add regression test

Author: estebank

src/test/rustdoc/auxiliary/through-proc-macro-aux.rs

@@ -0,0 +1,20 @@
+// force-host
+// no-prefer-dynamic
+#![crate_type = "proc-macro"]
+#![crate_name="some_macros"]
+
+extern crate proc_macro;
+use proc_macro::TokenStream;
+
+#[proc_macro_attribute]
+pub fn first(_attr: TokenStream, item: TokenStream) -> TokenStream {
+    item // This doesn't erase the spans.
+}
+
+#[proc_macro_attribute]
+pub fn second(_attr: TokenStream, item: TokenStream) -> TokenStream {
+    // Make a new `TokenStream` to erase the spans:
+    let mut out: TokenStream = TokenStream::new();
+    out.extend(item);
+    out
+}

src/test/rustdoc/through-proc-macro.rs

@@ -0,0 +1,12 @@
+// aux-build:through-proc-macro-aux.rs
+// build-aux-docs
+#![warn(intra_doc_link_resolution_failure)]
+extern crate some_macros;
+
+#[some_macros::second]
+pub enum Boom {
+    /// [Oooops]
+    Bam,
+}
+
+fn main() {}