Auto merge of #44818 - petrochenkov:astymac2, r=jseyfried

Improve resolution of associated types in declarative macros 2.0

Make various identifier comparisons for associated types (and sometimes other associated items) hygienic.
Now declarative macros 2.0 can use `Self::AssocTy`, `TyParam::AssocTy`, `Trait<AssocTy = u8>` where `AssocTy` is an associated type of a trait `Trait` visible from the macro. Also, `Trait` can now be implemented inside the macro and specialization should work properly (fixes https://github.com/rust-lang/rust/pull/40847#issuecomment-310867299).

r? @jseyfried or @eddyb

3 files changed, 135 insertions, 0 deletions

diff --git a/src/test/compile-fail/hygiene/assoc_item_ctxt.rs b/src/test/compile-fail/hygiene/assoc_item_ctxt.rs
new file mode 100644
index 00000000000..e336b0df13f
--- /dev/null
+++ b/src/test/compile-fail/hygiene/assoc_item_ctxt.rs
@@ -0,0 +1,52 @@
+// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// ignore-pretty pretty-printing is unhygienic
+
+#![feature(decl_macro)]
+#![allow(unused)]
+
+mod ok {
+    macro mac_trait_item($method: ident) {
+        fn $method();
+    }
+
+    trait Tr {
+        mac_trait_item!(method);
+    }
+
+    macro mac_trait_impl() {
+        impl Tr for u8 { // OK
+            fn method() {} // OK
+        }
+    }
+
+    mac_trait_impl!();
+}
+
+mod error {
+    macro mac_trait_item() {
+        fn method();
+    }
+
+    trait Tr {
+        mac_trait_item!();
+    }
+
+    macro mac_trait_impl() {
+        impl Tr for u8 { //~ ERROR not all trait items implemented, missing: `method`
+            fn method() {} //~ ERROR method `method` is not a member of trait `Tr`
+        }
+    }
+
+    mac_trait_impl!();
+}
+
+fn main() {}
diff --git a/src/test/compile-fail/hygiene/assoc_ty_bindings.rs b/src/test/compile-fail/hygiene/assoc_ty_bindings.rs
new file mode 100644
index 00000000000..46a138749ff
--- /dev/null
+++ b/src/test/compile-fail/hygiene/assoc_ty_bindings.rs
@@ -0,0 +1,49 @@
+// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// ignore-pretty pretty-printing is unhygienic
+
+#![feature(decl_macro, associated_type_defaults)]
+#![feature(rustc_attrs)]
+
+trait Base {
+    type AssocTy;
+    fn f();
+}
+trait Derived: Base {
+    fn g();
+}
+
+macro mac() {
+    type A = Base<AssocTy = u8>;
+    type B = Derived<AssocTy = u8>;
+
+    impl Base for u8 {
+        type AssocTy = u8;
+        fn f() {
+            let _: Self::AssocTy;
+        }
+    }
+    impl Derived for u8 {
+        fn g() {
+            let _: Self::AssocTy;
+        }
+    }
+
+    fn h<T: Base, U: Derived>() {
+        let _: T::AssocTy;
+        let _: U::AssocTy;
+    }
+}
+
+mac!();
+
+#[rustc_error]
+fn main() {} //~ ERROR compilation successful
diff --git a/src/test/run-pass/hygiene/specialization.rs b/src/test/run-pass/hygiene/specialization.rs
new file mode 100644
index 00000000000..3d46d2ec99e
--- /dev/null
+++ b/src/test/run-pass/hygiene/specialization.rs
@@ -0,0 +1,34 @@
+// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// ignore-pretty pretty-printing is unhygienic
+
+#![feature(decl_macro)]
+
+trait Tr {
+    fn f(&self) -> &'static str {
+        "This shouldn't happen"
+    }
+}
+
+pub macro m($t:ty) {
+    impl Tr for $t {
+        fn f(&self) -> &'static str {
+            "Run me"
+        }
+    }
+}
+
+struct S;
+m!(S);
+
+fn main() {
+    assert_eq!(S.f(), "Run me");
+}