Auto merge of #54750 - pietroalbini:beta-backports, r=pietroalbini

[beta] Rollup backports

Merged and approved:

* #54650: Don't lint non-extern-prelude extern crate's in Rust 2018.
* #54338: Use full name to identify a macro in a `FileName`.
* #54518: resolve: Do not block derive helper resolutions on single import resolutions
* #54581: Accept trailing comma in `cfg_attr`

r? @ghost

1 files changed, 1 insertions, 0 deletions

diff --git a/src/libsyntax/config.rs b/src/libsyntax/config.rs
index 63b70b12248..bc4b7385d8a 100644
--- a/src/libsyntax/config.rs
+++ b/src/libsyntax/config.rs
@@ -89,6 +89,7 @@ impl<'a> StripUnconfigured<'a> {
             parser.expect(&token::Comma)?;
             let lo = parser.span.lo();
             let (path, tokens) = parser.parse_meta_item_unrestricted()?;
+            parser.eat(&token::Comma); // Optional trailing comma
             parser.expect(&token::CloseDelim(token::Paren))?;
             Ok((cfg, path, tokens, parser.prev_span.with_lo(lo)))
         }) {