Delegation: support coercion for target expression

10 files changed, 158 insertions, 17 deletions

diff --git a/tests/ui/delegation/bad-resolve.rs b/tests/ui/delegation/bad-resolve.rs
index f378e05304b..f15e6aa81af 100644
--- a/tests/ui/delegation/bad-resolve.rs
+++ b/tests/ui/delegation/bad-resolve.rs
@@ -34,6 +34,9 @@ impl Trait for S {
 
     reuse foo { &self.0 }
     //~^ ERROR cannot find function `foo` in this scope
+    reuse Trait::foo2 { self.0 }
+    //~^ ERROR cannot find function `foo2` in trait `Trait`
+    //~| ERROR method `foo2` is not a member of trait `Trait`
 }
 
 mod prefix {}
diff --git a/tests/ui/delegation/bad-resolve.stderr b/tests/ui/delegation/bad-resolve.stderr
index 883ff523bcf..32d2f3b26cb 100644
--- a/tests/ui/delegation/bad-resolve.stderr
+++ b/tests/ui/delegation/bad-resolve.stderr
@@ -25,6 +25,15 @@ LL |     reuse <F as Trait>::baz;
    |     |                   help: there is an associated function with a similar name: `bar`
    |     not a member of trait `Trait`
 
+error[E0407]: method `foo2` is not a member of trait `Trait`
+  --> $DIR/bad-resolve.rs:37:5
+   |
+LL |     reuse Trait::foo2 { self.0 }
+   |     ^^^^^^^^^^^^^----^^^^^^^^^^^
+   |     |            |
+   |     |            help: there is an associated function with a similar name: `foo`
+   |     not a member of trait `Trait`
+
 error[E0423]: expected function, found associated constant `Trait::C`
   --> $DIR/bad-resolve.rs:24:11
    |
@@ -54,6 +63,15 @@ error[E0425]: cannot find function `foo` in this scope
 LL |     reuse foo { &self.0 }
    |           ^^^ not found in this scope
 
+error[E0425]: cannot find function `foo2` in trait `Trait`
+  --> $DIR/bad-resolve.rs:37:18
+   |
+LL |     fn foo(&self, x: i32) -> i32 { x }
+   |     ---------------------------- similarly named associated function `foo` defined here
+...
+LL |     reuse Trait::foo2 { self.0 }
+   |                  ^^^^ help: an associated function with a similar name exists: `foo`
+
 error[E0046]: not all trait items implemented, missing: `Type`
   --> $DIR/bad-resolve.rs:22:1
    |
@@ -64,18 +82,18 @@ LL | impl Trait for S {
    | ^^^^^^^^^^^^^^^^ missing `Type` in implementation
 
 error[E0433]: failed to resolve: use of undeclared crate or module `unresolved_prefix`
-  --> $DIR/bad-resolve.rs:40:7
+  --> $DIR/bad-resolve.rs:43:7
    |
 LL | reuse unresolved_prefix::{a, b, c};
    |       ^^^^^^^^^^^^^^^^^ use of undeclared crate or module `unresolved_prefix`
 
 error[E0433]: failed to resolve: `crate` in paths can only be used in start position
-  --> $DIR/bad-resolve.rs:41:29
+  --> $DIR/bad-resolve.rs:44:29
    |
 LL | reuse prefix::{self, super, crate};
    |                             ^^^^^ `crate` in paths can only be used in start position
 
-error: aborting due to 10 previous errors
+error: aborting due to 12 previous errors
 
 Some errors have detailed explanations: E0046, E0324, E0407, E0423, E0425, E0433, E0575, E0576.
 For more information about an error, try `rustc --explain E0046`.
diff --git a/tests/ui/delegation/explicit-paths-pass.rs b/tests/ui/delegation/explicit-paths-pass.rs
index fada793bd11..dd0ee2c732f 100644
--- a/tests/ui/delegation/explicit-paths-pass.rs
+++ b/tests/ui/delegation/explicit-paths-pass.rs
@@ -24,8 +24,8 @@ reuse to_reuse::zero_args { self }
 
 struct S(F);
 impl Trait for S {
-    reuse Trait::bar { &self.0 }
-    reuse Trait::description { &self.0 }
+    reuse Trait::bar { self.0 }
+    reuse Trait::description { self.0 }
     reuse <F as Trait>::static_method;
     reuse <F as Trait>::static_method2 { S::static_method(self) }
 }
diff --git a/tests/ui/delegation/explicit-paths.rs b/tests/ui/delegation/explicit-paths.rs
index a91ca4cb931..d42e305b252 100644
--- a/tests/ui/delegation/explicit-paths.rs
+++ b/tests/ui/delegation/explicit-paths.rs
@@ -34,7 +34,7 @@ mod inherent_impl_assoc_fn_to_other {
     use crate::*;
 
     impl S {
-        reuse Trait::foo1 { &self.0 }
+        reuse Trait::foo1 { self.0 }
         reuse <S as Trait>::foo2;
         reuse to_reuse::foo3;
         reuse F::foo4 { &self.0 }
@@ -46,7 +46,7 @@ mod trait_impl_assoc_fn_to_other {
     use crate::*;
 
     impl Trait for S {
-        reuse Trait::foo1 { &self.0 }
+        reuse Trait::foo1 { self.0 }
         reuse <F as Trait>::foo2;
         reuse to_reuse::foo3;
         //~^ ERROR method `foo3` is not a member of trait `Trait`
diff --git a/tests/ui/delegation/explicit-paths.stderr b/tests/ui/delegation/explicit-paths.stderr
index d33c5da4377..b5afe19f878 100644
--- a/tests/ui/delegation/explicit-paths.stderr
+++ b/tests/ui/delegation/explicit-paths.stderr
@@ -91,10 +91,17 @@ error[E0308]: mismatched types
 LL |     trait Trait2 : Trait {
    |     -------------------- found this type parameter
 LL |         reuse <F as Trait>::foo1 { self }
-   |                                    ^^^^ expected `&F`, found `&Self`
+   |                             ----   ^^^^ expected `&F`, found `&Self`
+   |                             |
+   |                             arguments to this function are incorrect
    |
    = note: expected reference `&F`
               found reference `&Self`
+note: method defined here
+  --> $DIR/explicit-paths.rs:5:8
+   |
+LL |     fn foo1(&self, x: i32) -> i32 { x }
+   |        ^^^^ -----
 
 error[E0277]: the trait bound `S2: Trait` is not satisfied
   --> $DIR/explicit-paths.rs:78:16
diff --git a/tests/ui/delegation/ice-issue-122550.stderr b/tests/ui/delegation/ice-issue-122550.stderr
index c92170644e7..1a01bee3e1e 100644
--- a/tests/ui/delegation/ice-issue-122550.stderr
+++ b/tests/ui/delegation/ice-issue-122550.stderr
@@ -4,15 +4,6 @@ error[E0308]: mismatched types
 LL |     fn description(&self) -> &str {}
    |                                   ^^ expected `&str`, found `()`
 
-error[E0308]: mismatched types
-  --> $DIR/ice-issue-122550.rs:13:39
-   |
-LL |     reuse <S as Trait>::description { &self.0 }
-   |                                       ^^^^^^^ expected `&S`, found `&F`
-   |
-   = note: expected reference `&S`
-              found reference `&F`
-
 error[E0277]: the trait bound `S: Trait` is not satisfied
   --> $DIR/ice-issue-122550.rs:13:12
    |
@@ -25,6 +16,22 @@ help: this trait has no implementations, consider adding one
 LL | trait Trait {
    | ^^^^^^^^^^^
 
+error[E0308]: mismatched types
+  --> $DIR/ice-issue-122550.rs:13:39
+   |
+LL |     reuse <S as Trait>::description { &self.0 }
+   |                         -----------   ^^^^^^^ expected `&S`, found `&F`
+   |                         |
+   |                         arguments to this function are incorrect
+   |
+   = note: expected reference `&S`
+              found reference `&F`
+note: method defined here
+  --> $DIR/ice-issue-122550.rs:5:8
+   |
+LL |     fn description(&self) -> &str {}
+   |        ^^^^^^^^^^^ -----
+
 error: aborting due to 3 previous errors
 
 Some errors have detailed explanations: E0277, E0308.
diff --git a/tests/ui/delegation/method-call-choice.rs b/tests/ui/delegation/method-call-choice.rs
new file mode 100644
index 00000000000..8d53d8bfdb7
--- /dev/null
+++ b/tests/ui/delegation/method-call-choice.rs
@@ -0,0 +1,25 @@
+#![feature(fn_delegation)]
+#![allow(incomplete_features)]
+
+trait Trait {
+    fn foo(&self) {}
+}
+
+struct F;
+impl Trait for F {}
+struct S(F);
+
+pub mod to_reuse {
+    use crate::F;
+
+    pub fn foo(_: &F) {}
+}
+
+impl Trait for S {
+    // Make sure that the method call is not generated if the path resolution
+    // does not have a `self` parameter.
+    reuse to_reuse::foo { self.0 }
+    //~^ ERROR mismatched types
+}
+
+fn main() {}
diff --git a/tests/ui/delegation/method-call-choice.stderr b/tests/ui/delegation/method-call-choice.stderr
new file mode 100644
index 00000000000..6757af20a6b
--- /dev/null
+++ b/tests/ui/delegation/method-call-choice.stderr
@@ -0,0 +1,21 @@
+error[E0308]: mismatched types
+  --> $DIR/method-call-choice.rs:21:27
+   |
+LL |     reuse to_reuse::foo { self.0 }
+   |                     ---   ^^^^^^ expected `&F`, found `F`
+   |                     |
+   |                     arguments to this function are incorrect
+   |
+note: function defined here
+  --> $DIR/method-call-choice.rs:15:12
+   |
+LL |     pub fn foo(_: &F) {}
+   |            ^^^ -----
+help: consider borrowing here
+   |
+LL |     reuse to_reuse::foo { &self.0 }
+   |                           +
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/tests/ui/delegation/method-call-priority.rs b/tests/ui/delegation/method-call-priority.rs
new file mode 100644
index 00000000000..8d68740d181
--- /dev/null
+++ b/tests/ui/delegation/method-call-priority.rs
@@ -0,0 +1,34 @@
+//@ run-pass
+
+#![feature(fn_delegation)]
+#![allow(incomplete_features)]
+#![allow(dead_code)]
+
+trait Trait1 {
+    fn foo(&self) -> i32 { 1 }
+}
+
+trait Trait2 {
+    fn foo(&self) -> i32 { 2 }
+}
+
+struct F;
+impl Trait1 for F {}
+impl Trait2 for F {}
+
+impl F {
+    fn foo(&self) -> i32 { 3 }
+}
+
+struct S(F);
+
+impl Trait1 for S {
+    // Make sure that the generated `self.0.foo()` does not turn into the inherent method `F::foo`
+    // that has a higher priority than methods from traits.
+    reuse Trait1::foo { self.0 }
+}
+
+fn main() {
+    let s = S(F);
+    assert_eq!(s.foo(), 1);
+}
diff --git a/tests/ui/delegation/self-coercion.rs b/tests/ui/delegation/self-coercion.rs
new file mode 100644
index 00000000000..96c1f1b140b
--- /dev/null
+++ b/tests/ui/delegation/self-coercion.rs
@@ -0,0 +1,26 @@
+//@ run-pass
+
+#![feature(fn_delegation)]
+#![allow(incomplete_features)]
+
+trait Trait : Sized {
+    fn by_value(self) -> i32 { 1 }
+    fn by_mut_ref(&mut self) -> i32 { 2 }
+    fn by_ref(&self) -> i32 { 3 }
+}
+
+struct F;
+impl Trait for F {}
+
+struct S(F);
+
+impl Trait for S {
+    reuse Trait::{by_value, by_mut_ref, by_ref} { self.0 }
+}
+
+fn main() {
+    let mut s = S(F);
+    assert_eq!(s.by_ref(), 3);
+    assert_eq!(s.by_mut_ref(), 2);
+    assert_eq!(s.by_value(), 1);
+}