Rollup merge of #59858 - mark-i-m:dup-matcher-bindings-3, r=Centril

Make duplicate matcher bindings a hard error

r? @Centril

Closes #57742

2 files changed, 4 insertions, 14 deletions

diff --git a/src/libsyntax/early_buffered_lints.rs b/src/libsyntax/early_buffered_lints.rs
index 29cb9cd7f30..977e6d45877 100644
--- a/src/libsyntax/early_buffered_lints.rs
+++ b/src/libsyntax/early_buffered_lints.rs
@@ -12,8 +12,6 @@ pub enum BufferedEarlyLintId {
     /// Usage of `?` as a macro separator is deprecated.
     QuestionMarkMacroSep,
     IllFormedAttributeInput,
-    /// Usage of a duplicate macro matcher binding name.
-    DuplicateMacroMatcherBindingName,
 }
 
 /// Stores buffered lint info which can later be passed to `librustc`.
diff --git a/src/libsyntax/ext/tt/macro_rules.rs b/src/libsyntax/ext/tt/macro_rules.rs
index 12912044e4e..b1b9d25b3d5 100644
--- a/src/libsyntax/ext/tt/macro_rules.rs
+++ b/src/libsyntax/ext/tt/macro_rules.rs
@@ -497,22 +497,14 @@ fn check_lhs_duplicate_matcher_bindings(
     node_id: ast::NodeId,
 ) -> bool {
     use self::quoted::TokenTree;
-    use crate::early_buffered_lints::BufferedEarlyLintId;
     for tt in tts {
         match *tt {
             TokenTree::MetaVarDecl(span, name, _kind) => {
                 if let Some(&prev_span) = metavar_names.get(&name) {
-                    // FIXME(mark-i-m): in a few cycles, make this a hard error.
-                    // sess.span_diagnostic
-                    //     .struct_span_err(span, "duplicate matcher binding")
-                    //     .span_note(prev_span, "previous declaration was here")
-                    //     .emit();
-                    sess.buffer_lint(
-                        BufferedEarlyLintId::DuplicateMacroMatcherBindingName,
-                        crate::source_map::MultiSpan::from(vec![prev_span, span]),
-                        node_id,
-                        "duplicate matcher binding"
-                    );
+                    sess.span_diagnostic
+                        .struct_span_err(span, "duplicate matcher binding")
+                        .span_note(prev_span, "previous declaration was here")
+                        .emit();
                     return false;
                 } else {
                     metavar_names.insert(name, span);