Implement `use` associated items of traits

6 files changed, 152 insertions, 14 deletions

diff --git a/tests/ui/use/import_trait_associated_functions-2015.rs b/tests/ui/use/import_trait_associated_functions-2015.rs
new file mode 100644
index 00000000000..3177aeefb09
--- /dev/null
+++ b/tests/ui/use/import_trait_associated_functions-2015.rs
@@ -0,0 +1,61 @@
+//@ edition:2015
+//@ check-pass
+#![feature(import_trait_associated_functions)]
+
+use std::collections::HashMap;
+
+use A::{DEFAULT, new};
+use std::default::Default::default;
+
+struct S {
+    a: HashMap<i32, i32>,
+}
+
+impl S {
+    fn new() -> S {
+        S { a: default() }
+    }
+}
+
+trait A: Sized {
+    const DEFAULT: Option<Self> = None;
+    fn new() -> Self;
+    fn do_something(&self);
+}
+
+mod b {
+    use super::A::{self, DEFAULT, new};
+
+    struct B();
+
+    impl A for B {
+        const DEFAULT: Option<Self> = Some(B());
+        fn new() -> Self {
+            B()
+        }
+
+        fn do_something(&self) {}
+    }
+
+    fn f() {
+        let b: B = new();
+        b.do_something();
+        let c: B = DEFAULT.unwrap();
+    }
+}
+
+impl A for S {
+    fn new() -> Self {
+        S::new()
+    }
+
+    fn do_something(&self) {}
+}
+
+fn f() {
+    let s: S = new();
+    s.do_something();
+    let t: Option<S> = DEFAULT;
+}
+
+fn main() {}
diff --git a/tests/ui/use/import_trait_associated_functions.rs b/tests/ui/use/import_trait_associated_functions.rs
new file mode 100644
index 00000000000..4dc473404db
--- /dev/null
+++ b/tests/ui/use/import_trait_associated_functions.rs
@@ -0,0 +1,61 @@
+//@ edition:2018
+//@ check-pass
+#![feature(import_trait_associated_functions)]
+
+use std::collections::HashMap;
+
+use A::{DEFAULT, new};
+use Default::default;
+
+struct S {
+    a: HashMap<i32, i32>,
+}
+
+impl S {
+    fn new() -> S {
+        S { a: default() }
+    }
+}
+
+trait A: Sized {
+    const DEFAULT: Option<Self> = None;
+    fn new() -> Self;
+    fn do_something(&self);
+}
+
+mod b {
+    use super::A::{self, DEFAULT, new};
+
+    struct B();
+
+    impl A for B {
+        const DEFAULT: Option<Self> = Some(B());
+        fn new() -> Self {
+            B()
+        }
+
+        fn do_something(&self) {}
+    }
+
+    fn f() {
+        let b: B = new();
+        b.do_something();
+        let c: B = DEFAULT.unwrap();
+    }
+}
+
+impl A for S {
+    fn new() -> Self {
+        S::new()
+    }
+
+    fn do_something(&self) {}
+}
+
+fn f() {
+    let s: S = new();
+    s.do_something();
+    let t: Option<S> = DEFAULT;
+}
+
+fn main() {}
diff --git a/tests/ui/use/use-from-trait-xc.rs b/tests/ui/use/use-from-trait-xc.rs
index b7b9c834b32..b030892aa26 100644
--- a/tests/ui/use/use-from-trait-xc.rs
+++ b/tests/ui/use/use-from-trait-xc.rs
@@ -3,13 +3,13 @@
 extern crate use_from_trait_xc;
 
 use use_from_trait_xc::Trait::foo;
-//~^ ERROR `foo` is not directly importable
+//~^ ERROR `use` associated items of traits is unstable [E0658]
 
 use use_from_trait_xc::Trait::Assoc;
 //~^ ERROR `Assoc` is not directly importable
 
 use use_from_trait_xc::Trait::CONST;
-//~^ ERROR `CONST` is not directly importable
+//~^ ERROR `use` associated items of traits is unstable [E0658]
 
 use use_from_trait_xc::Foo::new; //~ ERROR struct `Foo` is private
 //~^ ERROR unresolved import `use_from_trait_xc::Foo`
diff --git a/tests/ui/use/use-from-trait-xc.stderr b/tests/ui/use/use-from-trait-xc.stderr
index 4c4c2f6225f..0f8440aa530 100644
--- a/tests/ui/use/use-from-trait-xc.stderr
+++ b/tests/ui/use/use-from-trait-xc.stderr
@@ -1,8 +1,12 @@
-error[E0253]: `foo` is not directly importable
+error[E0658]: `use` associated items of traits is unstable
   --> $DIR/use-from-trait-xc.rs:5:5
    |
 LL | use use_from_trait_xc::Trait::foo;
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot be imported directly
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #134691 <https://github.com/rust-lang/rust/issues/134691> for more information
+   = help: add `#![feature(import_trait_associated_functions)]` to the crate attributes to enable
+   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
 error[E0253]: `Assoc` is not directly importable
   --> $DIR/use-from-trait-xc.rs:8:5
@@ -10,11 +14,15 @@ error[E0253]: `Assoc` is not directly importable
 LL | use use_from_trait_xc::Trait::Assoc;
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot be imported directly
 
-error[E0253]: `CONST` is not directly importable
+error[E0658]: `use` associated items of traits is unstable
   --> $DIR/use-from-trait-xc.rs:11:5
    |
 LL | use use_from_trait_xc::Trait::CONST;
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot be imported directly
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #134691 <https://github.com/rust-lang/rust/issues/134691> for more information
+   = help: add `#![feature(import_trait_associated_functions)]` to the crate attributes to enable
+   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
 error[E0432]: unresolved import `use_from_trait_xc::Foo`
   --> $DIR/use-from-trait-xc.rs:14:24
@@ -66,5 +74,5 @@ LL | struct Foo;
 
 error: aborting due to 9 previous errors
 
-Some errors have detailed explanations: E0253, E0432, E0603.
+Some errors have detailed explanations: E0253, E0432, E0603, E0658.
 For more information about an error, try `rustc --explain E0253`.
diff --git a/tests/ui/use/use-from-trait.rs b/tests/ui/use/use-from-trait.rs
index eab4bb6e3b5..89b7aaa4ba3 100644
--- a/tests/ui/use/use-from-trait.rs
+++ b/tests/ui/use/use-from-trait.rs
@@ -1,6 +1,6 @@
-use Trait::foo; //~ ERROR `foo` is not directly importable
+use Trait::foo; //~ ERROR `use` associated items of traits is unstable [E0658]
 use Trait::Assoc; //~ ERROR `Assoc` is not directly importable
-use Trait::C; //~ ERROR `C` is not directly importable
+use Trait::C; //~ ERROR `use` associated items of traits is unstable [E0658]
 
 use Foo::new; //~ ERROR unresolved import `Foo` [E0432]
 
diff --git a/tests/ui/use/use-from-trait.stderr b/tests/ui/use/use-from-trait.stderr
index a5b0e356b34..2dd78a35452 100644
--- a/tests/ui/use/use-from-trait.stderr
+++ b/tests/ui/use/use-from-trait.stderr
@@ -1,8 +1,12 @@
-error[E0253]: `foo` is not directly importable
+error[E0658]: `use` associated items of traits is unstable
   --> $DIR/use-from-trait.rs:1:5
    |
 LL | use Trait::foo;
-   |     ^^^^^^^^^^ cannot be imported directly
+   |     ^^^^^^^^^^
+   |
+   = note: see issue #134691 <https://github.com/rust-lang/rust/issues/134691> for more information
+   = help: add `#![feature(import_trait_associated_functions)]` to the crate attributes to enable
+   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
 error[E0253]: `Assoc` is not directly importable
   --> $DIR/use-from-trait.rs:2:5
@@ -10,11 +14,15 @@ error[E0253]: `Assoc` is not directly importable
 LL | use Trait::Assoc;
    |     ^^^^^^^^^^^^ cannot be imported directly
 
-error[E0253]: `C` is not directly importable
+error[E0658]: `use` associated items of traits is unstable
   --> $DIR/use-from-trait.rs:3:5
    |
 LL | use Trait::C;
-   |     ^^^^^^^^ cannot be imported directly
+   |     ^^^^^^^^
+   |
+   = note: see issue #134691 <https://github.com/rust-lang/rust/issues/134691> for more information
+   = help: add `#![feature(import_trait_associated_functions)]` to the crate attributes to enable
+   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
 error[E0432]: unresolved import `Foo`
   --> $DIR/use-from-trait.rs:5:5
@@ -30,5 +38,5 @@ LL | use Foo::C2;
 
 error: aborting due to 5 previous errors
 
-Some errors have detailed explanations: E0253, E0432.
+Some errors have detailed explanations: E0253, E0432, E0658.
 For more information about an error, try `rustc --explain E0253`.