Auto merge of #155674 - JonathanBrouwer:rollup-NG1fnzG, r=JonathanBrouwer

Rollup of 10 pull requests

Successful merges:

 - rust-lang/rust#146544 (mir-opt: Remove the workaround in UnreachableEnumBranching)
 - rust-lang/rust#154819 (Fix ICE for inherent associated type mismatches)
 - rust-lang/rust#155265 (Improved assumptions relating to isqrt)
 - rust-lang/rust#152576 (c-variadic: use `emit_ptr_va_arg` for  mips)
 - rust-lang/rust#154481 (Mark a function only used in nightly as nightly only)
 - rust-lang/rust#155614 (c-variadic: rename `VaList::arg` to `VaList::next_arg`)
 - rust-lang/rust#155630 (Make `//@ skip-filecheck` a normal compiletest directive)
 - rust-lang/rust#155641 (Remove non-working code for "running" mir-opt tests)
 - rust-lang/rust#155652 (Expand `Path::is_empty` docs)
 - rust-lang/rust#155656 (rustc_llvm: update opt-level handling for LLVM 23)

Author: bors

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() };

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

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) }

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 @@ fn forward_by_val() {
 
 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 @@ fn forward_by_ref() {
 #[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 @@ fn various_types() {
             }
         }
 
-        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 {