From 4eac6fe21e1f82b1cc3c528b6a4b241fe5509b40 Mon Sep 17 00:00:00 2001
From: Maybe Waffle <waffle.lapkin@gmail.com>
Date: Fri, 7 Apr 2023 17:23:03 +0000
Subject: [PATCH] Add test for `a.f(|this| a.g())`

---
 .../issue-109271-pass-self-into-closure.rs    | 38 ++++++++++
 ...issue-109271-pass-self-into-closure.stderr | 75 +++++++++++++++++++
 2 files changed, 113 insertions(+)
 create mode 100644 tests/ui/borrowck/issue-109271-pass-self-into-closure.rs
 create mode 100644 tests/ui/borrowck/issue-109271-pass-self-into-closure.stderr

diff --git a/tests/ui/borrowck/issue-109271-pass-self-into-closure.rs b/tests/ui/borrowck/issue-109271-pass-self-into-closure.rs
new file mode 100644
index 00000000000..16167914512
--- /dev/null
+++ b/tests/ui/borrowck/issue-109271-pass-self-into-closure.rs
@@ -0,0 +1,38 @@
+#![allow(unused)]
+struct S;
+
+impl S {
+    fn call(&mut self, f: impl FnOnce((), &mut Self)) {
+        // change state or something ...
+        f((), self);
+        // change state or something ...
+    }
+
+    fn get(&self) {}
+    fn set(&mut self) {}
+}
+
+fn main() {
+    let mut v = S;
+
+    v.call(|(), this: &mut S| v.get());
+    //~^ error: cannot borrow `v` as mutable because it is also borrowed as immutable
+    v.call(|(), this: &mut S| v.set());
+    //~^ error: cannot borrow `v` as mutable more than once at a time
+    //~| error: cannot borrow `v` as mutable more than once at a time
+
+    v.call(|(), this: &mut S| {
+        //~^ error: cannot borrow `v` as mutable more than once at a time
+        //~| error: cannot borrow `v` as mutable more than once at a time
+
+        _ = v;
+        v.set();
+        v.get();
+        S::get(&v);
+
+        use std::ops::Add;
+        let v = 0u32;
+        _ = v + v;
+        _ = v.add(3);
+    });
+}
diff --git a/tests/ui/borrowck/issue-109271-pass-self-into-closure.stderr b/tests/ui/borrowck/issue-109271-pass-self-into-closure.stderr
new file mode 100644
index 00000000000..8abbecad02a
--- /dev/null
+++ b/tests/ui/borrowck/issue-109271-pass-self-into-closure.stderr
@@ -0,0 +1,75 @@
+error[E0502]: cannot borrow `v` as mutable because it is also borrowed as immutable
+  --> $DIR/issue-109271-pass-self-into-closure.rs:18:5
+   |
+LL |     v.call(|(), this: &mut S| v.get());
+   |     ^^----^------------------^-^^^^^^^
+   |     | |    |                  |
+   |     | |    |                  first borrow occurs due to use of `v` in closure
+   |     | |    immutable borrow occurs here
+   |     | immutable borrow later used by call
+   |     mutable borrow occurs here
+
+error[E0499]: cannot borrow `v` as mutable more than once at a time
+  --> $DIR/issue-109271-pass-self-into-closure.rs:20:5
+   |
+LL |     v.call(|(), this: &mut S| v.set());
+   |     ^^----^------------------^-^^^^^^^
+   |     | |    |                  |
+   |     | |    |                  first borrow occurs due to use of `v` in closure
+   |     | |    first mutable borrow occurs here
+   |     | first borrow later used by call
+   |     second mutable borrow occurs here
+
+error[E0499]: cannot borrow `v` as mutable more than once at a time
+  --> $DIR/issue-109271-pass-self-into-closure.rs:20:12
+   |
+LL |     v.call(|(), this: &mut S| v.set());
+   |     -------^^^^^^^^^^^^^^^^^^---------
+   |     | |    |                  |
+   |     | |    |                  second borrow occurs due to use of `v` in closure
+   |     | |    second mutable borrow occurs here
+   |     | first borrow later used by call
+   |     first mutable borrow occurs here
+
+error[E0499]: cannot borrow `v` as mutable more than once at a time
+  --> $DIR/issue-109271-pass-self-into-closure.rs:24:5
+   |
+LL |       v.call(|(), this: &mut S| {
+   |       ^ ---- ------------------ first mutable borrow occurs here
+   |       | |
+   |  _____| first borrow later used by call
+   | |
+LL | |
+LL | |
+LL | |
+LL | |         _ = v;
+LL | |         v.set();
+   | |         - first borrow occurs due to use of `v` in closure
+...  |
+LL | |         _ = v.add(3);
+LL | |     });
+   | |______^ second mutable borrow occurs here
+
+error[E0499]: cannot borrow `v` as mutable more than once at a time
+  --> $DIR/issue-109271-pass-self-into-closure.rs:24:12
+   |
+LL |       v.call(|(), this: &mut S| {
+   |       - ---- ^^^^^^^^^^^^^^^^^^ second mutable borrow occurs here
+   |       | |
+   |  _____| first borrow later used by call
+   | |
+LL | |
+LL | |
+LL | |
+LL | |         _ = v;
+LL | |         v.set();
+   | |         - second borrow occurs due to use of `v` in closure
+...  |
+LL | |         _ = v.add(3);
+LL | |     });
+   | |______- first mutable borrow occurs here
+
+error: aborting due to 5 previous errors
+
+Some errors have detailed explanations: E0499, E0502.
+For more information about an error, try `rustc --explain E0499`.