From af710c9e79345497fdad53873f0acefa0e26fddf Mon Sep 17 00:00:00 2001
From: Mazdak Farrokhzad <twingoow@gmail.com>
Date: Sat, 22 Jun 2019 12:12:26 +0200
Subject: [PATCH] Add test for linting on 'cfg_attr(,)'.

---
 .../cfg-attr-empty-is-unused.rs               | 13 ++++++++++++
 .../cfg-attr-empty-is-unused.stderr           | 21 +++++++++++++++++++
 2 files changed, 34 insertions(+)
 create mode 100644 src/test/ui/conditional-compilation/cfg-attr-empty-is-unused.rs
 create mode 100644 src/test/ui/conditional-compilation/cfg-attr-empty-is-unused.stderr

diff --git a/src/test/ui/conditional-compilation/cfg-attr-empty-is-unused.rs b/src/test/ui/conditional-compilation/cfg-attr-empty-is-unused.rs
new file mode 100644
index 00000000000..4c96d6e7ca1
--- /dev/null
+++ b/src/test/ui/conditional-compilation/cfg-attr-empty-is-unused.rs
@@ -0,0 +1,13 @@
+// Check that `#[cfg_attr($PREDICATE,)]` triggers the `unused_attribute` lint.
+
+// compile-flags: --cfg TRUE
+
+#![deny(unused)]
+
+#[cfg_attr(FALSE,)] //~ ERROR unused attribute
+fn _f() {}
+
+#[cfg_attr(TRUE,)] //~ ERROR unused attribute
+fn _g() {}
+
+fn main() {}
diff --git a/src/test/ui/conditional-compilation/cfg-attr-empty-is-unused.stderr b/src/test/ui/conditional-compilation/cfg-attr-empty-is-unused.stderr
new file mode 100644
index 00000000000..cd3563e66c7
--- /dev/null
+++ b/src/test/ui/conditional-compilation/cfg-attr-empty-is-unused.stderr
@@ -0,0 +1,21 @@
+error: unused attribute
+  --> $DIR/cfg-attr-empty-is-unused.rs:7:1
+   |
+LL | #[cfg_attr(FALSE,)]
+   | ^^^^^^^^^^^^^^^^^^^
+   |
+note: lint level defined here
+  --> $DIR/cfg-attr-empty-is-unused.rs:5:9
+   |
+LL | #![deny(unused)]
+   |         ^^^^^^
+   = note: #[deny(unused_attributes)] implied by #[deny(unused)]
+
+error: unused attribute
+  --> $DIR/cfg-attr-empty-is-unused.rs:10:1
+   |
+LL | #[cfg_attr(TRUE,)]
+   | ^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 2 previous errors
+