rewrite inaccessible-temp-dir to rmake format

src/tools/tidy/src/allowed_run_make_makefiles.txt

@@ -66,7 +66,6 @@ run-make/foreign-double-unwind/Makefile
 run-make/foreign-exceptions/Makefile
 run-make/foreign-rust-exceptions/Makefile
 run-make/glibc-staticlib-args/Makefile
-run-make/inaccessible-temp-dir/Makefile
 run-make/include_bytes_deps/Makefile
 run-make/incr-add-rust-src-component/Makefile
 run-make/incr-foreign-head-span/Makefile

tests/run-make/inaccessible-temp-dir/rmake.rs

@@ -0,0 +1,44 @@
+// Issue #66530: We would ICE if someone compiled with `-o /dev/null`,
+// because we would try to generate auxiliary files in `/dev/` (which
+// at least the OS X file system rejects).
+//
+// An attempt to `-Ztemps-dir` into a directory we cannot write into should
+// indeed be an error; but not an ICE.
+//
+// However, some folks run tests as root, which can write `/dev/` and end
+// up clobbering `/dev/null`. Instead we'll use an inaccessible path, which
+// also used to ICE, but even root can't magically write there.
+//
+// Note that `-Ztemps-dir` uses `create_dir_all` so it is not sufficient to
+// use a directory with non-existing parent like `/does-not-exist/output`.
+// See https://github.com/rust-lang/rust/issues/66530
+
+//@ only-linux
+// Reason: set_mode is only available on Unix
+
+//@ ignore-arm
+// Reason: linker error on `armhf-gnu`
+
+use run_make_support::{fs_wrapper, rustc};
+
+fn main() {
+    // Create an inaccessible directory.
+    fs_wrapper::create_dir("inaccessible");
+    let meta = fs_wrapper::metadata("inaccessible");
+    let mut perms = meta.permissions();
+    perms.set_mode(0o000); // Lock down the directory.
+    fs_wrapper::set_permissions("inaccessible", perms);
+
+    // Run rustc with `-Z temps-dir` set to a directory *inside* the inaccessible one,
+    // so that it can't create `tmp`.
+    rustc()
+        .input("program.rs")
+        .arg("-Ztemps-dir=inaccessible/tmp")
+        .run_fail()
+        .assert_stderr_contains(
+            "failed to find or create the directory specified by `--temps-dir`",
+        );
+
+    perms.set_mode(0o666); // Unlock the directory, so that compiletest can delete it.
+    fs_wrapper::set_permissions("inaccessible", perms);
+}