From dc0db358abe19481e475e10c32149b53370f1a1c Mon Sep 17 00:00:00 2001
From: Daniel Baumann <daniel.baumann@progress-linux.org>
Date: Thu, 30 May 2024 05:57:31 +0200
Subject: Merging upstream version 1.72.1+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
---
 .../deref-ambiguity-becomes-nonambiguous.rs        | 40 ++++++++++++++++++++++
 1 file changed, 40 insertions(+)
 create mode 100644 tests/ui/autoref-autoderef/deref-ambiguity-becomes-nonambiguous.rs

(limited to 'tests/ui/autoref-autoderef/deref-ambiguity-becomes-nonambiguous.rs')

diff --git a/tests/ui/autoref-autoderef/deref-ambiguity-becomes-nonambiguous.rs b/tests/ui/autoref-autoderef/deref-ambiguity-becomes-nonambiguous.rs
new file mode 100644
index 000000000..d8034d57e
--- /dev/null
+++ b/tests/ui/autoref-autoderef/deref-ambiguity-becomes-nonambiguous.rs
@@ -0,0 +1,40 @@
+use std::ops::Deref;
+use std::rc::Rc;
+
+struct Value<T>(T);
+
+pub trait Wrap<T> {
+    fn wrap() -> Self;
+}
+
+impl<R, A1, A2> Wrap<fn(A1, A2) -> R> for Value<fn(A1, A2) -> R> {
+    fn wrap() -> Self {
+        todo!()
+    }
+}
+
+impl<F, R, A1, A2> Wrap<F> for Value<Rc<dyn Fn(A1, A2) -> R>> {
+    fn wrap() -> Self {
+        todo!()
+    }
+}
+
+impl<F> Deref for Value<Rc<F>> {
+    type Target = F;
+
+    fn deref(&self) -> &Self::Target {
+        &*self.0
+    }
+}
+
+fn main() {
+    let var_fn = Value::wrap();
+    //~^ ERROR type annotations needed for `Value<Rc<_>>`
+
+    // The combination of `Value: Wrap` obligation plus the autoderef steps
+    // (caused by the `Deref` impl above) actually means that the self type
+    // of the method fn below is constrained to be `Value<Rc<dyn Fn(?0, ?1) -> ?2>>`.
+    // However, that's only known to us on the error path -- we still need
+    // to emit an ambiguity error, though.
+    let _ = var_fn.clone();
+}
-- 
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