Deduplicate mismatched delimiter errors

Delay unmatched delimiter errors until after the parser has run to
deduplicate them when parsing and attempt recovering intelligently.

1 files changed, 25 insertions, 5 deletions

diff --git a/src/libsyntax/parse/token.rs b/src/libsyntax/parse/token.rs
index 3b1fa5ea01f..a0f3113a1cb 100644
--- a/src/libsyntax/parse/token.rs
+++ b/src/libsyntax/parse/token.rs
@@ -487,8 +487,8 @@ impl Token {
     /// Enables better error recovery when the wrong token is found.
     crate fn similar_tokens(&self) -> Option<Vec<Token>> {
         match *self {
-            Comma => Some(vec![Dot, Lt]),
-            Semi => Some(vec![Colon]),
+            Comma => Some(vec![Dot, Lt, Semi]),
+            Semi => Some(vec![Colon, Comma]),
             _ => None
         }
     }
@@ -545,7 +545,15 @@ impl Token {
             // FIXME(#43081): Avoid this pretty-print + reparse hack
             let source = pprust::token_to_string(self);
             let filename = FileName::macro_expansion_source_code(&source);
-            parse_stream_from_source_str(filename, source, sess, Some(span))
+            let (tokens, errors) = parse_stream_from_source_str(
+                filename, source, sess, Some(span));
+            for err in errors {
+                sess.span_diagnostic.struct_span_err(
+                    err.found_span,
+                    "unclosed delimiter for_real",
+                ).emit();
+            }
+            tokens
         });
 
         // During early phases of the compiler the AST could get modified
@@ -786,12 +794,18 @@ fn prepend_attrs(sess: &ParseSess,
         let source = pprust::attr_to_string(attr);
         let macro_filename = FileName::macro_expansion_source_code(&source);
         if attr.is_sugared_doc {
-            let stream = parse_stream_from_source_str(
+            let (stream, errors) = parse_stream_from_source_str(
                 macro_filename,
                 source,
                 sess,
                 Some(span),
             );
+            for err in errors {
+                sess.span_diagnostic.struct_span_err(
+                    err.found_span,
+                    "unclosed delimiter attrs",
+                ).emit();
+            }
             builder.push(stream);
             continue
         }
@@ -808,12 +822,18 @@ fn prepend_attrs(sess: &ParseSess,
         // ... and for more complicated paths, fall back to a reparse hack that
         // should eventually be removed.
         } else {
-            let stream = parse_stream_from_source_str(
+            let (stream, errors) = parse_stream_from_source_str(
                 macro_filename,
                 source,
                 sess,
                 Some(span),
             );
+            for err in errors {
+                sess.span_diagnostic.struct_span_err(
+                    err.found_span,
+                    "unclosed delimiter attrs 2",
+                ).emit();
+            }
             brackets.push(stream);
         }