Adjust `tests/ui/attr-usage-inline.rs`

- Move `tests/ui/attr-usage-inline.rs` to `tests/ui/attributes/inline/`.
- Briefly document test intent.
- Drop unnecessary `#[allow(dead_code)]` as this is allowed-by-default
  for ui test suite.

1 files changed, 26 insertions, 0 deletions

diff --git a/tests/ui/attributes/inline/attr-usage-inline.rs b/tests/ui/attributes/inline/attr-usage-inline.rs
new file mode 100644
index 00000000000..d8ca0fce163
--- /dev/null
+++ b/tests/ui/attributes/inline/attr-usage-inline.rs
@@ -0,0 +1,26 @@
+//! Check that `#[inline]` attribute can only be applied to fn-like targets (e.g. function or
+//! closure), and when misapplied to other targets an error is emitted.
+
+#[inline]
+fn f() {}
+
+#[inline] //~ ERROR: attribute should be applied to function or closure
+struct S;
+
+struct I {
+    #[inline]
+    i: u8,
+}
+
+#[macro_export]
+#[inline]
+macro_rules! m_e {
+    () => {};
+}
+
+#[inline] //~ ERROR: attribute should be applied to function or closure
+macro_rules! m {
+    () => {};
+}
+
+fn main() {}