Auto merge of #69012 - Dylan-DPC:rollup-13qn0fq, r=Dylan-DPC

Rollup of 6 pull requests

Successful merges:

 - #68694 (Reduce the number of `RefCell`s in `InferCtxt`.)
 - #68966 (Improve performance of coherence checks)
 - #68976 (Make `num::NonZeroX::new` an unstable `const fn`)
 - #68992 (Correctly parse `mut a @ b`)
 - #69005 (Small graphviz improvements for the new dataflow framework)
 - #69006 (parser: Keep current and previous tokens precisely)

Failed merges:

r? @ghost

5 files changed, 75 insertions, 0 deletions

diff --git a/src/test/ui/pattern/bindings-after-at/nested-binding-mode-lint.rs b/src/test/ui/pattern/bindings-after-at/nested-binding-mode-lint.rs
new file mode 100644
index 00000000000..497d94a3db0
--- /dev/null
+++ b/src/test/ui/pattern/bindings-after-at/nested-binding-mode-lint.rs
@@ -0,0 +1,13 @@
+// check-pass
+
+#![feature(bindings_after_at)]
+#![deny(unused_mut)]
+
+fn main() {
+    let mut is_mut @ not_mut = 42;
+    &mut is_mut;
+    &not_mut;
+    let not_mut @ mut is_mut = 42;
+    &mut is_mut;
+    &not_mut;
+}
diff --git a/src/test/ui/pattern/bindings-after-at/nested-binding-modes-mut.rs b/src/test/ui/pattern/bindings-after-at/nested-binding-modes-mut.rs
new file mode 100644
index 00000000000..54f04117f7d
--- /dev/null
+++ b/src/test/ui/pattern/bindings-after-at/nested-binding-modes-mut.rs
@@ -0,0 +1,13 @@
+#![feature(bindings_after_at)]
+
+fn main() {
+    let mut is_mut @ not_mut = 42;
+    &mut is_mut;
+    &mut not_mut;
+    //~^ ERROR cannot borrow
+
+    let not_mut @ mut is_mut = 42;
+    &mut is_mut;
+    &mut not_mut;
+    //~^ ERROR cannot borrow
+}
diff --git a/src/test/ui/pattern/bindings-after-at/nested-binding-modes-mut.stderr b/src/test/ui/pattern/bindings-after-at/nested-binding-modes-mut.stderr
new file mode 100644
index 00000000000..a8d5e4c4c69
--- /dev/null
+++ b/src/test/ui/pattern/bindings-after-at/nested-binding-modes-mut.stderr
@@ -0,0 +1,21 @@
+error[E0596]: cannot borrow `not_mut` as mutable, as it is not declared as mutable
+  --> $DIR/nested-binding-modes-mut.rs:6:5
+   |
+LL |     let mut is_mut @ not_mut = 42;
+   |                      ------- help: consider changing this to be mutable: `mut not_mut`
+LL |     &mut is_mut;
+LL |     &mut not_mut;
+   |     ^^^^^^^^^^^^ cannot borrow as mutable
+
+error[E0596]: cannot borrow `not_mut` as mutable, as it is not declared as mutable
+  --> $DIR/nested-binding-modes-mut.rs:11:5
+   |
+LL |     let not_mut @ mut is_mut = 42;
+   |         -------------------- help: consider changing this to be mutable: `mut not_mut`
+LL |     &mut is_mut;
+LL |     &mut not_mut;
+   |     ^^^^^^^^^^^^ cannot borrow as mutable
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0596`.
diff --git a/src/test/ui/pattern/bindings-after-at/nested-binding-modes-ref.rs b/src/test/ui/pattern/bindings-after-at/nested-binding-modes-ref.rs
new file mode 100644
index 00000000000..d5086aec93e
--- /dev/null
+++ b/src/test/ui/pattern/bindings-after-at/nested-binding-modes-ref.rs
@@ -0,0 +1,13 @@
+#![feature(bindings_after_at)]
+
+fn main() {
+    let ref is_ref @ is_val = 42;
+    *is_ref;
+    *is_val;
+    //~^ ERROR cannot be dereferenced
+
+    let is_val @ ref is_ref = 42;
+    *is_ref;
+    *is_val;
+    //~^ ERROR cannot be dereferenced
+}
diff --git a/src/test/ui/pattern/bindings-after-at/nested-binding-modes-ref.stderr b/src/test/ui/pattern/bindings-after-at/nested-binding-modes-ref.stderr
new file mode 100644
index 00000000000..9cc928d2149
--- /dev/null
+++ b/src/test/ui/pattern/bindings-after-at/nested-binding-modes-ref.stderr
@@ -0,0 +1,15 @@
+error[E0614]: type `{integer}` cannot be dereferenced
+  --> $DIR/nested-binding-modes-ref.rs:6:5
+   |
+LL |     *is_val;
+   |     ^^^^^^^
+
+error[E0614]: type `{integer}` cannot be dereferenced
+  --> $DIR/nested-binding-modes-ref.rs:11:5
+   |
+LL |     *is_val;
+   |     ^^^^^^^
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0614`.