resolve: Future-proof against imports referring to local variables and generic parameters

2 files changed, 99 insertions, 0 deletions

diff --git a/src/test/ui/rust-2018/future-proofing-locals.rs b/src/test/ui/rust-2018/future-proofing-locals.rs
new file mode 100644
index 00000000000..d2e6dbbb954
--- /dev/null
+++ b/src/test/ui/rust-2018/future-proofing-locals.rs
@@ -0,0 +1,49 @@
+// edition:2018
+
+#![feature(uniform_paths, underscore_imports)]
+
+mod T {
+    pub struct U;
+}
+mod x {
+    pub struct y;
+}
+
+fn type_param<T>() {
+    use T as _; //~ ERROR imports cannot refer to type parameters
+    use T::U; //~ ERROR imports cannot refer to type parameters
+    use T::*; //~ ERROR imports cannot refer to type parameters
+}
+
+fn self_import<T>() {
+    use T; // FIXME Should be an error, but future-proofing fails due to `T` being "self-shadowed"
+}
+
+fn let_binding() {
+    let x = 10;
+
+    use x as _; //~ ERROR imports cannot refer to local variables
+    use x::y; // OK
+    use x::*; // OK
+}
+
+fn param_binding(x: u8) {
+    use x; //~ ERROR imports cannot refer to local variables
+}
+
+fn match_binding() {
+    match 0 {
+        x => {
+            use x; //~ ERROR imports cannot refer to local variables
+        }
+    }
+}
+
+fn nested<T>() {
+    let x = 10;
+
+    use {T as _, x}; //~ ERROR imports cannot refer to type parameters
+                     //~| ERROR imports cannot refer to local variables
+}
+
+fn main() {}
diff --git a/src/test/ui/rust-2018/future-proofing-locals.stderr b/src/test/ui/rust-2018/future-proofing-locals.stderr
new file mode 100644
index 00000000000..68354b332a9
--- /dev/null
+++ b/src/test/ui/rust-2018/future-proofing-locals.stderr
@@ -0,0 +1,50 @@
+error: imports cannot refer to type parameters
+  --> $DIR/future-proofing-locals.rs:13:9
+   |
+LL |     use T as _; //~ ERROR imports cannot refer to type parameters
+   |         ^
+
+error: imports cannot refer to type parameters
+  --> $DIR/future-proofing-locals.rs:14:9
+   |
+LL |     use T::U; //~ ERROR imports cannot refer to type parameters
+   |         ^
+
+error: imports cannot refer to type parameters
+  --> $DIR/future-proofing-locals.rs:15:9
+   |
+LL |     use T::*; //~ ERROR imports cannot refer to type parameters
+   |         ^
+
+error: imports cannot refer to local variables
+  --> $DIR/future-proofing-locals.rs:25:9
+   |
+LL |     use x as _; //~ ERROR imports cannot refer to local variables
+   |         ^
+
+error: imports cannot refer to local variables
+  --> $DIR/future-proofing-locals.rs:31:9
+   |
+LL |     use x; //~ ERROR imports cannot refer to local variables
+   |         ^
+
+error: imports cannot refer to local variables
+  --> $DIR/future-proofing-locals.rs:37:17
+   |
+LL |             use x; //~ ERROR imports cannot refer to local variables
+   |                 ^
+
+error: imports cannot refer to type parameters
+  --> $DIR/future-proofing-locals.rs:45:10
+   |
+LL |     use {T as _, x}; //~ ERROR imports cannot refer to type parameters
+   |          ^
+
+error: imports cannot refer to local variables
+  --> $DIR/future-proofing-locals.rs:45:18
+   |
+LL |     use {T as _, x}; //~ ERROR imports cannot refer to type parameters
+   |                  ^
+
+error: aborting due to 8 previous errors
+