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, 18 insertions, 0 deletions

diff --git a/compiler/rustc_error_codes/src/error_codes/E0232.md b/compiler/rustc_error_codes/src/error_codes/E0232.md
new file mode 100644
index 000000000..b310caefa
--- /dev/null
+++ b/compiler/rustc_error_codes/src/error_codes/E0232.md
@@ -0,0 +1,18 @@
+The `#[rustc_on_unimplemented]` attribute lets you specify a custom error
+message for when a particular trait isn't implemented on a type placed in a
+position that needs that trait. For example, when the following code is
+compiled:
+
+```compile_fail,E0232
+#![feature(rustc_attrs)]
+
+#[rustc_on_unimplemented(lorem="")] // error!
+trait BadAnnotation {}
+```
+
+there will be an error about `bool` not implementing `Index<u8>`, followed by a
+note saying "the type `bool` cannot be indexed by `u8`".
+
+For this to work, some note must be specified. An empty attribute will not do
+anything, please remove the attribute or add some helpful note for users of the
+trait.