Add Location::file_with_nul

This is useful for C/C++ APIs which expect the const char* returned
from __FILE__ or std::source_location::file_name.

1 files changed, 25 insertions, 0 deletions

diff --git a/tests/ui/rfcs/rfc-2091-track-caller/file-is-nul-terminated.rs b/tests/ui/rfcs/rfc-2091-track-caller/file-is-nul-terminated.rs
new file mode 100644
index 00000000000..65e61a21f1a
--- /dev/null
+++ b/tests/ui/rfcs/rfc-2091-track-caller/file-is-nul-terminated.rs
@@ -0,0 +1,25 @@
+//@ run-pass
+#![feature(file_with_nul)]
+
+#[track_caller]
+const fn assert_file_has_trailing_zero() {
+    let caller = core::panic::Location::caller();
+    let file_str = caller.file();
+    let file_with_nul = caller.file_with_nul();
+    if file_str.len() != file_with_nul.count_bytes() {
+        panic!("mismatched lengths");
+    }
+    let trailing_byte: core::ffi::c_char = unsafe {
+        *file_with_nul.as_ptr().offset(file_with_nul.count_bytes() as _)
+    };
+    if trailing_byte != 0 {
+        panic!("trailing byte was nonzero")
+    }
+}
+
+#[allow(dead_code)]
+const _: () = assert_file_has_trailing_zero();
+
+fn main() {
+    assert_file_has_trailing_zero();
+}