Don't add attribute to allow unused-qualifications to derive impl's

Currently `#![forbid(unused_qualifications)]` is incompatible with all
derive's because we add `#[allow(unused_qualifications)]` in all
generated impl's.

2 files changed, 38 insertions, 0 deletions

diff --git a/src/test/ui/lint/auxiliary/add-impl.rs b/src/test/ui/lint/auxiliary/add-impl.rs
new file mode 100644
index 00000000000..9d0e3068aed
--- /dev/null
+++ b/src/test/ui/lint/auxiliary/add-impl.rs
@@ -0,0 +1,22 @@
+// force-host
+// no-prefer-dynamic
+
+#![crate_type = "proc-macro"]
+
+extern crate proc_macro;
+
+use proc_macro::TokenStream;
+
+#[proc_macro_derive(AddImpl)]
+// Unnecessary qualification `bar::foo`
+// https://github.com/rust-lang/rust/issues/71898
+pub fn derive(input: TokenStream) -> TokenStream {
+    "impl B {
+            fn foo(&self) { use bar::foo; bar::foo() }
+        }
+
+        fn foo() {}
+
+        mod bar { pub fn foo() {} }
+    ".parse().unwrap()
+}
diff --git a/src/test/ui/lint/unused-qualification-in-derive-expansion.rs b/src/test/ui/lint/unused-qualification-in-derive-expansion.rs
new file mode 100644
index 00000000000..c2efbf507fe
--- /dev/null
+++ b/src/test/ui/lint/unused-qualification-in-derive-expansion.rs
@@ -0,0 +1,16 @@
+// run-pass
+// aux-build:add-impl.rs
+
+#![forbid(unused_qualifications)]
+
+#[macro_use]
+extern crate add_impl;
+
+#[derive(AddImpl)]
+struct B;
+
+fn main() {
+    B.foo();
+    foo();
+    bar::foo();
+}