diff options
Diffstat (limited to 'compiler/rustc_expand/src/mbe/transcribe.rs')
| -rw-r--r-- | compiler/rustc_expand/src/mbe/transcribe.rs | 20 |
1 files changed, 11 insertions, 9 deletions
diff --git a/compiler/rustc_expand/src/mbe/transcribe.rs b/compiler/rustc_expand/src/mbe/transcribe.rs index 0e5c5fe4d44..3d8a4bbff18 100644 --- a/compiler/rustc_expand/src/mbe/transcribe.rs +++ b/compiler/rustc_expand/src/mbe/transcribe.rs @@ -232,17 +232,19 @@ pub(super) fn transcribe<'a>( // the meta-var. let ident = MacroRulesNormalizedIdent::new(orignal_ident); if let Some(cur_matched) = lookup_cur_matched(ident, interp, &repeats) { - if let MatchedNonterminal(ref nt) = cur_matched { - // FIXME #2887: why do we apply a mark when matching a token tree meta-var - // (e.g. `$x:tt`), but not when we are matching any other type of token - // tree? - if let NtTT(ref tt) = **nt { - result.push(tt.clone().into()); + if let MatchedNonterminal(nt) = cur_matched { + let token = if let NtTT(tt) = &**nt { + // `tt`s are emitted into the output stream directly as "raw tokens", + // without wrapping them into groups. + tt.clone() } else { + // Other variables are emitted into the output stream as groups with + // `Delimiter::None` to maintain parsing priorities. + // `Interpolated` is currenty used for such groups in rustc parser. marker.visit_span(&mut sp); - let token = TokenTree::token(token::Interpolated(nt.clone()), sp); - result.push(token.into()); - } + TokenTree::token(token::Interpolated(nt.clone()), sp) + }; + result.push(token.into()); } else { // We were unable to descend far enough. This is an error. return Err(cx.struct_span_err( |