Try to fix issue 68049

4 files changed, 67 insertions, 0 deletions

diff --git a/src/test/ui/suggestions/issue-68049-1.rs b/src/test/ui/suggestions/issue-68049-1.rs
new file mode 100644
index 00000000000..9b9ae429aeb
--- /dev/null
+++ b/src/test/ui/suggestions/issue-68049-1.rs
@@ -0,0 +1,16 @@
+use std::alloc::{GlobalAlloc, Layout};
+
+struct Test(u32);
+
+unsafe impl GlobalAlloc for Test {
+    unsafe fn alloc(&self, _layout: Layout) -> *mut u8 {
+        self.0 += 1;
+        0 as *mut u8
+    }
+
+    unsafe fn dealloc(&self, _ptr: *mut u8, _layout: Layout) {
+        unimplemented!();
+    }
+}
+
+fn main() { }
diff --git a/src/test/ui/suggestions/issue-68049-1.stderr b/src/test/ui/suggestions/issue-68049-1.stderr
new file mode 100644
index 00000000000..32367d2d0cf
--- /dev/null
+++ b/src/test/ui/suggestions/issue-68049-1.stderr
@@ -0,0 +1,9 @@
+error[E0594]: cannot assign to `self.0` which is behind a `&` reference
+  --> $DIR/issue-68049-1.rs:7:9
+   |
+LL |         self.0 += 1;
+   |         ^^^^^^^^^^^ `self` is a `&` reference, so the data it refers to cannot be written
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0594`.
diff --git a/src/test/ui/suggestions/issue-68049-2.rs b/src/test/ui/suggestions/issue-68049-2.rs
new file mode 100644
index 00000000000..22bb6b85d6f
--- /dev/null
+++ b/src/test/ui/suggestions/issue-68049-2.rs
@@ -0,0 +1,21 @@
+trait Hello {
+  fn example(&self, input: &i32); // should suggest here
+}
+
+struct Test1(i32);
+
+impl Hello for Test1 {
+  fn example(&self, input: &i32) { // should not suggest here
+      *input = self.0;
+  }
+}
+
+struct Test2(i32);
+
+impl Hello for Test2 {
+  fn example(&self, input: &i32) { // should not suggest here
+    self.0 += *input;
+  }
+}
+
+fn main() { }
diff --git a/src/test/ui/suggestions/issue-68049-2.stderr b/src/test/ui/suggestions/issue-68049-2.stderr
new file mode 100644
index 00000000000..f10a83c68a8
--- /dev/null
+++ b/src/test/ui/suggestions/issue-68049-2.stderr
@@ -0,0 +1,21 @@
+error[E0594]: cannot assign to `*input` which is behind a `&` reference
+  --> $DIR/issue-68049-2.rs:9:7
+   |
+LL |   fn example(&self, input: &i32); // should suggest here
+   |                            ---- help: consider changing that to be a mutable reference: `&mut i32`
+...
+LL |       *input = self.0;
+   |       ^^^^^^^^^^^^^^^ `input` is a `&` reference, so the data it refers to cannot be written
+
+error[E0594]: cannot assign to `self.0` which is behind a `&` reference
+  --> $DIR/issue-68049-2.rs:17:5
+   |
+LL |   fn example(&self, input: &i32); // should suggest here
+   |              ----- help: consider changing that to be a mutable reference: `&mut self`
+...
+LL |     self.0 += *input;
+   |     ^^^^^^^^^^^^^^^^ `self` is a `&` reference, so the data it refers to cannot be written
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0594`.