Rollup merge of #20998 - estsauver:20984, r=steveklabnik

There are a large number of places that incorrectly refer
to deriving in comments, instead of derives.

If someone could look at src/etc/generate-deriving-span-tests.py,
I'm not sure how those tests were passing before/if they were. 

1 files changed, 1 insertions, 1 deletions

diff --git a/src/libstd/fmt.rs b/src/libstd/fmt.rs
index 36afa0956d2..88fb983361a 100644
--- a/src/libstd/fmt.rs
+++ b/src/libstd/fmt.rs
@@ -221,7 +221,7 @@
 //! - `fmt::Show` implementations should be implemented for **all** public types.
 //!   Output will typically represent the internal state as faithfully as possible.
 //!   The purpose of the `Show` trait is to facilitate debugging Rust code. In
-//!   most cases, using `#[deriving(Show)]` is sufficient and recommended.
+//!   most cases, using `#[derive(Show)]` is sufficient and recommended.
 //!
 //! Some examples of the output from both traits:
 //!