Add more tests for underscore imports

src/test/ui/underscore-imports/hygiene-2.rs

@@ -0,0 +1,33 @@
+// Make sure that underscore imports with different contexts can exist in the
+// same scope.
+
+// check-pass
+
+#![feature(decl_macro)]
+
+mod x {
+    pub use std::ops::Deref as _;
+}
+
+macro n() {
+    pub use crate::x::*;
+}
+
+#[macro_export]
+macro_rules! p {
+    () => { pub use crate::x::*; }
+}
+
+macro m($y:ident) {
+    mod $y {
+        crate::n!(); // Reexport of `Deref` should not be imported in `main`
+        crate::p!(); // Reexport of `Deref` should be imported into `main`
+    }
+}
+
+m!(y);
+
+fn main() {
+    use crate::y::*;
+    (&()).deref();
+}

src/test/ui/underscore-imports/hygiene.rs

@@ -0,0 +1,40 @@
+// Make sure that underscore imports have the same hygiene considerations as
+// other imports.
+
+#![feature(decl_macro)]
+
+mod x {
+    pub use std::ops::Deref as _;
+}
+
+
+macro glob_import() {
+    pub use crate::x::*;
+}
+
+macro underscore_import() {
+    use std::ops::DerefMut as _;
+}
+
+mod y {
+    crate::glob_import!();
+    crate::underscore_import!();
+}
+
+macro create_module($y:ident) {
+    mod $y {
+        crate::glob_import!();
+        crate::underscore_import!();
+    }
+}
+
+create_module!(z);
+
+fn main() {
+    use crate::y::*;
+    use crate::z::*;
+    glob_import!();
+    underscore_import!();
+    (&()).deref();              //~ ERROR no method named `deref`
+    (&mut ()).deref_mut();      //~ ERROR no method named `deref_mut`
+}

src/test/ui/underscore-imports/hygiene.stderr

@@ -0,0 +1,27 @@
+error[E0599]: no method named `deref` found for type `&()` in the current scope
+  --> $DIR/hygiene.rs:38:11
+   |
+LL |     (&()).deref();
+   |           ^^^^^ method not found in `&()`
+   |
+   = help: items from traits can only be used if the trait is in scope
+help: the following trait is implemented but not in scope; perhaps add a `use` for it:
+   |
+LL | use std::ops::Deref;
+   |
+
+error[E0599]: no method named `deref_mut` found for type `&mut ()` in the current scope
+  --> $DIR/hygiene.rs:39:15
+   |
+LL |     (&mut ()).deref_mut();
+   |               ^^^^^^^^^ method not found in `&mut ()`
+   |
+   = help: items from traits can only be used if the trait is in scope
+help: the following trait is implemented but not in scope; perhaps add a `use` for it:
+   |
+LL | use std::ops::DerefMut;
+   |
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0599`.

src/test/ui/underscore-imports/macro-expanded.rs

@@ -0,0 +1,45 @@
+// Check that macro expanded underscore imports behave as expected
+
+// check-pass
+
+#![feature(decl_macro, rustc_attrs)]
+
+mod x {
+    pub use std::ops::Not as _;
+}
+
+macro m() {
+    mod w {
+        mod y {
+            pub use std::ops::Deref as _;
+        }
+        use crate::x::*;
+        use self::y::*;
+        use std::ops::DerefMut as _;
+        fn f() {
+            false.not();
+            (&()).deref();
+            (&mut ()).deref_mut();
+        }
+    }
+}
+
+#[rustc_macro_transparency = "transparent"]
+macro n() {
+    mod z {
+        pub use std::ops::Deref as _;
+    }
+    use crate::x::*;
+    use crate::z::*;
+    use std::ops::DerefMut as _;
+    fn f() {
+        false.not();
+        (&()).deref();
+        (&mut ()).deref_mut();
+    }
+}
+
+m!();
+n!();
+
+fn main() {}