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/E0750.md b/compiler/rustc_error_codes/src/error_codes/E0750.md
new file mode 100644
index 000000000..905e852f8
--- /dev/null
+++ b/compiler/rustc_error_codes/src/error_codes/E0750.md
@@ -0,0 +1,18 @@
+A negative impl was made default impl.
+
+Erroneous code example:
+
+```compile_fail,E0750
+# #![feature(negative_impls)]
+# #![feature(specialization)]
+trait MyTrait {
+    type Foo;
+}
+
+default impl !MyTrait for u32 {} // error!
+# fn main() {}
+```
+
+Negative impls cannot be default impls. A default impl supplies default values
+for the items within to be used by other impls, whereas a negative impl declares
+that there are no other impls. Combining it does not make sense.