Auto merge of #142300 - jieyouxu:exp-partial-revert-141576, r=<try>

[EXPERIMENTAL] Revert `mte-ffi` changes

Based on

> > it failed on aarch64 (on the new aarch64-gnu-llvm-19-1 job introduced in this PR)
>
> This feature requires ARMv8.5 or higher. And it has to be enabled. Maybe the CI job runner does not support this extension?

Let's revert the changes to this test in #141576.
However, I can't explain why the test manages to *pass* on `aarch64-gnu` but not `aarch64-gnu-llvm-1` #141600.

### References

- https://www.kernel.org/doc/html/v5.10/arm64/memory-tagging-extension.html
try-job: aarch64-gnu

Author: rust-bors[bot]

tests/run-make/mte-ffi/bar.h

@@ -1,5 +1,3 @@
-// FIXME(#141600) the mte-ffi test doesn't fail in aarch64-gnu
-
 #ifndef __BAR_H
 #define __BAR_H
 

tests/run-make/mte-ffi/bar_float.c

@@ -3,9 +3,9 @@
 #include <stdint.h>
 #include "bar.h"
 
-extern void foo(float*);
+extern void foo(char*);
 
-void bar(float *ptr) {
+void bar(char *ptr) {
     if (((uintptr_t)ptr >> 56) != 0x1f) {
         fprintf(stderr, "Top byte corrupted on Rust -> C FFI boundary!\n");
         exit(1);

tests/run-make/mte-ffi/bar_int.c

@@ -5,7 +5,7 @@
 
 extern void foo(unsigned int *);
 
-void bar(unsigned int *ptr) {
+void bar(char *ptr) {
     if (((uintptr_t)ptr >> 56) != 0x1f) {
         fprintf(stderr, "Top byte corrupted on Rust -> C FFI boundary!\n");
         exit(1);

tests/run-make/mte-ffi/bar_string.c

@@ -1,7 +1,6 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <stdint.h>
-#include <string.h>
 #include "bar.h"
 
 extern void foo(char*);
@@ -33,7 +32,7 @@ int main(void)
 
     // Store an arbitrary tag in bits 56-59 of the pointer (where an MTE tag may be),
     // and a different value in the ignored top 4 bits.
-    ptr = (char *)((uintptr_t)ptr | 0x1fl << 56);
+    ptr = (unsigned int *)((uintptr_t)ptr | 0x1fl << 56);
 
     if (mte_enabled()) {
         set_tag(ptr);

tests/run-make/mte-ffi/rmake.rs

@@ -16,6 +16,13 @@ fn main() {
 }
 
 fn run_test(variant: &str) {
+    let gcc_version =
+        std::process::Command::new("aarch64-linux-gnu-gcc").arg("-v").output().unwrap();
+    eprintln!("gcc_version: {}", String::from_utf8(gcc_version.stderr).unwrap());
+
+    let cpu_info = std::process::Command::new("lscpu").output().unwrap();
+    eprintln!("lscpu: {}", String::from_utf8(cpu_info.stdout).unwrap());
+
     let flags = {
         let mut flags = extra_c_flags();
         flags.push("-march=armv8.5-a+memtag");
@@ -30,4 +37,6 @@ fn run_test(variant: &str) {
         .args(&flags)
         .run();
     run("test");
+
+    panic!("[DEBUG] fail intentionally");
 }