() == 12);
+        continue_if!(ap.next_arg::<c_int>() == 'a' as c_int);
+        continue_if!(ap.next_arg::<c_double>().floor() == 6.18f64.floor());
+        continue_if!(compare_c_str(ap.next_arg::<*const c_char>(), "Hello"));
+        continue_if!(ap.next_arg::<c_int>() == 42);
+        continue_if!(compare_c_str(ap.next_arg::<*const c_char>(), "World"));
     }
 
     unsafe {
diff --git a/tests/assembly-llvm/c-variadic-arm.rs b/tests/assembly-llvm/c-variadic-arm.rs
index 2ef307405e13..1cfc115badee 100644
--- a/tests/assembly-llvm/c-variadic-arm.rs
+++ b/tests/assembly-llvm/c-variadic-arm.rs
@@ -18,8 +18,8 @@
     // CHECK: vadd.f64
     // CHECK: vldr
     // CHECK: vadd.f64
-    let b = args.arg::<f64>();
-    let c = args.arg::<f64>();
+    let b = args.next_arg::<f64>();
+    let c = args.next_arg::<f64>();
     a + b + c
 
     // CHECK: add sp, sp
diff --git a/tests/codegen-llvm/c-variadic-lifetime.rs b/tests/codegen-llvm/c-variadic-lifetime.rs
index fa38fbbc5381..302bc621df49 100644
--- a/tests/codegen-llvm/c-variadic-lifetime.rs
+++ b/tests/codegen-llvm/c-variadic-lifetime.rs
@@ -11,8 +11,8 @@
     // CHECK: call void @llvm.lifetime.start.p0({{(i64 [0-9]+, )?}}ptr nonnull %args)
     // CHECK: call void @llvm.va_start.p0(ptr nonnull %args)
 
-    let b = args.arg::<f64>();
-    let c = args.arg::<f64>();
+    let b = args.next_arg::<f64>();
+    let c = args.next_arg::<f64>();
 
     a + b + c
 
diff --git a/tests/codegen-llvm/cffi/c-variadic-inline.rs b/tests/codegen-llvm/cffi/c-variadic-inline.rs
index 369b7e571cab..0df5bd4a55b5 100644
--- a/tests/codegen-llvm/cffi/c-variadic-inline.rs
+++ b/tests/codegen-llvm/cffi/c-variadic-inline.rs
@@ -8,22 +8,22 @@
 
 #[inline(always)]
 unsafe extern "C" fn inline_always(mut ap: ...) -> u32 {
-    ap.arg::<u32>()
+    ap.next_arg::<u32>()
 }
 
 #[inline]
 unsafe extern "C" fn inline(mut ap: ...) -> u32 {
-    ap.arg::<u32>()
+    ap.next_arg::<u32>()
 }
 
 #[inline(never)]
 unsafe extern "C" fn inline_never(mut ap: ...) -> u32 {
-    ap.arg::<u32>()
+    ap.next_arg::<u32>()
 }
 
 #[cold]
 unsafe extern "C" fn cold(mut ap: ...) -> u32 {
-    ap.arg::<u32>()
+    ap.next_arg::<u32>()
 }
 
 #[unsafe(no_mangle)]
diff --git a/tests/codegen-llvm/cffi/c-variadic.rs b/tests/codegen-llvm/cffi/c-variadic.rs
index 5df256961de5..0fa63b42c2de 100644
--- a/tests/codegen-llvm/cffi/c-variadic.rs
+++ b/tests/codegen-llvm/cffi/c-variadic.rs
@@ -28,7 +28,7 @@
     // CHECK: call void @llvm.va_start
     let mut sum = 0;
     for _ in 0..n {
-        sum += ap.arg::<i32>();
+        sum += ap.next_arg::<i32>();
     }
     sum
     // CHECK: call void @llvm.va_end
diff --git a/tests/mir-opt/inline/inline_compatibility.rs b/tests/mir-opt/inline/inline_compatibility.rs
index 2b8280a3cfb0..a894bdf76842 100644
--- a/tests/mir-opt/inline/inline_compatibility.rs
+++ b/tests/mir-opt/inline/inline_compatibility.rs
@@ -70,7 +70,7 @@ pub unsafe fn not_inlined_c_variadic() {
     let mut s = 0;
     let mut i = 0;
     while i != n {
-        s += vs.arg::<u32>();
+        s += vs.next_arg::<u32>();
         i += 1;
     }
     s
diff --git a/tests/pretty/fn-variadic.rs b/tests/pretty/fn-variadic.rs
index e11ec9bcdcbb..88eecee6e380 100644
--- a/tests/pretty/fn-variadic.rs
+++ b/tests/pretty/fn-variadic.rs
@@ -9,7 +9,7 @@
 }
 
 pub unsafe extern "C" fn bar(_: i32, mut ap: ...) -> usize {
-    ap.arg::<usize>()
+    ap.next_arg::<usize>()
 }
 
 fn main() {}
diff --git a/tests/pretty/hir-fn-variadic.pp b/tests/pretty/hir-fn-variadic.pp
index 30423349241b..50ad30f7cc6c 100644
--- a/tests/pretty/hir-fn-variadic.pp
+++ b/tests/pretty/hir-fn-variadic.pp
@@ -11,7 +11,8 @@ extern "C" {
     unsafe fn foo(x: i32, va1: ...);
 }
 
-unsafe extern "C" fn bar(_: i32, mut va2: ...) -> usize { va2.arg::<usize>() }
+unsafe extern "C" fn bar(_: i32, mut va2: ...)
+    -> usize { va2.next_arg::<usize>() }
 
 fn main() {
     fn g1(_: extern "C" fn(_: u8, va: ...)) { }
diff --git a/tests/pretty/hir-fn-variadic.rs b/tests/pretty/hir-fn-variadic.rs
index ce1b0f835ab2..4daf8d9aeb52 100644
--- a/tests/pretty/hir-fn-variadic.rs
+++ b/tests/pretty/hir-fn-variadic.rs
@@ -9,7 +9,7 @@
 }
 
 pub unsafe extern "C" fn bar(_: i32, mut va2: ...) -> usize {
-    va2.arg::<usize>()
+    va2.next_arg::<usize>()
 }
 
 fn main() {
@@ -21,9 +21,17 @@ fn g4(_: extern "C" fn(u8, _: ...)) {}
     fn g5(_: extern "C" fn(va: ...)) {}
     fn g6(_: extern "C" fn(_: ...)) {}
 
-    _ = { unsafe extern "C" fn f1(_: u8, va: ...) {} };
-    _ = { unsafe extern "C" fn f2(_: u8, _: ...) {} };
+    _ = {
+        unsafe extern "C" fn f1(_: u8, va: ...) {}
+    };
+    _ = {
+        unsafe extern "C" fn f2(_: u8, _: ...) {}
+    };
 
-    _ = { unsafe extern "C" fn f5(va: ...) {} };
-    _ = { unsafe extern "C" fn f6(_: ...) {} };
+    _ = {
+        unsafe extern "C" fn f5(va: ...) {}
+    };
+    _ = {
+        unsafe extern "C" fn f6(_: ...) {}
+    };
 }
diff --git a/tests/run-make/c-link-to-rust-va-list-fn/checkrust.rs b/tests/run-make/c-link-to-rust-va-list-fn/checkrust.rs
index 109fbb1c6203..f3d82474e94a 100644
--- a/tests/run-make/c-link-to-rust-va-list-fn/checkrust.rs
+++ b/tests/run-make/c-link-to-rust-va-list-fn/checkrust.rs
@@ -17,59 +17,59 @@ unsafe fn compare_c_str(ptr: *const c_char, val: &CStr) -> bool {
 
 #[unsafe(no_mangle)]
 pub unsafe extern "C" fn check_list_0(mut ap: VaList) -> usize {
-    continue_if!(ap.arg::<c_longlong>() == 1);
-    continue_if!(ap.arg::<c_int>() == 2);
-    continue_if!(ap.arg::<c_longlong>() == 3);
+    continue_if!(ap.next_arg::<c_longlong>() == 1);
+    continue_if!(ap.next_arg::<c_int>() == 2);
+    continue_if!(ap.next_arg::<c_longlong>() == 3);
     0
 }
 
 #[unsafe(no_mangle)]
 pub unsafe extern "C" fn check_list_1(mut ap: VaList) -> usize {
-    continue_if!(ap.arg::<c_int>() == -1);
-    continue_if!(ap.arg::<c_int>() == 'A' as c_int);
-    continue_if!(ap.arg::<c_int>() == '4' as c_int);
-    continue_if!(ap.arg::<c_int>() == ';' as c_int);
-    continue_if!(ap.arg::<c_int>() == 0x32);
-    continue_if!(ap.arg::<i32>() == 0x10000001);
-    continue_if!(compare_c_str(ap.arg::<*const c_char>(), c"Valid!"));
+    continue_if!(ap.next_arg::<c_int>() == -1);
+    continue_if!(ap.next_arg::<c_int>() == 'A' as c_int);
+    continue_if!(ap.next_arg::<c_int>() == '4' as c_int);
+    continue_if!(ap.next_arg::<c_int>() == ';' as c_int);
+    continue_if!(ap.next_arg::<c_int>() == 0x32);
+    continue_if!(ap.next_arg::<i32>() == 0x10000001);
+    continue_if!(compare_c_str(ap.next_arg::<*const c_char>(), c"Valid!"));
     0
 }
 
 #[unsafe(no_mangle)]
 pub unsafe extern "C" fn check_list_2(mut ap: VaList) -> usize {
-    continue_if!(ap.arg::<c_double>() == 3.14);
-    continue_if!(ap.arg::<c_long>() == 12);
-    continue_if!(ap.arg::<c_int>() == 'a' as c_int);
-    continue_if!(ap.arg::<c_double>() == 6.28);
-    continue_if!(compare_c_str(ap.arg::<*const c_char>(), c"Hello"));
-    continue_if!(ap.arg::<c_int>() == 42);
-    continue_if!(compare_c_str(ap.arg::<*const c_char>(), c"World"));
+    continue_if!(ap.next_arg::<c_double>() == 3.14);
+    continue_if!(ap.next_arg::<c_long>() == 12);
+    continue_if!(ap.next_arg::<c_int>() == 'a' as c_int);
+    continue_if!(ap.next_arg::<c_double>() == 6.28);
+    continue_if!(compare_c_str(ap.next_arg::<*const c_char>(), c"Hello"));
+    continue_if!(ap.next_arg::<c_int>() == 42);
+    continue_if!(compare_c_str(ap.next_arg::<*const c_char>(), c"World"));
     0
 }
 
 #[unsafe(no_mangle)]
 pub unsafe extern "C" fn check_list_copy_0(mut ap: VaList) -> usize {
-    continue_if!(ap.arg::<c_double>() == 6.28);
-    continue_if!(ap.arg::<c_int>() == 16);
-    continue_if!(ap.arg::<c_int>() == 'A' as c_int);
-    continue_if!(compare_c_str(ap.arg::<*const c_char>(), c"Skip Me!"));
+    continue_if!(ap.next_arg::<c_double>() == 6.28);
+    continue_if!(ap.next_arg::<c_int>() == 16);
+    continue_if!(ap.next_arg::<c_int>() == 'A' as c_int);
+    continue_if!(compare_c_str(ap.next_arg::<*const c_char>(), c"Skip Me!"));
     let mut ap = ap.clone();
-    if compare_c_str(ap.arg::<*const c_char>(), c"Correct") { 0 } else { 0xff }
+    if compare_c_str(ap.next_arg::<*const c_char>(), c"Correct") { 0 } else { 0xff }
 }
 
 #[unsafe(no_mangle)]
 pub unsafe extern "C" fn check_varargs_0(_: c_int, mut ap: ...) -> usize {
-    continue_if!(ap.arg::<c_int>() == 42);
-    continue_if!(compare_c_str(ap.arg::<*const c_char>(), c"Hello, World!"));
+    continue_if!(ap.next_arg::<c_int>() == 42);
+    continue_if!(compare_c_str(ap.next_arg::<*const c_char>(), c"Hello, World!"));
     0
 }
 
 #[unsafe(no_mangle)]
 pub unsafe extern "C" fn check_varargs_1(_: c_int, mut ap: ...) -> usize {
-    continue_if!(ap.arg::<c_double>() == 3.14);
-    continue_if!(ap.arg::<c_long>() == 12);
-    continue_if!(ap.arg::<c_int>() == 'A' as c_int);
-    continue_if!(ap.arg::<c_longlong>() == 1);
+    continue_if!(ap.next_arg::<c_double>() == 3.14);
+    continue_if!(ap.next_arg::<c_long>() == 12);
+    continue_if!(ap.next_arg::<c_int>() == 'A' as c_int);
+    continue_if!(ap.next_arg::<c_longlong>() == 1);
     0
 }
 
@@ -80,65 +80,65 @@ unsafe fn compare_c_str(ptr: *const c_char, val: &CStr) -> bool {
 
 #[unsafe(no_mangle)]
 pub unsafe extern "C" fn check_varargs_3(_: c_int, mut ap: ...) -> usize {
-    continue_if!(ap.arg::<c_int>() == 1);
-    continue_if!(ap.arg::<c_int>() == 2);
-    continue_if!(ap.arg::<c_int>() == 3);
-    continue_if!(ap.arg::<c_int>() == 4);
-    continue_if!(ap.arg::<c_int>() == 5);
-    continue_if!(ap.arg::<c_int>() == 6);
-    continue_if!(ap.arg::<c_int>() == 7);
-    continue_if!(ap.arg::<c_int>() == 8);
-    continue_if!(ap.arg::<c_int>() == 9);
-    continue_if!(ap.arg::<c_int>() == 10);
+    continue_if!(ap.next_arg::<c_int>() == 1);
+    continue_if!(ap.next_arg::<c_int>() == 2);
+    continue_if!(ap.next_arg::<c_int>() == 3);
+    continue_if!(ap.next_arg::<c_int>() == 4);
+    continue_if!(ap.next_arg::<c_int>() == 5);
+    continue_if!(ap.next_arg::<c_int>() == 6);
+    continue_if!(ap.next_arg::<c_int>() == 7);
+    continue_if!(ap.next_arg::<c_int>() == 8);
+    continue_if!(ap.next_arg::<c_int>() == 9);
+    continue_if!(ap.next_arg::<c_int>() == 10);
     0
 }
 
 #[unsafe(no_mangle)]
 pub unsafe extern "C" fn check_varargs_4(_: c_double, mut ap: ...) -> usize {
-    continue_if!(ap.arg::<c_double>() == 1.0);
-    continue_if!(ap.arg::<c_double>() == 2.0);
-    continue_if!(ap.arg::<c_double>() == 3.0);
-    continue_if!(ap.arg::<c_double>() == 4.0);
-    continue_if!(ap.arg::<c_double>() == 5.0);
-    continue_if!(ap.arg::<c_double>() == 6.0);
-    continue_if!(ap.arg::<c_double>() == 7.0);
-    continue_if!(ap.arg::<c_double>() == 8.0);
-    continue_if!(ap.arg::<c_double>() == 9.0);
-    continue_if!(ap.arg::<c_double>() == 10.0);
-    continue_if!(ap.arg::<c_double>() == 11.0);
-    continue_if!(ap.arg::<c_double>() == 12.0);
-    continue_if!(ap.arg::<c_double>() == 13.0);
+    continue_if!(ap.next_arg::<c_double>() == 1.0);
+    continue_if!(ap.next_arg::<c_double>() == 2.0);
+    continue_if!(ap.next_arg::<c_double>() == 3.0);
+    continue_if!(ap.next_arg::<c_double>() == 4.0);
+    continue_if!(ap.next_arg::<c_double>() == 5.0);
+    continue_if!(ap.next_arg::<c_double>() == 6.0);
+    continue_if!(ap.next_arg::<c_double>() == 7.0);
+    continue_if!(ap.next_arg::<c_double>() == 8.0);
+    continue_if!(ap.next_arg::<c_double>() == 9.0);
+    continue_if!(ap.next_arg::<c_double>() == 10.0);
+    continue_if!(ap.next_arg::<c_double>() == 11.0);
+    continue_if!(ap.next_arg::<c_double>() == 12.0);
+    continue_if!(ap.next_arg::<c_double>() == 13.0);
     0
 }
 
 #[unsafe(no_mangle)]
 pub unsafe extern "C" fn check_varargs_5(_: c_int, mut ap: ...) -> usize {
-    continue_if!(ap.arg::<c_double>() == 1.0);
-    continue_if!(ap.arg::<c_int>() == 1);
-    continue_if!(ap.arg::<c_double>() == 2.0);
-    continue_if!(ap.arg::<c_int>() == 2);
-    continue_if!(ap.arg::<c_double>() == 3.0);
-    continue_if!(ap.arg::<c_int>() == 3);
-    continue_if!(ap.arg::<c_double>() == 4.0);
-    continue_if!(ap.arg::<c_int>() == 4);
-    continue_if!(ap.arg::<c_int>() == 5);
-    continue_if!(ap.arg::<c_double>() == 5.0);
-    continue_if!(ap.arg::<c_int>() == 6);
-    continue_if!(ap.arg::<c_double>() == 6.0);
-    continue_if!(ap.arg::<c_int>() == 7);
-    continue_if!(ap.arg::<c_double>() == 7.0);
-    continue_if!(ap.arg::<c_int>() == 8);
-    continue_if!(ap.arg::<c_double>() == 8.0);
-    continue_if!(ap.arg::<c_int>() == 9);
-    continue_if!(ap.arg::<c_double>() == 9.0);
-    continue_if!(ap.arg::<c_int>() == 10);
-    continue_if!(ap.arg::<c_double>() == 10.0);
-    continue_if!(ap.arg::<c_int>() == 11);
-    continue_if!(ap.arg::<c_double>() == 11.0);
-    continue_if!(ap.arg::<c_int>() == 12);
-    continue_if!(ap.arg::<c_double>() == 12.0);
-    continue_if!(ap.arg::<c_int>() == 13);
-    continue_if!(ap.arg::<c_double>() == 13.0);
+    continue_if!(ap.next_arg::<c_double>() == 1.0);
+    continue_if!(ap.next_arg::<c_int>() == 1);
+    continue_if!(ap.next_arg::<c_double>() == 2.0);
+    continue_if!(ap.next_arg::<c_int>() == 2);
+    continue_if!(ap.next_arg::<c_double>() == 3.0);
+    continue_if!(ap.next_arg::<c_int>() == 3);
+    continue_if!(ap.next_arg::<c_double>() == 4.0);
+    continue_if!(ap.next_arg::<c_int>() == 4);
+    continue_if!(ap.next_arg::<c_int>() == 5);
+    continue_if!(ap.next_arg::<c_double>() == 5.0);
+    continue_if!(ap.next_arg::<c_int>() == 6);
+    continue_if!(ap.next_arg::<c_double>() == 6.0);
+    continue_if!(ap.next_arg::<c_int>() == 7);
+    continue_if!(ap.next_arg::<c_double>() == 7.0);
+    continue_if!(ap.next_arg::<c_int>() == 8);
+    continue_if!(ap.next_arg::<c_double>() == 8.0);
+    continue_if!(ap.next_arg::<c_int>() == 9);
+    continue_if!(ap.next_arg::<c_double>() == 9.0);
+    continue_if!(ap.next_arg::<c_int>() == 10);
+    continue_if!(ap.next_arg::<c_double>() == 10.0);
+    continue_if!(ap.next_arg::<c_int>() == 11);
+    continue_if!(ap.next_arg::<c_double>() == 11.0);
+    continue_if!(ap.next_arg::<c_int>() == 12);
+    continue_if!(ap.next_arg::<c_double>() == 12.0);
+    continue_if!(ap.next_arg::<c_int>() == 13);
+    continue_if!(ap.next_arg::<c_double>() == 13.0);
     0
 }
 
diff --git a/tests/ui/abi/variadic-ffi.rs b/tests/ui/abi/variadic-ffi.rs
index 3ffa0bea0ecf..42ff8d0dbb36 100644
--- a/tests/ui/abi/variadic-ffi.rs
+++ b/tests/ui/abi/variadic-ffi.rs
@@ -28,20 +28,20 @@
 
     // Advance one pair in the copy before checking
     let mut ap2 = ap.clone();
-    let _ = ap2.arg::<u64>();
-    let _ = ap2.arg::<f64>();
+    let _ = ap2.next_arg::<u64>();
+    let _ = ap2.next_arg::<f64>();
     assert_eq!(rust_valist_interesting_average(2, ap2) as i64, 50);
 
     // Advance one pair in the original
-    let _ = ap.arg::<u64>();
-    let _ = ap.arg::<f64>();
+    let _ = ap.next_arg::<u64>();
+    let _ = ap.next_arg::<f64>();
 
     let ap2 = ap.clone();
     assert_eq!(rust_valist_interesting_average(2, ap2) as i64, 50);
 
     let mut ap2 = ap.clone();
-    let _ = ap2.arg::<u64>();
-    let _ = ap2.arg::<f64>();
+    let _ = ap2.next_arg::<u64>();
+    let _ = ap2.next_arg::<f64>();
     assert_eq!(rust_valist_interesting_average(2, ap2) as i64, 70);
 }
 
diff --git a/tests/ui/c-variadic/copy.rs b/tests/ui/c-variadic/copy.rs
index e9171738aa15..5f3ec25581c9 100644
--- a/tests/ui/c-variadic/copy.rs
+++ b/tests/ui/c-variadic/copy.rs
@@ -13,12 +13,12 @@ fn main() {
 unsafe extern "C" fn variadic(mut ap1: ...) {
     let mut ap2 = ap1.clone();
 
-    assert_eq!(ap1.arg::<i32>(), 1);
-    assert_eq!(ap2.arg::<i32>(), 1);
+    assert_eq!(ap1.next_arg::<i32>(), 1);
+    assert_eq!(ap2.next_arg::<i32>(), 1);
 
-    assert_eq!(ap2.arg::<i32>(), 2);
-    assert_eq!(ap1.arg::<i32>(), 2);
+    assert_eq!(ap2.next_arg::<i32>(), 2);
+    assert_eq!(ap1.next_arg::<i32>(), 2);
 
     drop(ap1);
-    assert_eq!(ap2.arg::<i32>(), 3);
+    assert_eq!(ap2.next_arg::<i32>(), 3);
 }
diff --git a/tests/ui/c-variadic/inherent-method.rs b/tests/ui/c-variadic/inherent-method.rs
index c5256aaa1fea..c71e57816c82 100644
--- a/tests/ui/c-variadic/inherent-method.rs
+++ b/tests/ui/c-variadic/inherent-method.rs
@@ -7,23 +7,23 @@
 
 impl S {
     unsafe extern "C" fn associated_function(mut ap: ...) -> i32 {
-        unsafe { ap.arg() }
+        unsafe { ap.next_arg() }
     }
 
     unsafe extern "C" fn method_owned(self, mut ap: ...) -> i32 {
-        self.0 + unsafe { ap.arg::<i32>() }
+        self.0 + unsafe { ap.next_arg::<i32>() }
     }
 
     unsafe extern "C" fn method_ref(&self, mut ap: ...) -> i32 {
-        self.0 + unsafe { ap.arg::<i32>() }
+        self.0 + unsafe { ap.next_arg::<i32>() }
     }
 
     unsafe extern "C" fn method_mut(&mut self, mut ap: ...) -> i32 {
-        self.0 + unsafe { ap.arg::<i32>() }
+        self.0 + unsafe { ap.next_arg::<i32>() }
     }
 
     unsafe extern "C" fn fat_pointer(self: Box<Self>, mut ap: ...) -> i32 {
-        self.0 + unsafe { ap.arg::<i32>() }
+        self.0 + unsafe { ap.next_arg::<i32>() }
     }
 }
 
diff --git a/tests/ui/c-variadic/not-dyn-compatible.rs b/tests/ui/c-variadic/not-dyn-compatible.rs
index b40a13e58476..6676cc661c87 100644
--- a/tests/ui/c-variadic/not-dyn-compatible.rs
+++ b/tests/ui/c-variadic/not-dyn-compatible.rs
@@ -12,7 +12,7 @@ trait Trait {
     fn get(&self) -> u64;
 
     unsafe extern "C" fn dyn_method_ref(&self, mut ap: ...) -> u64 {
-        self.get() + unsafe { ap.arg::<u64>() }
+        self.get() + unsafe { ap.next_arg::<u64>() }
     }
 }
 
diff --git a/tests/ui/c-variadic/roundtrip.rs b/tests/ui/c-variadic/roundtrip.rs
index b6a858c715df..22a545fec5a8 100644
--- a/tests/ui/c-variadic/roundtrip.rs
+++ b/tests/ui/c-variadic/roundtrip.rs
@@ -10,11 +10,11 @@
 
 #[allow(improper_ctypes_definitions)]
 const unsafe extern "C" fn variadic<T: VaArgSafe>(mut ap: ...) -> (T, T) {
-    let x = ap.arg::<T>();
+    let x = ap.next_arg::<T>();
     // Intersperse a small type to test alignment logic. A `u32` (i.e. `c_uint`) is the smallest
     // type that implements `VaArgSafe`: smaller types would automatically be promoted.
-    assert!(ap.arg::<u32>() == 0xAAAA_AAAA);
-    let y = ap.arg::<T>();
+    assert!(ap.next_arg::<u32>() == 0xAAAA_AAAA);
+    let y = ap.next_arg::<T>();
 
     (x, y)
 }
diff --git a/tests/ui/c-variadic/same-program-multiple-abis-arm.rs b/tests/ui/c-variadic/same-program-multiple-abis-arm.rs
index fbc5573c5d76..301485519b9b 100644
--- a/tests/ui/c-variadic/same-program-multiple-abis-arm.rs
+++ b/tests/ui/c-variadic/same-program-multiple-abis-arm.rs
@@ -25,8 +25,8 @@ fn main() {
 //
 // #[unsafe(no_mangle)]
 // unsafe extern "C" fn variadic(a: f64, mut args: ...) -> f64 {
-//     let b = args.arg::<f64>();
-//     let c = args.arg::<f64>();
+//     let b = args.next_arg::<f64>();
+//     let c = args.next_arg::<f64>();
 //
 //     a + b + c
 // }
diff --git a/tests/ui/c-variadic/same-program-multiple-abis-x86_64.rs b/tests/ui/c-variadic/same-program-multiple-abis-x86_64.rs
index b54b63289f34..1f6f67678005 100644
--- a/tests/ui/c-variadic/same-program-multiple-abis-x86_64.rs
+++ b/tests/ui/c-variadic/same-program-multiple-abis-x86_64.rs
@@ -24,8 +24,8 @@ fn main() {
 //
 // #[unsafe(no_mangle)]
 // unsafe extern "C" fn variadic(a: u32, mut args: ...) -> u32 {
-//     let b = args.arg::<u32>();
-//     let c = args.arg::<u32>();
+//     let b = args.next_arg::<u32>();
+//     let c = args.next_arg::<u32>();
 //
 //     a + b + c
 // }
diff --git a/tests/ui/c-variadic/trait-method.rs b/tests/ui/c-variadic/trait-method.rs
index 876a303f53ba..753c0fbe89f2 100644
--- a/tests/ui/c-variadic/trait-method.rs
+++ b/tests/ui/c-variadic/trait-method.rs
@@ -7,11 +7,11 @@
 
 impl Struct {
     unsafe extern "C" fn associated_function(mut ap: ...) -> i32 {
-        unsafe { ap.arg() }
+        unsafe { ap.next_arg() }
     }
 
     unsafe extern "C" fn method(&self, mut ap: ...) -> i32 {
-        self.0 + unsafe { ap.arg::<i32>() }
+        self.0 + unsafe { ap.next_arg::<i32>() }
     }
 }
 
@@ -19,23 +19,23 @@ trait Trait: Sized {
     fn get(&self) -> i32;
 
     unsafe extern "C" fn trait_associated_function(mut ap: ...) -> i32 {
-        unsafe { ap.arg() }
+        unsafe { ap.next_arg() }
     }
 
     unsafe extern "C" fn trait_method_owned(self, mut ap: ...) -> i32 {
-        self.get() + unsafe { ap.arg::<i32>() }
+        self.get() + unsafe { ap.next_arg::<i32>() }
     }
 
     unsafe extern "C" fn trait_method_ref(&self, mut ap: ...) -> i32 {
-        self.get() + unsafe { ap.arg::<i32>() }
+        self.get() + unsafe { ap.next_arg::<i32>() }
     }
 
     unsafe extern "C" fn trait_method_mut(&mut self, mut ap: ...) -> i32 {
-        self.get() + unsafe { ap.arg::<i32>() }
+        self.get() + unsafe { ap.next_arg::<i32>() }
     }
 
     unsafe extern "C" fn trait_fat_pointer(self: Box<Self>, mut ap: ...) -> i32 {
-        self.get() + unsafe { ap.arg::<i32>() }
+        self.get() + unsafe { ap.next_arg::<i32>() }
     }
 }
 
diff --git a/tests/ui/c-variadic/valid.rs b/tests/ui/c-variadic/valid.rs
index 8b42eb493290..2ea50e668d3b 100644
--- a/tests/ui/c-variadic/valid.rs
+++ b/tests/ui/c-variadic/valid.rs
@@ -4,16 +4,16 @@
 
 // In rust (and C23 and above) `...` can be the only argument.
 unsafe extern "C" fn only_dot_dot_dot(mut ap: ...) -> i32 {
-    unsafe { ap.arg() }
+    unsafe { ap.next_arg() }
 }
 
 unsafe extern "C-unwind" fn abi_c_unwind(mut ap: ...) -> i32 {
-    unsafe { ap.arg() }
+    unsafe { ap.next_arg() }
 }
 
 #[allow(improper_ctypes_definitions)]
 unsafe extern "C" fn mix_int_float(mut ap: ...) -> (i64, f64, *const i32, f64) {
-    (ap.arg(), ap.arg(), ap.arg(), ap.arg())
+    (ap.next_arg(), ap.next_arg(), ap.next_arg(), ap.next_arg())
 }
 
 fn main() {
diff --git a/tests/ui/consts/const-eval/c-variadic-fail.rs b/tests/ui/consts/const-eval/c-variadic-fail.rs
index 2cf5d05cb248..a394de34a480 100644
--- a/tests/ui/consts/const-eval/c-variadic-fail.rs
+++ b/tests/ui/consts/const-eval/c-variadic-fail.rs
@@ -13,7 +13,7 @@
     let mut i = N;
     while i > 0 {
         i -= 1;
-        let _ = ap.arg::<i32>();
+        let _ = ap.next_arg::<i32>();
     }
 }
 
@@ -34,7 +34,7 @@ unsafe fn read_too_many() {
 }
 
 const unsafe extern "C" fn read_as<T: core::ffi::VaArgSafe>(mut ap: ...) -> T {
-    ap.arg::<T>()
+    ap.next_arg::<T>()
 }
 
 unsafe fn read_cast() {
@@ -72,7 +72,7 @@ fn use_after_free() {
         unsafe {
             let ap = helper(1, 2, 3);
             let mut ap = std::mem::transmute::<_, VaList>(ap);
-            ap.arg::<i32>();
+            ap.next_arg::<i32>();
             //~^ ERROR memory access failed: ALLOC0 has been freed, so this pointer is dangling [E0080]
         }
     };
@@ -82,12 +82,12 @@ fn manual_copy_drop() {
     const unsafe extern "C" fn helper(ap: ...) {
         // A copy created using Clone is valid, and can be used to read arguments.
         let mut copy = ap.clone();
-        assert!(copy.arg::<i32>() == 1i32);
+        assert!(copy.next_arg::<i32>() == 1i32);
 
         let mut copy: VaList = unsafe { std::mem::transmute_copy(&ap) };
 
         // Using the copy is actually fine.
-        let _ = copy.arg::<i32>();
+        let _ = copy.next_arg::<i32>();
         drop(copy);
 
         // But then using the original is UB.
@@ -103,7 +103,7 @@ fn manual_copy_forget() {
         let mut copy: VaList = unsafe { std::mem::transmute_copy(&ap) };
 
         // Using the copy is actually fine.
-        let _ = copy.arg::<i32>();
+        let _ = copy.next_arg::<i32>();
         std::mem::forget(copy);
 
         // The read (via `copy`) deallocated the original allocation.
@@ -119,8 +119,8 @@ fn manual_copy_read() {
         let mut copy: VaList = unsafe { std::mem::transmute_copy(&ap) };
 
         // Reading from `ap` after reading from `copy` is UB.
-        let _ = copy.arg::<i32>();
-        let _ = ap.arg::<i32>();
+        let _ = copy.next_arg::<i32>();
+        let _ = ap.next_arg::<i32>();
     }
 
     const { unsafe { helper(1, 2, 3) } };
diff --git a/tests/ui/consts/const-eval/c-variadic-fail.stderr b/tests/ui/consts/const-eval/c-variadic-fail.stderr
index 14da5500cb1b..4b0aed10d764 100644
--- a/tests/ui/consts/const-eval/c-variadic-fail.stderr
+++ b/tests/ui/consts/const-eval/c-variadic-fail.stderr
@@ -7,9 +7,9 @@ LL |     const { read_n::<1>() }
 note: inside `read_n::<1>`
   --> $DIR/c-variadic-fail.rs:16:17
    |
-LL |         let _ = ap.arg::<i32>();
-   |                 ^^^^^^^^^^^^^^^
-note: inside `VaList::<'_>::arg::<i32>`
+LL |         let _ = ap.next_arg::<i32>();
+   |                 ^^^^^^^^^^^^^^^^^^^^
+note: inside `VaList::<'_>::next_arg::<i32>`
   --> $SRC_DIR/core/src/ffi/va_list.rs:LL:COL
 
 note: erroneous constant encountered
@@ -35,9 +35,9 @@ LL |     const { read_n::<2>(1) }
 note: inside `read_n::<2>`
   --> $DIR/c-variadic-fail.rs:16:17
    |
-LL |         let _ = ap.arg::<i32>();
-   |                 ^^^^^^^^^^^^^^^
-note: inside `VaList::<'_>::arg::<i32>`
+LL |         let _ = ap.next_arg::<i32>();
+   |                 ^^^^^^^^^^^^^^^^^^^^
+note: inside `VaList::<'_>::next_arg::<i32>`
   --> $SRC_DIR/core/src/ffi/va_list.rs:LL:COL
 
 note: erroneous constant encountered
@@ -63,9 +63,9 @@ LL |     const { read_as::<u32>(1i32) };
 note: inside `read_as::<u32>`
   --> $DIR/c-variadic-fail.rs:37:5
    |
-LL |     ap.arg::<T>()
-   |     ^^^^^^^^^^^^^
-note: inside `VaList::<'_>::arg::<u32>`
+LL |     ap.next_arg::<T>()
+   |     ^^^^^^^^^^^^^^^^^^
+note: inside `VaList::<'_>::next_arg::<u32>`
   --> $SRC_DIR/core/src/ffi/va_list.rs:LL:COL
 
 note: erroneous constant encountered
@@ -91,9 +91,9 @@ LL |     const { read_as::<i32>(1u32) };
 note: inside `read_as::<i32>`
   --> $DIR/c-variadic-fail.rs:37:5
    |
-LL |     ap.arg::<T>()
-   |     ^^^^^^^^^^^^^
-note: inside `VaList::<'_>::arg::<i32>`
+LL |     ap.next_arg::<T>()
+   |     ^^^^^^^^^^^^^^^^^^
+note: inside `VaList::<'_>::next_arg::<i32>`
   --> $SRC_DIR/core/src/ffi/va_list.rs:LL:COL
 
 note: erroneous constant encountered
@@ -119,9 +119,9 @@ LL |     const { read_as::<i32>(1u64) };
 note: inside `read_as::<i32>`
   --> $DIR/c-variadic-fail.rs:37:5
    |
-LL |     ap.arg::<T>()
-   |     ^^^^^^^^^^^^^
-note: inside `VaList::<'_>::arg::<i32>`
+LL |     ap.next_arg::<T>()
+   |     ^^^^^^^^^^^^^^^^^^
+note: inside `VaList::<'_>::next_arg::<i32>`
   --> $SRC_DIR/core/src/ffi/va_list.rs:LL:COL
 
 note: erroneous constant encountered
@@ -147,9 +147,9 @@ LL |     const { read_as::<f64>(1i32) };
 note: inside `read_as::<f64>`
   --> $DIR/c-variadic-fail.rs:37:5
    |
-LL |     ap.arg::<T>()
-   |     ^^^^^^^^^^^^^
-note: inside `VaList::<'_>::arg::<f64>`
+LL |     ap.next_arg::<T>()
+   |     ^^^^^^^^^^^^^^^^^^
+note: inside `VaList::<'_>::next_arg::<f64>`
   --> $SRC_DIR/core/src/ffi/va_list.rs:LL:COL
 
 note: erroneous constant encountered
@@ -175,9 +175,9 @@ LL |     const { read_as::<*const u8>(1i32) };
 note: inside `read_as::<*const u8>`
   --> $DIR/c-variadic-fail.rs:37:5
    |
-LL |     ap.arg::<T>()
-   |     ^^^^^^^^^^^^^
-note: inside `VaList::<'_>::arg::<*const u8>`
+LL |     ap.next_arg::<T>()
+   |     ^^^^^^^^^^^^^^^^^^
+note: inside `VaList::<'_>::next_arg::<*const u8>`
   --> $SRC_DIR/core/src/ffi/va_list.rs:LL:COL
 
 note: erroneous constant encountered
@@ -197,10 +197,10 @@ LL |     const { read_as::<*const u8>(1i32) };
 error[E0080]: memory access failed: ALLOC0 has been freed, so this pointer is dangling
   --> $DIR/c-variadic-fail.rs:75:13
    |
-LL |             ap.arg::<i32>();
-   |             ^^^^^^^^^^^^^^^ evaluation of `use_after_free::{constant#0}` failed inside this call
+LL |             ap.next_arg::<i32>();
+   |             ^^^^^^^^^^^^^^^^^^^^ evaluation of `use_after_free::{constant#0}` failed inside this call
    |
-note: inside `VaList::<'_>::arg::<i32>`
+note: inside `VaList::<'_>::next_arg::<i32>`
   --> $SRC_DIR/core/src/ffi/va_list.rs:LL:COL
 
 note: erroneous constant encountered
@@ -300,9 +300,9 @@ LL |     const { unsafe { helper(1, 2, 3) } };
 note: inside `manual_copy_read::helper`
   --> $DIR/c-variadic-fail.rs:123:17
    |
-LL |         let _ = ap.arg::<i32>();
-   |                 ^^^^^^^^^^^^^^^
-note: inside `VaList::<'_>::arg::<i32>`
+LL |         let _ = ap.next_arg::<i32>();
+   |                 ^^^^^^^^^^^^^^^^^^^^
+note: inside `VaList::<'_>::next_arg::<i32>`
   --> $SRC_DIR/core/src/ffi/va_list.rs:LL:COL
 
 note: erroneous constant encountered
diff --git a/tests/ui/consts/const-eval/c-variadic.rs b/tests/ui/consts/const-eval/c-variadic.rs
index 2f8d043fb5db..b8f02ea8a084 100644
--- a/tests/ui/consts/const-eval/c-variadic.rs
+++ b/tests/ui/consts/const-eval/c-variadic.rs
@@ -21,7 +21,7 @@ fn ignores_arguments() {
 
 fn echo() {
     const unsafe extern "C" fn variadic(mut ap: ...) -> i32 {
-        ap.arg()
+        ap.next_arg()
     }
 
     assert_eq!(unsafe { variadic(1) }, 1);
@@ -35,7 +35,7 @@ fn echo() {
 
 fn forward_by_val() {
     const unsafe fn helper(mut ap: VaList) -> i32 {
-        ap.arg()
+        ap.next_arg()
     }
 
     const unsafe extern "C" fn variadic(ap: ...) -> i32 {
@@ -53,7 +53,7 @@ fn forward_by_val() {
 
 fn forward_by_ref() {
     const unsafe fn helper(ap: &mut VaList) -> i32 {
-        ap.arg()
+        ap.next_arg()
     }
 
     const unsafe extern "C" fn variadic(mut ap: ...) -> i32 {
@@ -72,7 +72,7 @@ fn forward_by_ref() {
 #[allow(improper_ctypes_definitions)]
 fn nested() {
     const unsafe fn helper(mut ap1: VaList, mut ap2: VaList) -> (i32, i32) {
-        (ap1.arg(), ap2.arg())
+        (ap1.next_arg(), ap2.next_arg())
     }
 
     const unsafe extern "C" fn variadic2(ap1: VaList, ap2: ...) -> (i32, i32) {
@@ -112,13 +112,13 @@ macro_rules! continue_if {
             }
         }
 
-        continue_if!(ap.arg::<c_double>().floor() == 3.14f64.floor());
-        continue_if!(ap.arg::<c_long>() == 12);
-        continue_if!(ap.arg::<c_int>() == 'a' as c_int);
-        continue_if!(ap.arg::<c_double>().floor() == 6.18f64.floor());
-        continue_if!(compare_c_str(ap.arg::<*const c_char>(), "Hello"));
-        continue_if!(ap.arg::<c_int>() == 42);
-        continue_if!(compare_c_str(ap.arg::<*const c_char>(), "World"));
+        continue_if!(ap.next_arg::<c_double>().floor() == 3.14f64.floor());
+        continue_if!(ap.next_arg::<c_long>() == 12);
+        continue_if!(ap.next_arg::<c_int>() == 'a' as c_int);
+        continue_if!(ap.next_arg::<c_double>().floor() == 6.18f64.floor());
+        continue_if!(compare_c_str(ap.next_arg::<*const c_char>(), "Hello"));
+        continue_if!(ap.next_arg::<c_int>() == 42);
+        continue_if!(compare_c_str(ap.next_arg::<*const c_char>(), "World"));
     }
 
     unsafe {
diff --git a/tests/ui/explicit-tail-calls/c-variadic.rs b/tests/ui/explicit-tail-calls/c-variadic.rs
index e6eebe4228e5..affe90c60652 100644
--- a/tests/ui/explicit-tail-calls/c-variadic.rs
+++ b/tests/ui/explicit-tail-calls/c-variadic.rs
@@ -3,7 +3,7 @@
 #![allow(unused)]
 
 unsafe extern "C" fn foo(mut ap: ...) -> u32 {
-    ap.arg::<u32>()
+    ap.next_arg::<u32>()
 }
 
 extern "C" fn bar() -> u32 {
diff --git a/tests/ui/sanitizer/kcfi-c-variadic.rs b/tests/ui/sanitizer/kcfi-c-variadic.rs
index 45d00a4524eb..651029ab7dfe 100644
--- a/tests/ui/sanitizer/kcfi-c-variadic.rs
+++ b/tests/ui/sanitizer/kcfi-c-variadic.rs
@@ -8,7 +8,7 @@
 
 trait Trait {
     unsafe extern "C" fn foo(x: i32, y: i32, mut ap: ...) -> i32 {
-        x + y + ap.arg::<i32>() + ap.arg::<i32>()
+        x + y + ap.next_arg::<i32>() + ap.next_arg::<i32>()
     }
 }