compiletest: update to Edition 2024

Author: jieyouxu

src/tools/compiletest/Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "compiletest"
 version = "0.0.0"
-edition = "2021"
+edition = "2024"
 
 [lib]
 doctest = false

src/tools/compiletest/src/debuggers.rs

@@ -40,7 +40,9 @@ pub(crate) fn configure_gdb(config: &Config) -> Option<Arc<Config>> {
         //
         // we should figure out how to lift this restriction! (run them all
         // on different ports allocated dynamically).
-        env::set_var("RUST_TEST_THREADS", "1");
+        //
+        // SAFETY: at this point we are still single-threaded.
+        unsafe { env::set_var("RUST_TEST_THREADS", "1") };
     }
 
     Some(Arc::new(Config { debugger: Some(Debugger::Gdb), ..config.clone() }))

src/tools/compiletest/src/lib.rs

@@ -529,10 +529,14 @@ pub fn run_tests(config: Arc<Config>) {
     }
     // Prevent issue #21352 UAC blocking .exe containing 'patch' etc. on Windows
     // If #11207 is resolved (adding manifest to .exe) this becomes unnecessary
-    env::set_var("__COMPAT_LAYER", "RunAsInvoker");
-
-    // Let tests know which target they're running as
-    env::set_var("TARGET", &config.target);
+    //
+    // SAFETY: at this point we're still single-threaded.
+    unsafe { env::set_var("__COMPAT_LAYER", "RunAsInvoker") };
+
+    // Let tests know which target they're running as.
+    //
+    // SAFETY: at this point we're still single-threaded.
+    unsafe { env::set_var("TARGET", &config.target) };
 
     let mut configs = Vec::new();
     if let Mode::DebugInfo = config.mode {