Adding upstream version 1.64.0+dfsg1.upstream/1.64.0+dfsg1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 27 insertions, 0 deletions

diff --git a/compiler/rustc_error_codes/src/error_codes/E0468.md b/compiler/rustc_error_codes/src/error_codes/E0468.md
new file mode 100644
index 000000000..cf8664718
--- /dev/null
+++ b/compiler/rustc_error_codes/src/error_codes/E0468.md
@@ -0,0 +1,27 @@
+A non-root module tried to import macros from another crate.
+
+Example of erroneous code:
+
+```compile_fail,E0468
+mod foo {
+    #[macro_use(debug_assert)]  // error: must be at crate root to import
+    extern crate core;          //        macros from another crate
+    fn run_macro() { debug_assert!(true); }
+}
+```
+
+Only `extern crate` imports at the crate root level are allowed to import
+macros.
+
+Either move the macro import to crate root or do without the foreign macros.
+This will work:
+
+```
+#[macro_use(debug_assert)] // ok!
+extern crate core;
+
+mod foo {
+    fn run_macro() { debug_assert!(true); }
+}
+# fn main() {}
+```