Rename lint unused_doc_comment to unused_doc_comments

[bjgill]

This looks to be a useful PR, thanks. Is this back-compatible? The travis failure perhaps suggests not.

EDIT: it looks as if you might want something like:

diff --git a/src/error_chain.rs b/src/error_chain.rs
index ddba192..3ef7dc2 100644
--- a/src/error_chain.rs
+++ b/src/error_chain.rs
@@ -179,7 +179,7 @@ macro_rules! impl_error_chain_processed {
                 self.description()
             }

-            #[allow(unknown_lints, unused_doc_comments)]
+            #[allow(unknown_lints, unused_doc_comment, unused_doc_comment, unused_doc_comments)]
             fn cause(&self) -> Option<&::std::error::Error> {
                 match self.1.next_error {
                     Some(ref c) => Some(&**c),
@@ -421,7 +421,7 @@ macro_rules! impl_extract_backtrace {
     ($error_name: ident
      $error_kind_name: ident
      $([$link_error_path: path, $(#[$meta_links: meta])*])*) => {
-        #[allow(unknown_lints, unused_doc_comments)]
+        #[allow(unknown_lints, unused_doc_comment, unused_doc_comments)]
         fn extract_backtrace(e: &(::std::error::Error + Send + 'static))
             -> Option<$crate::InternalBacktrace> {
             if let Some(e) = e.downcast_ref::<$error_name>() {
diff --git a/src/impl_error_chain_kind.rs b/src/impl_error_chain_kind.rs
index 2d51a92..6c89d00 100644
--- a/src/impl_error_chain_kind.rs
+++ b/src/impl_error_chain_kind.rs
@@ -224,7 +224,7 @@ macro_rules! impl_error_chain_kind {
             $item:ident: $imode:tt [$(#[$imeta:meta])*] [$( $var:ident: $typ:ty ),*] {$( $funcs:tt )*}
         )*}
     ) => {
-        #[allow(unknown_lints, unused, unused_doc_comments)]
+        #[allow(unknown_lints, unused, unused_doc_comment, unused_doc_comments)]
         impl ::std::fmt::Display for $name {
             fn fmt(&self, fmt: &mut ::std::fmt::Formatter)
                 -> ::std::fmt::Result
@@ -247,7 +247,7 @@ macro_rules! impl_error_chain_kind {
                 }
             }
         }
-        #[allow(unknown_lints, unused, unused_doc_comments)]
+        #[allow(unknown_lints, unused, unused_doc_comment, unused_doc_comments)]
         impl $name {
             /// A string describing the error kind.
             pub fn description(&self) -> &str {

[df5602]

@bjgill Won't this still generate the same warnings that prompted this pull request? (see issue #245 )

[bjgill]

Good point - we also need to allow renamed_and_removed_lints. I've done that in https://github.com/bjgill/error-chain/tree/lint-problem, which compiles without warnings in both stable and nightly (c.f. this PR, which has warnings ins stable, and master, which has warnings in nightly).

@hoodie - do you want to take on my back-compatibility enhancement (or equivalent)? Otherwise, I'll open a new PR tomorrow.

[TedDriggs]

What are the cases that generate unused doc comments? If we can fix those, then we can remove the lint outright, and have no version compatibility concerns.

[bjgill]

I believe the problem is https://github.com/rust-lang-nursery/error-chain/issues/63 (attribute handling in links)

[Yamakaky]

Closing for #247