From 698f8c2f01ea549d77d7dc3338a12e04c11057b9 Mon Sep 17 00:00:00 2001
From: Daniel Baumann <daniel.baumann@progress-linux.org>
Date: Wed, 17 Apr 2024 14:02:58 +0200
Subject: Adding upstream version 1.64.0+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
---
 .../rustc_error_codes/src/error_codes/E0193.md     | 44 ++++++++++++++++++++++
 1 file changed, 44 insertions(+)
 create mode 100644 compiler/rustc_error_codes/src/error_codes/E0193.md

(limited to 'compiler/rustc_error_codes/src/error_codes/E0193.md')

diff --git a/compiler/rustc_error_codes/src/error_codes/E0193.md b/compiler/rustc_error_codes/src/error_codes/E0193.md
new file mode 100644
index 000000000..e29a949ff
--- /dev/null
+++ b/compiler/rustc_error_codes/src/error_codes/E0193.md
@@ -0,0 +1,44 @@
+#### Note: this error code is no longer emitted by the compiler.
+
+`where` clauses must use generic type parameters: it does not make sense to use
+them otherwise. An example causing this error:
+
+```
+trait Foo {
+    fn bar(&self);
+}
+
+#[derive(Copy,Clone)]
+struct Wrapper<T> {
+    Wrapped: T
+}
+
+impl Foo for Wrapper<u32> where Wrapper<u32>: Clone {
+    fn bar(&self) { }
+}
+```
+
+This use of a `where` clause is strange - a more common usage would look
+something like the following:
+
+```
+trait Foo {
+    fn bar(&self);
+}
+
+#[derive(Copy,Clone)]
+struct Wrapper<T> {
+    Wrapped: T
+}
+impl <T> Foo for Wrapper<T> where Wrapper<T>: Clone {
+    fn bar(&self) { }
+}
+```
+
+Here, we're saying that the implementation exists on Wrapper only when the
+wrapped type `T` implements `Clone`. The `where` clause is important because
+some types will not implement `Clone`, and thus will not get this method.
+
+In our erroneous example, however, we're referencing a single concrete type.
+Since we know for certain that `Wrapper<u32>` implements `Clone`, there's no
+reason to also specify it in a `where` clause.
-- 
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