diff --git a/.github/workflows/daily-grammar-check.yml b/.github/workflows/daily-grammar-check.yml
index 7cf4417528..8b90c2e53b 100644
--- a/.github/workflows/daily-grammar-check.yml
+++ b/.github/workflows/daily-grammar-check.yml
@@ -41,6 +41,7 @@ jobs:
         cargo run --release -p grammar-check -- lex-compare --path rust
         cargo run --release -p grammar-check -- lex-compare --permute Token --tool rustc_parse
         cargo run --release -p grammar-check -- lex-compare --permute three
+        cargo run --release -p grammar-check -- lex-compare --tool rustc_parse
 
     - name: Check for existing open issues
       if: steps.grammar-check.outcome == 'failure'
diff --git a/src/comments.md b/src/comments.md
index 7102bf5825..44ef06fc33 100644
--- a/src/comments.md
+++ b/src/comments.md
@@ -17,8 +17,8 @@ LINE_COMMENT ->
     | `//` _immediately followed by LF_
 
 BLOCK_COMMENT ->
-    `/*` !(`!` | `*` ![`*` `/`]) ^
-      ( BLOCK_COMMENT_OR_DOC | (!`*/` CHAR) )*
+    `/*` ^
+      ( BLOCK_COMMENT | BLOCK_CHAR )*
     `*/`
 
 INNER_LINE_DOC ->
@@ -27,7 +27,7 @@ INNER_LINE_DOC ->
 LINE_DOC_COMMENT_CONTENT -> (!CR ~LF)*
 
 INNER_BLOCK_DOC ->
-    `/*!` ^ ( BLOCK_COMMENT_OR_DOC | BLOCK_CHAR )* `*/`
+    `/*!` ^ ( NESTED_BLOCK_DOC_COMMENT | DOC_BLOCK_CHAR )* `*/`
 
 OUTER_LINE_DOC ->
     `///` ^ LINE_DOC_COMMENT_CONTENT (LF | EOF)
@@ -35,16 +35,16 @@ OUTER_LINE_DOC ->
 OUTER_BLOCK_DOC ->
     `/**` ![`*` `/`]
       ^
-      ( ~[`*` CR] | BLOCK_COMMENT_OR_DOC )
-      ( BLOCK_COMMENT_OR_DOC | BLOCK_CHAR )*
+      ~[`*` CR]
+      ( NESTED_BLOCK_DOC_COMMENT | DOC_BLOCK_CHAR )*
     `*/`
 
-BLOCK_CHAR -> (!(`*/` | CR) CHAR)
+BLOCK_CHAR -> !`*/` CHAR
 
-BLOCK_COMMENT_OR_DOC ->
-      INNER_BLOCK_DOC
-    | OUTER_BLOCK_DOC
-    | BLOCK_COMMENT
+DOC_BLOCK_CHAR -> (!(`*/` | CR) CHAR)
+
+NESTED_BLOCK_DOC_COMMENT ->
+    `/*` ( NESTED_BLOCK_DOC_COMMENT | DOC_BLOCK_CHAR )* `*/`
 ```
 
 r[comments.normal]
diff --git a/tools/grammar-check/src/main.rs b/tools/grammar-check/src/main.rs
index 12512d26dd..ea571d59e3 100644
--- a/tools/grammar-check/src/main.rs
+++ b/tools/grammar-check/src/main.rs
@@ -419,6 +419,7 @@ fn translate_position(input: &str, index: usize) -> (&str, usize, usize) {
 
 fn display_line(src: &str, range: &Range<usize>) -> String {
     let (line, line_no, col_no) = translate_position(src, range.start);
+    let line = line.replace('\r', "␍");
     let prefix = format!("{line_no}: ");
     let indent = col_no.saturating_sub(1);
     let len = (range.end - range.start).min(line.len().saturating_sub(indent));
diff --git a/tools/grammar-check/src/test_cases.rs b/tools/grammar-check/src/test_cases.rs
index da3a13e19c..7b7b7f6606 100644
--- a/tools/grammar-check/src/test_cases.rs
+++ b/tools/grammar-check/src/test_cases.rs
@@ -41,6 +41,27 @@ cases! {
         "/// ☃"
     comment::outer_block_doc =>
         "/** outer block doc */"
+    comment::cr_starting_block_doc =>
+        "/**\r CR starting block doc comment */"
+    comment::cr_starting_inner_block_doc =>
+        "/*!\r CR starting inner block doc comment */"
+
+    comment::block::nested_cr1 =>
+        "/* /**\r*/ */"
+    comment::block::nested_cr2 =>
+        "/* /*!\r*/ */"
+    comment::block::nested_cr3 =>
+        "/* /** x\r y */ */"
+    comment::block::nested_cr4 =>
+        "/** /*\r*/ */"
+    comment::block::nested_cr5 =>
+        "/*! /*\r*/ */"
+    comment::block::nested_cr6 =>
+        "/** /* x\r y */ */"
+    comment::block::nested_cr7 =>
+        "/** /* /*\r*/ */ */"
+    comment::block::nested_cr8 =>
+        "/* /* /**\r*/ */ */"
 
     reserved::pounds =>
         "##"
@@ -54,6 +75,9 @@ cases! {
         "'x'"
     string =>
         "\"string\""
+    string::continuation::bare_carriage =>
+        "\"string\\\n\n\r\tcontinuation\""
+
     raw_string =>
         "r\"raw string\""
         "r#\"raw string\"#"
@@ -81,4 +105,7 @@ cases! {
     identifier =>
         "ident"
         "fn"
+
+    shebang::doc_comment =>
+        "#! /** doc */ [attr]\n"
 }